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Note: This page contains sample records for the topic "high entropy alloy" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


1

Progress in High-Entropy Alloys  

SciTech Connect

Strictly speaking, high-entropy alloys (HEAs) refer to single-phase, solid-solution alloys with multiprincipal elements in an equal or a near-equal molar ratio whose configurational entropy is tremendously high. This special topic was organized to reflect the focus and diversity of HEA research topics in the community.

Gao, Michael C.

2013-12-01T23:59:59.000Z

2

Laser assisted high entropy alloy coating on aluminum: Microstructural evolution  

SciTech Connect

High entropy alloy (Al-Fe-Co-Cr-Ni) coatings were synthesized using laser surface engineering on aluminum substrate. Electron diffraction analysis confirmed the formation of solid solution of body centered cubic high entropy alloy phase along with phases with long range periodic structures within the coating. Evolution of such type of microstructure was a result of kinetics associated with laser process, which generates higher temperatures and rapid cooling resulting in retention of high entropy alloy phase followed by reheating and/or annealing in subsequent passes of the laser track giving rise to partial decomposition. The partial decomposition resulted in formation of precipitates having layered morphology with a mixture of high entropy alloy rich phases, compounds, and long range ordered phases.

Katakam, Shravana; Joshi, Sameehan S.; Mridha, Sanghita; Mukherjee, Sundeep; Dahotre, Narendra B., E-mail: Narendra.Dahotre@unt.edu [Department of Materials Science and Engineering, University of North Texas, 1150 Union Circle, 305310 Denton, Texas 76203-5017 (United States)

2014-09-14T23:59:59.000Z

3

Effects of Annealing on the Microstructure and Properties of 6FeNiCoCrAlTiSi High-Entropy Alloy Coating Prepared by Laser Cladding  

Science Journals Connector (OSTI)

The content of each constituent element in the newly developed high-entropy alloys is always restricted in equimolar or near-equimolar ratios to avoid the formation of complex brittle phases during the solidifica...

Hui Zhang; Ye Pan; Yizhu He

2011-09-01T23:59:59.000Z

4

Elevated-Temperature Corrosion of CoCrCuFeNiAl0.5Bx High-Entropy Alloys in Simulated Syngas Containing H2S  

SciTech Connect

High-entropy alloys are formed by synthesizing five or more principal elements in equimolar or near equimolar concentrations. Microstructure of the CoCrCuFeNiAl{sub 0.5}B{sub x} (x = 0, 0.2, 0.6, 1) high-entropy alloys under investigation is composed of a mixture of disordered bcc and fcc phases and borides. These alloys were tested gravimetrically for their corrosion resistance in simulated syngas containing 0, 0.01, 0.1, and 1 % H{sub 2}S at 500 °C. The exposed coupons were characterized using XRD and SEM. No significant corrosion was detected at 500 °C in syngas containing 0 and 0.01 % H{sub 2}S while significant corrosion was observed in syngas containing 0.1 and 1 % H{sub 2}S. Cu{sub 1.96}S was the primary sulfide in the external corrosion scale on the low-boron high-entropy alloys, whereas FeCo{sub 4}Ni{sub 4}S{sub 8} on the high-boron high-entropy alloys. Multi-phase Cu-rich regions in the low-B high-entropy alloys were vulnerable to corrosive attack.

Dogan, Omer N.; Nielsen, Benjamin C.; Hawk, Jeffrey A.

2013-08-01T23:59:59.000Z

5

A Successful Synthesis of the CoCrFeNiAl{sub 0.3} Single-Crystal, High-Entropy Alloy by Bridgman Solidification  

SciTech Connect

For the first time, a face-centered-cubic, single-crystal CoCrFeNiAl{sub 0.3} (designated as Al0.3), high-entropy alloy (HEA) was successfully synthesized by the Bridgman solidification (BS) method, at an extremely low withdrawal velocity through a constant temperature gradient, for which it underwent two BS steps. Specially, at the first BS step, the alloy sample underwent several morphological transitions accompanying the crystal growth from the melt. This microstructure evolves from as-cast dendrites, to equiaxed grains, and then to columnar crystals, and last to the single crystal. In particular, at the equiaxed-grain region, some visible annealing twins were observed, which indicates a low stacking fault energy of the Al0.3 alloy. Although a body-centered- cubic CoCrFeNiAl (Al1) HEA was also prepared under the same conditions, only a single columnar-crystal structure with instinctively preferential crystallographic orientations was obtained by the same procedure. A similar morphological transition from dendrites to equiaxed grains occurred at the equiaxed-grain region in Al1 alloy, but the annealing twins were not observed probably because a higher Al addition leads to a higher stacking fault energy for this alloy.

Ma, S. G.; Zhang, S. F.; Gao, M. C.; Liaw, P. K.; Zhang, Y.

2013-12-01T23:59:59.000Z

6

High strength alloys  

DOE Patents (OSTI)

High strength metal alloys are described herein. At least one composition of a metal alloy includes chromium, nickel, copper, manganese, silicon, niobium, tungsten and iron. System, methods, and heaters that include the high strength metal alloys are described herein. At least one heater system may include a canister at least partially made from material containing at least one of the metal alloys. At least one system for heating a subterranean formation may include a tubular that is at least partially made from a material containing at least one of the metal alloys.

Maziasz, Phillip James [Oak Ridge, TN; Shingledecker, John Paul [Knoxville, TN; Santella, Michael Leonard [Knoxville, TN; Schneibel, Joachim Hugo [Knoxville, TN; Sikka, Vinod Kumar [Oak Ridge, TN; Vinegar, Harold J [Bellaire, TX; John, Randy Carl [Houston, TX; Kim, Dong Sub [Sugar Land, TX

2010-08-31T23:59:59.000Z

7

Highly Scalable Genotype Phasing by Entropy Minimization  

E-Print Network (OSTI)

become the next high-priority in genomics after the completion of the Human Genome project. In diploid After the completion of the Human Genome Project has provided us with a blueprint of the DNA present in each human cell, genomics research is now focusing on the study of DNA variations that occur between

Mandoiu, Ion

8

ITP Metal Casting: Corrosion Testing Practices - High Alloy Corrosion...  

Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

Metal Casting: Corrosion Testing Practices - High Alloy Corrosion Program ITP Metal Casting: Corrosion Testing Practices - High Alloy Corrosion Program lehighfs.pdf More Documents...

9

Entropy Production at High Energy and mu_B  

E-Print Network (OSTI)

The systematics of bulk entropy production in experimental data on A+A, p+p and e+e- interactions at high energies and large mu_B is discussed. It is proposed that scenarios with very early thermalization, such as Landau's hydrodynamical model, capture several essential features of the experimental results. It is also pointed out that the dynamics of systems which reach the hydrodynamic regime give similar multiplicities and angular distributions as those calculated in weak-coupling approximations (e.g. pQCD) over a wide range of beam energies. Finally, it is shown that the dynamics of baryon stopping are relevant to the physics of total entropy production, explaining why A+A and e+e- multiplicities are different at low beam energies.

Peter Steinberg

2007-02-08T23:59:59.000Z

10

Thermal stability of high temperature structural alloys  

SciTech Connect

High temperature structural alloys were evaluated for suitability for long term operation at elevated temperatures. The effect of elevated temperature exposure on the microstructure and mechanical properties of a number of alloys was characterized. Fe-based alloys (330 stainless steel, 800H, and mechanically alloyed MA 956), and Ni-based alloys (Hastelloy X, Haynes 230, Alloy 718, and mechanically alloyed MA 758) were evaluated for room temperature tensile and impact toughness properties after exposure at 750 C for 10,000 hours. Of the Fe-based alloys evaluated, 330 stainless steel and 800H showed secondary carbide (M{sub 23}C{sub 6}) precipitation and a corresponding reduction in ductility and toughness as compared to the as-received condition. Within the group of Ni-based alloys tested, Alloy 718 showed the most dramatic structure change as it formed delta phase during 10,000 hours of exposure at 750 C with significant reductions in strength, ductility, and toughness. Haynes 230 and Hastelloy X showed significant M{sub 23}C{sub 6} carbide precipitation and a resulting reduction in ductility and toughness. Haynes 230 was also evaluated after 10,000 hours of exposure at 850, 950, and 1050 C. For the 750--950 C exposures the M{sub 23}C{sub 6} carbides in Haynes 230 coarsened. This resulted in large reductions in impact strength and ductility for the 750, 850 and 950 C specimens. The 1050 C exposure specimens showed the resolution of M{sub 23}C{sub 6} secondary carbides, and mechanical properties similar to the as-received solution annealed condition.

Jordan, C.E.; Rasefske, R.K.; Castagna, A. [Lockheed Martin Corp., Schenectady, NY (United States)

1999-03-01T23:59:59.000Z

11

High Bandgap III-V Alloys for High Efficiency Optoelectronics...  

NLE Websites -- All DOE Office Websites (Extended Search)

bandgap alloys for high efficiency optoelectronics are disclosed. An exemplary optoelectronic device may include a substrate, at least one Al.sub.1-xIn.sub.xP layer, and a...

12

Thermal expansion of Mg(OH)2 brucite under high pressure and pressure dependence of entropy  

Science Journals Connector (OSTI)

An equation of state for Mg(OH)2 brucite under high-pressure and high-temperature conditions ... -ray diffraction. Pressure dependence of entropy of brucite has been calculated with thermal expansion coefficient....

H. Fukui; O. Ohtaka; T. Suzuki; K. Funakoshi

2003-10-01T23:59:59.000Z

13

HIGHLY DISPERSED ALLOY CATHODE CATALYST FOR DURABILITY  

E-Print Network (OSTI)

Understanding high performance materials Pt/C cathode B.S.E. Pt PtCo/C cathode IrB.S.E. Pt Co PtIrCo/C cathodeHIGHLY DISPERSED ALLOY CATHODE CATALYST FOR DURABILITY T. D. Jarvi UTC Power Corporation Electrochemical Area Loss Activity at 900 mVRHE (IR-Free) 0.44 A/mg Pt Specific Activity at 900 m

14

A Metallic Alloy That is Tough and Ductile at Cryogenic Temperature...  

NLE Websites -- All DOE Office Websites (Extended Search)

A Metallic Alloy That is Tough and Ductile at Cryogenic Temperatures Researchers at Berkeley and Oak Ridge Labs Test a Multi-element High-Entropy Alloy with Surprising Results At...

15

A minimum entropy principle of high order schemes for gas ...  

E-Print Network (OSTI)

The entropy solutions of the compressible Euler equations satisfy a minimum principle for the specific ... where ? is the density, u is the velocity, m is the momentum, E is the total energy and p is the pressure. ... can enforce this condition without destroying conservation. .... achieved under a standard CFL condition ? (|u| + c) ...

2011-09-15T23:59:59.000Z

16

ITP Metal Casting: Corrosion Testing Practices ? High Alloy...  

Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

Office of Energy Efficiency and Renewable Energy INDUSTRIAL TECHNOLOGIES PROGRAM Corrosion Testing Practices - High Alloy Corrosion Program This subtask under ESMARRT Material...

17

High-Temperature Aluminum Alloys | Department of Energy  

Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

and Vehicle Technologies Program Annual Merit Review and Peer Evaluation Meeting pm044smith2012o.pdf More Documents & Publications High-Temperature Aluminum Alloys Vehicle...

18

Highly Dispersed Alloy Cathode Catalyst for Durability  

Energy.gov (U.S. Department of Energy (DOE))

This presentation, which focuses on alloy cathode catalysts, was given by T. D. Jarvi of UTC Power at a February 2007 meeting on new fuel cell projects.

19

CoNiGa High Temperature Shape Memory Alloys  

E-Print Network (OSTI)

commercially successful SMAs such as NiTi and Cu-based alloys. In recent years, the CoNiGa system has emerged as a new ferromagnetic shape memory alloy with some compositions exhibiting high martensitic transformation temperatures which makes CoNiGa a potential...

Dogan, Ebubekir

2011-10-21T23:59:59.000Z

20

Irradiation damage in multicomponent equimolar alloys and high entropy alloys (HEAs)  

Science Journals Connector (OSTI)

......and improve the safety and efficiency of nuclear reactors, development of new and advanced nuclear materials with superior resistance to irradiation damage is necessary. Recently, a new generation of structural materials, termed as multicomponent......

Takeshi Nagase; Philip D. Rack; Takeshi Egami

2014-11-01T23:59:59.000Z

Note: This page contains sample records for the topic "high entropy alloy" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


21

Improved high temperature creep resistant austenitic alloy  

DOE Patents (OSTI)

An improved austenitic alloy having in wt% 19-21 Cr, 30-35 Ni, 1.5-2.5 Mn, 2-3 Mo, 0.1-0.4 Si, 0.3-0.5 Ti, 0.1-0.3 Nb, 0.1-0.5 V, 0.001-0.005 P, 0.08-0.12 C, 0.01-0.03 N, 0.005-0.01 B and the balance iron that is further improved by annealing for up to 1 hour at 1150-1200/degree/C and then cold deforming 5-15%. The alloy exhibits dramatically improved creep rupture resistance and ductility at 700/degree/C. 2 figs.

Maziasz, P.J.; Swindeman, R.W.; Goodwin, G.M.

1988-05-13T23:59:59.000Z

22

Amorphous Alloy Membranes for High Temperature Hydrogen Separation  

SciTech Connect

At the beginning of this project, thin film amorphous alloy membranes were considered a nascent but promising new technology for industrial-scale hydrogen gas separations from coal- derived syngas. This project used a combination of theoretical modeling, advanced physical vapor deposition fabricating, and laboratory and gasifier testing to develop amorphous alloy membranes that had the potential to meet Department of Energy (DOE) targets in the testing strategies outlined in the NETL Membrane Test Protocol. The project is complete with Southwest Research Institute® (SwRI®), Georgia Institute of Technology (GT), and Western Research Institute (WRI) having all operated independently and concurrently. GT studied the hydrogen transport properties of several amorphous alloys and found that ZrCu and ZrCuTi were the most promising candidates. GT also evaluated the hydrogen transport properties of V, Nb and Ta membranes coated with different transition-metal carbides (TMCs) (TM = Ti, Hf, Zr) catalytic layers by employing first-principles calculations together with statistical mechanics methods and determined that TiC was the most promising material to provide catalytic hydrogen dissociation. SwRI developed magnetron coating techniques to deposit a range of amorphous alloys onto both porous discs and tubular substrates. Unfortunately none of the amorphous alloys could be deposited without pinhole defects that undermined the selectivity of the membranes. WRI tested the thermal properties of the ZrCu and ZrNi alloys and found that under reducing environments the upper temperature limit of operation without recrystallization is ~250 °C. There were four publications generated from this project with two additional manuscripts in progress and six presentations were made at national and international technical conferences. The combination of the pinhole defects and the lack of high temperature stability make the theoretically identified most promising candidate amorphous alloys unsuitable for application as hydrogen separation membranes in coal fire systems.

Coulter, K

2013-09-30T23:59:59.000Z

23

TEMPERATURE DEPENDENCE OF ELECTRICAL RESISTIVITY IN HIGHLY RESISTIVE ALLOYS  

E-Print Network (OSTI)

L-323 TEMPERATURE DEPENDENCE OF ELECTRICAL RESISTIVITY IN HIGHLY RESISTIVE ALLOYS F. BROUERS at finite temperature yields an expression for the resistivity which is consistent with a gene- ral analysis-dependence of the resistivity and appears as an alternative model to describe the resistivity of crystalline, liquid

Boyer, Edmond

24

Computational and Experimental Development of Novel High-Temperature Alloys  

NLE Websites -- All DOE Office Websites (Extended Search)

Development of Novel High-Temperature Alloys Background The need for fossil-fueled power plants to run cleaner and more efficiently leads toward ever-higher operating temperatures and pressures. Gas turbines, which can be fueled by natural gas, synthetic gas (syngas), or a high-hydrogen stream derived from coal, are critical components in this development. High-temperature operation of turbines is generally achieved by using nickel-chrome superalloys with coatings

25

Facile synthesis of PtAu alloy nanoparticles with high activity...  

NLE Websites -- All DOE Office Websites (Extended Search)

synthesis of PtAu alloy nanoparticles with high activity for formic acid oxidation. Facile synthesis of PtAu alloy nanoparticles with high activity for formic acid oxidation....

26

High pressure/high temperature hydrogen permeability in candidate stirling engine alloys  

Science Journals Connector (OSTI)

Hydrogen permeation tests of eight high-temperature engineering alloys were conducted in 20.7 MPa hydrogen at 923 to 1088 K for assessing suitability in Stirling engine application for heater head and heater head...

S. Bhattacharyya; E. J. Vesely; V. L. Hill

1982-03-01T23:59:59.000Z

27

High-strain-rate nanoindentation behavior of fine-grained magnesium alloys  

E-Print Network (OSTI)

The effects of temperature and alloying elements on deformation in the high-strain-rate regime were investigated by testing fine-grained magnesium alloys with an average grain size of 2 ? 3 ?m by a nanoindentation technique. ...

Somekawa, Hidetoshi

28

High-temperature Hydrogen Permeation in Nickel Alloys  

SciTech Connect

In gas cooled Very High Temperature Reactor concepts, tritium is produced as a tertiary fission product and by activation of graphite core contaminants, such as lithium; of the helium isotope, He-3, that is naturally present in the He gas coolant; and the boron in the B4C burnable poison. Because of its high mobility at the reactor outlet temperatures, tritium poses a risk of permeating through the walls of the intermediate heat exchanger (IHX) or steam generator (SG) systems, potentially contaminating the environment and in particular the hydrogen product when the reactor heat is utilized in connection with a hydrogen generation plant. An experiment to measure tritium permeation in structural materials at temperatures up to 1000 C has been constructed at the Idaho National Laboratory Safety and Tritium Applied Research (STAR) facility within the Next Generation Nuclear Plant program. The design is based on two counter flowing helium loops to represent heat exchanger conditions and was optimized to allow control of the materials surface condition and the investigation of the effects of thermal fatigue. In the ongoing campaign three nickel alloys are being considered because of their high-temperature creep properties, alloy 617, 800H and 230. This paper introduces the general issues related to tritium in the on-going assessment of gas cooled VHTR systems fission product transport and outlines the planned research activities in this area; outlines the features and capabilities of the experimental facility being operated at INL; presents and discusses the initial results of hydrogen permeability measurements in two of the selected alloys and compares them with the available database from previous studies.

P. Calderoni; M. Ebner; R. Pawelko

2010-10-01T23:59:59.000Z

29

Highly Mismatched Alloys for Intermediate Band Solar Cells  

SciTech Connect

It has long been recognized that the introduction of a narrow band of states in a semiconductor band gap could be used to achieve improved power conversion efficiency in semiconductor-based solar cells. The intermediate band would serve as a ''stepping stone'' for photons of different energy to excite electrons from the valence to the conduction band. An important advantage of this design is that it requires formation of only a single p-n junction, which is a crucial simplification in comparison to multijunction solar cells. A detailed balance analysis predicts a limiting efficiency of more than 50% for an optimized, single intermediate band solar cell. This is higher than the efficiency of an optimized two junction solar cell. Using ion beam implantation and pulsed laser melting we have synthesized Zn{sub 1-y}Mn{sub y}O{sub x}Te{sub 1-x} alloys with x<0.03. These highly mismatched alloys have a unique electronic structure with a narrow oxygen-derived intermediate band. The width and the location of the band is described by the Band Anticrossing model and can be varied by controlling the oxygen content. This provides a unique opportunity to optimize the absorption of solar photons for best solar cell performance. We have carried out systematic studies of the effects of the intermediate band on the optical and electrical properties of Zn{sub 1-y}Mn{sub y}O{sub x}Te{sub 1-x} alloys. We observe an extension of the photovoltaic response towards lower photon energies, which is a clear indication of optical transitions from the valence to the intermediate band.

Walukiewicz, W.; Yu, K.M.; Wu, J.; Ager III, J.W.; Shan, W.; Scrapulla, M.A.; Dubon, O.D.; Becla, P.

2005-03-21T23:59:59.000Z

30

An effective model for entropy deposition in high-energy pp, pA, and AA collisions  

E-Print Network (OSTI)

We introduce TRENTO, a new initial condition model for high-energy nuclear collisions based on eikonal entropy deposition via a "reduced thickness" function. The model simultaneously predicts the shapes of experimental proton-proton, proton-nucleus, and nucleus-nucleus multiplicity distributions, and generates nucleus-nucleus eccentricity harmonics consistent with experimental flow constraints. In addition, the model provides a possible resolution to the "knee" puzzle in ultra-central uranium-uranium collisions.

J. Scott Moreland; Jonah E. Bernhard; Steffen A. Bass

2014-12-15T23:59:59.000Z

31

Laves phase hydrogen storage alloys for super-high-pressure metal hydride hydrogen compressors  

Science Journals Connector (OSTI)

Ti-Cr- and Ti-Mn-based alloys were prepared to be low- and high-pressure stage metals for a double-stage super-high-pressure metal hydride hydrogen compressor. Their crystallographic characteristics and hydrogen

Xiumei Guo; Shumao Wang; Xiaopeng Liu; Zhinian Li; Fang Lü; Jing Mi; Lei Hao…

2011-06-01T23:59:59.000Z

32

Advanced Alloys for Compact, High-Efficiency, High-Temperature Heat-Exchangers  

SciTech Connect

Oak Ridge National Laboratory (ORNL) has conducted research and development for several years which has been focused on the behavior and performance improvements of sheets and foils of various alloys for compact heat-exchangers (recuperators) for advanced microturbines. The performance and reliability of such thin sections are challenged at 650-750 C by fine grain size causing excessive creep, and by moisture effects greatly enhancing oxidation attack in exhaust gas environments. Standard 347 stainless steel has been used successfully at or below 600 C, but has suffered from both of these kinds of degradation at 650 C and above. Alloys have been identified which can have very good properties for such heat-exchangers, especially with careful control of microstructure during processing, including alloy 625, HR120 and the new AL20-25+Nb. These alloys, and the mechanistic understanding behind their behavior, are also applicable to achieving the better heat-exchanger technology needed for fuel cells or other high-temperature, clean-energy applications.

Maziasz, Philip J [ORNL; Pint, Bruce A [ORNL; Shingledecker, John P [ORNL; Evans, Neal D [ORNL; Yamamoto, Yukinori [ORNL; More, Karren Leslie [ORNL; Lara-Curzio, Edgar [ORNL

2006-01-01T23:59:59.000Z

33

Copper modified austenitic stainless steel alloys with improved high temperature creep resistance  

DOE Patents (OSTI)

An improved austenitic stainless steel that incorporates copper into a base Fe-Ni-Cr alloy having minor alloying substituents of Mo, Mn, Si, T, Nb, V, C, N, P, B which exhibits significant improvement in high temperature creep resistance over previous steels. 3 figs.

Swindeman, R.W.; Maziasz, P.J.

1987-04-28T23:59:59.000Z

34

High Shear Deformation to Produce High Strength and Energy Absorption in Mg Alloys  

SciTech Connect

Magnesium alloys have the potential to reduce the mass of transportation systems however to fully realize the benefits it must be usable in more applications including those that require higher strength and ductility. It has been known that fine grain size in Mg alloys leads to high strength and ductility. However, the challenge is how to achieve this optimal microstructure in a cost effective way. This work has shown that by using optimized high shear deformation and second phase particles of Mg2Si and MgxZnZry the energy absorption of the extrusions can exceed that of AA6061. The extrusion process under development described in this presentation appears to be scalable and cost effective. In addition to process development a novel modeling approach to understand the roles of strain and state-of-strain on particle fracture and grain size control has been developed

Joshi, Vineet V.; Jana, Saumyadeep; Li, Dongsheng; Garmestani, Hamid; Nyberg, Eric A.; Lavender, Curt A.

2014-02-01T23:59:59.000Z

35

Two-phase chromium-niobium alloys exhibiting improved mechanical properties at high temperatures  

DOE Patents (OSTI)

The specification discloses chromium-niobium alloys which exhibit improved mechanical properties at high temperatures in the range of 1250.degree. C. and improved room temperature ductility. The alloys contain a Cr.sub.2 Nb-rich intermetallic phase and a Cr-rich phase with an overall niobium concentration in the range of from about 5 to about 18 at. %. The high temperature strength is substantially greater than that of state of the art nickel-based superalloys for enhanced high temperature service. Further improvements in the properties of the compositions are obtained by alloying with rhenium and aluminum; and additional rare-earth and other elements.

Liu, Chain T. (Oak Ridge, TN); Takeyama, Masao (Tokyo, JP)

1994-01-01T23:59:59.000Z

36

Two-phase chromium-niobium alloys exhibiting improved mechanical properties at high temperatures  

DOE Patents (OSTI)

The specification discloses chromium-niobium alloys which exhibit improved mechanical properties at high temperatures in the range of 1250 C and improved room temperature ductility. The alloys contain a Cr[sub 2]Nb-rich intermetallic phase and a Cr-rich phase with an overall niobium concentration in the range of from about 5 to about 18 at. %. The high temperature strength is substantially greater than that of state of the art nickel-based superalloys for enhanced high temperature service. Further improvements in the properties of the compositions are obtained by alloying with rhenium and aluminum; and additional rare-earth and other elements. 14 figures.

Liu, C.T.; Takeyama, Masao.

1994-02-01T23:59:59.000Z

37

High Temperature Corrosion Behavior of Iron Aluminide Alloys and Coatings  

SciTech Connect

A multi-year effort has been focused on optimizing the long-term oxidation performance of ingot-processed (IP) and oxide-dispersion strengthened (ODS) Fe{sub 3}Al and iron aluminide-based coatings. Based on results from several composition iterations, a Hf-doped alloy (Fe-28Al-2Cr-0.05at.%Hf) has been developed with significantly better high temperature oxidation resistance than other iron aluminides. The scale adhesion is not significantly better; however, the {alpha}-Al{sub 2}O{sub 3} scale grows at a slower rate, approximately a factor of 10 less than undoped iron aluminide. The benefit of Hf is greatest at 1100-1200 C. Long-term oxidation resistance of commercially fabricated ODS Fe{sub 3}Al has been determined and compared to commercially available ODS FeCrAl. Scale spallation rates for ODS Fe{sub 3}Al are higher than for ODS FeCrAl. To complement studies of iron-aluminide weld-overlay coatings, carbon steel was coated with Fe-Al-Cr by thermal spraying. These specimens were then exposed in air at 900 and 1000 C and in air-1%SO{sub 2} at 800 C. Most likely due to an inadequate aluminum concentration in the coatings, continuous protective Al{sub 2}O{sub 3} could not be maintained and, consequently, the corrosion performance was significantly worse than what is normally observed for Fe{sub 3}Al.

Pint, B.A.

2001-10-22T23:59:59.000Z

38

Thermomechanical Cyclic Response of TiNiPd High-Temperature Shape Memory Alloys  

E-Print Network (OSTI)

TiNiPd high-temperature shape memory alloys (HTSMAs) have attracted considerable attention as potential solid-state actuators capable of operating at temperatures up to 500 °C, exhibiting excellent corrosion resistance, adequate ductility levels...

Atli, Kadri

2012-10-19T23:59:59.000Z

39

Computational Thermodynamics of CoNiGa High Temperature Shape Memory Alloys  

E-Print Network (OSTI)

Shape Memory Alloys (SMAs) are advanced materials with interesting properties such as pseudoelasticity (PE) and the shape memory effect (SME). Recently, the CoNiGa system has emerged as the basis for very promising High Temperature Shape Memory...

Chari, Arpita

2012-10-19T23:59:59.000Z

40

Vehicle Technologies Office Merit Review 2014: High Energy Novel Cathode / Alloy Automotive Cell  

Energy.gov (U.S. Department of Energy (DOE))

Presentation given by 3M at 2014 DOE Hydrogen and Fuel Cells Program and Vehicle Technologies Office Annual Merit Review and Peer Evaluation Meeting about high energy novel cathode / alloy...

Note: This page contains sample records for the topic "high entropy alloy" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


41

Iron-niobium-aluminum alloy having high-temperature corrosion resistance  

DOE Patents (OSTI)

An alloy for use in high temperature sulfur and oxygen containing environments, having aluminum for oxygen resistance, niobium for sulfur resistance and the balance iron, is discussed. 4 figs., 2 tabs.

Hsu, Huey S.

1988-04-14T23:59:59.000Z

42

High Permeability Ternary Palladium Alloy Membranes with Improved Sulfur and Halide Tolerance  

NLE Websites -- All DOE Office Websites (Extended Search)

9 9 HigH Permeability ternary Palladium alloy membranes witH imProved sulfur and Halide tolerance Description A critical step in the transition to the hydrogen economy is the separation of hydrogen from coal gasification gases (syngas) or methane. This is typically accomplished through membrane separation. Past research has shown that palladium (Pd) alloys possess great potential as robust and economical membranes. However, the search for the optimal binary or ternary alloys is an involved and costly process due to the immense number of alloy variations that could be prepared and tested. Recent modeling work at Georgia Institute of Technology using density functional theory (DFT) identified several promising ternary alloy compositions with improved

43

Candidate alloys for cost-effective, high-efficiency, high-temperature compact/foil heat-exchangers  

SciTech Connect

Solid oxide fuel cell (SOFC) and molten carbonate fuel cell (MCFC) systems operate at high temperatures (up to 1000 C and 650 C, respectively), which makes them especially attractive sources for combined heat and power (CHP) cogeneration. However, improvements in the efficiency of heat exchange in these fuel cells require both development and careful processing of advanced cost-effective alloys for use in such high-temperature service conditions. The high-temperature properties of both sheet and foil forms of several alloys being considered for use in compact heat-exchangers (recuperators) have been characterized. Mechanical and creep-rupture testing, oxidation studies, and microstructural studies have been performed on commercially available sheet and foil forms of alloy 347, alloys 625, HR230, HR120, and the new AL20-25+Nb. These studies have led to a mechanistic understanding of the responses of these alloys to anticipated service conditions, and suggest that these alloys developed for gas- and micro-turbine recuperator applications are also suitable for use in fuel cell heat-exchangers. Additional work is still required to achieve foil forms with creep life comparable to thicker-section wrought product forms of the same alloys.

Evans, Neal D [ORNL; Maziasz, Philip J [ORNL; Shingledecker, John P [ORNL; Pint, Bruce A [ORNL; Yamamoto, Yukinori [ORNL

2007-01-01T23:59:59.000Z

44

Advanced nickel base alloys for high strength, corrosion applications  

DOE Patents (OSTI)

Improved nickel-base alloys of enhanced strength and corrosion resistance, produced by atomization of an alloy melt under an inert gas atmosphere and of composition 0--20Fe, 10--30Cr, 2--12Mo, 6 max. Nb, 0.05--3 V, 0.08 max. Mn, 0.5 max. Si, less than 0.01 each of Al and Ti, less than 0.05 each of P and S, 0.01--0.08C, less than 0.2N, 0.1 max. 0, bal. Ni. 3 figs.

Flinn, J.E.

1998-11-03T23:59:59.000Z

45

Continuous electric resistance heating—Hot forming system for high-alloy metals with poor workability  

Science Journals Connector (OSTI)

A new hot forming system for high-alloy metals with poor workability is developed. This forming system is a direct combination of a forming machine and continuous electric resistance heating, and is capable of the high-speed forming of metals with flexible and precise control of elevated temperature. The prototype of the new forming system is applied to the forming of high-alloy metals with poor formability, such as a Ti–6Al–4V bar, and the basic characteristics of this forming system are clarified. Using this system, sound, high speed forming of high alloys becomes possible, and the Ti–6Al–4V bar is successfully formed without fracture.

Jun Yanagimoto; Ryo Izumi

2009-01-01T23:59:59.000Z

46

Experimental study of a structural magnesium alloy with high absorption energy under dynamic loading  

SciTech Connect

It has been demonstrated that pure Mg exhibits low ductility under dynamic loading at room temperature owing to its HCP structure. Very limited data are currently available for magnesium alloys under dynamic loading. In order to be used for structural components, it is necessary to improve the mechanical properties of magnesium alloys. Lahaise et al. reported the yield strength of the AZ91 magnesium alloy increased with refining its microstructure. Mohri et al. has already been reported the ductility enhancement of a Mg-Y-RE(Rare Earth) alloy by hot extrusion. They mentioned the enhancement of ductility is due to the refining microstructure of magnesium. Thus refining microstructure enables to raise the possibility for the development of a structural magnesium alloy with high ductility at dynamic strain rate. In this paper, the possibility of a fine-grained WE43 magnesium alloy is investigated to raise the high speed impact performance against the foreign object damage by the enhancement of ductility and absorption energy under dynamic loading.

Mukai, T.; Ishikawa, K. [Osaka Municipal Technical Research Inst. (Japan). Mechanical Engineering Dept.] [Osaka Municipal Technical Research Inst. (Japan). Mechanical Engineering Dept.; Mohri, T. [Nagoya Municipal Industrial Research Inst. Rokuban, Atsuta (Japan)] [Nagoya Municipal Industrial Research Inst. Rokuban, Atsuta (Japan); Nakamura, M. [National Industrial Research Inst., Nagoya (Japan)] [National Industrial Research Inst., Nagoya (Japan); Higashi, K. [Osaka Prefecture Univ., Sakai (Japan)] [Osaka Prefecture Univ., Sakai (Japan)

1998-10-05T23:59:59.000Z

47

Quantitative Evaluation of Bulk and Interface Microstructures in Al-3003 Alloy Builds Made by Very High Power Ultrasonic Additive Manufacturing  

Science Journals Connector (OSTI)

Ultrasonically consolidated 3003 aluminum alloy builds were prepared with constituent tapes by using a very high power ultrasonic additive manufacturing (UAM) process. Microstructures of interface and...

Hiromichi T. Fujii; M. R. Sriraman…

2011-12-01T23:59:59.000Z

48

Embrittlement and DBTT of High-Burnup PWR Fuel Cladding Alloys | Department  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

Embrittlement and DBTT of High-Burnup PWR Fuel Cladding Alloys Embrittlement and DBTT of High-Burnup PWR Fuel Cladding Alloys Embrittlement and DBTT of High-Burnup PWR Fuel Cladding Alloys Structural analyses of high-burnup (HBU) fuel require cladding mechanical properties and failure limits to assess fuel behavior during long-term dry-cask storage and transportation. Pre-storage drying-transfer operations and early stage storage subject cladding to higher temperatures and pressure-induced tensile hoop stresses relative to in-reactor operation and pool storage. Under these conditions, radial hydrides may precipitate during slow cooling and provide an additional embrittlement mechanism as the cladding temperature decreases below the ductile-to-brittle transition temperature (DBTT). Graphic and photographic details of the testing are

49

Evaluation of high strength, high conductivity CuNiBe alloys for fusion energy applications  

SciTech Connect

The unirradiated tensile properties for several different heats and thermomechanical treatment conditions of precipitation strengthened Hycon 3HPTM CuNiBe (Cu-2%Ni-0.35%Be in wt.%) have been measured over the temperature range of 20-500 C for longitudinal and long transverse orientations. The room temperature electrical conductivity has also been measured for several heats, and the precipitate microstructure was characterized using transmission electron microscopy. The CuNiBe alloys exhibit very good combination of strength and conductivity at room temperature, with yield strengths of 630-725 MPa and electrical conductivities of 65-72% International Annealed Copper Standard (IACS). The strength remained relatively high at all test temperatures, with yield strengths of 420-520 MPa at 500 C. However, low levels of ductility (<5% uniform elongation) were observed at test temperatures above 200-250 C, due to flow localization near grain boundaries (exacerbated by having only 10-20 grains across the gage thickness of the miniaturized sheet tensile specimens). Scanning electron microscopy observation of the fracture surfaces found a transition from ductile transgranular to ductile intergranular fracture with increasing test temperature. Fission neutron irradiation to a dose of ~0.7 displacements per atom (dpa) at temperatures between 100 and 240 C produced a slight increase in strength and a significant decrease in ductility. The measured tensile elongation increased with increasing irradiation temperature, with a uniform elongation of ~3.3% observed at 240 C. The electrical conductivity decreased slightly following irradiation, due to the presence of defect clusters and Ni, Zn, Co transmutation products. Considering also previously published fracture toughness data, this indicates that CuNiBe alloys have irradiated tensile and electrical properties comparable or superior to CuCrZr and oxide dispersion strengthened copper at temperatures <250 C, and may be an attractive candidate for certain fusion energy structural applications. Conversely, CuNiBe may not be preferred at intermediate temperatures of 250-500 C due to the poor ductility and fracture toughness of CuNiBe alloys at temperatures >250 C. The potential deformation mechanisms responsible for the transition from transgranular to intergranular fracture are discussed. The possible implications for other precipitation hardened alloys such as nickel based superalloys are briefly discussed.

Zinkle, Steven J [ORNL] [ORNL

2014-01-01T23:59:59.000Z

50

High permeance sulfur tolerant Pd/Cu alloy membranes  

DOE Patents (OSTI)

A method of making a membrane permeable to hydrogen gas (H.sub.2.uparw.) is disclosed. The membrane is made by forming a palladium layer, depositing a layer of copper on the palladium layer, and galvanically displacing a portion of the copper with palladium. The membrane has improved resistance to poisoning by H.sub.2S compared to a palladium membrane. The membrane also has increased permeance of hydrogen gas compared to palladium-copper alloys. The membrane can be annealed at a lower temperature for a shorter amount of time.

Ma, Yi Hua; Pomerantz, Natalie

2014-02-18T23:59:59.000Z

51

F A T I G U E 2 0 0 2 HIGH-CYCLE FATIGUE OF BETA TITANIUM ALLOYS  

E-Print Network (OSTI)

-object damage on jet engine fan blades is used as an engineering example of potential HCF applicationsF A T I G U E 2 0 0 2 HIGH-CYCLE FATIGUE OF BETA TITANIUM ALLOYS J. O. Peters*+ , G. Lütjering*, R) properties of the high-strength titanium alloys -Cez and Ti-6246 (in two distinctly different + processed

Ritchie, Robert

52

The corrosion performance of high chromium stainless steels and titanium alloys at a reverse osmosis plant in Arabian Gulf seawater  

SciTech Connect

Electrochemical impedance spectroscopy (EIS) was used to evaluate the corrosion performance of four high chromium stainless steels and Grade 2 titanium in flowing Arabian Gulf natural seawater. The EIS provided information concerning the changes to the interfacial impedance as a function of exposure time for these alloys. The impedance spectra for all the alloys showed slight changes at the low frequency region over the exposure period. The open-circuit potentials (OCP) of these alloys were also monitored as a function of exposure time. The stainless steel alloys exhibited slight fluctuation in potential around the initial exposure potential. However, Grade 2 titanium initial potential was more active and then gradually shifted towards the noble direction. The linear polarization resistance (LPR) method indicated that Grade 2 titanium exhibited the lowest corrosion rate with respect to the stainless steel alloys. The results of the EIS analysis and OCP indicated that Grade 2 titanium performed better than the four high chromium stainless steel alloys.

Al-Odwani, A.; Al-Tabatabaei, M.; Carew, J.; Al-Hashem, A. [Kuwait Inst. for Scientific Research, Safat (Kuwait)

1997-08-01T23:59:59.000Z

53

Fracture Behavior of a Laser Beam Welded High-strength Al-Zn Alloy  

Science Journals Connector (OSTI)

Abstract Laser beam welding of butt joints made of the newly developed high-strength Al-Zn alloy PA734 is conducted. A new approach of the Helmholtz-Zentrum Geesthacht is used to solve the problems of weldability and softening. The results of the fatigue, fatigue crack propagation and fracture toughness tests are discussed relating to the microstructural characteristics and the mechanical properties of the laser welded joints and compared to the base material. The obtained data can be used for the assessment of the damage tolerance behaviour of the laser welded integral aircraft structures made of Al-Zn alloys.

J. Enz; H. Iwan; S. Riekehr; V. Ventzke; N. Kashaev

2014-01-01T23:59:59.000Z

54

Electrical resistivity and thermal conductivity of liquid Fe alloys at high P and T, and  

E-Print Network (OSTI)

Electrical resistivity and thermal conductivity of liquid Fe alloys at high P and T, and heat flux to crystallize (1, 4). Existing estimates of thermal conductivity (kel) and electrical resistivity (el) of Earth of electrical resistivity to temperature, its invariability along and across the Fe liquidus, and adherence

Steinle-Neumann, Gerd

55

Universal relation between thermal entropy and entanglement entropy in CFT  

E-Print Network (OSTI)

Inspired by the holographic computation of large interval entanglement entropy of two dimensional conformal field theory at high temperature, it was proposed that the thermal entropy is related to the entanglement entropy as $S_{th}=\\displaystyle{\\lim_{l \\to 0}(S_{EE}(R-l)-S_{EE}(l))}$. In this letter, we prove this relation for 2D CFT with discrete spectrum in two different ways. Moreover we show that this relation could break down for 2D noncompact free scalar, which is a CFT with continuous spectrum.

Chen, Bin

2014-01-01T23:59:59.000Z

56

Horizon Entropy  

E-Print Network (OSTI)

Although the laws of thermodynamics are well established for black hole horizons, much less has been said in the literature to support the extension of these laws to more general settings such as an asymptotic de Sitter horizon or a Rindler horizon (the event horizon of an asymptotic uniformly accelerated observer). In the present paper we review the results that have been previously established and argue that the laws of black hole thermodynamics, as well as their underlying statistical mechanical content, extend quite generally to what we call here "causal horizons". The root of this generalization is the local notion of horizon entropy density.

Ted Jacobson; Renaud Parentani

2003-02-25T23:59:59.000Z

57

Amorphous Alloy Membranes for High Temperature Hydrogen Separations  

NLE Websites -- All DOE Office Websites (Extended Search)

for High for High Temperature Hydrogen Separations Background Coal and biomass are readily available in the United States and can be mixed for thermal processing to produce hydrogen and power. The produced hydrogen can be sent directly to a fuel cell for highly efficient and environmentally clean power generation. For coal and biomass to become economically viable sources of hydrogen, more efficient production processes need to be developed. To meet this

58

Evaluation of High-Temperature Alloys for Helium Gas Turbines  

Science Journals Connector (OSTI)

C. 1. Mechanical Property / Status of Metallic Materials Development for Application in Advanced High-Temperature Gas-Cooled Reactor / Material

Wolfgang Jakobeit; Jörn-Peter Pfeifer; Georg Ullrich

59

A View of Compatible Heat-Resistant Alloy and Coating Systems at High-Temperatures  

SciTech Connect

Conventional and advanced coatings were reviewed, and it was pointed out that the coated Ni-base superalloys decreased their creep rupture life significantly at higher temperatures, and the advanced high strength superalloy became more remarkably. Concept of diffusion barrier coating system (DBC system) and their formation process was introduced, and the results obtained for several heat-resistant alloys, stainless steel (SUS310S), Ni-Mo base alloy (Hastelloy-X), and 4{sup th} generation single crystal superalloy (TMS-138) were given. It was noted that creep-rupture life of the SUS310S and Hastelloy-X with the DBC system became longer than those of the bare alloys with or without conventional {beta}-NiAl coatings. This is due to slow creep-deformation of the Re-base alloy layer as the diffusion barrier. A novel concept based on combination of superalloys and coatings was proposed, by taking both the materials science and corrosion science into consideration.

Narita, Toshio [Specially Promoted Research Laboratory of Advanced Coatings, Hokkaido University, Kite-13 Nishi-8, Kita-Ku, Sapporo 060-8628 (Japan)

2009-09-14T23:59:59.000Z

60

"Exploring damage management of high performance metallic alloys in critical  

E-Print Network (OSTI)

. of Materials Science & Engineering University of Virginia Charlottesville, VA 434.982.5782 High Performance in aerospace, transportation infrastructure, military, power generation, and petrochemical technologies. Our promotes a variety of cracking modes in metals. The opportunity exists to implement advanced prognosis

Acton, Scott

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they are not comprehensive nor are they the most current set.
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61

High Temperature Oxidation of Iron-Chromium Alloys  

E-Print Network (OSTI)

and Peter H. Larsen for many good discussions during the work. #12;3 Abstract The high temperature oxidation: References: Abstract (max. 2000 char.): See page 3 Information Service Department Risø National Laboratory P of Southern Denmark. The majority of the work is based on studies performed at the SOFC group at the Materials

62

Effects of alloying elements on microstructure, hardness, and fracture toughness of centrifugally cast high-speed steel rolls  

Science Journals Connector (OSTI)

A study was made of the effects of alloying elements on the microstructure, hardness, and fracture toughness of centrifugally cast high-speed steel (HSS) rolls. Particular emphasis was placed on the role of ha...

Chang Kyu Kim; Yong Chan Kim; Jong Il Park…

2005-01-01T23:59:59.000Z

63

Corrosion of high temperature alloys in solar salt at 400, 500, and 680%C2%B0C.  

SciTech Connect

Corrosion tests at 400, 500, and 680%C2%B0C were performed using four high temperature alloys; 347SS, 321SS In625, and HA230. Molten salt chemistry was monitored over time through analysis of nitrite, carbonate, and dissolved metals. Metallography was performed on alloys at 500 and 680%C2%B0C, due to the relatively thin oxide scale observed at 400%C2%B0C. At 500%C2%B0C, corrosion of iron based alloys took the form of chromium depletion and iron oxides, while nickel based alloys also had chromium depletion and formation of NiO. Chromium was detected in relatively low concentrations at this temperature. At 680%C2%B0C, significant surface corrosion occurred with metal losses greater than 450microns/year after 1025hours of exposure. Iron based alloys formed complex iron, sodium, and chromium oxides. Some data suggests grain boundary chromium depletion of 321SS. Nickel alloys formed NiO and metallic nickel corrosion morphologies, with HA230 displaying significant internal oxidation in the form of chromia. Nickel alloys both exhibited worse corrosion than iron based alloys likely due to preferential dissolution of chromium, molybdenum, and tungsten.

Kruizenga, Alan Michael; Gill, David Dennis; LaFord, Marianne Elizabeth

2013-09-01T23:59:59.000Z

64

On the entropic stabilisation of an Al0.5CrFeCoNiCu high entropy alloy  

E-Print Network (OSTI)

continuous cooling conditions. Acta Mater 2001;49:4149e60. [22] Furrer DU, Fecht H-J. g0 formation in superalloy U720Li. Scr Mater 1999;40: 1215e20. [23] Yoon KE, Noebe RD, Seidman DN. Effects of rhenium addition on the temporalsolution. Therefore, enthalpic...

Jones, N.G.; Aveson, J.W.; Bhowmik, A.; Conduit, B.D.; Stone, H.J.

2014-06-28T23:59:59.000Z

65

Development of a Two-Phase Model for the Hot Deformation of Highly-Alloyed Aluminum  

SciTech Connect

Conventional processing methods for highly alloyed aluminum consist of ingot casting, followed by hot rolling and thermal treatments. Defects result in lost productivity and wasted energy through the need to remelt and reprocess the material. This research centers on developing a fundamental understanding for deformation of wrought 705X series alloys, a key alloy system used in structural airframe applications. The development of damage at grain boundaries is characterized through a novel test that provides initiation of failure while preserving a controlled deformation response. Data from these mechanical tests are linked to computer simulations of the hot rolling process through a critical measure of damage. Transmission electron microscopy provides fundamental insight into deformation at these high working temperatures, and--in a novel link between microscale and macroscale response--the evolution of microstructure (crystallographic orientation) provides feedback for tuning of friction in the hot rolling process. The key product of this research is a modeling framework for the analysis of industrial hot rolling.

A. J. Beaudoin; J. A. Dantzig; I. M. Robertson; B. E. Gore; S. F. Harnish; H. A. Padilla

2005-10-31T23:59:59.000Z

66

Enhanced near net-shape ceramic refractory composite high temperature cartridge by VPS metallurgical alloying techniques  

SciTech Connect

High performance cartridges are being developed by vacuum plasma spray (VPS) forming to near net-shape for use in high temperature space furnaces. A VPS metallurgical alloying technique utilizing alloying elements (rhenium, nickel, etc.) has been developed that produces robust physical properties without jeopardizing the unique chemical properties of the VPS formed tungsten structure. Thin walled cartridges, 0.069 mm (0.027 in.) thick, are produced in continuous lengths of 58.4 cm (23 in.). A refractory metal (i.e. tungsten) is VPS formed as the cartridge wall structure, with a protective ceramic (i.e., alumina) coating inside and out. The ceramic-refractory-ceramic composite provides environmental protection to the refractory metal structure from both chemical attack inside and oxidation outside. The VPS metallurgical alloying process interjected during the spraying operation greatly reduces porosity of the microstructure while enhancing the ductility of the cartridge. Thin walled cartridges have been shown to hermetically seal demonstrating no through porosity. Microstructures have been characterized and material properties will be presented.

Krotz, P.D.; Liaw, Y.; McKechnie, T.N. [Rocketdyne, Huntsville, AL (United States); Holmes, R.; Zimmerman, F. [National Aeronautics and Space Administration, Huntsville, AL (United States). Marshall Space Flight Center

1995-12-31T23:59:59.000Z

67

High emissivity coatings on titanium alloy prepared by micro-arc oxidation for high temperature application  

Science Journals Connector (OSTI)

Micro-arc oxidation coatings were prepared on Ti6Al4V alloy in...3PO4-based electrolyte with different additives such as FeSO4, Co(CH3COO)2, Ni(CH3COO)2, and K2ZrF6. The composition, structure, surface morphology...

H. Tang; Q. Sun; C. G. Yi; Z. H. Jiang; F. P. Wang

2012-03-01T23:59:59.000Z

68

Corrosion and Creep of Candidate Alloys in High Temperature Helium and Steam Environments for the NGNP  

SciTech Connect

This project aims to understand the processes by which candidate materials degrade in He and supercritical water/steam environments characteristic of the current NGNP design. We will focus on understanding the roles of temperature, and carbon and oxygen potential in the 750-850 degree C range on both uniform oxidation and selective internal oxidation along grain boundaries in alloys 617 and 800H in supercritical water in the temperature range 500-600 degree C; and examining the application of static and cyclic stresses in combination with impure He environments in the temperature rang 750-850 degree C; and examining the application of static and cyclic stresses in combination with impure He environments in the temperature range 750-850 degree C over a range of oxygen and carbon potentials in helium. Combined, these studies wil elucidate the potential high damage rate processes in environments and alloys relevant to the NGNP.

Was, Gary; Jones, J. W.

2013-06-21T23:59:59.000Z

69

Highly mismatched crystalline and amorphous GaN(1-x)As(x) alloys in the whole composition range  

SciTech Connect

Alloying is a commonly accepted method to tailor properties of semiconductor materials for specific applications. Only a limited number of semiconductor alloys can be easily synthesized in the full composition range. Such alloys are, in general, formed of component elements that are well matched in terms of ionicity, atom size, and electronegativity. In contrast there is a broad class of potential semiconductor alloys formed of component materials with distinctly different properties. In most instances these mismatched alloys are immiscible under standard growth conditions. Here we report on the properties of GaN1-xAsx, a highly mismatched, immiscible alloy system that was successfully synthesized in the whole composition range using a nonequilibrium low temperature molecular beam epitaxy technique. The alloys are amorphous in the composition range of 0.17alloys with x>0.2, and to the upward movement of the valence band for alloys with x<0.2. The unique features of the band structure offer an opportunity of using GaN1-xAsx alloys for various types of solar power conversion devices.

Yu, K. M.; Novikov, S. V.; Broesler, R.; Demchenko, I. N.; Denlinger, J. D.; Liliental-Weber, Z.; Luckert, F.; Martin, R. W.; Walukiewicz, W.; Foxon, C. T.

2009-08-29T23:59:59.000Z

70

Estimation of Atmospheric Corrosion of High-Strength, Low-Alloy Steels  

E-Print Network (OSTI)

the corrosion resistance of low-alloy weathering steels from chemical composition data and from actual

71

Development of Advanced Corrosion-Resistant Fe-Cr-Ni Austenitic Stainless Steel Alloy with Improved High Temperature Strenth and Creep-Resistance  

SciTech Connect

In February of 1999, a Cooperative Research and Development Agreement (CRADA) was undertaken between Oak Ridge National Laboratory (ORNL) and Special Metals Corporation-Huntington Alloys (formerly INCO Alloys International, Inc.) to develop a modified wrought austenitic stainless alloy with considerably more strength and corrosion resistance than alloy 800H or 800HT, but with otherwise similar engineering and application characteristics. Alloy 800H and related alloys have extensive use in coal flue gas environments, as well as for tubing or structural components in chemical and petrochemical applications. The main concept of the project was make small, deliberate elemental microalloying additions to this Fe-based alloy to produce, with proper processing, fine stable carbide dispersions for enhanced high temperature creep-strength and rupture resistance, with similar or better oxidation/corrosion resistance. The project began with alloy 803, a Fe-25Cr-35NiTi,Nb alloy recently developed by INCO, as the base alloy for modification. Smaller commercial developmental alloy heats were produced by Special Metals. At the end of the project, three rounds of alloy development had produced a modified 803 alloy with significantly better creep resistance above 815EC (1500EC) than standard alloy 803 in the solution-annealed (SA) condition. The new upgraded 803 alloy also had the potential for a processing boost in that creep resistance for certain kinds of manufactured components that was not found in the standard alloy. The upgraded 803 alloy showed similar or slightly better oxidation and corrosion resistance relative to standard 803. Creep strength and oxidation/corrosion resistance of the upgraded 803 alloy were significantly better than found in alloy 800H, as originally intended. The CRADA was terminated in February 2003. A contributing factor was Special Metals Corporation being in Chapter 11 Bankruptcy. Additional testing, further commercial scale-up, and any potential invention disclosures were not pursued. One objective of this project was to improve the high temperature creep resistance of the recently developed 803 alloy, while another was to have a wrought modified 803 alloy with significantly better creep resistance and corrosion resistance than the commonly used alloy 800H. The project was intended to use the established expertise at ORNL to design specific microalloying element additions to appropriately tailor the microstructure during aging or creep so that fine, stable carbides develop for strength. If possible, oxidation/corrosion resistance at high temperatures would also be enhanced. Optimum processing was to be developed for plate and tube products.

Maziasz, PJ

2004-09-30T23:59:59.000Z

72

Mechanical properties of welds in commercial alloys for high-temperature gas-cooled reactor components  

SciTech Connect

Weld properties of Hastelloy-X, Incoloy alloy 800H (with and without Inconel-82 cladding), and 2 1/4 Cr-1 Mo are being studied to provide design data to support the development of steam generator, core auxiliary heat exchanger, and metallic thermal barrier components of the high-temperature gas-cooled reactor (HTGR) steam cycle/cogeneration plant. Tests performed include elevated-temperature creep rupture tests and tensile tests. So far, data from the literature and from relatively short-term tests at GA Technologies Inc. indicate that the weldments are satisfactory for HTGR application.

Lindgren, J.R.; Li, C.C.; Ryder, R.H.; Thurgood, B.E.

1984-07-01T23:59:59.000Z

73

Effect of laser tempering of high alloy powder metallurgical tool steels after laser cladding  

Science Journals Connector (OSTI)

Abstract The effect of tempering after laser cladding of a high alloyed powder metallurgical tool steel was studied for die repairing purposes. In particular, a high power diode laser with scanning optics was employed for tempering. The laser tempering temperature was proven to be a critical factor in improving the mechanical properties of the coatings. In order to measure and evaluate the effect of different processing parameters (mainly laser power and linear speed) on the achieved temperature, an infrared camera and a two-color pyrometer were used. The tempering effect was mainly evaluated through cross-section microhardness profiles. The microstructure of the coatings was also studied using optical and scanning electron microscope, and the volumetric fraction of retained austenite was determined by X-ray diffraction. Experimental results demonstrated that laser tempering is a useful and appealing technique to improve the hardness of laser deposited coatings of high alloyed tool steels, which is a clear advantage when large parts have to be repaired or reinforced by laser cladding.

Josu Leunda; Virginia García Navas; Carlos Soriano; Carmen Sanz

2014-01-01T23:59:59.000Z

74

On some entropy inequalities  

E-Print Network (OSTI)

In this short report, we give some new entropy inequalities based on R\\'{e}nyi relative entropy and the observation made by Berta {\\em et al} [arXiv:1403.6102]. These inequalities obtained extends some well-known entropy inequalities. We also obtain a condition under which a tripartite operator becomes a Markov state.

Lin Zhang

2014-03-26T23:59:59.000Z

75

Effect of Acid Treatment on the High-Temperature Surface Oxidation Behavior of FeCrAlloy Foil Used for Methane Combustion Catalyst Support  

Science Journals Connector (OSTI)

The catalytic flameless combustion of low alkans improves the efficiency of energy production and reduces NOx emission. ... (3-5) Fe?Cr?Al alloy (FeCrAlloy) has superior stability to other iron-based alloys at high temperatures and has been used in the fabrication of gas burners, industrial heaters, and other high-temperature devices. ... The heating rate was 10 °C/min. ...

Dong Zhang; Lihong Zhang; Bin Liang; Yongdan Li

2009-04-24T23:59:59.000Z

76

Solid State Joining of High Temperature Alloy Tubes for USC and Heat-Exchanger Systems  

SciTech Connect

The principal objective of this project was to develop materials enabling joining technologies for use in forward looking heat-exchanger fabrication in Brayton cycle HIPPS, IGCC, FutureGen concepts capable of operating at temperatures in excess of 1000{degree}C as well as conventional technology upgrades via Ultra Super-Critical (USC) Rankine-cycle boilers capable of operating at 760{degree}C (1400F)/38.5MPa (5500psi) steam, while still using coal as the principal fossil fuel. The underlying mission in Rankine, Brayton or Brayton-Rankine, or IGCC combined cycle heat engine is a steady quest to improving operating efficiency while mitigating global environmental concerns. There has been a progressive move to higher overall cycle efficiencies, and in the case of fossil fuels this has accelerated recently in part because of concerns about greenhouse gas emissions, notably CO{sub 2}. For a heat engine, the overall efficiency is closely related to the difference between the highest temperature in the cycle and the lowest temperature. In most cases, efficiency gains are prompted by an increase in the high temperature, and this in turn has led to increasing demands on the materials of construction used in the high temperature end of the systems. Our migration to new advanced Ni-base and Oxide Dispersion Strengthened (ODS) alloys poses significant fabrication challenges, as these materials are not readily weldable or the weld performs poorly in the high temperature creep regime. Thus the joining challenge is two-fold to a) devise appropriate joining methodologies for similar/dissimilar Ni-base and ODS alloys while b) preserving the near baseline creep performance in the welded region. Our program focus is on solid state joining of similar and dissimilar metals/alloys for heat exchanger components currently under consideration for the USC, HIPPS and IGCC power systems. The emphasis is to manipulate the joining methods and variables available to optimize joint creep performance compared to the base material creep performance. Similar and dissimilar butt joints were fabricated of MA956, IN740 alloys and using inertia welding techniques. We evaluated joining process details and heat treatments and its overall effect on creep response. Fixed and incrementally accelerated temperature creep tests were performed for similar and dissimilar joints and such incremental creep life data is compiled and reported. Long term MA956-MA556 joint tests indicate a firm 2Ksi creep stress threshold performance at 850{degree}C with a maximum exposure of over 9725 hours recorded in the current program. A Larsen Miller Parameter (LMP) of 48.50 for a 2Ksi test at 850{degree}C was further corroborated with tests at 2Ksi stress at 900{degree}C yielding a LMP=48.80. Despite this threshold the joints exhibit immense temperature sensitivity and fail promptly when test temperature raised above 900{degree}C. In comparison the performance of dissimilar joints was inferior, perhaps dictated by the creep characteristics of the mating nickel-base alloys. We describe a parametric window of joint development, and post weld heat treatment (PWHT) in dissimilar joints with solid solution (IN601, IN617) and precipitate strengthened (IN740) materials. Some concerns are evident regarding the diffusion of aluminum in dissimilar joints during high temperature recrystallization treatments. It is noted that aggressive treatments rapidly deplete the corrosion protecting aluminum reservoir in the vicinity of the joint interface. Subsequently, the impact of varying PWHT has been evaluated in the context on ensuing creep performance.

Bimal Kad

2011-12-31T23:59:59.000Z

77

Microstructure and High Temperature Oxidation Behavior of Cr-W Alloys  

SciTech Connect

Cr alloys containing 0-30%W by weight were investigated for use in elevated temperature applications. The alloys were melted in a water-cooled, copper-hearth arc furnace. Microstructure of the alloys was characterized using x-ray diffraction, scanning electron microscopy, and light microscopy. A pseudocyclic oxidation test was employed to study scale formation at 1000ºC in dry air. The scale was predominantly chromia and spalled upon cooling. Alloying with aluminum up to 8 weight percent reduced the spalling drastically. Furthermore, aluminizing the surface of the Cr-W alloys completely stopped the spalling.

Dogan, O.N.

2007-02-01T23:59:59.000Z

78

Pitting resistance of Alloy 800 as a function of temperature and prefilming in high temperature water  

SciTech Connect

The pitting behavior of Alloy 800 was investigated as a function of temperature and prefilming in high temperature water. The pitting behavior was characterized in terms of the pitting potential and the pit density. The pitting potential decreases with increasing temperature and chloride activity. Prefilming of test coupons over a time period between 100 and 5,000 hours in ammoniated water at 300 C has no apparent influence on the pitting potential at room temperature, 180 C and 300 C. However, the number of pits in prefilmed coupons is much higher than in coupons covered with an air passive layer. The effect of prefilming on pit nucleation was investigated in more detail with regard to a model and test methods developed by Bianchi and co-workers. Density of pits in prefilmed coupons is at least one order of magnitude higher than in air passive coupons. Maximum pit density was measured after a prefilming period of 1 00 hours. The effect is discussed in terms of Bianchi`s model and in terms of features of passive films. It is outlined that the initially amorphous metastable passive film on Alloy 800 becomes crystalline at increased temperatures. Crystallization induces lattice defects, such as dislocations and grain boundaries, in the passive film. The film grows and slowly transforms into a thick oxide layer. The transformation process is associated with enhanced susceptibility to pit nucleation.

Stellwag, B. [Siemens Power Generation, Erlangen (Germany)

1995-12-31T23:59:59.000Z

79

Amorphous and nanocrystalline phase formation in highly-driven Al-based binary alloys  

SciTech Connect

Remarkable advances have been made since rapid solidification was first introduced to the field of materials science and technology. New types of materials such as amorphous alloys and nanostructure materials have been developed as a result of rapid solidification techniques. While these advances are, in many respects, ground breaking, much remains to be discerned concerning the fundamental relationships that exist between a liquid and a rapidly solidified solid. The scope of the current dissertation involves an extensive set of experimental, analytical, and computational studies designed to increase the overall understanding of morphological selection, phase competition, and structural hierarchy that occurs under far-from equilibrium conditions. High pressure gas atomization and Cu-block melt-spinning are the two different rapid solidification techniques applied in this study. The research is mainly focused on Al-Si and Al-Sm alloy systems. Silicon and samarium produce different, yet favorable, systems for exploration when alloyed with aluminum under far-from equilibrium conditions. One of the main differences comes from the positions of their respective T{sub 0} curves, which makes Al-Si a good candidate for solubility extension while the plunging T{sub 0} line in Al-Sm promotes glass formation. The rapidly solidified gas-atomized Al-Si powders within a composition range of 15 to 50 wt% Si are examined using scanning and transmission electron microscopy. The non-equilibrium partitioning and morphological selection observed by examining powders at different size classes are described via a microstructure map. The interface velocities and the amount of undercooling present in the powders are estimated from measured eutectic spacings based on Jackson-Hunt (JH) and Trivedi-Magnin-Kurz (TMK) models, which permit a direct comparison of theoretical predictions. For an average particle size of 10 {micro}m with a Peclet number of {approx}0.2, JH and TMK deviate from each other. This deviation indicates an adiabatic type solidification path where heat of fusion is reabsorbed. It is interesting that this particle size range is also consistent with the appearance of a microcellular growth. While no glass formation is observed within this system, the smallest size powders appear to consist of a mixture of nanocrystalline Si and Al. Al-Sm alloys have been investigated within a composition range of 34 to 42 wt% Sm. Gas atomized powders of Al-Sm are investigated to explore the morphological and structural hierarchy that correlates with different degrees of departure from full equilibrium conditions. The resultant powders show a variety of structural selection with respect to amount of undercooling, with an amorphous structure appearing at the highest cooling rates. Because of the chaotic nature of gas atomization, Cu-block melt-spinning is used to produce a homogeneous amorphous structure. The as-quenched structure within Al-34 to 42 wt% Sm consists of nanocrystalline fcc-Al (on the order of 5 nm) embedded in an amorphous matrix. The nucleation density of fcc-Al after initial crystallization is on the order of 10{sup 22}-10{sup 23} m{sup -3}, which is 10{sup 5}-10{sup 6} orders of magnitude higher than what classical nucleation theory predicts. Detailed analysis of liquid and as-quenched structures using high energy synchrotron X-ray diffraction, high energy transmission electron microscopy, and atom probe tomography techniques revealed an Al-Sm network similar in appearance to a medium range order (MRO) structure. A model whereby these MRO clusters promote the observed high nucleation density of fcc-Al nanocrystals is proposed. The devitrification path was identified using high temperature, in-situ, high energy synchrotron X-ray diffraction techniques and the crystallization kinetics were described using an analytical Johnson-Mehl-Avrami (JMA) approach.

Kalay, Yunus Eren

2008-10-15T23:59:59.000Z

80

Localized effects of macrofouling species on electrochemical corrosion of high grade alloys  

SciTech Connect

Interactions between macrofouling and corrosion on some stainless steels, UNS N06625 and UNS R30006 have been studied in long-term tests conducted in natural seawater off the west coast of Scotland. After a 18-month exposure period, the specimens were heavily fouled primarily with barnacles and mussels and all the materials exhibited crevice corrosion although this was less extensive on the Ni-base alloy. Localized corrosion was observed under the base of live barnacles on UNS S31603 stainless steel. DC electrochemical anodic polarization tests undertaken after the 18-month exposure period, yielded unusually high currents in the range of potential between the free corrosion value and the breakdown potential. This observation was associated with the appearance, after the anodic polarization, of black sulfide corrosion products at the specimen/resin crevices, around barnacles and around mussel byssus threads.

Hodgkiess, T. [Univ. of Glasgow (United Kingdom). Dept. of Mechanical Engineering; Nevilie, A. [Heriot Watt Univ., Edinburgh (United Kingdom). Dept. of Mechanical and Chemical Engineering

1998-12-31T23:59:59.000Z

Note: This page contains sample records for the topic "high entropy alloy" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


81

Evaporation behavior of Hastelloy-X alloys in simulated very high temperature reactor environments  

SciTech Connect

A sequential analysis was made on the material degradations during exposure of nickel-base corrosionresistant austenitic alloys to simulated very high temperature reactor environments. The materials tested were two modified versions of Hastelloy-X in terms of both increased manganese content for improved compatibility and decreased manganese content for possible adverse effects. Quantitative analysis of the specimens after exposure for 1000 h at several temperature steps from 850 to 1050/sup 0/C have revealed the temperature-dependent aspects of the processes including the depletion of chromium and manganese due to oxidation, evaporation, and carbon transfer into and/or from the materials. The material with enriched manganese, developed and specified as Hastelloy-XR, showed enhanced resistance to loss of chromium in terms of both oxidation and evaporation.

Shindo, M.; Kondo, T.

1984-08-01T23:59:59.000Z

82

Recombination dynamics and carrier lifetimes in highly mismatched ZnTeO alloys  

SciTech Connect

This study investigates the recombination dynamics in highly mismatched ZnTeO alloys using time-resolved photoluminescence (PL) spectroscopy. The large PL energy redshift with increasing O content and the disappearance of the ZnTe emission verify the O-induced conduction band anticrossing effect. The incorporation of O generates electron localization below the E{sub ?} conduction subband tail, which provide additional optical transitions and cause complex recombination mechanisms. Photoexcited free electrons in both the E{sub +} and the E{sub ?} conduction subbands favor rapid relaxation to low energy states. Additionally, temperature-independent long carrier lifetimes (>130.0?ns) that are induced by localized electrons increase with O concentration.

Lin, Yan-Cheng, E-mail: bryanlin@mail.nctu.edu.tw, E-mail: wuchingchou@mail.nctu.edu.tw; Tasi, Ming-Jui; Chou, Wu-Ching, E-mail: bryanlin@mail.nctu.edu.tw, E-mail: wuchingchou@mail.nctu.edu.tw; Chang, Wen-Hao; Chen, Wei-Kuo [Department of Electrophysics, National Chiao Tung University, Hsinchu 30010, Taiwan (China)] [Department of Electrophysics, National Chiao Tung University, Hsinchu 30010, Taiwan (China); Tanaka, Tooru [Department of Electrical and Electronic Engineering, Saga University, Saga 840-8502 (Japan) [Department of Electrical and Electronic Engineering, Saga University, Saga 840-8502 (Japan); PRESTO, Japan Science and Technology Agency (JST), Kawaguchi, Saitama 332-0012 (Japan); Guo, Qixin [Synchrotron Light Application Center, Saga University, 1 Honjo, Saga 840-8502 (Japan)] [Synchrotron Light Application Center, Saga University, 1 Honjo, Saga 840-8502 (Japan); Nishio, Mitsuhiro [Department of Electrical and Electronic Engineering, Saga University, Saga 840-8502 (Japan)] [Department of Electrical and Electronic Engineering, Saga University, Saga 840-8502 (Japan)

2013-12-23T23:59:59.000Z

83

Iron-aluminum alloys having high room-temperature and method for making same  

DOE Patents (OSTI)

A wrought and annealed iron-aluminum alloy is described consisting essentially of 8 to 9.5% aluminum, an effective amount of chromium sufficient to promote resistance to aqueous corrosion of the alloy, and an alloying constituent selected from the group of elements consisting of an effective amount of molybdenum sufficient to promote solution hardening of the alloy and resistance of the alloy to pitting when exposed to solutions containing chloride, up to about 0.05% carbon with up to about 0.5% of a carbide former which combines with the carbon to form carbides for controlling grain growth at elevated temperatures, and mixtures thereof, and the balance iron, wherein said alloy has a single disordered [alpha] phase crystal structure, is substantially non-susceptible to hydrogen embrittlement, and has a room-temperature ductility of greater than 20%.

Sikka, V.K.; McKamey, C.G.

1993-08-24T23:59:59.000Z

84

Modelling the coarsening behaviour of TiC precipitates in high-strength, low-alloy steels  

E-Print Network (OSTI)

Modelling the coarsening behaviour of TiC precipitates in high-strength, low-alloy steels Jae Hoon­sheet steels rely on a dispersion of fine precipitates based on TiC, generated during the major phase changes of the stoichiometry of titanium and carbon. The purpose was to assess the influences of interface energy and Ti/C

Cambridge, University of

85

Earth's extensive entropy bound  

E-Print Network (OSTI)

The possibility of planetary mass black hole production by crossing entropy limits is addressed. Such a possibility is given by pointing out that two geophysical quantities have comparable values: first, Earth's total negative entropy flux integrated over geological time and, second, its extensive entropy bound, which follows as a tighter bound to the Bekenstein limit when entropy is an extensive function. The similarity between both numbers suggests that the formation of black holes from planets may be possible through a strong fluctuation toward thermodynamic equilibrium which results in gravothermal instability and final collapse. Briefly discussed are implications for the astronomical observation of low mass black holes and for Fermi's paradox.

A. M. Lisewski

2012-12-20T23:59:59.000Z

86

High-temperature corrosion of metallic alloys in an oxidizing atmosphere containing NaCl  

SciTech Connect

A particular heat-exchanger application involved metallic alloys exposed to flue gases of an aluminum remelt furnace. Because the flue gases might contain NaCl and other halides, the corrosion behavior of the alloys was to be investigated. Planned direct exposure of candidate alloys to the flue gases, however, was not conducted because of premature termination of the project. Complementary laboratory testing was conducted on seven commercially available alloys and two nickel aluminides. These materials were exposed to an oxidizing atmosphere containing 0.06 wt % NaCl for 1100 h at 1000/degree/C. Most of the alloy exhibited grain-boundary attack, which resulted in complete oxidation of enveloped grains. The alloys Incoloy MA-956, Incoloy 800, Inconel 625, Inconel 601, Hastelloy X, Haynes 188, and nickel aluminide IC-50 were substantially more corroded than Alloy 214 and nickel aluminide IC-221. The latter two alloys, therefore, would probably be superior to the others in application involving flue gases containing NaCl. Strength fabricability, and weldability, which are briefly discussed, would also affect selection of materials. 8 refs., 12 figs., 5 tabs.

Federer, J.I.

1989-02-01T23:59:59.000Z

87

Fusion neutron irradiation of Ni(Si) alloys at high temperature  

SciTech Connect

Two Ni-4% Si alloys, with different cold work levels, are irradiated with 14 MeV fusion neutrons at 623 K, and their Curie temperatures are monitored during irradiation. The results are compared to those of an identical alloy irradiated by 2 MeV electrons. The results show that increasing dislocation density increases the Curie temperature change rate. At the same damage rate, the Curie temperature change rate for the alloy irradiated by 14 MeV fusion neutrons is only 6 to 7% of that for an identical alloy irradiated by 2 MeV electrons. It is well known that the migration of radiation induced defects contributes to segregation of silicon atoms at sinks in this alloy, causing the Curie temperature changes. The current results imply that the relative free defect production efficiency decreases from one for the electron irradiated sample to 6 to 7% for the fusion neutron irradiated sample. 17 refs., 4 figs., 1 tab.

Huang, J.S.; Guinan, M.W.; Hahn, P.A.

1987-09-01T23:59:59.000Z

88

TEM Characterization of High Burn-up Microstructure of U-7Mo Alloy  

SciTech Connect

As an essential part of global nuclear non-proliferation effort, the RERTR program is developing low enriched U-Mo fuels (< 20% U-235) for use in research and test reactors that currently employ highly enriched uranium fuels. One type of fuel being developed is a dispersion fuel plate comprised of U-7Mo particles dispersed in Al alloy matrix. Recent TEM characterizations of the ATR irradiated U-7Mo dispersion fuel plates include the samples with a local fission densities of 4.5, 5.2, 5.6 and 6.3 E+21 fissions/cm3 and irradiation temperatures of 101-136?C. The development of the irradiated microstructure of the U-7Mo fuel particles consists of fission gas bubble superlattice, large gas bubbles, solid fission product precipitates and their association to the large gas bubbles, grain subdivision to tens or hundreds of nanometer size, collapse of bubble superlattice, and amorphisation. This presentation will describe the observed microstructures specifically focusing on the U-7Mo fuel particles. The impact of the observed microstructure on the fuel performance and the comparison of the relevant features with that of the high burn-up UO2 fuels will be discussed.

Jian Gan; Brandon Miller; Dennis Keiser; Adam Robinson; James Madden; Pavel Medvedev; Daniel Wachs

2014-04-01T23:59:59.000Z

89

STRUCTURE AND HIGH-FIELD PERFORMANCE OF JELLY ROLL PROCESSED Nb{sub 3}Sn WIRES USING Sn-Ta AND Sn-Ti BASED ALLOY SHEET  

SciTech Connect

Sn-Ta based alloy buttons of different compositions were prepared by the melt diffusion process among constituent metal powders, and then pressed into plates. Meanwhile Sn-Ti based alloy plates were sliced from the melt and cast ingot. Resulting Sn-based alloy plates were rolled into thin sheets. The Sn-based alloy sheet was laminated with a Nb sheet, and wound into a Jelly Roll (JR) composite. The composite was encased in a sheath, and fabricated into a thin wire followed by the heat treatment. The application of hydrostatic extrusion is useful at the initial stage of the fabrication. The JR wires using Sn-Ta and Sn-Ti based alloy sheets show a non-Cu J{sub c} of {approx}250 A/mm{sup 2} and {approx}150 A/mm{sup 2} at 20 T and 22 T, respectively, at 4.2 K. It has been found that the Nb impregnates into the Sn-based alloy layers during the reaction, and Nb{sub 3}Sn layers are synthesized by the mutual diffusion between the Nb sheet and the Sn-based alloy sheet without formation of voids. Sn-Ti based alloy sheets are attractive due to their easiness of mass production. Structure and high-field performance of JR processed Nb{sub 3}Sn wires prepared from Sn-based alloy sheets with different compositions are compared in this article.

Tachikawa, K.; Tsuyuki, T.; Hayashi, Y.; Nakata, K. [Faculty of Engineering, Tokai University Hiratsuka, Kanagawa 259-1292 (Japan); Takeuchi, T. [National Institute for Materials Science Tsukuba, Ibaraki 305-0047 (Japan)

2008-03-03T23:59:59.000Z

90

Enhanced high-field current carrying capacities and pinning behavior of NbTi-based superconducting alloys  

SciTech Connect

High-field critical current densities J/sub c/ and pinning behavior are discussed for Nb-63a/oTi, Nb-61.7a/oTi-3a/oHf, and Nb-64.7a/oTi-7.2a/oTa superconducting alloys. J/sub c/ properties for 8--12 T in these alloy superconductors under superfluid helium environments can be even superior to those in Nb/sub 3/Sn at 4.2 K, when they are heavily cold-worked after final heat treatments. A temperature scaling law of the flux pinning force F/sub p/ is found to hold for these alloys in the form of F/sub P/ = K (B/sub c/2(T))/sup n/b/sup p/(1-b)/sup q/, where B/sub c/2 is the upper critical field and bequivalentB/B/sub c/2. The peak reduced field, b/sub m/, in the F/sub p/-b curve depends upon how the alloys have been processed. The origins of n, p, and q are discussed in terms of the processing condition.

Wada, H.; Itoh, K.; Tachikawa, K.; Yamada, Y.; Murase, S.

1985-05-01T23:59:59.000Z

91

Solid state thin film battery having a high temperature lithium alloy anode  

DOE Patents (OSTI)

An improved rechargeable thin-film lithium battery involves the provision of a higher melting temperature lithium anode. Lithium is alloyed with a suitable solute element to elevate the melting point of the anode to withstand moderately elevated temperatures.

Hobson, David O. (Oak Ridge, TN)

1998-01-01T23:59:59.000Z

92

Complex magnetic behavior and high spin polarization in Fe3-xMnxSi alloys  

Science Journals Connector (OSTI)

Fe3Si is a ferromagnetic material with possible applications in magnetic tunnel junctions. When doped with Mn, the material shows a complex magnetic behavior, as suggested by older experiments. We employed the Korringa-Kohn-Rostoker Green-function method within density-functional theory in order to study the alloy Fe3-xMnxSi, with 0?x?1. Chemical disorder is described within the coherent potential approximation. In agreement with experiment, we find that the Mn atoms align ferromagnetically to the Fe atoms, and that the magnetization and Curie temperature drop with increasing Mn concentration x. The calculated spin polarization P at the Fermi level varies strongly with x, from P=-0.3 at x=0 (ordered Fe3Si) through P=0 at x=0.28, to P=+1 for x>0.75; i.e., at high Mn concentrations the system is half metallic. We discuss the origin of the trends of magnetic moments, exchange interactions, Curie temperature, and the spin polarization.

Marjana Ležai?, Phivos Mavropoulos, Stefan Blügel, and Hubert Ebert

2011-03-30T23:59:59.000Z

93

PVD synthesis and high-throughput property characterization of Ni?Fe?Cr alloy libraries  

SciTech Connect

Three methods of alloy library synthesis, thick-layer deposition followed by interdiffusion, composition-spread codeposition and electron-beam melting of thick deposited layers, have been applied to Ni-Fe-Cr ternary and Ni-Cr binary alloys. Structural XRD mapping and mechanical characterization by means of nanoindentation have been used to characterize the properties of the libraries. The library synthesis methods are compared from the point of view of the structural and mechanical information they can provide.

Rar, A.; Frafjord, J.J.; Fowlkes, Jason D.; Specht, E.D.; Rack, P.D.; Santella, M.L.; Bei, H.; George, E.P.; Pharr, G.M. (Tennessee-K); (Tennessee-K); (ORNL)

2010-11-10T23:59:59.000Z

94

High Growth Rate of Epitaxial Silicon-Carbon Alloys by High-Order Silane Precursor and Chemical Vapor Deposition  

E-Print Network (OSTI)

rates typically achieved by disilane and silane, respectively, at 575o C. The rate at present is limited precursor HOS than disilane in CVD, even at lower temperatures. Our current growth rates of Si1-yCy alloys

95

Information and entropy  

Science Journals Connector (OSTI)

The Landauer cost for erasing information demands that information about a physical system be included in the total entropy, as proposed by Zurek [Nature 341, 119 (1989); Phys. Rev. A 40, 4731 (1989)]. A consequence is that most system states—either classical phase-space distributions or quantum pure states—have total entropy much larger than thermal equilibrium. If total entropy is to be a useful concept, this must imply that work can be extracted in going from equilibrium to a typical system state. The work comes from randomization of a ‘‘memory’’ that holds a record of the system state.

Carlton M. Caves

1993-06-01T23:59:59.000Z

96

High-temperature low-cycle fatigue and tensile properties of Hastelloy X and alloy 617 in air and HTGR-helium  

SciTech Connect

Results of strain controlled fatigue and tensile tests are presented for two nickel base solution hardened alloys which are reference structural alloys for use in several high temperature gas cooled reactor concepts. These alloys, Hastelloy X Inconel 617, were tested at temperatures ranging from room temperature to 871/sup 0/C in air and impure helium. Materials were tested in the solution annealed as well as in the pre-aged condition where aging consisted of isothermal exposure at one of several temperatures for periods of up to 20,000 h. Comparisons are also given between the strain controlled fatigue lives of these alloys and several other commonly used alloys all tested at 538/sup 0/C.

Strizak, J.P.; Brinkman, C.R.; Rittenhouse, P.L.

1981-01-01T23:59:59.000Z

97

PdAgAu alloy with high resistance to corrosion by H{sub 2}S  

SciTech Connect

PdAgAu alloy films were prepared on porous stainless steel supports by sequential electroless deposition. Two specific compositions, Pd{sub 83}Ag{sub 2}Au{sub 15} and Pd{sub 74}Ag{sub 14}Au{sub 12}, were studied for their sulfur tolerance. The alloys and a reference Pd foil were exposed to 1000 H{sub 2}S/H{sub 2} at 623 K for periods of 3 and 30 hours. The microstructure, morphology and bulk composition of both nonexposed and H{sub 2}S-exposed samples were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). XRD and SEM analysis revealed time-dependent growth of a bulk Pd{sub 4}S phase on the Pd foil during H{sub 2}S exposure. In contrast, the PdAgAu ternary alloys displayed the same FCC structure before and after H{sub 2}S exposure. In agreement with the XRD and SEM results, sulfur was not detected in the bulk of either ternary alloy samples by EDS, even after 30 hours of H{sub 2}S exposure. X-ray photoelectron spectroscopy (XPS) depth profiles were acquired for both PdAgAu alloys after 3 and 30 hours of exposure to characterize sulfur contamination near their surfaces. Very low S 2p and S 2s XPS signals were observed at the top-surfaces of the PdAgAu alloys, and those signals disappeared before the etch depth reached ~ 10 nm, even for samples exposed to H{sub 2}S for 30 hours. The depth profile analyses also revealed silver and gold segregation to the surface of the alloys; preferential location of Au on the alloys surface may be related to their resistance to bulk sulfide formation. In preliminary tests, a PdAgAu alloy membrane displayed higher initial H{sub 2} permeability than a similarly prepared pure Pd sample and, consistent with resistance to bulk sulfide formation, lower permeability loss in H{sub 2}S than pure Pd.

Braun, Fernando; Miller, James B.; Gellman, Andrew J.; Tarditi, Ana M.; Fleutot, Benoit; Petro, Kondratyuk, Cornaglia, Laura M

2012-12-01T23:59:59.000Z

98

On Black Hole Entropy  

E-Print Network (OSTI)

Two techniques for computing black hole entropy in generally covariant gravity theories including arbitrary higher derivative interactions are studied. The techniques are Wald's Noether charge approach introduced recently, and a field redefinition method developed in this paper. Wald's results are extended by establishing that his local geometric expression for the black hole entropy gives the same result when evaluated on an arbitrary cross-section of a Killing horizon (rather than just the bifurcation surface). Further, we show that his expression for the entropy is not affected by ambiguities which arise in the Noether construction. Using the Noether charge expression, the entropy is evaluated explicitly for black holes in a wide class of generally covariant theories. Further, it is shown that the Killing horizon and surface gravity of a stationary black hole metric are invariant under field redefinitions of the metric of the form $\\bar{g}_{ab}\\equiv g_{ab} + \\Delta_{ab}$, where $\\Delta_{ab}$ is a tensor field constructed out of stationary fields. Using this result, a technique is developed for evaluating the black hole entropy in a given theory in terms of that of another theory related by field redefinitions. Remarkably, it is established that certain perturbative, first order, results obtained with this method are in fact {\\it exact}. The possible significance of these results for the problem of finding the statistical origin of black hole entropy is discussed.}

Ted Jacobson; Gungwon Kang; Robert C. Myers

1994-01-03T23:59:59.000Z

99

Entropy of quasiblack holes  

SciTech Connect

We trace the origin of the black hole entropy S, replacing a black hole by a quasiblack hole. Let the boundary of a static body approach its own gravitational radius, in such a way that a quasihorizon forms. We show that if the body is thermal with the temperature taking the Hawking value at the quasihorizon limit, it follows, in the nonextremal case, from the first law of thermodynamics that the entropy approaches the Bekenstein-Hawking value S=A/4. In this setup, the key role is played by the surface stresses on the quasihorizon and one finds that the entropy comes from the quasihorizon surface. Any distribution of matter inside the surface leads to the same universal value for the entropy in the quasihorizon limit. This can be of some help in the understanding of black hole entropy. Other similarities between black holes and quasiblack holes such as the mass formulas for both objects had been found previously. We also discuss the entropy for extremal quasiblack holes, a more subtle issue.

Lemos, Jose P. S.; Zaslavskii, Oleg B. [Centro Multidisciplinar de Astrofisica-CENTRA, Departamento de Fisica, Instituto Superior Tecnico-IST, Universidade Tecnica de Lisboa-UTL, Avenida Rovisco Pais 1, 1049-001 Lisboa (Portugal); Astronomical Institute of Kharkov, V. N. Karazin National University, 35 Sumskaya Street, Kharkov, 61022 (Ukraine)

2010-03-15T23:59:59.000Z

100

Development of High-Temperature Ferritic Alloys and Performance Prediction Methods for Advanced Fission Energy Systems  

SciTech Connect

Reports the results of a comprehensive development and analysis of a database on irradiation hardening and embrittlement of tempered martensitic steels (TMS). Alloy specific quantitative semi-empirical models were derived for the dpa dose, irradiation temperature (ti) and test (Tt) temperature of yield stress hardening (or softening) .

G. RObert Odette; Takuya Yamamoto

2009-08-14T23:59:59.000Z

Note: This page contains sample records for the topic "high entropy alloy" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


101

High post-irradiation ductility thermomechanical treatment for precipitation strengthened austenitic alloys  

DOE Patents (OSTI)

A method for improving the post-irradiation ductility is described which prises a solution heat treatment following which the materials are cold worked. They are included to demonstrate the beneficial effect of this treatment on the swelling resistance and the ductility of these austenitic precipitation hardenable alloys.

Laidler, James J. (Richland, WA); Borisch, Ronald R. (Kennewick, WA); Korenko, Michael K. (Rockville, MD)

1982-01-01T23:59:59.000Z

102

Solid state thin film battery having a high temperature lithium alloy anode  

DOE Patents (OSTI)

An improved rechargeable thin-film lithium battery involves the provision of a higher melting temperature lithium anode. Lithium is alloyed with a suitable solute element to elevate the melting point of the anode to withstand moderately elevated temperatures. 2 figs.

Hobson, D.O.

1998-01-06T23:59:59.000Z

103

Characteristics of lead induced stress corrosion cracking of alloy 690 in high temperature  

SciTech Connect

Slow strain rate tests (SSRT) were conducted on alloy 690 in various lead chloride solutions and metal lead added to 100 ppm chloride solution at 288 C. The corrosion potential (rest potential) for the alloy was measured with SSRT tests. The cracking was observed by metallographic examination and electron probe micro analyzer. Also, the corrosion behavior of the alloy was evaluated by anodic polarized measurement at 30 C. Resulting from the tests, cracking was characterized by cracking behavior, crack length and crack growth rate, and lead effects on cracking. The cracking was mainly intergranular in mode, approximately from 60 um to 450 um in crack length, and approximately 10{sup {minus}6} to 10{sup {minus}7} mmS-1 in crack velocity. The cracking was evaluated through the variation the corrosion potential in potential-time and lead behavior during SSRTs. The lead effect in corrosion was evaluated through active to passive transition behavior in anodic polarized curves. The corrosion reactions in the cracking region were confirmed by electron probe microanalysis. Alloy 690 is used for steam generation tubes in pressurized water reactors.

Chung, K.K. [Korea Inst. of Nuclear Safety, Taejon (Korea, Republic of); Lim, J.K. [Chonbuk National Univ., Chonju (Korea, Republic of); Watanabe, Yutaka; Shoji, Tetsuo [Tohoku Univ., Sendai (Japan). Research Inst. for Fracture Technology

1996-10-01T23:59:59.000Z

104

High Permeability Ternary Palladium Alloy Membranes with Improved Sulfur and Halide Tolerances  

SciTech Connect

The project team consisting of Southwest Research Institute{reg_sign} (SwRI{reg_sign}), Georgia Institute of Technology (GT), the Colorado School of Mines (CSM), TDA Research, and IdaTech LLC was focused on developing a robust, poison-tolerant, hydrogen selective free standing membrane to produce clean hydrogen. The project completed on schedule and on budget with SwRI, GT, CSM, TDA and IdaTech all operating independently and concurrently. GT has developed a robust platform for performing extensive DFT calculations for H in bulk palladium (Pd), binary alloys, and ternary alloys of Pd. Binary alloys investigated included Pd96M4 where M = Li, Na, Mg, Al, Si, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Y, Zr, Nb, Mo, Tc, Ru, Rh, Ag, Cd, In, Sn, Sb, Te, Hf, Ta, W, Re, Os, Ir, Pt, Au, Tl, Pb, Bi, Ce, Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu. They have also performed a series of calculations on Pd{sub 70}Cu{sub 26}Ag{sub 4}, Pd{sub 70}Cu{sub 26}Au{sub 4}, Pd{sub 70}Cu{sub 26}Ni{sub 4}, Pd{sub 70}Cu{sub 26}Pt{sub 4}, and Pd{sub 70}Cu{sub 26}Y{sub 4}. SwRI deposited and released over 160 foils of binary and ternary Pd alloys. There was considerable work on characterizing and improving the durability of the deposited foils using new alloy compositions, post annealing and ion bombardment. The 10 and 25 {micro}m thick films were sent to CSM, TDA and IdaTech for characterization and permeation testing. CSM conducted over 60 pure gas permeation tests with SwRI binary and ternary alloy membranes. To date the PdAu and PdAuPt membranes have exhibited the best performance at temperatures in the range of 423-773 C and their performance correlates well with the predictions from GT. TDA completed testing under the Department of Energy (DOE) WGS conditions on over 16 membranes. Of particular interest are the PdAuPt alloys that exhibited only a 20% drop in flux when sulfur was added to the gas mixture and the flux was completely recovered when the sulfur flow was stopped. IdaTech tested binary and ternary membranes on a simulated flue gas stream and experienced significant difficulty in mounting and testing the sputter deposited membranes. IdaTech was able to successfully test PdAu and PdAuPt membranes and saw similar sulfur tolerance to what TDA found. The Program met all the deliverables on schedule and on budget. Over ten presentations at national and international conferences were made, four papers were published (two in progress) in technical journals, and three students (2 at GT and 1 at CSM) completed their doctorates using results generated during the course of the program. The three major findings of program were; (1) the DFT modeling was verified as a predictive tool for the permeability of Pd based ternary alloys, (2) while magnetron sputtering is useful in precisely fabricating binary and ternary alloys, the mechanical durability of membranes fabricated using this technique are inferior compared to cold rolled membranes and this preparation method is currently not ready for industrial environments, (3) based on both modeling and experimental verification in pure gas and mixed gas environments PdAu and PdAuPt alloys were found to have the combination of the highest permeability and tolerance to sulfur.

K. Coulter

2010-12-31T23:59:59.000Z

105

Standard practice for evaluation of disbonding of bimetallic stainless alloy/steel plate for use in high-pressure, high-temperature refinery hydrogen service  

E-Print Network (OSTI)

1.1 This practice covers a procedure for the evaluation of disbonding of bimetallic stainless alloy/steel plate for use in refinery high-pressure/high-temperature (HP/HT) gaseous hydrogen service. It includes procedures to (1) produce suitable laboratory test specimens, (2) obtain hydrogen charging conditions in the laboratory that are similar to those found in refinery HP/HT hydrogen gas service for evaluation of bimetallic specimens exposed to these environments, and (3) perform analysis of the test data. The purpose of this practice is to allow for comparison of data among test laboratories on the resistance of bimetallic stainless alloy/steels to hydrogen-induced disbonding (HID). 1.2 This practice applies primarily to bimetallic products fabricated by weld overlay of stainless alloy onto a steel substrate. Most of the information developed using this practice has been obtained for such materials. The procedures described herein, may also be appropriate for evaluation of hot roll bonded, explosive bonded...

American Society for Testing and Materials. Philadelphia

2001-01-01T23:59:59.000Z

106

Rank and directional entropy Rank and directional entropy  

E-Print Network (OSTI)

Rank and directional entropy Rank and directional entropy E. Arthur (Robbie) Robinson (Joint work with Ayse Sahin) The George Washington University Talk at KIAS, Seoul, Korea. September 27, 2010 #12;Rank and directional entropy Outline 1 Introduction 2 Finite rank, Z case 3 The formal definition 4 The Z2 case 5

Robinson Jr., E. Arthur (Robbie)

107

High-capacity nanostructured germanium-containing materials and lithium alloys thereof  

DOE Patents (OSTI)

Electrodes comprising an alkali metal, for example, lithium, alloyed with nanostructured materials of formula Si.sub.zGe.sub.(z-1), where 0

Graetz, Jason A. (Upton, NY); Fultz, Brent T. (Pasadena, CA); Ahn, Channing (Pasadena, CA); Yazami, Rachid (Los Angeles, CA)

2010-08-24T23:59:59.000Z

108

Approximate von Neumann entropy for directed graphs  

Science Journals Connector (OSTI)

In this paper, we develop an entropy measure for assessing the structural complexity of directed graphs. Although there are many existing alternative measures for quantifying the structural properties of undirected graphs, there are relatively few corresponding measures for directed graphs. To fill this gap in the literature, we explore an alternative technique that is applicable to directed graphs. We commence by using Chung's generalization of the Laplacian of a directed graph to extend the computation of von Neumann entropy from undirected to directed graphs. We provide a simplified form of the entropy which can be expressed in terms of simple node in-degree and out-degree statistics. Moreover, we find approximate forms of the von Neumann entropy that apply to both weakly and strongly directed graphs, and that can be used to characterize network structure. We illustrate the usefulness of these simplified entropy forms defined in this paper on both artificial and real-world data sets, including structures from protein databases and high energy physics theory citation networks.

Cheng Ye; Richard C. Wilson; César H. Comin; Luciano da F. Costa; Edwin R. Hancock

2014-05-12T23:59:59.000Z

109

Pitting resistance of alloy 800 as a function of temperature and prefilming in high-temperature water  

SciTech Connect

Pitting behavior of alloy 800 was investigated as a function of temperature and prefilming in high-temperature water. The behavior was characterized in terms of pitting potential (U{sub p}) and pit density (n{sub p}). U{sub p} decreased with increasing temperature and chloride activity. Prefilming of test coupons over a period between 100 h and 5,000 h in ammoniated water at 300 C had no apparent influence on U{sub p} at room temperature, 180 C, and 300 C. However, the number of pits in prefilmed coupons was much higher than in coupons covered with an air passive layer. The effect of prefilming on pit nucleation was investigated in detail with regard to a model and test methods developed by Bianchi, et al. Density of pits in prefilmed coupons was at least 1 order of magnitude higher than in air passive coupons. Maximum pit density was measured after a prefilming period of 100 h. The effect was discussed in terms of Bianchi`s model and in terms of features of passive films. The initially amorphous metastable passive film on alloy 800 became crystalline at increased temperatures. Crystallization induced lattice defects, such as dislocations and grain boundaries, in the passive film. The film grew and slowly transformed into a thick oxide layer. The transformation process was associated with enhanced susceptibility to pit nucleation.

Stellwag, B. [Siemens Power Generation, Erlangen (Germany)

1997-02-01T23:59:59.000Z

110

High temperature (600 to 800/sup 0/C) thermally activated deformation behavior of. cap alpha. -Zircaloy-4-oxygen alloys. [DS  

SciTech Connect

The high temperature thermally activated deformation behavior of Zircaloy-4-oxygen alloys containing oxygen up to 1 wt % has been investigated. Decremental unloading technique (Dip technique) was employed to determine the internal stress (tau/sub ..mu../) and thus the effective stress (tau*). Strain rate change tests were done to determine strain rate sensitivity (m) and activation volume (V*). Activation energy (..delta..G/sup ..mu../) was calculated from the above data. Oxygen was found to produce an increase in y.s. (0.2%), tau* and ..delta..G/sub 0//sup ..mu../ and a decrease in m and V* while tau/sub ..mu../ was not affected significantly. These experimental results support the view that the predominant rate controlling mechanism for deformation in this temperature regime is the thermally activated breaking of attractive junctions for these alloys. Oxygen atoms, pairs or clusters of oxygen atoms, are ruled out as barriers, instead the strengthening is attributed to an increase in the core width of the dislocations due to the presence of oxygen. This in turn results in a more stable attractive junction, which is reflected in the increasing values of ..delta..G/sub 0//sup ..mu../ with the increase in oxygen. Finally it is suggested that the atypical temperature dependence of tau/sub ..mu..//..mu.. and ..delta..G/sup ..mu../ is a direct consequence of dynamic recovery.

Mehrotra, B.N.; Tangri, K.

1980-10-01T23:59:59.000Z

111

E-Print Network 3.0 - alloys project quarterly Sample Search...  

NLE Websites -- All DOE Office Websites (Extended Search)

ALLOY CATHODE CATALYST FOR DURABILITY Summary: fundamentals: experimental Catalyst fundamentals: modeling 12;HIGHLY DISPERSED ALLOY CATALYST Project... timeline Project...

112

Structure of high-temperature nickel alloy ZhS36VI for single-crystal blades of high-pressure turbines  

Science Journals Connector (OSTI)

The fine structure, phase composition, and segregation inhomogeneity of carbonless single-crystal rhenium-alloyed alloy ZhS36VI in cast and heat-treated conditions are studied. The structural and phase stabili...

V. P. Kuznetsov; V. P. Lesnikov; E. V. Moroz…

2008-03-01T23:59:59.000Z

113

Entropy Meters and the Entropy of Non-extensive Systems  

E-Print Network (OSTI)

In our derivation of the second law of thermodynamics from the relation of adiabatic accessibility of equilibrium states we stressed the importance of being able to scale a system's size without changing its intrinsic properties. This leaves open the question of defining the entropy of macroscopic, but unscalable systems, such as gravitating bodies or systems where surface effects are important. We show here how the problem can be overcome, in principle, with the aid of an `entropy meter'. An entropy meter can also be used to determine entropy functions for non-equilibrium states and mesoscopic systems.

Elliott H. Lieb; Jakob Yngvason

2014-03-30T23:59:59.000Z

114

Response of nanostructured ferritic alloys to high-dose heavy ion irradiation  

SciTech Connect

A latest-generation aberration-corrected scanning/transmission electron microscope (STEM) is used to study heavy-ion-irradiated nanostructured ferritic alloys (NFAs). Results are presented for STEM X-ray mapping of NFA 14YWT irradiated with 10 MeV Pt to 16 or 160 dpa at -100°C and 750°C, as well as pre-irradiation reference material. Irradiation at -100°C results in ballistic destruction of the beneficial microstructural features present in the pre-irradiated reference material, such as Ti-Y-O nanoclusters (NCs) and grain boundary (GB) segregation. Irradiation at 750°C retains these beneficial features, but indicates some coarsening of the NCs, diffusion of Al to the NCs, and a reduction of the Cr-W GB segregation (or solute excess) content. Ion irradiation combined with the latest-generation STEM hardware allows for rapid screening of fusion candidate materials and improved understanding of irradiation-induced microstructural changes in NFAs.

Parish, Chad M.; White, Ryan M.; LeBeau, James M.; Miller, Michael K.

2014-02-01T23:59:59.000Z

115

Entanglement entropy of black holes  

E-Print Network (OSTI)

The entanglement entropy is a fundamental quantity which characterizes the correlations between sub-systems in a larger quantum-mechanical system. For two sub-systems separated by a surface the entanglement entropy is proportional to the area of the surface and depends on the UV cutoff which regulates the short-distance correlations. The geometrical nature of the entanglement entropy calculation is particularly intriguing when applied to black holes when the entangling surface is the black hole horizon. I review a variety of aspects of this calculation: the useful mathematical tools such as the geometry of spaces with conical singularities and the heat kernel method, the UV divergences in the entropy and their renormalization, the logarithmic terms in the entanglement entropy in 4 and 6 dimensions and their relation to the conformal anomalies. The focus in the review is on the systematic use of the conical singularity method. The relations to other known approaches such as 't Hooft's brick wall model and the Euclidean path integral in the optical metric are discussed in detail. The puzzling behavior of the entanglement entropy due to fields which non-minimally couple to gravity is emphasized. The holographic description of the entanglement entropy of the black hole horizon is illustrated on the two- and four-dimensional examples. Finally, I examine the possibility to interpret the Bekenstein-Hawking entropy entirely as the entanglement entropy.

Sergey N. Solodukhin

2011-04-19T23:59:59.000Z

116

An XPS study of passive films on stainless steels and a high-grade Ni-base alloy in seawater environments  

SciTech Connect

In the present study an assessment has been made of the air-formed passive film and the passive film existing after a short exposure to a synthetic seawater environment on austenitic (UNS S31603), superaustenitic (UNS S31254 and UNS S32654) and superduplex (UNS S32760) stainless steels and a Ni-based alloy (UNS N06625) using X-Ray Photoelectron Spectroscopy (XPS). Assessment of their corrosion behavior has been made through use of electrochemical accelerated tests supported by post-test microscopy. The passive film on the Ni-base (low Fe) UNS N06625 alloy is remarkably similar to those formed on the high Cr and Mo stainless steels. It has been demonstrated that the Fe/Cr ratio in the passive film is dependent on alloy composition and on the conditions to which the material has been exposed and a general correlation between passive film constitution and corrosion resistance is evident.

Hodgkiess, T. [Univ. of Glasgow (United Kingdom); Neville, A. [Heriot-Watt Univ., Edinburgh (United Kingdom). Dept. of Mechanical and Chemical Engineering

1999-11-01T23:59:59.000Z

117

Development of high, stable-efficiency triple-junction a-Si alloy solar cells. Final technical report  

SciTech Connect

This report summarizes Energy Conversion Devices, Inc.`s (ECD) research under this program. ECD researchers explored the deposition of a-Si at high rates using very-high-frequency plasma MHz, and compared these VHF i-layers with radio-frequency (RF) plasma-deposited i-layers. ECD conducted comprehensive research to develop a {mu}c-Si p{sup +} layer using VHF deposition process with the objectives of establishing a wider process window for the deposition of high-quality p{sup +} materials and further enhancing their performance of a-Si solar cells by improving its p-layers. ECD optimized the deposition of the intrinsic a-Si layer and the boron-doped {mu}c-Si p{sup +} layer to improve the V{sub oc}. Researchers deposited wide-bandgap a-Si films using high hydrogen dilution; investigated the deposition of the ZnO layer (for use in back-reflector) using a sputter deposition process involving metal Zn targets; and obtained a baseline fabrication for single-junction a-Si n-i-p devices with 10.6% initial efficiency and a baseline fabrication for triple-junction a-Si devices with 11.2% initial efficiency. ECD researchers also optimized the deposition parameters for a-SiGe with high Ge content; designed a novel structure for the p-n tunnel junction (recombination layer) in a multiple-junction solar cell; and demonstrated, in n-i-p solar cells, the improved stability of a-Si:H:F materials when deposited using a new fluorine precursor. Researchers investigated the use of c-Si(n{sup +})/a-Si alloy/Pd Schottky barrier device as a tool for the effective evaluation of photovoltaic performance on a-Si alloy materials. Through alterations in the deposition conditions and system hardware, researchers improved their understanding for the deposition of uniform and high-quality a-Si and a-SiGe films over large areas. ECD researchers also performed extensive research to optimize the deposition process of the newly constructed 5-MW back-reflector deposition machine.

Deng, X.; Jones, S.J.; Liu, T.; Izu, M. [Energy Conversion Devices, Inc., Troy, MI (United States)

1998-04-01T23:59:59.000Z

118

The Unique High-Pressure Behavior of Curium Probed Further Using Alloys  

SciTech Connect

The changing role of the 5f electrons across the actinide series has been of prime interest for many years. The remarkable behavior of americium's 5f electrons under pressure was determined experimentally a few years ago and it precipitated a strong interest in the heavy element community. Theoretical treatments of americium's behavior under pressure followed and continue today. Experimental and theoretical findings regarding curium's behavior under pressure have shown that the pressure behavior of curium was not a mirror image of that for americium. Rather, one of the five crystallographic phases observed with curium (versus four for americium) was a unique monoclinic structure whose existence is due to a spin stabilization effect by curium's 5f{sup 7} electronic configuration and its half-filled 5f-shell. We review briefly the behavior of pure curium under pressure but focus on the pressure behaviors of three curium alloys with the intent of comparing them with pure curium. An important experimental finding confirmed by theoretical computations, is that dilution of curium with its near neighbors is sufficient to prevent the formation of the unique C2/c phase that appears in pure Cm metal under pressure. As this unique C2/c phase is very sensitive to having a 5f{sup 7} configuration to maximize the magnetic spin polarization, dilution of this state with adjacent actinide neighbors reduces its stability.

Heathman, S. [European Commission Joint Research Centre; Haire, Richard {Dick} G [ORNL; LeBihan, T. [CEA-Centre de Valduc, Is-sur-Tille, France; Ahuja, R. [Uppsala University, Uppsala, Sweden; Li, S. [Virginia Commonwealth University, Richland; Luo, W. [Uppsala University, Uppsala, Sweden; Johansson, B. [Royal Institute of Technology, Stockholm, Sweden

2007-01-01T23:59:59.000Z

119

Sandia National Laboratories: Sandia-Developed Alloy Has Potential...  

NLE Websites -- All DOE Office Websites (Extended Search)

contain lead. Read the Sandia news release. Tagged with: downhole electronics * Geothermal Energy * gold-silver-germanium alloy * High Temperature Electronics * lead-free alloy *...

120

Entropy of Lovelock Black Holes  

E-Print Network (OSTI)

A general formula for the entropy of stationary black holes in Lovelock gravity theories is obtained by integrating the first law of black hole mechanics, which is derived by Hamiltonian methods. The entropy is not simply one quarter of the surface area of the horizon, but also includes a sum of intrinsic curvature invariants integrated over a cross section of the horizon.

Ted Jacobson; Robert C. Myers

1993-05-06T23:59:59.000Z

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121

Information entropy of complex structures  

Science Journals Connector (OSTI)

The information entropy function provides a sensitive measure of the complexity of a multi-component material system, where “complexity” refers to the range of length scales over which morphological features are present. This is demonstrated for an evolving, two-phase microstructure simulated by a population of interacting particles on a two-dimensional surface. The information entropy increases at all length scales as the initially random configuration of particles evolves to produce a distribution of ramified clusters. Maxima in the normalized information entropy function, which is obtained by subtracting the information entropy of a perfectly random configuration from that of the clustered configuration, occur at length scales for which the system most differs from a random configuration, while minima occur at length scales for which the system is periodic or relatively ordered. Besides analysis of complex microstructures, information entropy is useful in detecting features present in any collection of data.

Clinton DeW. Van Siclen

1997-11-01T23:59:59.000Z

122

AN EVALUATION OF HYDROGEN INDUCED CRACKING SUSCEPTIBILITY OF TITANIUM ALLOYS IN US HIGH-LEVEL NUCLEAR WASTE REPOSITORY ENVIRONMENTS  

SciTech Connect

This paper evaluates hydrogen-induced cracking (HIC) susceptibility of titanium alloys in environments anticipated in the Yucca Mountain nuclear waste repository with particular emphasis on the. effect of the oxide passive film on the hydrogen absorption process of titanium alloys being evaluated. The titanium alloys considered in this review include Ti 2, 5 , 7, 9, 11, 12, 16, 17, 18, 24 and 29. In general, the concentration of hydrogen in a titanium alloy can increase due to absorption of atomic hydrogen produced from passive general corrosion of that alloy or galvanic coupling of it to a less noble metal. It is concluded that under the exposure conditions anticipated in the Yucca Mountain repository, the HIC of titanium drip shield will not occur because there will not be sufficient hydrogen in the metal even after 10,000 years of emplacement. Due to the conservatisms adopted in the current evaluation, this assessment is considered very conservative.

G. De; K. Mon; G. Gordon; D. Shoesmith; F. Hua

2006-02-21T23:59:59.000Z

123

The Stress Corrosion Crack Growth Rate of Alloy 600 Heat Affected Zones Exposed to High Purity Water  

SciTech Connect

Grain boundary chromium carbides improve the resistance of nickel based alloys to primary water stress corrosion cracking (PWSCC). However, in weld heat affected zones (HAZ's), thermal cycles from fusion welding can solutionize beneficial grain boundary carbides, produce locally high residual stresses and strains, and promote PWSCC. The present research investigates the crack growth rate of an A600 HAZ as a function of test temperature. The A600 HAZ was fabricated by building up a gas-tungsten-arc-weld deposit of EN82H filler metal onto a mill-annealed A600 plate. Fracture mechanics based, stress corrosion crack growth rate testing was performed in high purity water between 600 F and 680 F at an initial stress intensity factor of 40 ksi {radical}in and at a constant electrochemical potential. The HAZ samples exhibited significant SCC, entirely within the HAZ at all temperatures tested. While the HAZ samples showed the same temperature dependence for SCC as the base material (HAZ: 29.8 {+-} 11.2{sub 95%} kcal/mol vs A600 Base: 35.3 {+-} 2.58{sub 95%} kcal/mol), the crack growth rates were {approx} 30X faster than the A600 base material tested at the same conditions. The increased crack growth rates of the HAZ is attributed to fewer intergranular chromium rich carbides and to increased plastic strain in the HAZ as compared to the unaffected base material.

George A. Young; Nathan Lewis

2003-04-05T23:59:59.000Z

124

Vehicle Technologies Office Merit Review 2014: High Speed Joining of Dissimilar Alloy Aluminum Tailor Welded Blanks  

Energy.gov (U.S. Department of Energy (DOE))

Presentation given by Pacific Northwest National Laboratory at 2014 DOE Hydrogen and Fuel Cells Program and Vehicle Technologies Office Annual Merit Review and Peer Evaluation Meeting about high...

125

Weldable ductile molybdenum alloy development  

SciTech Connect

Molybdenum and its alloys are attractive structural materials for high-temperature applications. However, various practical issues have limited its use. One concern relates to the loss of ductility occurring in the heat-affected weld zone caused by segregation of oxygen to grain boundaries. In this study, a series of arc melted molybdenum alloys have been produced containing controlled additions of B, C, Zr, and Al. These alloys were characterized with respect to their tensile properties, smooth bend properties, and impact energy for both the base metal and welds. These alloys were compared with a very high purity low carbon arc cast molybdenum reference. For discussion purposes the alloys produced are separated into two categories: Mo Al B alloys, and Mo Zr B alloys. The properties of Mo Zr B alloy welds containing higher carbon levels exhibited slight improvement over unalloyed molybdenum, though the base-metal properties for all Mo Zr B alloys were somewhat inconsistent with properties better, or worse, than unalloyed molybdenum. A Mo Al B alloy exhibited the best DBTT values for welds, and the base metal properties were comparable to or slightly better than unalloyed molybdenum. The Mo Al B alloy contained a low volume fraction of second-phase particles, with segregation of boron and carbon to grain boundaries believed to displace oxygen resulting in improved weld properties. The volume fractions of second-phase particles are higher for the Mo Zr B alloys, and these alloys were prone to brittle fracture. It is also noted that these Mo Zr B alloys exhibited segregation of zirconium, boron and carbon to the grain boundaries.

Cockeram, B. V. [Bettis Atomic Power Laboratory, West Mifflin, PA; Ohriner, Evan Keith [ORNL; Byun, Thak Sang [ORNL; Schneibel, Joachim H [ORNL; Miller, Michael K [ORNL; Snead, Lance Lewis [ORNL

2008-01-01T23:59:59.000Z

126

Rindler Energy is Wald Entropy  

E-Print Network (OSTI)

We show that, in any theory of gravity, the entropy of any nonextreme black hole is given by $2 \\pi E_R$ where $E_R$ is the dimensionless Rindler energy. Separately, we show that $E_R$ is exactly Wald's Noether charge and therefore this entropy is identical to Wald entropy. However, it is off--shell and derived solely from the time evolution of the black hole. We examine Gauss--Bonnet black holes as an example and speculate on the degrees of freedom that $E_R$ counts.

Edi Halyo

2014-03-10T23:59:59.000Z

127

Wear resistance of titanium-alloyed high-aluminum bronzes under cavitation  

Science Journals Connector (OSTI)

Aluminum-nickel bronzes are known to have a high cavitation-erosion resistance; this is especially true of bronzes containing 11–14% Al, which can be used to restore worn parts of hydraulic engines, marine engine...

Yu. N. Tsvetkov; L. I. Pogodaev

1994-02-01T23:59:59.000Z

128

Perturbation theory of von Neumann Entropy  

E-Print Network (OSTI)

In quantum information theory, von Neumann entropy plays an important role. The entropies can be obtained analytically only for a few states. In continuous variable system, even evaluating entropy numerically is not an easy task since the dimension is infinite. We develop the perturbation theory systematically for calculating von Neumann entropy of non-degenerate systems as well as degenerate systems. The result turns out to be a practical way of the expansion calculation of von Neumann entropy.

Xiao-yu Chen

2009-02-27T23:59:59.000Z

129

Embrittlement of Stainless Steels and Nickel-Based Alloys at High Temperature Induced by Neutron Radiation  

Science Journals Connector (OSTI)

... not recovered15. Thus, the precipitation effects are not the prime cause of the embrittlement.Boron-10 appeared the most likely isotope because of its high thermal neutron cross-section. Rather ... metallurgical changes induced) a constant amount of boron was added in the form of either boron-10 or boron-11. Irradiation of these chemically and metallurgically similar steels clearly showed that ...

R. S. BARNES

1965-06-26T23:59:59.000Z

130

High-pressure alloying of potassium and iron: Radioactivity in the Earth's core?  

E-Print Network (OSTI)

/U (potassium/uranium) ratios of $1 Ã? 104 on Earth are distinct from the 8 Ã? 104 ratio found in chondrites argued that because potassium is a moderately volatile element, it is depleted due to the high for the depletion of K in the terrestrial planets, as a mass-dependent depletion of the isotopes would

Lee, Kanani K. M.

131

Ni{sub 3}Al aluminide alloys  

SciTech Connect

This paper provides a brief review of the recent progress in research and development of Ni{sub 3}Al and its alloys. Emphasis has been placed on understanding low ductility and brittle fracture of Ni{sub 3}Al alloys at ambient and elevated temperatures. Recent studies have resulted in identifying both intrinsic and extrinsic factors governing the fracture behavior of Ni{sub 3}Al alloys. Parallel efforts on alloy design using physical metallurgy principles have led to properties for structural use. Industrial interest in these alloys is high, and examples of industrial involvement in processing and utilization of these alloys are briefly mentioned.

Liu, C.T.

1993-10-01T23:59:59.000Z

132

High Accuracy U-235 Enrichment Verification Station for Low Enriched Uranium Alloys  

SciTech Connect

The Y-12 National Security Complex is playing a role in the U.S. High Performance Research Reactor (USHPRR) Conversion program sponsored by the U.S. National Nuclear Security Administration's Office of Global Threat Reduction. The USHPRR program has a goal of converting remaining U.S. reactors that continue to use highly enriched uranium (HEU) fuel to low enriched uranium (LEU) fuel. The USHPRR program is currently developing a LEU Uranium-Molybdenum (U-Mo) monolithic fuel for use in the U.S. high performance research reactors.Y-12 is supporting both the fuel development and fuel fabrication efforts by fabricating low enriched U-Mo foils from its own source material for irradiation experiments and for optimizing the fabrication process in support of scaling up the process to a commercial production scale. Once the new fuel is qualified, Y-12 will produce and ship U-Mo coupons with verified 19.75% +0.2% - 0.3% U-235 enrichment to be fabricated into fuel elements for the USHPRRs. Considering this small enrichment tolerance and the transition into HEU being set strictly at 20% U-235, a characterization system with a measurement uncertainty of less than or equal to 0.1% in enrichment is desired to support customer requirements and minimize production costs. Typical uncertainty for most available characterization systems today is approximately 1-5%; therefore, a specialized system must be developed which results in a reduced measurement uncertainty. A potential system using a High-Purity Germanium (HPGe) detector has been procured, and tests have been conducted to verify its capabilities with regards to the requirements. Using four U-Mo enrichment standards fabricated with complete isotopic and chemical characterization, infinite thickness and peak-ratio enrichment measurement methods have been considered for use. As a result of inhomogeneity within the U-Mo samples, FRAM, an isotopic analysis software, has been selected for initial testing. A systematic approach towards observing effects on FRAM's enrichment analysis has been conducted with regards to count and dead time.

Lillard, C. R.; Hayward, J. P.; Williamson, M. R.

2012-06-07T23:59:59.000Z

133

SEM Characterization of the High Burn-up Microstructure of U-7Mo Alloy  

SciTech Connect

During irradiation, the microstructure of U-7Mo evolves until at a fission density near 5x1021 f/cm3 a high-burnup microstructure exists that is very different than what was observed at lower fission densities. This microstructure is dominated by randomly distributed, relatively large, homogeneous fission gas bubbles. The bubble superlattice has collapsed in many microstructural regions, and the fuel grain sizes, in many areas, become sub-micron in diameter with both amorphous fuel and crystalline fuel present. Solid fission product precipitates can be found inside the fission gas bubbles. To generate more information about the characteristics of the high-fission density microstructure, three samples irradiated in the RERTR-7 experiment have been characterized using a scanning electron microscope equipped with a focused ion beam. The FIB was used to generate samples for SEM imaging and to perform 3D reconstruction of the microstructure, which can be used to look for evidence of possible fission gas bubble interlinkage.

Dennis D. Keiser, Jr.; Jan-Fong Jue; Jian Gan; Brandon Miller; Adam Robinson; Pavel Medvedev; James Madden; Dan Wachs; M. Teague

2014-04-01T23:59:59.000Z

134

PROCESSING OF HIGH-PERFORMANCE Nb{sub 3}Sn WIRES THROUGH A NEW DIFFUSION REACTION USING Sn BASED ALLOYS  

SciTech Connect

Tightly consolidated Sn-Ta and Sn-B based alloys have been prepared by the reaction among constituent metal powders at 750-775 deg. C. Sn-Ta and Sn-B based alloys exhibit quite similar microstructures. A small amount of Ti addition seems to improve the bonding between Ta or B particles and Sn matrix. Nb{sub 3}Sn wires have been fabricated by the Jelly Roll (JR) and Multi-rod (MR) process using Sn based alloy sheet and rod, respectively. Thick Nb{sub 3}Sn layers with nearly stoichiometric A15 composition are synthesized through a new diffusion mechanism between Nb and Sn based alloy. B{sub c2}(4.2 K)'s of 26.9 T (mid) and 26.5 T (mid) have been obtained in the JR and MR processed wires, respectively, using Sn-Ta based alloy. These wires exhibit enough non-Cu J{sub c} to be used above 20 T and 4.2 K. T{sub c} of JR wires using Sn-B based sheet is 18.14 K (offset) which is slightly higher than that of wires using Sn-Ta based sheet.

Tachikawa, K.; Sasaki, H.; Yamaguchi, M.; Hayashi, Y.; Nakata, K. [Faculty of Engineering, Tokai University, Hiratsuka, Kanagawa 259-1292 (Japan); Takeuchi, T. [National Institute for Materials Science, Tsukuba, Ibaraki 305-0047 (Japan)

2010-04-08T23:59:59.000Z

135

Welding of dissimilar alloys for high temperature heat exchangers for SOFC  

SciTech Connect

Reduction in the cost of balance of plant applications is one of the top priority focus areas for the successful implementation of solid oxide fuel cell technology. High temperature heat exchangers are employed to heat cathode air utilizing either hot gases coming from the anode side of the stack or other hot gases generated by external processes. In order to reduce the cost of heat exchangers, it may be necessary to apply several different materials, each in a different temperature zone, for the construction of the heat exchanger. This technique would require the joining of dissimilar materials in the construction. In this work, welding of commercial candidate dissimilar materials is explored. Filler materials were identified using equilibrium phase diagrams and thermodynamic simulation software. Autogenous welding was performed and the welding defects were characterized. Finally, experimental weld microstructures were compared to phases predicted by the simulations.

Wilson, R.D.; Hatem, J.; Dogan, O.N.; King, P.E.

2006-10-01T23:59:59.000Z

136

High Temperature Oxidation Behavior of gamma-Ni+gamma'-Ni3Al Alloys and Coatings Modified with Pt and Reactive Elements  

SciTech Connect

Materials for high-pressure turbine blades must be able to operate in the high-temperature gases (above 1000 C) emerging from the combustion chamber. Accordingly, the development of nickel-based superalloys has been constantly motivated by the need to have improved engine efficiency, reliability and service lifetime under the harsh conditions imposed by the turbine environment. However, the melting point of nickel (1455 C) provides a natural ceiling for the temperature capability of nickel-based superalloys. Thus, surface-engineered turbine components with modified diffusion coatings and overlay coatings are used. Theses coatings are capable of forming a compact and adherent oxide scale, which greatly impedes the further transport of reactants between the high-temperature gases and the underlying metal and thus reducing attack by the atmosphere. Typically, these coatings contain {beta}-NiAl as a principal constituent phase in order to have sufficient aluminum content to form an Al{sub 2}O{sub 3} scale at elevated temperatures. The drawbacks to the currently-used {beta}-based coatings, such as phase instabilities, associated stresses induced by such phase instabilities, and extensive coating/substrate interdiffusion, are major motivations in this study to seek next-generation coatings. The high-temperature oxidation resistance of novel Pt + Hf-modified {gamma}-Ni + {gamma}-Ni{sub 3}Al-based alloys and coatings were investigated in this study. Both early-stage and 4-days isothermal oxidation behavior of single-phase {gamma}-Ni and {gamma}{prime}-Ni{sub 3}Al alloys were assessed by examining the weight changes, oxide-scale structures, and elemental concentration profiles through the scales and subsurface alloy regions. It was found that Pt promotes Al{sub 2}O{sub 3} formation by suppressing the NiO growth on both {gamma}-Ni and {gamma}{prime}Ni{sub 3}Al single-phase alloys. This effect increases with increasing Pt content. Moreover, Pt exhibits this effect even at lower temperatures ({approx}970 C) in the very early stage of oxidation. It was also inferred that Pt enhances the diffusive flux of aluminum from the substrate to the scale/alloy interface. Relatively low levels of hafnium addition to Pt-free {gamma}{prime}-Ni{sub 3}Al increased the extent of external NiO formation due to non-protective HfO{sub 2} formation. Accordingly, this effect intensified with increasing Hf content from 0.2 to 0.5 at.%.

Nan Mu

2007-12-01T23:59:59.000Z

137

Black hole entanglement entropy regularized in a freely falling frame  

Science Journals Connector (OSTI)

We compute the black hole horizon entanglement entropy SE for a massless scalar field, first with a hard cutoff and then with high frequency dispersion, both imposed in a frame that falls freely across the horizon. Using WKB methods, we find that SE is finite for a hard cutoff or superluminal dispersion, because the mode oscillations do not diverge at the horizon and the contribution of high transverse momenta is cut off by the angular momentum barrier. For subluminal dispersion, the entropy depends on the behavior at arbitrarily high transverse momenta. In all cases it scales with the horizon area. For the hard cutoff it is linear in the cutoff, rather than quadratic. This discrepancy from the familiar result arises from the difference between the free-fall frame and the static frame in which a cutoff is usually imposed. In the superluminal case the entropy scales with a fractional power of the cutoff that depends on the index of the dispersion relation. Implications for the possible relation between regularized entanglement entropy and the Bekenstein-Hawking entropy are discussed. An appendix provides an explicit derivation of the entangled, thermal nature of the near-horizon free-fall vacuum for a dispersive scalar field in four dimensions.

Ted Jacobson and Renaud Parentani

2007-07-13T23:59:59.000Z

138

High resolution microstructure analysis of the decomposition of Cu{sub 90}CO{sub 10} alloys  

SciTech Connect

Homogeneous Cu-Co alloys with a Co concentration up to 10 at.% Co are prepared by rapid quenching. This allows for the first time the investigation of the decomposition process of the Cu{sub 90}Co{sub 10} supersaturated solid solution on a nanometer scale using a combination of atom probe/field ion microscopy (AP/FIM) analyses and transmission electron microscopy. Annealing of a Cu{sub 90}Co{sub 10} alloy at 440 C for various times leads to a compositional modulated microstructure. The composition profiles determined by AP/FIM analyses clearly exclude a classical nucleation and growth behavior and instead suggest a spinodal type decomposition whereby the compositions of the precipitates continuously increase. In contrast, at the grain boundaries of the Cu{sub 90}Co{sub 10} alloy heterogeneous nucleation of pure Co particles is observed.

Busch, R.; Gaertner, F.; Borchers, C.; Haasen, P. [Univ. Goettingen (Germany). Inst. fuer Metallphysik] [Univ. Goettingen (Germany). Inst. fuer Metallphysik; Bormann, R. [GKSS-Research Center, Geesthacht (Germany). Inst. for Materials Research] [GKSS-Research Center, Geesthacht (Germany). Inst. for Materials Research

1996-06-01T23:59:59.000Z

139

Sulfur Tolerant Pd/Cu and Pd/Au Alloy Membranes for H2 Separation with High Pressure CO2 for Sequestration  

SciTech Connect

The effect of H{sub 2}S poisoning on Pd, Pd/Cu, and Pd/Au alloy composite membranes prepared by the electroless deposition method on porous Inconel supports was investigated to provide a fundamental understanding of the durability and preparation of sulfur tolerant membranes. X-ray photoelectron spectroscopy (XPS) studies showed that the exposure of pure Pd to 50 ppm H{sub 2}S/H{sub 2} mixtures caused bulk sulfide formation at lower temperatures and surface sulfide formation at higher temperatures. Lower temperatures, longer exposure times, and higher H{sub 2}S concentrations resulted in a higher degree of sulfidation. In a Pd membrane, the bulk sulfide formation caused a drastic irrecoverable H{sub 2} permeance decline and an irreparable loss in selectivity. Pd/Cu and Pd/Au alloy membranes exhibited permeance declines due to surface sulfide formation upon exposure to 50 ppm H{sub 2}S/H{sub 2} gas mixtures. However in contrast to the pure Pd membrane, the permeances of the Pd/Cu and Pd/Au alloy membranes were mostly recovered in pure H{sub 2} and the selectivity of the Pd alloy layers remained essentially intact throughout the characterization in H{sub 2}, He and H{sub 2}S/H{sub 2} mixtures which lasted several thousand hours. The amount of irreversible sulfur poisoning decreased with increasing temperature due to the exothermicity of H{sub 2}S adsorption. Longer exposure times increased the amount of irreversible poisoning of the Pd/Cu membrane but not the Pd/Au membrane. Pd/Au coupon studies of the galvanic displacement method showed that higher Au{sup 3+} concentrations, lower pH values, higher bath temperatures and stirring the bath at a rate of 200 rpm yielded faster displacement rates, more uniform depositions, and a higher Au content within the layers. While 400 C was found to be sufficient to form a Pd/Au alloy on the surface, high temperature X-ray diffraction (HTXRD) studies showed that even after annealing between 500-600 C, the Pd/Cu alloys could have part or all of the surface in the less sulfur resistant {beta} phase.

Yi Hua Ma; Natalie Pomerantz; Chao-Huang Chen

2008-09-30T23:59:59.000Z

140

Grain boundary depletion and migration during selective oxidation of Cr in a Ni-5Cr binary alloy exposed to high-temperature hydrogenated water  

SciTech Connect

High-resolution microscopy of a high-purity Ni-5Cr alloy exposed to 360°C hydrogenated water reveals intergranular selective oxidation of Cr accompanied by local Cr depletion and diffusion-induced grain boundary migration (DIGM). The corrosion-product oxide consists of a porous, interconnected network of Cr2O3 platelets with no further O ingress into the metal ahead. Extensive grain boundary depletion of Cr (to <0.05at.%) is observed typically 20–100 nm wide as a result of DIGM and reaching depths of many micrometers beyond the oxidation front.

Schreiber, Daniel K.; Olszta, Matthew J.; Bruemmer, Stephen M.

2014-10-15T23:59:59.000Z

Note: This page contains sample records for the topic "high entropy alloy" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


141

Deformation behavior of laser welds in high temperature oxidation resistant Fe–Cr–Al alloys for fuel cladding applications  

Science Journals Connector (OSTI)

Abstract Ferritic-structured Fe–Cr–Al alloys are being developed and show promise as oxidation resistant accident tolerant light water reactor fuel cladding. This study focuses on investigating the weldability and post-weld mechanical behavior of three model alloys in a range of Fe–(13–17.5)Cr–(3–4.4)Al (wt.%) with a minor addition of yttrium using modern laser-welding techniques. A detailed study on the mechanical performance of bead-on-plate welds using sub-sized, flat dog-bone tensile specimens and digital image correlation (DIC) has been carried out to determine the performance of welds as a function of alloy composition. Results indicated a reduction in the yield strength within the fusion zone compared to the base metal. Yield strength reduction was found to be primarily constrained to the fusion zone due to grain coarsening with a less severe reduction in the heat affected zone. For all proposed alloys, laser welding resulted in a defect free weld devoid of cracking or inclusions.

Kevin G. Field; Maxim N. Gussev; Yukinori Yamamoto; Lance L. Snead

2014-01-01T23:59:59.000Z

142

Friction stir additive manufacturing for high structural performance through microstructural control in an Mg based WE43 alloy  

Science Journals Connector (OSTI)

Abstract Structural performance is a key challenge pertinent to additive manufacturing. A majority of the current techniques employed for metallic materials involve liquid–solid transformation and their performance is limited by solidification microstructures. Depending on the type of metallic alloy, this can be a serious impediment to structural properties. In this regard, solid-state additive manufacturing techniques have lagged behind. This study is focused on friction stir additive manufacturing (FSAM) as a potential technique to attain structurally efficient magnesium alloys. In this study, a multilayered stack of an Mg based WE43 alloy was built using FSAM at two different welding parameters. Formation of defects is sensitive to the heat input. In addition, dynamic recrystallization led to finer grain size (2–3 ?m). Such fine grain size coupled with desirable precipitate characteristics culminated in superior mechanical properties. Maximum hardness of 115 HV was obtained in as-fabricated state and increased to 135 HV after aging. These levels are similar to Al 2XXX alloys. In fact, in terms of strength, it translates to 400 MPa and 17% ductility and is significantly higher than the base material subjected to aging. Mechanical properties have been correlated with detailed microstructural observations. Texture is discussed for a higher heat input sample using orientation imaging microscopy.

S. Palanivel; P. Nelaturu; B. Glass; R.S. Mishra

2015-01-01T23:59:59.000Z

143

Universality in holographic entropy production  

E-Print Network (OSTI)

We consider the time evolution of two entropy-like quantities, the holographic entanglement entropy and causal holographic information, in a model of holographic thermalization dual to the gravitational collapse of a thin planar shell. Unlike earlier calculations valid in different limits, we perform a full treatment of the dynamics of the system, varying both the shell's equation of state and initial position. In all cases considered, we find that between an early period related to the acceleration of the shell and a late epoch of saturation towards the thermal limit, the entanglement entropy exhibits universal linear growth in time in accordance with the prediction of Liu and Suh. As intermediate steps of our analysis, we explicitly construct a coordinate system continuous at the location of an infinitely thin shell and derive matching conditions for geodesics and extremal surfaces traversing this region.

Keranen, Ville; Stricker, Stefan; Taanila, Olli; Vuorinen, Aleksi

2014-01-01T23:59:59.000Z

144

Universality in holographic entropy production  

E-Print Network (OSTI)

We consider the time evolution of two entropy-like quantities, the holographic entanglement entropy and causal holographic information, in a model of holographic thermalization dual to the gravitational collapse of a thin planar shell. Unlike earlier calculations valid in different limits, we perform a full treatment of the dynamics of the system, varying both the shell's equation of state and initial position. In all cases considered, we find that between an early period related to the acceleration of the shell and a late epoch of saturation towards the thermal limit, the entanglement entropy exhibits universal linear growth in time in accordance with the prediction of Liu and Suh. As intermediate steps of our analysis, we explicitly construct a coordinate system continuous at the location of an infinitely thin shell and derive matching conditions for geodesics and extremal surfaces traversing this region.

Ville Keranen; Hiromichi Nishimura; Stefan Stricker; Olli Taanila; Aleksi Vuorinen

2014-05-27T23:59:59.000Z

145

Use of mutual information to decrease entropy: Implications for the second law of thermodynamics  

Science Journals Connector (OSTI)

Several theorems on the mechanics of gathering information are proved, and the possibility of violating the second law of thermodynamics by obtaining information is discussed in light of these theorems. Maxwell’s demon can lower the entropy of his surroundings by an amount equal to the difference between the maximum entropy of his recording device and its initial entropy, without generating a compensating entropy increase. A demon with human-scale recording devices can reduce the entropy of a gas by a negligible amount only, but the proof of the demon’s impracticability leaves open the possibility that systems highly correlated with their environment can reduce the environment’s entropy by a substantial amount without increasing entropy elsewhere. In the event that a boundary condition for the universe requires it to be in a state of low entropy when small, the correlations induced between different particle modes during the expansion phase allow the modes to behave like Maxwell’s demons during the contracting phase, reducing the entropy of the universe to a low value.

Seth Lloyd

1989-05-15T23:59:59.000Z

146

ENTROPY PRODUCTION AND RADIATION ENTROPY FLUX OF THE EARTH SYSTEM  

E-Print Network (OSTI)

the assumption of an isotropic gray-body Earth and isotropic reflecting TOA shortwave (SW) radiation. It is shown entropy flux can be improved by relaxing the commonly used Lambertian assumption. __________ NOTICE- 98CH10886 with the U.S. Department of Energy. The publisher by accepting the manuscript

147

Remainder terms for some quantum entropy inequalities  

SciTech Connect

We consider three von Neumann entropy inequalities: subadditivity; Pinsker's inequality for relative entropy; and the monotonicity of relative entropy. For these we state conditions for equality, and we prove some new error bounds away from equality, including an improved version of Pinsker's inequality.

Carlen, Eric A.; Lieb, Elliott H. [Department of Mathematics, Hill Center, Rutgers University, 110 Frelinghuysen Road, Piscataway, New Jersey 08854-8019 (United States) [Department of Mathematics, Hill Center, Rutgers University, 110 Frelinghuysen Road, Piscataway, New Jersey 08854-8019 (United States); Departments of Mathematics and Physics, Jadwin Hall, Princeton University, Washington Road, Princeton, New Jersey 08544-0001 (United States)

2014-04-15T23:59:59.000Z

148

Entropy, Stochastic Matrices, and Quantum Operations  

E-Print Network (OSTI)

The goal of the present paper is to derive some conditions on saturation of (strong) subadditivity inequality for the stochastic matrices. The notion of relative entropy of stochastic matrices is introduced by mimicking quantum relative entropy. Some properties of this concept are listed and the connection between the entropy of the stochastic quantum operations and that of stochastic matrices are discussed.

Lin Zhang

2011-10-28T23:59:59.000Z

149

Computer Simulation and Experimental Validation on the Oxidation and Sulfate Corrosion Resistance of Novel Chromium-Based High-temperature Alloys  

NLE Websites -- All DOE Office Websites (Extended Search)

Computer Simulation and Experimental Computer Simulation and Experimental Validation on the Oxidation and Sulfate Corrosion Resistance of Novel Chromium-Based High-temperature Alloys Background Advanced coal power generation is a critical component of the U.S. energy portfolio. The U.S. Department of Energy (DOE) is committed to supporting research that will increase the efficiency and decrease the environmental impact of coal-fired plants, thus enabling the long term use of a low cost domestic fuel source. One key factor to

150

Black Holes And Their Entropy  

E-Print Network (OSTI)

This dissertation covers two di erent but related topics: the construction of new black hole solutions and the study of the microscopic origin of black hole entropy. In the solution part, two di erent sets of new solutions are found. The rst...

Mei, Jianwei

2010-10-12T23:59:59.000Z

151

The structural and mechanical properties of a Cu??Zr??(at. %) alloy processed by High-Velocity-Injection (HVI)  

E-Print Network (OSTI)

) cooling rate, (3) defects and/or defect structure, (4) density and, (5) purity. The samples investigated in this research will be a copper- zirconium alloy of composition Cu Zr (at. ?) . This alloy was chosen because it is a member of a group...+Zr, C E6 8220C 4~0. 2 a~Zr, Cu 3200 2800 u 2600 ur 2400 g O 2200 ~ 2000 ~ i800 ~ l 600 i 100'C piZrCu3 965'C 935'C 895 C )I Sar I I g 47 92PC ~ 'C 1 400 Zr, cu $ ZrCu R O ZrCu~+Cu l200 lO 20 30 40 50 60 70 80 90 l00 WEIGHT...

Hays, Charles C.

2012-06-07T23:59:59.000Z

152

Origin of Entropy Convergence in Hydrophobic Hydration and Protein Folding  

SciTech Connect

An information theory model of hydrophobic effects is used to construct a molecular explanation why hydrophobic solvation entropies of protein unfolding measured by high sensitivity calorimetry converge to zero at a common convergence temperature. The entropy convergence follows directly from the weak temperature dependence of occupancy fluctuations {l_angle}{delta}{ital n}{sup 2}{r_angle} for molecular-scale volumes in water. The macroscopic expression of the contrasting entropic behavior of water relative to common organic solvents is the {ital relative} temperature insensitivity of the water isothermal compressibility compared to hydrocarbon liquids. The information theory model used provides a quantitative description of small molecule hydration and, in addition, predicts that the value of the entropy at convergence is slightly {ital negative}. Interpretations of entropic contributions to protein folding should account for this result. {copyright} {ital 1996 The American Physical Society.}

Garde, S.; Hummer, G.; Garcia, A.E.; Paulaitis, M.E.; Pratt, L.R. [Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)] [Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); [Center for Molecular and Engineering Thermodynamics, Department of Chemical Engineering, University of Delaware, Newark, Delaware 19716 (United States); [Department of Chemical Engineering, Johns Hopkins University, Baltimore, Maryland 21218 (United States)

1996-12-01T23:59:59.000Z

153

Attack of high-strength, oxidation-resistant alloys during in-can melting of simulated waste glasses  

SciTech Connect

The restistance of candidate canister alloys to penetration under the most severe conditions expected during in-can melting was directly proportional to the chromium content of the alloy, and inversely proportional to the Na/sub 2/O content of the glass melt. Specimens were exposed for 24 hours, which is the time required for in-can melting full-size waste-glass forms based on tests carried out at Pacific Northwest Laboratories (PNL) and at SRL. The penetration resistance to Frit 211 at 1150/sup 0/C for 24 hours of most alloys tested was satisfactory. The amount of penetration would not affect the integrity of the waste form. Inconel 625, Hastelloy X, and Inconel 601 were penetrated < 20 mils. This was considered excellent. Incoloy 801, Type 310 stainless steel, Type 304L stainless steel, Inconel 600, and Type 347 stainless steel were penetrated < 40 mils. This was considered good. Hastelloy C-4 was penetrated > 100 mils by a glass composed of 65 wt % Frit 21 and 35 wt % composite sludge (with uranium) at 1150/sup 0/C for only 7 hours. This amount of penetration of an in-can melting canister would not be satisfactory. 12 figures.

Rankin, W.N.

1980-01-01T23:59:59.000Z

154

E-Print Network 3.0 - alloy semiconductor crystals Sample Search...  

NLE Websites -- All DOE Office Websites (Extended Search)

for binary alloys. The high... , and the correlations are then used to accelerate identification of stable crystal structures in new alloys. Keywords... of structural...

155

E-Print Network 3.0 - alloy steel weldment Sample Search Results  

NLE Websites -- All DOE Office Websites (Extended Search)

controlling usage of welded high-strength, low-alloy steels in sour enviroments... Steel Pipeline Base Alloy Compositions (wt-%) and Pipe ... Source: Ohio State University,...

156

Composition–Structure–Function Diagrams of Ti–Ni–Au Thin Film Shape Memory Alloys  

Science Journals Connector (OSTI)

thin films; annealing; high temperature shape memory alloys; combinatorial materials science; phase transformation ...

Pio John S. Buenconsejo; Alfred Ludwig

2014-11-04T23:59:59.000Z

157

Single-step high-speed nanogranulation of metal alloy around carbon nanotubes by flash light irradiation  

Science Journals Connector (OSTI)

We demonstrate to decorate carbon nanotubes (CNTs) with metal alloy nanoparticles by flash light from a xenon lamp highlighting dramatically simplified process and ultrafast speed of millisecond. By managing the pulse energy of the irradiation, we customize the nucleation and growth rates of homogeneous binary and ternary nanoparticles with Pt–Ru and Pt–Ru–Mo thin layers that are e-beam deposited onto CNTs. No damage of \\{CNTs\\} during the light-induced nanogranulation is guaranteed by the rapid and surface-localized heating mechanism. The fabricated nanoparticle/CNT nanostructures are characterized using variety of microscopic and spectroscopic techniques such as SEM, TEM and Raman spectroscopy.

Yong-Won Song; Sung-Hyeon Park; Won-Suk Han; Jae-Min Hong; Hak-Sung Kim

2011-01-01T23:59:59.000Z

158

Entanglement entropy for even spheres  

E-Print Network (OSTI)

The coefficient of the logarithmic term in the entropy on even spheres is re-computed by the local technique of integrating the finite temperature energy density up to the horizon on static d--dimensional de Sitter space and thence finding the entropy by thermodynamics. Numeric evaluation yields the known answer i.e. (minus) the conformal anomaly on the d-sphere. The de Sitter quantities are obtained by conformal transformation of the Rindler ones, themselves obtained, for convenience, from those around a cosmic string. The expressions are given in terms of generalised Bernoulli polynomials for which an identity is derived. The arising spherical conformal anomaly is discussed and a formula is given for it for Branson's higher GJMS Laplacian, P_2k, as an oscillating polynomial in the level, k.

J. S. Dowker

2010-09-20T23:59:59.000Z

159

High Mg-content wurtzite MgZnO alloys and their application in deep-ultraviolet light-emitters pumped by accelerated electrons  

SciTech Connect

High Mg-content single-phase wurtzite MgZnO alloys with a bandgap of 4.35?eV have been obtained on sapphire substrate by introducing a composition-gradient Mg{sub x}Zn{sub 1?x}O buffer layer. By employing the accelerated electrons obtained in a solid-state structure as an excitation source, an emission at around 285?nm, which is originated from the near-band-edge emission of the Mg{sub 0.51}Zn{sub 0.49}O active layer, has been observed. The results reported in this paper may provide a promising route to high performance deep-ultraviolet light-emitting devices by bypassing the challenging doping issues of wide bandgap semiconductors.

Ni, Pei-Nan [State Key Laboratory of Luminescence and Applications, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033 (China); University of Chinese Academy of Sciences, Beijing 100049 (China); Shan, Chong-Xin, E-mail: shancx@ciomp.ac.cn, E-mail: shendz@ciomp.ac.cn; Li, Bing-Hui; Shen, De-Zhen, E-mail: shancx@ciomp.ac.cn, E-mail: shendz@ciomp.ac.cn [State Key Laboratory of Luminescence and Applications, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, Changchun 130033 (China)

2014-01-20T23:59:59.000Z

160

A stronger monotonicity inequality of quantum relative entropy: A unifying approach via Rényi relative entropy  

E-Print Network (OSTI)

In this paper, a stronger monotonicity inequality of quantum relative entropy is derived by employing a property of $\\alpha$-R\\'{e}nyi relative entropy. In view of this inequality, a unifying treatment towards improvement of some quantum entropy inequalities is developed. In particular, an emphasis is put on a lower bound of quantum conditional mutual information because this lower bound gives a Pinsker-like lower bound for strong subadditivity inequality of von Neumann entropy.

Lin Zhang

2014-03-21T23:59:59.000Z

Note: This page contains sample records for the topic "high entropy alloy" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


161

Entropy generation in a chemical reaction  

E-Print Network (OSTI)

Entropy generation in a chemical reaction is analyzed without using the general formalism of non-equilibrium thermodynamics at a level adequate for advanced undergraduates. In a first approach to the problem, the phenomenological kinetic equation of an elementary first order reaction is used to show that entropy production is always positive. A second approach assumes that the reaction is near equilibrium to prove that the entropy generated is always greater than zero, without any reference to the kinetics of the reaction. Finally, it is shown that entropy generation is related to fluctuations in the number of particles at equilibrium, i.e. it is associated to a microscopic process.

E. N. Miranda

2012-08-10T23:59:59.000Z

162

High-Velocity Oxygen Fuel Thermal Spray of Fe-Based Amorphous Alloy: a Numerical and Experimental Study  

E-Print Network (OSTI)

High-Velocity Oxygen Fuel Thermal Spray of Fe-Basedusing a high velocity oxygen fuel (HVOF) spray processstructure. [12] High velocity oxygen fuel (HVOF) thermal

Ajdelsztajn, L.; Dannenberg, J.; Lopez, J.; Yang, N.; Farmer, J.; Lavernia, E. J.

2009-01-01T23:59:59.000Z

163

Numerical simulation for formed projectile of depleted uranium alloy  

Science Journals Connector (OSTI)

The numerical simulation for forming projectile of depleted uranium alloy with the SPH (Smooth Particle Hydrodynamic ... . To describe the deformed behaviors of the depleted uranium alloy under high pressure and ...

Song Shun-cheng; Gao Ping; Cai Hong-nian

2003-09-01T23:59:59.000Z

164

Effect of zirconium addition on the impact toughness of the heat affected zone in a high strength low alloy pipeline steel  

SciTech Connect

The effect of zirconium additions on the impact toughness of the heat affected zone in a high strength low alloy pipeline steel was studied, and the corresponding toughening mechanism examined when the welding was conducted with large heat input. The welding of steels was simulated on a Gleeble 2000. Microstructural observations, energy dispersive X-ray spectroscopy and diffraction analyses were conducted using optical microscopy, scanning electron microscopy and transmission electron microscopy, respectively. The impact toughness of the heat affected zone was improved by addition of zirconium into steel, especially when a large welding heat input was used. This improvement is attributable to MnS precipitation on the pre-formed ZrO{sub 2} as well as the formation of intragranular ferrite.

Guo, A.M. [School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Technology Center, Wuhan Iron and Steel (Group) Company, Wuhan 430080 (China); Department of Applied Physics, Wuhan University of Science and Technology, Wuhan 430081 (China); Li, S.R. [School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Technology Center, Wuhan Iron and Steel (Group) Company, Wuhan 430080 (China); Guo, J. [School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083 (China); Li, P.H.; Ding, Q.F. [Technology Center, Wuhan Iron and Steel (Group) Company, Wuhan 430080 (China); Wu, K.M. [Department of Applied Physics, Wuhan University of Science and Technology, Wuhan 430081 (China)], E-mail: wukaiming@wust.edu.cn; He, X.L. [School of Materials Science and Engineering, University of Science and Technology Beijing, Beijing 100083 (China)

2008-02-15T23:59:59.000Z

165

High temperature low-cycle fatigue of friction welded joints - type 304-304 stainless steel and alloy 718-718 nickel base superalloy  

SciTech Connect

This paper assesses the high-temperature low-cycle fatigue of the Type 304 stainless steel and Alloy 718 superalloy friction-welded joints. Strain controlled low-cycle fatigue tests for 304-304 and 718-718 friction-welded specimens were carried out at 923 K in air to obtain the fatigue strength of the joints. These materials were selected as the cyclic hardening and softening materials, respectively. The 304-304 welded specimens showed inferior fatigue strength in comparison with the base metal while the 718-718 specimens exhibited fatigue strength equivalent to that of the base metal. The difference in the fatigue strength between the two materials is discussed from the viewpoint of the cyclic deformation behavior and strain reduction at weld interface.

Wakai, T. (Power Reactor and Nuclear Fuel Development Corp., Ibaraki (Japan). Oarai Engineering Center); Sakane, M.; Ohnami, M. (Ritsumeikan Univ., Kyoto (Japan). Dept. of Mechanical Engineering); Okita, K. (Hyogo Prefectural Inst. of Industrial Research, Miki (Japan). Technical Center for Machinery and Metals); Fukuchi, Y. (Hyogo Prefectural Inst. of Industrial Research, Kobe (Japan))

1993-01-01T23:59:59.000Z

166

Heat Capacity of Palladium and Dilute Palladium: Iron Alloys from 1.4 to 100°K  

Science Journals Connector (OSTI)

Heat-capacity measurements have been made on pure palladium and a series of dilute palladium-iron alloys over the temperature range 1.4 to 100°K. All alloys exhibit a ferromagnetic specific heat anomaly, the entropy of which is proportional to iron concentration. This entropy corresponds to a mean spin of 1.1±0.3 per iron atom. The disagreement between the latter figure and the value obtained from the saturation moment of more concentrated alloys is discussed. For the most concentrated alloy a T32 spin-wave term is observed, the magnitude of which is in approximate agreement with theory. The Debye ? for pure palladium appears to have an anomalous temperature dependence.

Boyd W. Veal and John A. Rayne

1964-07-20T23:59:59.000Z

167

Dissimilar friction welding of titanium alloys to alloy 718  

SciTech Connect

The design of advanced, high-performance gas-turbine engines will require the utilization of elevated-temperature titanium-based materials, including conventional alloys, titanium aluminides, and titanium metal-matrix composites. The most efficient utilization of these materials in the engine compressor section would be achieved by directly joining these materials to existing nickel-base superalloys, such as Alloy 718. To date, the dissimilar welding of titanium alloys to nickel-based alloys has not been common practice because intermetallic compounds form in the weld and cause embrittlement. Special welding techniques must be developed to inhibit this compound formation and to provide high strength welds. In this investigation, a friction welding process was developed for joining titanium alloys (Ti-6Al-2Sn-4Zr-2Mo and Ti-6Al-4V) to nickel-based superalloy Alloy 718. An interlayer system comprised of copper and niobium sheet layers was employed as a diffusion barrier and weld deformation enhancer. A postweld heat treatment (PWHT, 700{degrees}C for 20 min in vacuum) under axial pressure (Ksi) was used to improve the joint strength consistency. The following conclusions can be drawn from this investigation: (1) A friction welding technique has been developed for joining titanium alloys (Ti-6Al-2Sn-4Zr-2Mo and Ti-6Al-4V) to Alloy 718 using an interlayer system of niobium and copper. Joint strengths averaging approximately 50 Ksi were achieved. (2) Deformation was concentrated in the interlayers, especially the copper interlayer, during friction welding. Increased reduction in length (RIL) during friction welding resulted in a decrease in the interlayer thicknesses. (3) The EDS results showed that the niobium and copper interlayers prevent interdiffusion between the two parent metals, producing formation of detrimental phases.

Kuo, M.; Albright, C.E.; Baeslack, W.A. III

1994-12-31T23:59:59.000Z

168

q calculus and entropy in nonextensive statistical physics  

Science Journals Connector (OSTI)

The connection between Tsallis entropy for a multifractal distribution and Jackson’s q derivative is established. Based on this derivation and definition of a homogeneous function, a q analog of Shannon’s entropy is defined. Tsallis entropy can also be accommodated in this formalism. Pseudoadditivity of the q entropies is proved. We also define a q analog of Kullback relative entropy. The implications of the lattice structure beneath the q calculus are highlighted in the context of the q entropy.

Ramandeep S. Johal

1998-10-01T23:59:59.000Z

169

E-Print Network 3.0 - alloys reveal fundamental Sample Search...  

NLE Websites -- All DOE Office Websites (Extended Search)

team Catalyst fundamentals Catalyst development... fundamentals: experimental Catalyst fundamentals: modeling 12;HIGHLY DISPERSED ALLOY CATALYST Project... HIGHLY DISPERSED...

170

Entropy Of Maps With Horizontal Gaps  

E-Print Network (OSTI)

We study the behavior of topological entropy in one-parameter families of interval maps obtained from a continuous map f by truncating it at the level depending on the parameter. When f is piecewise monotone, the entropy function has the devil's staircase structure.

Micha Misiurewicz March

171

The role of entropy in magnetotail dynamics  

SciTech Connect

The role of entropy conservation and loss in magnetospheric dynamics, particularly in relation to substorm phases, is discussed on the basis of MHD theory and simulations, using comparisons with PIC simulations for validation. Entropy conservation appears to be a crucial element leading to the formation of thin embedded current sheets in the late substorm growth phase and the potential loss of equilibrium. Entropy loss (in the form of plasmoids) is essential in the earthward transport of flux tubes (bubbles, bursty bulk flows). Entropy loss also changes the tail stability properties and may render ballooning modes unstable and thus contribute to cross-tail variability. We illustrate these effects through results from theory and simulations. Entropy conservation also governs the accessibility of final states of evolution and the amount of energy that may be released.

Birn, Joachim [Los Alamos National Laboratory; Zaharia, Sorin [Los Alamos National Laboratory; Hesse, Michael [NASA/GSFC; Schindler, K [INSTITUT FOR THEORETISCHE

2008-01-01T23:59:59.000Z

172

Critical insulation thickness for maximum entropy generation  

Science Journals Connector (OSTI)

Critical insulation thickness is known to refer to the insulation thickness that maximises the rate of heat transfer in cylindrical and spherical systems. The same analogy is extended to the rate of entropy generation in the present study. The possible critical insulation thickness that yields a maximum rate of entropy generation is investigated. Entropy generation is related to heat transfer through and temperature distribution within the insulation material. It is found that there exists a critical insulation thickness for maximising the rate of entropy generation that is a function of the Bi number and the surface to ambient temperature ratio. The solution of such critical thickness is formulated analytically for both cylindrical and spherical geometries. It is also found that the critical insulation thickness for the rate of entropy generation does not coincide with that for the rate of heat transfer.

Ahmet Z. Sahin

2012-01-01T23:59:59.000Z

173

Generalized entropies in a turbulent dynamo simulation  

Science Journals Connector (OSTI)

A simulation of hydromagnetic turbulence exhibiting dynamo action is employed to estimate the generalized entropies, Hq, from the distribution of moments of local expansion factors of material line elements. These generalized entropies can be used to characterize the dynamics of turbulence and of nonlinear dynamo action. The value of the metric entropy, H1, is comparable to the largest Lyapunov exponent describing the divergence of trajectories in phase space, which in turn is somewhat larger than the growth rate of the magnetic energy. The value of the topological entropy, H0, is similar to the conversion rate of kinetic to magnetic energy, but larger than the growth rate of the dynamo. This is in agreement with results stating that the growth rate of the kinematic dynamo is limited by the topological entropy. The dependence of Hq on q leads to a criterion from which we infer that the degree of intermittency in our particular system is weak.

Axel Brandenburg; Isaac Klapper; Jürgen Kurths

1995-11-01T23:59:59.000Z

174

Surface alloying of silicon into aluminum substrate.  

SciTech Connect

Aluminum alloys that are easily castable tend to have lower silicon content and hence lower wear resistance. The use of laser surface alloying to improve the surface wear resistance of 319 and 320 aluminum alloys was examined. A silicon layer was painted onto the surface to be treated. A high power pulsed Nd:YAG laser with fiberoptic beam delivery was used to carry out the laser surface treatment to enhance the silicon content. Process parameters were varied to minimize the surface roughness from overlap of the laser beam treatment. The surface-alloyed layer was characterized and the silicon content was determined.

Xu, Z.

1998-10-28T23:59:59.000Z

175

Control Volume Analysis, Entropy Balance and the Entropy Production in Flow Systems  

E-Print Network (OSTI)

This chapter concerns "control volume analysis", the standard engineering tool for the analysis of flow systems, and its application to entropy balance calculations. Firstly, the principles of control volume analysis are enunciated and applied to flows of conserved quantities (e.g. mass, momentum, energy) through a control volume, giving integral (Reynolds transport theorem) and differential forms of the conservation equations. Several definitions of steady state are discussed. The concept of "entropy" is then established using Jaynes' maximum entropy method, both in general and in equilibrium thermodynamics. The thermodynamic entropy then gives the "entropy production" concept. Equations for the entropy production are then derived for simple, integral and infinitesimal flow systems. Some technical aspects are examined, including discrete and continuum representations of volume elements, the effect of radiation, and the analysis of systems subdivided into compartments. A Reynolds decomposition of the entropy production equation then reveals an "entropy production closure problem" in fluctuating dissipative systems: even at steady state, the entropy production based on mean flow rates and gradients is not necessarily in balance with the outward entropy fluxes based on mean quantities. Finally, a direct analysis of an infinitesimal element by Jaynes' maximum entropy method yields a theoretical framework with which to predict the steady state of a flow system. This is cast in terms of a "minimum flux potential" principle, which reduces, in different circumstances, to maximum or minimum entropy production (MaxEP or MinEP) principles. It is hoped that this chapter inspires others to attain a deeper understanding and higher technical rigour in the calculation and extremisation of the entropy production in flow systems of all types.

Robert K. Niven; Bernd R. Noack

2014-07-21T23:59:59.000Z

176

Effect of aluminizing of Cr-containing ferritic alloys on the seal strength of a novel high-temperature solid oxide fuel cell sealing glass  

SciTech Connect

A novel high-temperature alkaline-earth silicate sealing glass was developed for solid oxide fuel cell (SOFC) applications. The glass was used to join two metallic coupons of Cr-containing ferritic stainless steel for seal strength evaluation. In previous work, SrCrO4 was found to form along the glass/steel interface, which led to severe strength degradation. In the present study, aluminization of the steel surface was investigated as a remedy to minimize or prevent the strontium chromate formation. Three different processes for aluminization were evaluated with Crofer22APU stainless steel: pack cementation, vapor phase deposition, and aerosol spraying. It was found that pack cementation resulted in a rough surface with occasional cracks in the Al-diffused region. Vapor phase deposition yielded a smoother surface, but the resulting high Al content increased the coefficient of thermal expansion (CTE), resulting in failure of joined coupons. Aerosol spraying of an Al-containing salt resulted in formation of a thin aluminum oxide layer without any surface damage. The room temperature seal strength was evaluated in the as-fired state and in environmentally aged conditions. In contrast to earlier results with uncoated Crofer22APU, the aluminized samples showed no strength degradation even for samples aged in air. Interfacial and chemical compatibility was also investigated. The results showed aluminization to be a viable candidate approach to minimize undesirable chromate formation between alkaline earth silicate sealing glass and Cr-containing interconnect alloys for SOFC applications.

Chou, Y. S.; Stevenson, Jeffry W.; Singh, Prabhakar

2008-12-01T23:59:59.000Z

177

Entropy viscosity Jean-Luc Guermond, B. Popov  

E-Print Network (OSTI)

Entropy viscosity Jean-Luc Guermond, B. Popov Department of Mathematics Texas A&M University-Luc Guermond, B. Popov Residual/Entropy viscosity #12;Acknowledgments Collaborator: Richard Pasquetti, Univ/Entropy viscosity #12;Outline 1 TRANSPORT EQUATION Jean-Luc Guermond, B. Popov Residual/Entropy viscosity #12

Guermond, Jean-Luc

178

Vehicle Technologies Office Merit Review 2014: Development of Advanced High Strength Cast Alloys for Heavy Duty Engines  

Energy.gov (U.S. Department of Energy (DOE))

Presentation given by Caterpillar at 2014 DOE Hydrogen and Fuel Cells Program and Vehicle Technologies Office Annual Merit Review and Peer Evaluation Meeting about development of advanced high...

179

Metal alloy identifier  

DOE Patents (OSTI)

To identify the composition of a metal alloy, sparks generated from the alloy are optically observed and spectrographically analyzed. The spectrographic data, in the form of a full-spectrum plot of intensity versus wavelength, provide the "signature" of the metal alloy. This signature can be compared with similar plots for alloys of known composition to establish the unknown composition by a positive match with a known alloy. An alternative method is to form intensity ratios for pairs of predetermined wavelengths within the observed spectrum and to then compare the values of such ratios with similar values for known alloy compositions, thereby to positively identify the unknown alloy composition.

Riley, William D. (Avondale, MD); Brown, Jr., Robert D. (Avondale, MD)

1987-01-01T23:59:59.000Z

180

12/10/12 Entropy | Special Issue: Entropy and the Second Law of Thermodynamics 1/2www.mdpi.com/journal/entropy/special_issues/second-law-of-thermodynamics  

E-Print Network (OSTI)

12/10/12 Entropy | Special Issue: Entropy and the Second Law of Thermodynamics 1/2www.mdpi.com/journal/entropy/special_issues/second-law-of-thermodynamics -- Issue Clear Article Type all Special Issue Entropy and the Second Law of ThermodynamicsPage Search Special Issue "Entropy and the Second Law of Thermodynamics" A special issue of Entropy (ISSN 1099

Kostic, Milivoje M.

Note: This page contains sample records for the topic "high entropy alloy" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


181

A brief commentary on black hole entropy  

E-Print Network (OSTI)

It is commonplace, in the literature, to find that the Bekenstein-Hawking entropy has been endowed with having an explicit statistical interpretation. In the following essay, we discuss why such a viewpoint warrants a certain degree of caution.

A. J. M. Medved

2004-10-18T23:59:59.000Z

182

Negative Casimir Entropies in Nanoparticle Interactions  

E-Print Network (OSTI)

Negative entropy has been known in Casimir systems for some time. For example, it can occur between parallel metallic plates modeled by a realistic Drude permittivity. Less well known is that negative entropy can occur purely geometrically, say between a perfectly conducting sphere and a conducting plate. The latter effect is most pronounced in the dipole approximation, which is reliable when the size of the sphere is small compared to the separation between the sphere and the plate. Therefore, here we examine cases where negative entropy can occur between two electrically and magnetically polarizable nanoparticles or atoms, which need not be isotropic, and between such a small object and a conducting plate. Negative entropy can occur even between two perfectly conducting spheres, between two electrically polarizable nano-particles if there is sufficient anisotropy, between a perfectly conducting sphere and a Drude sphere,and between a sufficiently anisotropic electrically polarizable nano-particle and a transverse magnetic conducting plate.

K. A. Milton; Romain Guérout; Gert-Ludwig Ingold; Astrid Lambrecht; Serge Reynaud

2014-05-01T23:59:59.000Z

183

Entropy production in quantum spin systems  

E-Print Network (OSTI)

We consider a quantum spin system consisting of a finite subsystem connected to infinite reservoirs at different temperatures. In this setup we define nonequilibrium steady states and prove that the rate of entropy production in such states is nonnegative.

David Ruelle

2000-06-07T23:59:59.000Z

184

Entropy Production in Driven Spatially Extended Systems  

E-Print Network (OSTI)

This is a short review of the statistical mechanical definition of entropy production for systems composed of a large number of interacting components. Emphasis is on open systems driven away from equilibrium where the entropy production can be identified with a logarithmic ratio of microstate multiplicities of the original macrostate with respect to the time-reversed state. A special role is taken by Gibbs measures for the stationary spatio-temporal distribution of trajectories. The mean entropy production is always non-negative and it is zero only when the system is in equilibrium. The fluctuations of the entropy production satisfy a (Gallavotti-Cohen)symmetry first observed and then derived for the phase space contraction rate in a class of strongly chaotic dynamical systems. Aspects of the general framework are illustrated via a bulk driven diffusive lattice gas.

Christian Maes

2001-01-05T23:59:59.000Z

185

High-temperature gas-cooled reactor helium compatibility studies: results of 10,000-hour exposure of selected alloys in simulated reactor helium  

SciTech Connect

Work on the HTGR Helium Compatibility Task accomplished during the period March 31, 1977 through September 30, 1979, is documented in this report. Emphasis is on the results and analyses of creep data to 10,000 h and the detailed metallurgical evaluations performed on candidate alloy specimens tested for up to 10,000 h. Long-term creep and unstressed aging data in controlled-impurity helium and in air at 800, 900, and 1000/sup 0/C are reported for alloys included in the program in FY-76, including the wrought solid-solution-strengthened alloys, Hastelloy X, Hastelloy S, RA 333, and HD 556, and the centrifugally cast austenitic alloys, HK 40, Supertherm, Manaurite 36X, Manaurite 36XS, and Manaurite 900.

Lechtenberg, T.A.; Stevenson, R.D.; Johnson, W.R.

1980-05-01T23:59:59.000Z

186

Monotonicity of a relative Rényi entropy  

SciTech Connect

We show that a recent definition of relative Rényi entropy is monotone under completely positive, trace preserving maps. This proves a recent conjecture of Müller-Lennert et al. [“On quantum Rényi entropies: A new definition, some properties,” J. Math. Phys. 54, 122203 (2013); e-print http://arxiv.org/abs/arXiv:1306.3142v1 ; see also e-print http://arxiv.org/abs/arXiv:1306.3142 ].

Frank, Rupert L., E-mail: rlfrank@caltech.edu [Mathematics 253-37, Caltech, Pasadena, California 91125 (United States); Lieb, Elliott H., E-mail: lieb@princeton.edu [Departments of Mathematics and Physics, Princeton University, Washington Road, Princeton, New Jersey 08544 (United States)

2013-12-15T23:59:59.000Z

187

Transfer Entropy Analysis of the Stock Market  

E-Print Network (OSTI)

In terms of transfer entropy, we investigated the strength and the direction of information transfer in the US stock market. Through the directionality of the information transfer, the more influential company between the correlated ones can be found and also the market leading companies are selected. Our entropy analysis shows that the companies related with energy industries such as oil, gas, and electricity influence the whole market.

Baek, S K; Kwon, O; Moon, H T; Baek, Seung Ki; Jung, Woo-Sung; Kwon, Okyu; Moon, Hie-Tae

2005-01-01T23:59:59.000Z

188

Black hole entropy and higher curvature interactions  

Science Journals Connector (OSTI)

A general formula for the entropy of stationary black holes in Lovelock higher-curvature gravity theories is obtained by integrating the first law of black hole mechanics, which is derived by Hamiltonian methods. The entropy is not simply one quarter of the surface area of the horizon, but also includes a sum of intrinsic curvature invariants integrated over a cross section of the horizon.

Ted Jacobson and Robert C. Myers

1993-06-14T23:59:59.000Z

189

Black hole entropy: inside or out?  

E-Print Network (OSTI)

A trialogue. Ted, Don, and Carlo consider the nature of black hole entropy. Ted and Carlo support the idea that this entropy measures in some sense ``the number of black hole microstates that can communicate with the outside world.'' Don is critical of this approach, and discussion ensues, focusing on the question of whether the first law of black hole thermodynamics can be understood from a statistical mechanics point of view.

Ted Jacobson; Donald Marolf; Carlo Rovelli

2005-01-14T23:59:59.000Z

190

Viscosity, entropy and the viscosity to entropy density ratio; how perfect is a nucleonic fluid?  

E-Print Network (OSTI)

The viscosity of hadronic matter is studied using a classical evaluation of the scattering angle and a quantum mechanical discussion based on phase shifts from a potential. Semi classical limits of the quantum theory are presented. A hard sphere and an attractive square well potential step are each considered as well as the combined effects of both. The lowest classical value of the viscosity for an attractive potential is shown to be a hard sphere limit. The high wave number-short wavelength limits of the quantum result have scaling laws associated with it for both the viscosity and entropy. These scaling laws are similar to the Fraunhoher diffraction increase for the hard sphere geometric cross section. Specific examples for nuclear collisions are given. The importance of the nuclear tensor force and hard core is mentioned. The viscosity (eta), entropy density (s) and eta/s ratio are calculated for a gas of dilute neutrons in the unitary limit of large scattering length. Away from the unitary limit, the ratio of the interaction radius or the scattering length to the interparticle spacing introduces a variable y besides the fugacity z. The isothermal compressibility is shown to impose important constraints. The results for eta/s are compared to the AdS/CFT string theory minimum of (1/4Pi)hbar/kb to see how close a nucleonic gas is to being a perfect fluid. The eta/s ~1hbar/kb for a neutron gas in its unitary limit. The eta/s 3hbar/kb treating the nuclear scattering as billiard ball collisions. The minimum eta/s for a neutron gas occurs in regions of negative isothermal compressibility and high fugacity where higher virial terms are important. In a neutron-proton system higher virial terms are associated with a liquid-gas phase transition and critical opalescent phenomena.The type of flow-laminar,vortex, turbulent- is investigated.

Aram Z. Mekjian

2010-09-29T23:59:59.000Z

191

The entropy power inequality for quantum systems  

E-Print Network (OSTI)

When two independent analog signals, X and Y are added together giving Z=X+Y, the entropy of Z, H(Z), is not a simple function of the entropies H(X) and H(Y), but rather depends on the details of X and Y's distributions. Nevertheless, the entropy power inequality (EPI), which states that exp [2H(Z)] \\geq exp[2H(X)] + exp[2H(Y)], gives a very tight restriction on the entropy of Z. This inequality has found many applications in information theory and statistics. The quantum analogue of adding two random variables is the combination of two independent bosonic modes at a beam splitter. The purpose of this work is to give a detailed outline of the proof of two separate generalizations of the entropy power inequality to the quantum regime. Our proofs are similar in spirit to standard classical proofs of the EPI, but some new quantities and ideas are needed in the quantum setting. Specifically, we find a new quantum de Bruijin identity relating entropy production under diffusion to a divergence-based quantum Fisher information. Furthermore, this Fisher information exhibits certain convexity properties in the context of beam splitters.

Robert Koenig; Graeme Smith

2012-05-15T23:59:59.000Z

192

Cosmic rays, lithium abundance and excess entropy in galaxy clusters  

E-Print Network (OSTI)

We consider the production of $^6$Li in spallation reactions by cosmic rays in order to explain the observed abundance in halo metal-poor stars. We show that heating of ambient gas by cosmic rays is an inevitable consequence of this process, and estimate the energy input required to reproduce the observed abundance of $^6$Li/H$\\sim 10^{-11}$ to be of order a few hundred eV per particle. We draw attention to the possibility that this could explain the excess entropy in gas in galaxy groups and clusters. The evolution of $^6$Li and the accompanying heating of gas is calculated for structures collapsing at the present epoch with injection of cosmic rays at high redshift. We determine the energy required to explain the abundance of $^6$Li at $z \\sim 2$ corresponding to the formation epoch of halo metal-poor stars, and also an increased entropy level of $\\sim 300$ keV cm$^2$ necessary to explain X-ray observations of clusters. The energy budget for this process is consistent with the expected energy output of radio-loud AGNs, and the diffusion length scale of cosmic-ray protons responsible for heating is comparable to the size of regions with excess entropy. We also discuss the constraints imposed by the extragalactic gamma-ray background.

Biman B. Nath; Piero Madau; Joseph Silk

2005-11-21T23:59:59.000Z

193

Method of treating intermetallic alloy hydrogenation/oxidation catalysts for improved impurity poisoning resistance, regeneration and increased activity  

DOE Patents (OSTI)

Alternate, successive high temperature oxidation and reduction treatments, in either order, of intermetallic alloy hydrogenation and intermetallic alloy oxidation catalysts unexpectedly improves the impurity poisoning resistance, regeneration capacity and/or activity of the catalysts. The particular alloy, and the final high temperature treatment given alloy (oxidation or reduction) will be chosen to correspond to the function of the catalyst (oxidation or hydrogenation).

Wright, Randy B. (Idaho Falls, ID)

1992-01-01T23:59:59.000Z

194

1983 paper on entanglement entropy: "On the Entropy of the Vacuum outside a Horizon"  

E-Print Network (OSTI)

I introduce the concept of *entanglement entropy* (as it's now called) and point out that it follows an *area law* which renders it a suitable source of black hole entropy. I also suggest to conceive the latter as residing on the horizon at approximately one bit per "Planckian plaquette".

Rafael D. Sorkin

2014-02-15T23:59:59.000Z

195

Refractory Alloy Welding [Laser Applications Laboratory] - Nuclear  

NLE Websites -- All DOE Office Websites (Extended Search)

Refractory Alloy Welding Refractory Alloy Welding Capabilities Engineering Experimentation Reactor Safety Experimentation Aerosol Experiments System Components Laser Applications Overview Laser Oil & Gas Well Drilling Laser Heat Treatment Laser Welding of Metals On-line Monitoring Laser Beam Delivery Laser Glazing of Railroad Rails High Power Laser Beam Delivery Decontamination and Decommissioning Refractory Alloy Welding Robots Applications Other Facilities Other Capabilities Work with Argonne Contact us For Employees Site Map Help Join us on Facebook Follow us on Twitter NE on Flickr Laser Applications Laboratory Refractory Alloy Welding Project description: Welding of refractory metals such as vanadium alloys. Category: internal R&D project Bookmark and Share Butt weld of two 4 mm thick V-4Cr-4Ti plates made by a pulsed Nd:YAG laser

196

Rigorous and General Definition of Thermodynamic Entropy  

E-Print Network (OSTI)

The physical foundations of a variety of emerging technologies --- ranging from the applications of quantum entanglement in quantum information to the applications of nonequilibrium bulk and interface phenomena in microfluidics, biology, materials science, energy engineering, etc. --- require understanding thermodynamic entropy beyond the equilibrium realm of its traditional definition. This paper presents a rigorous logical scheme that provides a generalized definition of entropy free of the usual unnecessary assumptions which constrain the theory to the equilibrium domain. The scheme is based on carefully worded operative definitions for all the fundamental concepts employed, including those of system, property, state, isolated system, environment, process, separable system, system uncorrelated from its environment, and parameters of a system. The treatment considers also systems with movable internal walls and/or semipermeable walls, with chemical reactions and/or external force fields, and with small numbers of particles. The definition of reversible process is revised by introducing the new concept of scenario. The definition of entropy involves neither the concept of heat nor that of quasistatic process; it applies to both equilibrium and nonequilibrium states. The role of correlations on the domain of definition and on the additivity of energy and entropy is discussed: it is proved that energy is defined and additive for all separable systems, while entropy is defined and additive only for separable systems uncorrelated from their environment; decorrelation entropy is defined. The definitions of energy and entropy are extended rigorously to open systems. Finally, to complete the discussion, the existence of the fundamental relation for stable equilibrium states is proved, in our context, for both closed and open systems.

Gian Paolo Beretta; Enzo Zanchini

2010-10-05T23:59:59.000Z

197

Fundamental studies of stress distributions and stress relaxation in oxide scales on high temperature alloys. [Final progress report  

SciTech Connect

This report summarizes a three-year study of stresses arising in the oxide scale and underlying metal during high temperature oxidation and of scale cracking. In-situ XRD was developed to measure strains during oxidation over 1000{degrees}C on pure metals. Acoustic emission was used to observe scale fracture during isothermal oxidation and cooling, and statistical analysis was used to infer mechanical aspects of cracking. A microscratch technique was used to measure the fracture toughness of scale/metal interface. A theoretical model was evaluated for the development and relaxation of stresses in scale and metal substrate during oxidation.

Shores, D.A.; Stout, J.H.; Gerberich, W.W.

1993-06-01T23:59:59.000Z

198

Electrochemical determination of the corrosion behavior of candidate alloys proposed for containment of high level nuclear waste in tuff  

SciTech Connect

Long-term geological disposal of nuclear waste requires corrosion-resistant canister materials for encapsulation. Several austenitic stainless steels are under consideration for such purposes for the disposal of high-level waste at the candidate repository site located at Yucca Mountain, Nevada. With regard to corrosion considerations, a worst case scenario at this prospective repository location would result from the intrusion of vadose water. This preliminary study focuses on the electrochemical and corrosion behavior of the candidate canister materials under worst-case repository environments. Electrochemical parameters related to localized attack (e.g., pitting potentials) and the electrochemical corrosion rates have been examined. 15 references, 15 figures, 4 tables.

Glass, R.S.; Overturf, G.E.; Garrison, R.E.; McCright, R.D.

1984-06-18T23:59:59.000Z

199

Generalized gravitational entropy without replica symmetry  

E-Print Network (OSTI)

We explore several extensions of the generalized entropy construction of Lewkowycz and Maldacena, including a formulation that does not rely on preserving replica symmetry in the bulk. We show that an appropriately general ansatz for the analytically continued replica metric gives us the flexibility needed to solve the gravitational field equations beyond general relativity. As an application of this observation we study Einstein-Gauss-Bonnet gravity with a small Gauss-Bonnet coupling and derive the condition that the holographic entanglement entropy must be evaluated on a surface which extremizes the Jacobson-Myers entropy. We find that in both general relativity and Einstein-Gauss-Bonnet gravity replica symmetry breaking terms are permitted by the field equations, suggesting that they do not generically vanish.

Joan Camps; William R. Kelly

2015-01-13T23:59:59.000Z

200

The Entropy Law and the impossibility of perpetual economic growth  

E-Print Network (OSTI)

Every production-recycling iteration accumulates an inevitable proportion of its matter-energy in the environment, lest the production process itself would be a system in perpetual motion, violating the second law of Thermodynamics. Such high-entropy matter depletes finite stocks of ecosystem services provided by the ecosphere, hence are incompatible with the long-term growth in the material scale of the economic process. Moreover, the complex natural systems governing such stocks respond to depletion by possibly sudden environmental transitions, thus hindering markets' very ability to adapt to the new equilibrium conditions. Consequently, uncertainty of critical resilience thresholds constrains material economic growth.

Earp, Henrique N Sá

2013-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "high entropy alloy" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


201

Rhenium alloying of tungsten heavy alloys  

SciTech Connect

Alloying experiments were performed using rhenium additions to a classic 90 mass % tungsten heavy alloy. The mixed-powder system was liquid phase sintered to full density at 1500 C in 60 min The rhenium-modified alloys exhibited a smaller grain size, higher hardness, higher strength, and lower ductility than the unalloyed system. For an alloy with a composition of 84W-6Re-8Ni-2Fe, the sintered density was 17, 4 Mg/m{sup 3} with a yield strength of 815 MPa, tensile strength of 1180 MPa, and elongation to failure of 13%. This property combination results from the aggregate effects of grain size reduction and solid solution hardening due to rhenium. In the unalloyed system these properties require post-sintering swaging and aging; thus, alloying with rhenium is most attractive for applications where net shaping is desired, such as by powder injection molding.

German, R.M.; Bose, A.; Jerman, G.

1989-01-01T23:59:59.000Z

202

Application of Entropy Theory in Hydrologic Analysis and Simulation  

E-Print Network (OSTI)

streamflow. Both methods are shown to preserve statistics, such as mean, standard deviation, skenwess and lag-one correlation, well for monthly streamflow in the Colorado River basin. The entropy and entropy-copula methods are also extended for multi...

Hao, Zengchao

2012-07-16T23:59:59.000Z

203

BLACK HOLE ENTROPY IN HIGHER CURVATURE GRAVITY  

E-Print Network (OSTI)

We discuss some recent results on black hole thermodynamics within the context of effective gravitational actions including higher-curvature interactions. Wald's derivation of the First Law demonstrates that black hole entropy can always be expressed as a local geometric density integrated over a space-like cross-section of the horizon. In certain cases, it can also be shown that these entropy expressions satisfy a Second Law. One such simple example is considered from the class of higher curvature theories where the Lagrangian consists of a polynomial in the Ricci scalar.

TED JACOBSON; GUNGWON KANG; ROBERT C. MYERS

1995-02-27T23:59:59.000Z

204

Waste heat boiler optimization by entropy minimization principle  

SciTech Connect

A second law analysis has been undertaken for a waste heat boiler having an economizer, evaporator and superheater. Following the principle of minimization of entropy generation, a general equation for entropy generation number is derived, which incorporates all the operating variables. By differentiating the entropy generation number equation with respect to the operating parameters, various optimization parameters can be obtained. Few illustrations have been made to see the effect of various parameters on entropy generation number.

Reddy, B.V.; Murali, J.; Satheesh, V.S. [Vellore Engineering Coll. (India). Mechanical Engineering Dept.; Nag, P.K. [Indian Inst. of Tech., Kharagpur (India). Mechanical Engineering Dept.

1996-12-31T23:59:59.000Z

205

Solid solution lithium alloy cermet anodes  

DOE Patents (OSTI)

A metal-ceramic composite ("cermet") has been produced by a chemical reaction between a lithium compound and another metal. The cermet has advantageous physical properties, high surface area relative to lithium metal or its alloys, and is easily formed into a desired shape. An example is the formation of a lithium-magnesium nitride cermet by reaction of lithium nitride with magnesium. The reaction results in magnesium nitride grains coated with a layer of lithium. The nitride is inert when used in a battery. It supports the metal in a high surface area form, while stabilizing the electrode with respect to dendrite formation. By using an excess of magnesium metal in the reaction process, a cermet of magnesium nitride is produced, coated with a lithium-magnesium alloy of any desired composition. This alloy inhibits dendrite formation by causing lithium deposited on its surface to diffuse under a chemical potential into the bulk of the alloy.

Richardson, Thomas J.

2013-07-09T23:59:59.000Z

206

Entropy Calculations and the Third Law of Thermodynamics Chemistry 223  

E-Print Network (OSTI)

Entropy Calculations and the Third Law of Thermodynamics Chemistry 223 1. Entropy Calculations I We heat of fusion, sublimation, or vaporization) is added to the system, with no resulting change, 2014 #12;Entropy Calculations and the Third Law -2- Chemistry 223 STiT f = T0 Ti CP,i(T, P, N) T d

Ronis, David M.

207

ASYMPTOTIC BEHAVIOR OF THE ENTROPY OF INTERVAL MAPS  

E-Print Network (OSTI)

ASYMPTOTIC BEHAVIOR OF THE ENTROPY OF INTERVAL MAPS ALEXANDER BLOKH AND JOZEF BOBOK Abstract. We obtain upper estimates on the entropy of interval maps of given modality and Sharkovskii type. Following our results we formulate a conjecture on asymptotic behavior of the entropy of interval maps. 1

Blokh, Alexander

208

VOLUME ENTROPY OF HYPERBOLIC BUILDINGS FRANCOIS LEDRAPPIER AND SEONHEE LIM  

E-Print Network (OSTI)

VOLUME ENTROPY OF HYPERBOLIC BUILDINGS FRANC¸OIS LEDRAPPIER AND SEONHEE LIM Abstract. We characterize the volume entropy of a regular building as the topological pressure of the geodesic flow building. As a consequence, we obtain a strict lower bound on the volume entropy in terms of the branching

Lim, Seonhee

209

Effect of thermally stable Cu- and Mg-rich aluminides on the high temperature strength of an AlSi12CuMgNi alloy  

SciTech Connect

The internal architecture of an AlSi12CuMgNi piston alloy, revealed by synchrotron tomography, consists of three dimensional interconnected hybrid networks of Cu-rich aluminides, Mg-rich aluminides and eutectic/primary Si embedded in an ?-Al matrix. The strength at room temperature and at 300°C is studied as a function of solution treatment time at 490°C and compared with results previously reported for an AlSi12Ni alloy. The addition of 1 wt% Cu and 1 wt% Mg to AlSi12CuMgNi increases the room temperature strength by precipitation hardening while the strength at 300°C is similar for both alloys in as-cast condition. The strength of AlSi12CuMgNi decreases with solution treatment time and stabilizes at 4 h solution treatment. The effect of solution treatment time on the strength of the AlSi12CuMgNi alloy is less pronounced than for the AlSi12Ni alloy both at room temperature and at 300°C. - Highlights: • The 3D microstructure of AlSi12CuMgNi is revealed by synchrotron tomography. • An imaging analysis procedure to segment phases with similar contrasts is presented. • 1 wt% Cu and Mg results in the formation of 3D networks of rigid phases. • AlSi12CuMgNi is stronger than AlSi12Ni owing to the stability of the 3D networks.

Asghar, Z., E-mail: zhdasghar@yahoo.com [Materials Division, Directorate of Technology, PINSTECH, P. O. Nilore, Islamabad (Pakistan); Vienna University of Technology, Institute of Materials Science and Technology, Karlsplatz 13/308, A-1040 Vienna (Austria); Requena, G. [Vienna University of Technology, Institute of Materials Science and Technology, Karlsplatz 13/308, A-1040 Vienna (Austria); Zahid, G.H.; Rafi-ud-Din [Materials Division, Directorate of Technology, PINSTECH, P. O. Nilore, Islamabad (Pakistan)

2014-02-15T23:59:59.000Z

210

Oxidation of advanced steam turbine alloys  

SciTech Connect

Advanced or ultra supercritical (USC) steam power plants offer the promise of higher efficiencies and lower emissions. Current goals of the U.S. Department of Energy’s Advanced Power Systems Initiatives include coal generation at 60% efficiency, which would require steam temperatures of up to 760°C. This research examines the steamside oxidation of advanced alloys for use in USC systems, with emphasis placed on alloys for high- and intermediate-pressure turbine sections.

Holcomb, G.R.; Covino, B.S., Jr.; Bullard, S.J.; Ziomek-Moroz, M.

2006-03-01T23:59:59.000Z

211

High-Temperature Aluminum Alloys  

Energy.gov (U.S. Department of Energy (DOE))

2013 DOE Hydrogen and Fuel Cells Program and Vehicle Technologies Program Annual Merit Review and Peer Evaluation Meeting

212

Viscosity to entropy ratio at extremality  

E-Print Network (OSTI)

Assuming gauge theory realization at the boundary, we show that the viscosity to entropy ratio is 1/(4 pi) where the bulk is represented by a large class of extremal black holes in anti-de Sitter space. In particular, this class includes multiple R-charged black holes in various dimensions.

Sayan K. Chakrabarti; Sachin Jain; Sudipta Mukherji

2009-10-27T23:59:59.000Z

213

Entropy viscosity method applied to Euler equations  

SciTech Connect

The entropy viscosity method [4] has been successfully applied to hyperbolic systems of equations such as Burgers equation and Euler equations. The method consists in adding dissipative terms to the governing equations, where a viscosity coefficient modulates the amount of dissipation. The entropy viscosity method has been applied to the 1-D Euler equations with variable area using a continuous finite element discretization in the MOOSE framework and our results show that it has the ability to efficiently smooth out oscillations and accurately resolve shocks. Two equations of state are considered: Ideal Gas and Stiffened Gas Equations Of State. Results are provided for a second-order time implicit schemes (BDF2). Some typical Riemann problems are run with the entropy viscosity method to demonstrate some of its features. Then, a 1-D convergent-divergent nozzle is considered with open boundary conditions. The correct steady-state is reached for the liquid and gas phases with a time implicit scheme. The entropy viscosity method correctly behaves in every problem run. For each test problem, results are shown for both equations of state considered here. (authors)

Delchini, M. O.; Ragusa, J. C. [Nuclear Engineering Department, Texas A and M University, 3133 TAMU, College Station, TX 77843-3133 (United States); Berry, R. A. [Idaho National Laboratory, P.O. Box 1625, Idaho Falls, ID 83415-3840 (United States)

2013-07-01T23:59:59.000Z

214

E-Print Network 3.0 - alloy-c-103 Sample Search Results  

NLE Websites -- All DOE Office Websites (Extended Search)

materials are illustrated in Fig. 6(a): a Niobium alloy (C... -103), the ceramic matrix composite C-SiC (benchmark material), a high-temperature Copper alloy (Gr Source:...

215

Entropy Generation In The Viscous Layer Of A Turbulent Channel Flow  

SciTech Connect

The local (pointwise) entropy generation rate per unit volume S''' is a key to improving many energy processes and applications. Entropy generation due to friction occurs from viscous dissipation of mean-flow kinetic energy (called "direct dissipation") and dissipation of turbulent kinetic energy into thermal energy ("indirect" or turbulent dissipation). The objective of the present study is to compare two approaches for the prediction of S''' for the viscous layer in near asymptotic (high Reynolds number) turbulent flows. By employing available direct numerical simulations (DNS) it was found that about two-thirds of the entropy generation occurs in this layer. A popular approximate approach does not agree with the result from the more exact evaluation of S''' but its integral falls within about four per cent at the edge of the viscous layer.

D. M. McEligot; E. J. Walsh; E. Laurien; James R. Wolf

2006-09-01T23:59:59.000Z

216

Stress dependent activation entropy for dynamic fatigue of pristine silica optical fibers  

E-Print Network (OSTI)

Subcritical crack growth in fused silica is treated as a stress assisted chemical reaction between water distilled water and pH 7 buffer solution, and the results are found to be similar. The fatigue parameters to the barrier height. The results show subcritical crack growth in high strength silica is dominated by entropy

Matthewson, M. John

217

Breakthrough Research on Platinum-Nickel Alloys  

NLE Websites -- All DOE Office Websites (Extended Search)

Breakthrough Research on Platinum-Nickel Alloys Print Breakthrough Research on Platinum-Nickel Alloys Print Two out of three of the kinetic barriers to the practical use of polymer electrolyte membrane (PEM) hydrogen fuel cells in automobiles have been breached: the impractically high amount of extra energy needed for the oxidation reduction reaction (ORR) on the catalyst and the loss of catalytic surface areas available for ORR. Using a combination of probes and calculations, a group of scientists has demonstrated that the Pt3Ni(111) alloy is ten times more active for ORR than the corresponding Pt(111) surface and ninety times more active than the current state-of-the-art Pt/C catalysts used in existing PEM fuel cells. This new variation of the platinum-nickel alloy is the most active oxygen-reducing catalyst ever reported.

218

Synthesis of alloys with controlled phase structure  

DOE Patents (OSTI)

A method for preparing controlled phase alloys useful for engineering and hydrogen storage applications. This novel method avoids melting the constituents by employing vapor transport, in a hydrogen atmosphere, of an active metal constituent, having a high vapor pressure at temperatures .apprxeq.300 C. and its subsequent condensation on and reaction with the other constituent (substrate) of an alloy thereby forming a controlled phase alloy and preferably a single phase alloy. It is preferred that the substrate material be a metal powder such that diffusion of the active metal constituent, preferably magnesium, and reaction therewith can be completed within a reasonable time and at temperatures .apprxeq.300 C. thereby avoiding undesirable effects such as sintering, local compositional inhomogeneities, segregation, and formation of unwanted second phases such as intermetallic compounds.

Guthrie, Stephen Everett (Livermore, CA); Thomas, George John (Livermore, CA); Bauer, Walter (Livermore, CA); Yang, Nancy Yuan Chi (Lafayette, CA)

1999-04-20T23:59:59.000Z

219

Synthesis of alloys with controlled phase structure  

DOE Patents (OSTI)

A method is described for preparing controlled phase alloys useful for engineering and hydrogen storage applications. This novel method avoids melting the constituents by employing vapor transport, in a hydrogen atmosphere, of an active metal constituent, having a high vapor pressure at temperatures {approx_equal}300 C and its subsequent condensation on and reaction with the other constituent (substrate) of an alloy thereby forming a controlled phase alloy and preferably a single phase alloy. It is preferred that the substrate material be a metal powder such that diffusion of the active metal constituent, preferably magnesium, and reaction therewith can be completed within a reasonable time and at temperatures {approx_equal}300 C thereby avoiding undesirable effects such as sintering, local compositional inhomogeneities, segregation, and formation of unwanted second phases such as intermetallic compounds. 4 figs.

Guthrie, S.E.; Thomas, G.J.; Bauer, W.; Yang, N.Y.C.

1999-04-20T23:59:59.000Z

220

Breakthrough Research on Platinum-Nickel Alloys  

NLE Websites -- All DOE Office Websites (Extended Search)

Breakthrough Research on Breakthrough Research on Platinum-Nickel Alloys Breakthrough Research on Platinum-Nickel Alloys Print Wednesday, 28 February 2007 00:00 Two out of three of the kinetic barriers to the practical use of polymer electrolyte membrane (PEM) hydrogen fuel cells in automobiles have been breached: the impractically high amount of extra energy needed for the oxidation reduction reaction (ORR) on the catalyst and the loss of catalytic surface areas available for ORR. Using a combination of probes and calculations, a group of scientists has demonstrated that the Pt3Ni(111) alloy is ten times more active for ORR than the corresponding Pt(111) surface and ninety times more active than the current state-of-the-art Pt/C catalysts used in existing PEM fuel cells. This new variation of the platinum-nickel alloy is the most active oxygen-reducing catalyst ever reported.

Note: This page contains sample records for the topic "high entropy alloy" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


221

Low activation ferritic alloys  

DOE Patents (OSTI)

Low activation ferritic alloys, specifically bainitic and martensitic stainless steels, are described for use in the production of structural components for nuclear fusion reactors. They are designed specifically to achieve low activation characteristics suitable for efficient waste disposal. The alloys essentially exclude molybdenum, nickel, nitrogen and niobium. Strength is achieved by substituting vanadium, tungsten, and/or tantalum in place of the usual molybdenum content in such alloys.

Gelles, D.S.; Ghoniem, N.M.; Powell, R.W.

1985-02-07T23:59:59.000Z

222

Cosmic rays, lithium abundance and excess entropy in galaxy clusters  

E-Print Network (OSTI)

We consider the production of $^6$Li in spallation reactions by cosmic rays in order to explain the observed abundance in halo metal-poor stars. We show that heating of ambient gas by cosmic rays is an inevitable consequence of this process, and estimate the energy input required to reproduce the observed abundance of $^6$Li/H$\\sim 10^{-11}$ to be of order a few hundred eV per particle. We draw attention to the possibility that this could explain the excess entropy in gas in galaxy groups and clusters. The evolution of $^6$Li and the accompanying heating of gas is calculated for structures collapsing at the present epoch with injection of cosmic rays at high redshift. We determine the energy required to explain the abundance of $^6$Li at $z \\sim 2$ corresponding to the formation epoch of halo metal-poor stars, and also an increased entropy level of $\\sim 300$ keV cm$^2$ necessary to explain X-ray observations of clusters. The energy budget for this process is consistent with the expected energy output of radi...

Nath, B B; Silk, J; Nath, Biman B.; Madau, Piero; Silk, Joseph

2006-01-01T23:59:59.000Z

223

Nonperturbative black hole entropy and Kloosterman sums  

E-Print Network (OSTI)

Non-perturbative quantum corrections to supersymmetric black hole entropy often involve nontrivial number-theoretic phases called Kloosterman sums. We show how these sums can be obtained naturally from the functional integral of supergravity in asymptotically AdS_2 space for a class of black holes. They are essentially topological in origin and correspond to charge-dependent phases arising from the various gauge and gravitational Chern-Simons terms and boundary Wilson lines evaluated on Dehn-filled solid 2-torus. These corrections are essential to obtain an integer from supergravity in agreement with the quantum degeneracies, and reveal an intriguing connection between topology, number theory, and quantum gravity. We give an assessment of the current understanding of quantum entropy of black holes.

Dabholkar, Atish; Murthy, Sameer

2014-01-01T23:59:59.000Z

224

Entropy of Contracting Universe in Cyclic Cosmology  

E-Print Network (OSTI)

Following up a recent proposal \\cite{BF} for a cyclic model based on phantom dark energy, we examine the content of the contracting universe (cu) and its entropy $S_{cu}$. We find that beyond dark energy the universe contains on average zero or at most a single photon which if present immediately after turnaround has infinitesimally energy which subsequently blue shifts to produce $e^+e^-$ pairs. These statements are independent of the equation of state $\\omega = p/\\rho$ of dark energy provided $\\omega < -1$. Thus $S_{cu} = 0$ and if observations confirm $\\omega < -1$ the entropy problem is solved. We discuss the absence of a theoretical lower bound on $\\phi = |\\omega + 1|$, then describe an anthropic fine tuning argument that renders unlikely extremely small $\\phi$. The present bound $\\phi \\lesssim 0.1$ already implies a time until turnaround of $(t_T - t_0) \\gtrsim 100$ Gy.

Lauris Baum; Paul H. Frampton

2007-03-18T23:59:59.000Z

225

Entropy of pseudo-random-number generators  

Science Journals Connector (OSTI)

Since the work of Ferrenberg et al. [Phys. Rev. Lett. 69, 3382 (1992)] some pseudo-random-number generators are known to yield wrong results in cluster Monte Carlo simulations. In this contribution the fundamental mechanism behind this failure is discussed. Almost all random-number generators calculate a new pseudo-random-number xi from preceding values, xi=f(xi?1,xi?2,…,xi?q). Failure of these generators in cluster Monte Carlo simulations and related experiments can be attributed to the low entropy of the production rule f() conditioned on the statistics of the input values xi?1,…,xi?q. Being a measure only of the arithmetic operations in the generator rule, the conditional entropy is independent of the lag in the recurrence or the period of the sequence. In that sense it measures a more profound quality of a random-number generator than empirical tests with their limited horizon.

Stephan Mertens and Heiko Bauke

2004-05-21T23:59:59.000Z

226

Structural alloy with a protective coating containing silicon or silicon-oxide  

DOE Patents (OSTI)

An iron-based alloy is described containing chromium and optionally, nickel. The alloy has a surface barrier of silicon or silicon plus oxygen which converts at high temperature to a protective silicon compound. The alloy can be used in oxygen-sulfur mixed gases at temperatures up to about 1100 C. 8 figures.

Natesan, K.

1994-12-27T23:59:59.000Z

227

Structural alloy with a protective coating containing silicon or silicon-oxide  

DOE Patents (OSTI)

This invention is comprised of an iron-based alloy containing chromium and optionally, nickel. The alloy has a surface barrier of silicon or silicon plus oxygen which converts at high temperature to a protective silicon compound. The alloy can be used in oxygen-sulfur mixed gases at temperatures up to about 1100{degrees}C.

Natesan, K.

1992-01-01T23:59:59.000Z

228

Hot cracking in tungsten inert gas welding of magnesium alloy AZ91D  

E-Print Network (OSTI)

Hot cracking in tungsten inert gas welding of magnesium alloy AZ91D W. Zhou*, T. Z. Long and C. K ductility, and the HAZ was found to be the `weakest link'. Keywords: Magnesium alloy, AZ91D, TIG welding, Hot cracking, Liquation, Fracture Introduction Magnesium alloys have high strength/weight ratio

Zhou, Wei

229

Neutron Absorbing Alloys  

DOE Patents (OSTI)

The present invention is drawn to new classes of advanced neutron absorbing structural materials for use in spent nuclear fuel applications requiring structural strength, weldability, and long term corrosion resistance. Particularly, an austenitic stainless steel alloy containing gadolinium and less than 5% of a ferrite content is disclosed. Additionally, a nickel-based alloy containing gadolinium and greater than 50% nickel is also disclosed.

Mizia, Ronald E. (Idaho Falls, ID); Shaber, Eric L. (Idaho Falls, ID); DuPont, John N. (Whitehall, PA); Robino, Charles V. (Albuquerque, NM); Williams, David B. (Bethlehem, PA)

2004-05-04T23:59:59.000Z

230

Superconductivity of Zirconium Alloys  

Science Journals Connector (OSTI)

The superconducting transition temperatures of alloys between zirconium and VIIIth column elements are substantially higher than those of zirconium. The same is true for zirconium-gold alloys. This observation confirms a rule previously established about the height of transition temperatures.

B. T. Matthias and E. Corenzwit

1955-10-15T23:59:59.000Z

231

Aluminum battery alloys  

DOE Patents (OSTI)

Aluminum alloys suitable for use as anode structures in electrochemical cells are disclosed. These alloys include iron levels higher than previously felt possible, due to the presence of controlled amounts of manganese, with possible additions of magnesium and controlled amounts of gallium.

Thompson, D.S.; Scott, D.H.

1984-09-28T23:59:59.000Z

232

Aluminum battery alloys  

DOE Patents (OSTI)

Aluminum alloys suitable for use as anode structures in electrochemical cs are disclosed. These alloys include iron levels higher than previously felt possible, due to the presence of controlled amounts of manganese, with possible additions of magnesium and controlled amounts of gallium.

Thompson, David S. (Richmond, VA); Scott, Darwin H. (Mechanicsville, VA)

1985-01-01T23:59:59.000Z

233

Heat treatment of NiCrFe alloy to optimize resistance to intergrannular stress corrosion  

DOE Patents (OSTI)

A process of producing a NiCrFe alloy having a high resistance to stress corrosion cracking comprising heating a NiCrFe alloy to a temperature sufficient to enable the carbon present in the alloy body in the form of carbide deposits to enter into solution, rapidly cool the alloy body, and heat the cooled body to a temperature between 1100.degree. to 1500.degree. F. for about 1 to 30 hours.

Steeves, Arthur F. (Schenectady, NY); Bibb, Albert E. (Clifton Park, NY)

1984-01-01T23:59:59.000Z

234

Time-dependent entropy of simple quantum model systems  

Science Journals Connector (OSTI)

Information-theoretic entropy measures are useful tools for quantifying the spreading of quantum states in phase space. In the present paper, we compare the time evolution of the joint entropy for three simple quantum systems: (i) a free Gaussian wave packet, (ii) a wave packet in a monochromatic electromagnetic field, and (iii) a wave packet tunneling through a ? barrier. As initial condition maximal classical states are used, which minimize the Heisenberg uncertainty and the entropy. It is found that, in all three cases, the joint entropy increases in time.

Jörn Dunkel and Sergey A. Trigger

2005-05-10T23:59:59.000Z

235

Generalized Gravitational Entropy of Interacting Scalar Field and Maxwell Field  

E-Print Network (OSTI)

The generalized gravitational entropy proposed by Lewkowycz and Maldacena in recent is extended to the interacting real scalar field and Maxwell field system. Using the BTZ geometry we first investigate the case of free real scalar field and then show a possible way to calculate the entropy of the interacting scalar field. Next, we investigate the Maxwell field system. We exactly solve the wave equation and calculate the analytic value of the generalized gravitational entropy. We also use the Einstein equation to find the effect of backreaction of the Maxwell field on the area of horizon. The associated modified area law is consistent with the generalized gravitational entropy.

Wung-Hong Huang

2014-11-11T23:59:59.000Z

236

On divergence, relative entropy and the substate property  

E-Print Network (OSTI)

In this article we study relationship between three measures of distinguishability of quantum states called as divergence, relative entropy and the substate property.

Jain, R; Sen, P; Jain, Rahul; Radhakrishnan, Jaikumar; Sen, Pranab

2005-01-01T23:59:59.000Z

237

On divergence, relative entropy and the substate property  

E-Print Network (OSTI)

In this article we study relationship between three measures of distinguishability of quantum states called as divergence, relative entropy and the substate property.

Rahul Jain; Jaikumar Radhakrishnan; Pranab Sen

2005-06-24T23:59:59.000Z

238

Microscopic diagonal entropy and its connection to basic thermodynamic relations  

SciTech Connect

We define a diagonal entropy (d-entropy) for an arbitrary Hamiltonian system as S{sub d}=-{Sigma}{sub n{rho}nn}ln{rho}{sub nn} with the sum taken over the basis of instantaneous energy states. In equilibrium this entropy coincides with the conventional von Neumann entropy S{sub n} = -Tr{rho} ln {rho}. However, in contrast to S{sub n}, the d-entropy is not conserved in time in closed Hamiltonian systems. If the system is initially in stationary state then in accord with the second law of thermodynamics the d-entropy can only increase or stay the same. We also show that the d-entropy can be expressed through the energy distribution function and thus it is measurable, at least in principle. Under very generic assumptions of the locality of the Hamiltonian and non-integrability the d-entropy becomes a unique function of the average energy in large systems and automatically satisfies the fundamental thermodynamic relation. This relation reduces to the first law of thermodynamics for quasi-static processes. The d-entropy is also automatically conserved for adiabatic processes. We illustrate our results with explicit examples and show that S{sub d} behaves consistently with expectations from thermodynamics.

Polkovnikov, Anatoli, E-mail: asp@bu.edu [Department of Physics, Boston University, Boston, MA 02215 (United States)

2011-02-15T23:59:59.000Z

239

Mutual Entropy in Quantum Information and Information Genetics  

E-Print Network (OSTI)

After Shannon, entropy becomes a fundamental quantity to describe not only uncertainity or chaos of a system but also information carried by the system. Shannon's important discovery is to give a mathematical expression of the mutual entropy (information), information transmitted from an input system to an output system, by which communication processes could be analyzed on the stage of mathematical science. In this paper, first we review the quantum mutual entropy and discuss its uses in quantum information theory, and secondly we show how the classical mutual entropy can be used to analyze genomes, in particular, those of HIV.

Masanori Ohya

2004-06-30T23:59:59.000Z

240

Osmosis, colligative properties, entropy, free energy and the chemical potential  

E-Print Network (OSTI)

A diffusive model of osmosis is presented that explains currently available experimental data. It makes predictions that distinguish it from the traditional convective flow model of osmosis, some of which have already been confirmed experimentally and others have yet to be tested. It also provides a simple kinetic explanation of Raoult's law and the colligative properties of dilute aqueous solutions. The diffusive model explains that when a water molecule jumps from low to high osmolarity at equilibrium, the free energy change is zero because the work done pressurizing the water molecule is balanced by the entropy of mixing. It also explains that equal chemical potentials are required for particle exchange equilibrium in analogy with the familiar requirement of equal temperatures at thermal equilibrium.

Peter Hugo Nelson

2014-09-13T23:59:59.000Z

Note: This page contains sample records for the topic "high entropy alloy" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


241

The Birmingham-CfA cluster scaling project - III: entropy and similarity in galaxy systems  

E-Print Network (OSTI)

We examine profiles and scaling properties of the entropy of the intergalactic gas in a sample of 66 virialized systems, ranging in mass from single elliptical galaxies to rich clusters, for which we have resolved X-ray temperature profiles. Some of the properties we derive appear to be inconsistent with any of the models put forward to explain the breaking of self-similarity in the baryon content of clusters. In particular, the entropy profiles, scaled to the virial radius, are broadly similar in form across the sample, apart from a normalization factor which differs from the simple self-similar scaling with temperature. Low mass systems do not show the large isentropic cores predicted by preheating models, and the high entropy excesses reported at large radii in groups by Finoguenov et al (2002) are confirmed, and found to extend even to moderately rich clusters. We discuss the implications of these results for the evolutionary history of the hot gas in clusters, and suggest that preheating may affect the entropy of intracluster gas primarily by reducing the density of material accreting into groups and clusters along cosmic filaments.

T. J. Ponman; A. J. R. Sanderson; A. Finoguenov

2003-04-02T23:59:59.000Z

242

Conformal perturbation theory and higher spin entanglement entropy on the torus  

E-Print Network (OSTI)

We study the free fermion theory in 1+1 dimensions deformed by chemical potentials for holomorphic, conserved currents at finite temperature and on a spatial circle. For a spin-three chemical potential \\mu, the deformation is related at high temperatures to a higher spin black hole in hs[0] theory on AdS_3 spacetime. We calculate the order \\mu^2 corrections to the single interval Renyi and entanglement entropies on the torus using the bosonized formulation. A consistent result, satisfying all checks, emerges upon carefully accounting for both perturbative and winding mode contributions in the bosonized language. The order \\mu^2 corrections involve integrals that are finite but potentially sensitive to contact term singularities. We propose and apply a prescription for defining such integrals which matches the Hamiltonian picture and passes several non-trivial checks for both thermal corrections and the Renyi entropies at this order. The thermal corrections are given by a weight six quasi-modular form, whilst the Renyi entropies are controlled by quasi-elliptic functions of the interval length with modular weight six. We also point out the well known connection between the perturbative expansion of the partition function in powers of the spin-three chemical potential and the Gross-Taylor genus expansion of large-N Yang-Mills theory on the torus. We note the absence of winding mode contributions in this connection, which suggests qualitatively different entanglement entropies for the two systems.

Shouvik Datta; Justin R. David; S. Prem Kumar

2014-12-12T23:59:59.000Z

243

Rare Earth Metals and Alloys | Ames Laboratory  

NLE Websites -- All DOE Office Websites (Extended Search)

Mpc » Rare Earth Metals and Alloys Mpc » Rare Earth Metals and Alloys Rare Earth Metals and Alloys Terbium (Tb) and Cerium (Ce) phosphors in your computer screen allow you to see GREEN. Europium (Eu) is the source of the RED light and BLUE emitted by our display. The Ames Laboratory has been actively involved in the preparation of very pure rare earth metals since the early 1940's when Dr. Frank H. Spedding and his group of pioneers developed the ion-exchange process, a technique that separates the "fraternal fifteen" plus yttrium and scandium. As a result of this and subsequent work, high-purity oxides are available from which high-purity rare earth metals can be prepared. In most cases, the rare earth oxides are first converted to their respective fluorides and are then reduced metallothermicaly on a kilogram

244

Friction Properties of Molybdenum Alloyed Steel at Elevated Temperatures  

SciTech Connect

The high-temperature properties of steel surface can be improved by molybdenum surface alloying. Molybdenzing was carried out on carbon steel in the multi-function double glow plasma surface alloying furnace. The friction and wear tests were conducted on a high temperature ball-on-disk tribometer under the temperature of 25 deg. C{approx}600 deg. C. The contents of alloy element varied with alloyed layer were detected by SEM attached with EDS. The molybdenized layer is composed of the deposited layer and diffused layer. The micro-hardness of alloyed layer decreases from HV650 on the top layer to HV240. The friction coefficient of molybdenized layer decreases from 0.5{approx}0.6 to 0.2{approx}0.3 and wear rate decreases by 20% at elevated temperature after molybdenizing.

Li Jianliang; Xiong Dangsheng [Department of Material Science and Engineering, Nanjing University of Science and Technology, Nanjing, 210094 (China); Wu Hongyan [College of Math and Physics, Nanjing University of Information and Technology, Nanjing, 210044 (China)

2011-01-17T23:59:59.000Z

245

Theory: Biological systems organize to maximize entropy production subject to information and biophysicochemical constraints.  

E-Print Network (OSTI)

Theory: Biological systems organize to maximize entropy production subject to information production. While organized structures decrease the entropy of the system, they are maintained by external selection produce biological systems that tend to follow a pathway of maximum entropy production

Vallino, Joseph J.

246

Universality and Shannon entropy of codon usage  

Science Journals Connector (OSTI)

The distribution functions of codon usage probabilities, computed over all the available GenBank data for 40 eukaryotic biological species and five chloroplasts, are best fitted by the sum of a constant, an exponential, and a linear function in the rank of usage. For mitochondria the analysis is not conclusive. These functions are characterized by parameters that strongly depend on the total guanine and cytosine (GC) content of the coding regions of biological species. It is predicted that the codon usage is the same in all exonic genes with the same GC content. The Shannon entropy for codons, also strongly dependent on the exonic GC content, is computed.

L. Frappat; C. Minichini; A. Sciarrino; P. Sorba

2003-12-24T23:59:59.000Z

247

Algorithms for the Markov entropy decomposition  

Science Journals Connector (OSTI)

The Markov entropy decomposition (MED) is a recently proposed, cluster-based simulation method for finite temperature quantum systems with arbitrary geometry. In this paper, we detail numerical algorithms for performing the required steps of the MED, principally solving a minimization problem with a preconditioned Newton's algorithm, as well as how to extract global susceptibilities and thermal responses. We demonstrate the power of the method with the spin-1/2 XXZ model on the 2D square lattice, including the extraction of critical points and details of each phase. Although the method shares some qualitative similarities with exact diagonalization, we show that the MED is both more accurate and significantly more flexible.

Andrew J. Ferris and David Poulin

2013-05-20T23:59:59.000Z

248

Theory of enthalpy-entropy compensation  

SciTech Connect

The ubiquitous nature of enthalpy-entropy compensation calls for a general model. The present model, which is formulated with compensation in ion exchange in mind, is an extension of an older general approach in that the molar fractions of the species that are exchanged in the process enter explicitly. In a different way, it is an extension to the theory of conformal solutions, which only leads to compensation under the condition of conformity. The present model allows one to decide from experiment whether interactions between exchanging species or interactions with third species (or external fields) are responsible for the compensation effect.

Boots, H.M.J.; de Bokx, P.K. (Philips Research Labs., Eindhoven (Netherlands))

1989-12-14T23:59:59.000Z

249

A geometric entropy measuring networks complexity  

E-Print Network (OSTI)

A central issue of the science of complex systems is the quantitative characterization of complexity. In the present work a new entropic measure of complexity is proposed which has unprecedented advantages. Starting from the framework of the so-called information geometry we propose a new and constructive way to associate to a - in principle any - network a differentiable object (a Riemannian manifold) whose volume is used to define an entropy. The effectiveness of this new entropic measure of networks complexity is successfully proved through its capability of detecting a classical phase transition in random graphs: the emergence of the "giant component" according to the celebrated Erd\\"os-R\\'enyi theorem.

Roberto Franzosi; Domenico Felice; Stefano Mancini; Marco Pettini

2014-10-20T23:59:59.000Z

250

Oxidation and volatilization of a niobium alloy  

SciTech Connect

This report presents the findings from a preliminary investigation into oxidation and volatilization characteristics of a niobium alloy. Niobium is a candidate alloy for use in plasma facing components (PFCS) in experimental fusion reactors like the Intemational Thermonuclear Experimental Reactor (ITER). An experimental alloy was tailored to simulate small changes in chemistry which could result from transmutations from irradiation. The alloy was exposed in air and steam between 800[degree]C and 1200[degree]C. Volatilized products and hydrogen were collected and measured. Post-test examinations were also performed on the samples to determine the amount of material loss during the exposures. The obtained measurements of volatilization flux (g/m[sup 2]-s), hydrogen generation rates (liters/m[sup 2]-s), and recession rates (mm/s) are data which can be used for safety analyses and material performance to predict consequences which may result from an accident involving the ingress of air or steam into the plasma chamber of fusion reactor. In our volatility tests, only molybdenum and niobium were found at release levels above the detection limit. Although molybdenum is present at only 0.12 wt%, the quantities of this element volatilized in air are nearly comparable to the quantities of niobium released. The niobium release in steam is only three to four times higher than that of molybdenum in steam. The hydrogen production of the niobium alloy is compared with other PFC materials that we have tested, specifically, beryllium, graphite, and a tunesten alloy. At high temperatures, the hydrogen production rate of the niobium alloy is among the lowest of these materials, significantly lower than beryllium. To understand what this means in an accident situation, modeling is necessary to predict temperatures, and therefore total hydrogen production. The INEL is currently doing this modeling.

Smolik, G.R.; McCarthy, K.A.

1992-07-01T23:59:59.000Z

251

Minimum entropy generation due to heat transfer and fluid friction in a parabolic trough receiver with non-uniform heat flux at different rim angles and concentration ratios  

Science Journals Connector (OSTI)

Abstract In this paper, Monte Carlo ray-tracing and computational fluid dynamics are used to numerically investigate the minimum entropy generation due to heat transfer and fluid friction in a parabolic trough receiver. The analysis was carried out for rim angles in the range 40°–120°, concentration ratios in the range 57–143, Reynolds numbers in the range 1.02 × 104–1.36 × 106 and fluid temperatures in the range 350–650 K. Results show existence of an optimal Reynolds number at any given combination of fluid temperature, concentration ratio and rim angle for which the total entropy generation is a minimum. The total entropy generation was found to increase as the rim angle reduced, concentration ratio increased and fluid temperature reduced. The high entropy generation rates at low rim angles are mainly due to high peak temperatures in the absorber tube at these low rim angles.

Aggrey Mwesigye; Tunde Bello-Ochende; Josua P. Meyer

2014-01-01T23:59:59.000Z

252

Method of treating intermetallic alloy hydrogenation/oxidation catalysts for improved impurity poisoning resistance, regeneration and increased activity  

DOE Patents (OSTI)

Alternate, successive high temperature oxidation and reduction treatments, in either order, of intermetallic alloy hydrogenation and intermetallic alloy oxidation catalysts unexpectedly improves the impurity poisoning resistance, regeneration capacity and/or activity of the catalysts. The particular alloy, and the final high temperature treatment given alloy (oxidation or reduction) will be chosen to correspond to the function of the catalyst (oxidation or hydrogenation). 23 figs.

Wright, R.B.

1992-01-14T23:59:59.000Z

253

Stable lattice Boltzmann schemes with a dual entropy approach  

E-Print Network (OSTI)

Stable lattice Boltzmann schemes with a dual entropy approach for monodimensional nonlinear waves of a lattice Boltzmann scheme. This method is expressed in terms of the dual of the mathematical entropy with D1Q3 lattice Boltzmann schemes for the Burgers equation. It conducts to the explicitation of three

Boyer, Edmond

254

Differential Entropy Dynamics: A Possible Cause of Coherence Resonance  

E-Print Network (OSTI)

Coherence resonance can be explained using differential entropy and mutual information. This theory explores the role of external noise in stabilising chaotic circuits such as the uni-junction transistor relaxation oscillator.The phenomenon of coherence resonance maximizes differential entropy and mutual information.Thus most natural chaotic oscillators show coherence resonance in the presence of an external driving noise.

Juhi Rajhans; A. N. Sekar Iyengar

2013-12-01T23:59:59.000Z

255

Measuring the Entropy and Testing the Second Law of Thermodynamics  

E-Print Network (OSTI)

Evidence implies that basic laws of thermodynamics must be tested by experiments. In this paper, an experiment is designed to measure the entropy of a system with at least one known (measurable) equation of state, especially the gas systems. Since the entropy can be measured now, the formulae related to the second law of thermodynamics can be examined by other experiments.

Bin Zhou

2002-03-19T23:59:59.000Z

256

Numerical Entropy Production on Shocks and Smooth Transitions  

E-Print Network (OSTI)

production does not result in a substantial extra computational cost. We consider the one-dimensional system we started in [5]. We compute the entropy production on a gas dynamic test problem for severalNumerical Entropy Production on Shocks and Smooth Transitions Gabriella Puppo z November 12, 2001

Ceragioli, Francesca

257

Statistics of Entropy Production in Linearized Stochastic System  

E-Print Network (OSTI)

We consider a wide class of linear stochastic problems driven off the equilibrium by a multiplicative asymmetric force. The force brakes detailed balance, maintained otherwise, thus producing entropy. The large deviation function of the entropy production in the system is calculated explicitly. The general result is illustrated using an example of a polymer immersed in a gradient flow and subject to thermal fluctuations.

K. Turitsyn; M. Chertkov; V. Y. Chernyak; A. Puliafito

2007-02-20T23:59:59.000Z

258

RELAP-7 Numerical Stabilization: Entropy Viscosity Method  

SciTech Connect

The RELAP-7 code is the next generation nuclear reactor system safety analysis code being developed at the Idaho National Laboratory (INL). The code is based on the INL's modern scientific software development framework, MOOSE (Multi-Physics Object Oriented Simulation Environment). The overall design goal of RELAP-7 is to take advantage of the previous thirty years of advancements in computer architecture, software design, numerical integration methods, and physical models. The end result will be a reactor systems analysis capability that retains and improves upon RELAP5's capability and extends the analysis capability for all reactor system simulation scenarios. RELAP-7 utilizes a single phase and a novel seven-equation two-phase flow models as described in the RELAP-7 Theory Manual (INL/EXT-14-31366). The basic equation systems are hyperbolic, which generally require some type of stabilization (or artificial viscosity) to capture nonlinear discontinuities and to suppress advection-caused oscillations. This report documents one of the available options for this stabilization in RELAP-7 -- a new and novel approach known as the entropy viscosity method. Because the code is an ongoing development effort in which the physical sub models, numerics, and coding are evolving, so too must the specific details of the entropy viscosity stabilization method. Here the fundamentals of the method in their current state are presented.

R. A. Berry; M. O. Delchini; J. Ragusa

2014-06-01T23:59:59.000Z

259

Entanglement Entropy and Entanglement Spectrum of the Kitaev Model  

Science Journals Connector (OSTI)

In this Letter, we obtain an exact formula for the entanglement entropy of the ground state and all excited states of the Kitaev model. Remarkably, the entanglement entropy can be expressed in a simple separable form S=SG+SF, with SF the entanglement entropy of a free Majorana fermion system and SG that of a Z2 gauge field. The Z2 gauge field part contributes to the universal “topological entanglement entropy” of the ground state while the fermion part is responsible for the nonlocal entanglement carried by the Z2 vortices (visons) in the non-Abelian phase. Our result also enables the calculation of the entire entanglement spectrum and the more general Renyi entropy of the Kitaev model. Based on our results we propose a new quantity to characterize topologically ordered states—the capacity of entanglement, which can distinguish the states with and without topologically protected gapless entanglement spectrum.

Hong Yao and Xiao-Liang Qi

2010-08-16T23:59:59.000Z

260

Interacting entropy-corrected holographic Chaplygin gas model  

E-Print Network (OSTI)

Holographic dark energy (HDE), presents a dynamical view of dark energy which is consistent with the observational data and has a solid theoretical background. Its definition follows from the entropy-area relation $S(A)$, where $S$ and $A$ are entropy and area respectively. In the framework of loop quantum gravity, a modified definition of HDE called "entropy-corrected holographic dark energy" (ECHDE) has been proposed recently to explain dark energy with the help of quantum corrections to the entropy-area relation. Using this new definition, we establish a correspondence between modified variable Chaplygin gas, new modified Chaplygin gas and the viscous generalized Chaplygin gas with the entropy corrected holographic dark energy and reconstruct the corresponding scalar potentials which describe the dynamics of the scalar field.

M. Umar Farooq; Muneer A. Rashid; Mubasher Jamil

2010-03-17T23:59:59.000Z

Note: This page contains sample records for the topic "high entropy alloy" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


261

Thermophysical Properties of U-10MO Alloy  

SciTech Connect

This report provides an overview of thermophysical properties of unirradiated uranium alloyed with ten weight percent molybdenum (U 10Mo), with particular focus on those material properties needed for modeling of new fuels for HPRRs (High Performance Research Reactors). The report contains both historical data available in the literature on U-10Mo, as well as more recent results conducted by the Global Threat Reduction Initiative fuel development program. The main use of the report is intended as a standard U-10Mo alloy properties reference for reactor models and simulations.

A. M. Phillips; G. S. Mickum; D. E. Burkes

2010-11-01T23:59:59.000Z

262

Creep-Resisting Alloys For Gas Turbines  

Science Journals Connector (OSTI)

... ON February 22 and 23, a symposium on High-Temperature Steels and Alloys for Gas Turbines was held under the auspices of the Iron and Steel Institute in the rooms of ... metallurgical progress to which his invention gave rise, and discussing the problems of the gas turbine at its present stage of development.

N. P. ALLEN

1951-05-26T23:59:59.000Z

263

Irradiation creep of vanadium-base alloys.  

SciTech Connect

A study of irradiation creep in vanadium-base alloys is underway with experiments in the Advanced Test Reactor (ATR) and the High Flux Isotope Reactor (HFIR) in the US. Test specimens are thin-wall sealed tubes with internal pressure loading. The results from the initial ATR irradiation at low temperature (200-300 C) to a neutron damage level of 4.7 dpa show creep rates ranging from {approx}0 to 1.2 x 10{sup {minus}5}/dpa/MPa for a 500-kg heat of V-4Cr-4Ti alloy. These rates were generally lower than reported from a previous experiment in BR-10. Because both the attained neutron damage levels and the creep strains were low in the present study, however, these creep rates should be regarded as only preliminary. Substantially more testing is required before a data base on irradiation creep of vanadium alloys can be developed and used with confidence.

Tsai, H.; Matsui, H.; Billone, M. C.; Strain, R. V.; Smith, D. L.

1998-05-18T23:59:59.000Z

264

Dispersoid reinforced alloy powder and method of making  

DOE Patents (OSTI)

A method of making dispersion-strengthened alloy particles involves melting an alloy having a corrosion and/or oxidation resistance-imparting alloying element, a dispersoid-forming element, and a matrix metal wherein the dispersoid-forming element exhibits a greater tendency to react with a reactive species acquired from an atomizing gas than does the alloying element. The melted alloy is atomized with the atomizing gas including the reactive species to form atomized particles so that the reactive species is (a) dissolved in solid solution to a depth below the surface of atomized particles and/or (b) reacted with the dispersoid-forming element to form dispersoids in the atomized particles to a depth below the surface of said atomized particles. Bodies made from the dispersion strengthened solidified particles exhibit enhanced fatigue and creep resistance and reduced wear as well as enhanced corrosion and/or oxidation resistance at high temperatures.

Anderson, Iver E; Terpstra, Robert L

2014-10-21T23:59:59.000Z

265

Selecting copper and copper alloys; Part 2: Cast products  

SciTech Connect

This article provides an introduction to the properties, characteristics, and applications of cast coppers and copper alloys. An overview of alloy families is presented since it is impractical to describe all 130 standard grades in detail. However, additional technical information is readily available from the Copper Development Assn. Inc. (CDA) and the resources listed in the references and bibliography at the end of the article. Copper casting alloys are primarily selected for either their corrosion resistance, or their combination of corrosion resistance and mechanical properties. The materials also feature good castability, high machinability, and, compared with other corrosion-resistant alloys, reasonable cost. Additional benefits include biofouling resistance--important in marine applications--and a spectrum of attractive colors. Many of the alloys also have favorable tribological properties, which explains their widespread use for sleeve bearings, wear plates, gears, and other wear-prone components.

Peters, D.T. (Copper Development Association Inc., New York, NY (United States)); Kundig, K.J.A. (Kundig (Konrad J.A.), Randolph, NJ (United States))

1994-06-01T23:59:59.000Z

266

Degassing of molten alloys with the assistance of ultrasonic vibration  

DOE Patents (OSTI)

An apparatus and method are disclosed in which ultrasonic vibration is used to assist the degassing of molten metals or metal alloys thereby reducing gas content in the molten metals or alloys. High-intensity ultrasonic vibration is applied to a radiator that creates cavitation bubbles, induces acoustic streaming in the melt, and breaks up purge gas (e.g., argon or nitrogen) which is intentionally introduced in a small amount into the melt in order to collect the cavitation bubbles and to make the cavitation bubbles survive in the melt. The molten metal or alloy in one version of the invention is an aluminum alloy. The ultrasonic vibrations create cavitation bubbles and break up the large purge gas bubbles into small bubbles and disperse the bubbles in the molten metal or alloy more uniformly, resulting in a fast and clean degassing.

Han, Qingyou (Knoxville, TN); Xu, Hanbing (Knoxville, TN); Meek, Thomas T. (Knoxville, TN)

2010-03-23T23:59:59.000Z

267

Hydrodynamic equations for electrons in graphene obtained from the maximum entropy principle  

SciTech Connect

The maximum entropy principle is applied to the formal derivation of isothermal, Euler-like equations for semiclassical fermions (electrons and holes) in graphene. After proving general mathematical properties of the equations so obtained, their asymptotic form corresponding to significant physical regimes is investigated. In particular, the diffusive regime, the Maxwell-Boltzmann regime (high temperature), the collimation regime and the degenerate gas limit (vanishing temperature) are considered.

Barletti, Luigi, E-mail: luigi.barletti@unifi.it [Dipartimento di Matematica e Informatica “Ulisse Dini”, Università degli Studi di Firenze, Viale Morgagni 67/A, 50134 Firenze (Italy)

2014-08-15T23:59:59.000Z

268

Double-Sided Arc Welding of AZ31B Magnesium Alloy Sheet.  

E-Print Network (OSTI)

??Magnesium alloys are of interest to the automotive industry because of their high specific strength and potential to reduce vehicle weight and fuel consumption. In… (more)

Shuck, Gerald

2013-01-01T23:59:59.000Z

269

E-Print Network 3.0 - alloyed molybdenum disilicide Sample Search...  

NLE Websites -- All DOE Office Websites (Extended Search)

Ecole Polytechnique, Centre de mathmatiques Collection: Mathematics 2 FATIGUE AND FRACTURE BEHAVIOR OF HIGH TEMPERATURE MATERIALS Summary: . These alloys can Boron-containing...

270

Platinum- and Platinum Alloy-Coated Palladium and Palladium Alloy...  

NLE Websites -- All DOE Office Websites (Extended Search)

Hydrogen and Fuel Cell Hydrogen and Fuel Cell Find More Like This Return to Search Platinum- and Platinum Alloy-Coated Palladium and Palladium Alloy Particles and Uses Thereof...

271

Crossed products and entropy of automorphisms  

E-Print Network (OSTI)

Let A be an exact C^*-algebra, let G be a locally compact group, and let (A,G,\\alpha) be a C*-dynamical system. Each automorphism \\alpha_g induces a spatial automorphism Ad_{\\lamba_g} on the reduced crossed product A\\times_\\alpha G. In this paper we examine the question, first raised by E. Stormer, of when the topological entropies of \\alpha_g and Ad_{\\alpha_g} coincide. This had been answered by N. Brown for the particular case of discrete abelian groups. Using different methods, we extend his result to a wider class of groups called locally [FIA]^-. This class includes all abelian groups, both discrete and continuous, as well as all compact groups.

Ciprian Pop; Roger R. Smith

2002-09-02T23:59:59.000Z

272

Entropy-energy inequalities for qudit states  

E-Print Network (OSTI)

We establish a procedure to find the extremal density matrices for any finite Hamiltonian of a qudit system. These extremal density matrices provide an approximate description of the energy spectra of the Hamiltonian. In the case of restricting the extremal density matrices by pure states, we show that the energy spectra of the Hamiltonian is recovered for $d=2$ and $3$. We conjecture that by means of this approach the energy spectra can be recovered for the Hamiltonian of an arbitrary finite qudit system. For a given qudit system Hamiltonian, we find new inequalities connecting the mean value of the Hamiltonian and the entropy of an arbitrary state. We demonstrate that these inequalities take place for both the considered extremal density matrices and generic ones.

Armando Figueroa; Julio López; Octavio Castaños; Ramón López-Peña; Margarita A. Man'ko; Vladimir I. Man'ko

2014-12-08T23:59:59.000Z

273

Extremal limits and black hole entropy  

E-Print Network (OSTI)

Taking the extremal limit of a non-extremal Reissner-Nordstr\\"om black hole (by externally varying the mass or charge), the region between the inner and outer event horizons experiences an interesting fate -- while this region is absent in the extremal case, it does not disappear in the extremal limit but rather approaches a patch of $AdS_2\\times S^2$. In other words, the approach to extremality is not continuous, as the non-extremal Reissner-Nordstr\\"om solution splits into two spacetimes at extremality: an extremal black hole and a disconnected $AdS$ space. We suggest that the unusual nature of this limit may help in understanding the entropy of extremal black holes.

Sean M. Carroll; Matthew C. Johnson; Lisa Randall

2009-01-08T23:59:59.000Z

274

Entropy Production : From Open Volume Preserving to Dissipative Systems  

E-Print Network (OSTI)

We generalize Gaspard's method for computing the \\epsilon-entropy production rate in Hamiltonian systems to dissipative systems with attractors considered earlier by T\\'el, Vollmer, and Breymann. This approach leads to a natural definition of a coarse grained Gibbs entropy which is extensive, and which can be expressed in terms of the SRB measures and volumes of the coarse graining sets which cover the attractor. One can also study the entropy and entropy production as functions of the degree of resolution of the coarse graining process, and examine the limit as the coarse graining size approaches zero. We show that this definition of the Gibbs entropy leads to a positive rate of irreversible entropy production for reversible dissipative systems. We apply the method to the case of a two dimensional map, based upon a model considered by Vollmer, T\\'el and Breymann, that is a deterministic version of a biased-random walk. We treat both volume preserving and dissipative versions of the basic map, and make a comparison between the two cases. We discuss the \\epsilon-entropy production rate as a function of the size of the coarse graining cells for these biased-random walks and, for an open system with flux boundary conditions, show regions of exponential growth and decay of the rate of entropy production as the size of the cells decreases. This work describes in some detail the relation between the results of Gaspard, those of T\\'el, Vollmer and Breymann, and those of Ruelle, on entropy production in various systems described by Anosov or Anosov-like maps.

T. Gilbert; J. R. Dorfman

1999-03-11T23:59:59.000Z

275

Thermodynamic efficiency and entropy production in the climate system  

Science Journals Connector (OSTI)

We present an outlook on the climate system thermodynamics. First, we construct an equivalent Carnot engine with efficiency ? and frame the Lorenz energy cycle in a macroscale thermodynamic context. Then, by exploiting the second law, we prove that the lower bound to the entropy production is ? times the integrated absolute value of the internal entropy fluctuations. An exergetic interpretation is also proposed. Finally, the controversial maximum entropy production principle is reinterpreted as requiring the joint optimization of heat transport and mechanical work production. These results provide tools for climate change analysis and for climate models’ validation.

Valerio Lucarini

2009-08-21T23:59:59.000Z

276

Black hole entanglement entropy and the renormalization group  

Science Journals Connector (OSTI)

We investigate the contributions of quantum fields to black hole entropy by using a cutoff scale at which the theory is described with a Wilsonian effective action. For both free and interacting fields, the total black hole entropy can be partitioned into a contribution derived from the gravitational effective action and a contribution from quantum fluctuations below the cutoff scale. In general, the latter includes a quantum contribution to the Noether charge. We analyze whether it is appropriate to identify the rest with horizon entanglement entropy, and find several complications for this interpretation, which are especially problematic for interacting fields.

Ted Jacobson and Alejandro Satz

2013-04-18T23:59:59.000Z

277

Black hole entanglement entropy and the renormalization group  

E-Print Network (OSTI)

We investigate the contributions of quantum fields to black hole entropy by using a cutoff scale at which the theory is described with a Wilsonian effective action. For both free and interacting fields, the total black hole entropy can be partitioned into a contribution derived from the gravitational effective action and a contribution from quantum fluctuations below the cutoff scale. In general the latter includes a quantum contribution to the Noether charge. We analyze whether it is appropriate to identify the rest with horizon entanglement entropy, and find several complications for this interpretation, which are especially problematic for interacting fields.

Ted Jacobson; Alejandro Satz

2013-03-21T23:59:59.000Z

278

The compression behavior of niobium alloyed {gamma}-titanium aluminides  

SciTech Connect

The underlying mechanisms behind the reported high strength of titanium aluminide alloys containing a large addition of niobium has been investigated by determining the flow stresses and activation parameters of plastic deformation. It has been found that alloys such as Ti-45Al-10Nb (at.%) and Ti-45Al-5Nb have 1.25% flow stress values in compression of > 800 MPa at room temperature and > 500 MPa at 1,173 K. When compared with values from a more conventional alloy, Ti-47Al-2Cr-0.2Si, they represent a considerable increase in strength. However, the activation volumes after 1.25% deformation are very similar to those of conventional alloys, particularly up to 973 K. This suggests that athermal dislocation mechanisms are responsible for the increased flow stress of the niobium containing alloys. By comparing the properties of the niobium containing alloys with different binary alloys it has been shown that the high strength is solely a result of the reduced aluminum content and that niobium plays no role in strengthening or work hardening.

Paul, J.D.H.; Appel, F.; Wagner, R. [GKSS Research Centre, Geesthacht (Germany). Inst. for Materials Research] [GKSS Research Centre, Geesthacht (Germany). Inst. for Materials Research

1998-02-13T23:59:59.000Z

279

Improved oxidation sulfidation resistance of Fe-Cr-Ni alloys  

DOE Patents (OSTI)

High temperature resistance of Fe-Cr-Ni alloy compositions to oxidative and/or sulfidative conditions is provided by the incorporation of about 1 to 8 wt % of Zr or Nb and results in a two-phase composition having an alloy matrix as the first phase and a fine grained intermetallic composition as the second phase. The presence and location of the intermetallic composition between grains of the matrix provides mechanical strength, enhanced surface scale adhesion, and resistance to corrosive attack between grains of the alloy matrix at temperatures of 500 to 1000/sup 0/C.

Natesan, K.; Baxter, D.J.

1983-07-26T23:59:59.000Z

280

Entropy of the two-dimensional Ising model  

Science Journals Connector (OSTI)

A numerical calculation of the entropy of the two-dimensional Ising model is described, for nonzero external field. The calculation makes use of the Monte Carlo method to simulate a kind of microcanonical ensemble.

Daniel R. Stump

1987-11-01T23:59:59.000Z

Note: This page contains sample records for the topic "high entropy alloy" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


281

Black hole quantum tunnelling and black hole entropy correction  

E-Print Network (OSTI)

Parikh-Wilczek tunnelling framework, which treats Hawking radiation as a tunnelling process, is investigated again. As the first order correction, the log-corrected entropy-area relation naturally emerges in the tunnelling picture if we consider the emission of a spherical shell. The second order correction of the emission rate for the Schwarzschild black hole is calculated too. In this level, the result is still in agreement with the unitary theory, however, the entropy of the black hole will contain three parts: the usual Bekenstein-Hawking entropy, the logarithmic term and the inverse area term. In our results the coefficient of the logarithmic term is -1. Apart from a coefficient, Our correction to the black hole entropy is consistent with that of loop quantum gravity.

Jingyi Zhang

2008-06-15T23:59:59.000Z

282

Counterfactuals, dispositions, and conscious experience : essays on entropy  

E-Print Network (OSTI)

Chapter 1 of this thesis concerns counterfactual conditionals. David Lewis has offered a natural and influential analysis of counterfactuals. But the analysis fails to take into account the asymmetry of entropy, and comes ...

Elga, Adam Newman, 1974-

2001-01-01T23:59:59.000Z

283

Propane spectral resolution enhancement by the maximum entropy method  

Science Journals Connector (OSTI)

The Burg algorithm for maximum entropy power spectral density estimation is applied to a time series of data obtained from a Michelson interferometer and compared with a standard fast...

Bonavito, N L; Yeh, K C; Stewart, K P; Inguva, R; Hurley, E J

1990-01-01T23:59:59.000Z

284

Entropy satisfying flux vector splittings and kinetic BGK models  

Science Journals Connector (OSTI)

We establish forward and backward relations between entropy satisfying BGK relaxation models such as those introduced previously by the author and the first order flux vector splitting numerical methods for general systems of conservation laws. Classically, ...

F. Bouchut

2003-06-01T23:59:59.000Z

285

Entropy and Energy: Toward a Definition of Physical Sustainability  

E-Print Network (OSTI)

calculate the amount of energy for rapid mix E rapid = G 2 µand entropy changes. Energy is used to mix water with the= The total energy imparted by mixing E mix is 8.7 J. 2 . 3

Hermanowicz, Slawomir W

2005-01-01T23:59:59.000Z

286

20 - Physical Metallurgy of Light Alloys  

Science Journals Connector (OSTI)

Abstract Improvements in energy efficiency, reduction of greenhouse gas emissions and 3R (reduce, reuse and recycle) have been one of the central topics in recent years in environment and climate change. Reducing the overall weight of the planet transportation fleet is critical to achieving these goals. It is foreseeable that, driven by environmental legislation, lightweight products will gain much wider applications in the near future. Aluminum, magnesium and titanium are all lightweight metals. At room temperature, the density of aluminum is 2.70 g cm?3, which is about one-third that of steel; the density of magnesium is 1.74 g cm?3, one-fourth that of steel; and the density of titanium is 4.51 g cm?3, approximately 55% that of steel. Light alloys based on aluminum, magnesium and titanium have become important classes of engineering materials. Among these materials, aluminum has found the widest applications in the transportation, construction, and packaging industries. The importance of aluminum alloys is reflected by the fact that the global aluminum production reached 45 million tons in 2011. Magnesium metal has received renewed and increasingly high interest since 2000 for potential applications in the automotive, aerospace and 3C (computer, communication and consumer electronic products) industries. The global magnesium production each year was about 250,000 tons before 2000. But over the past 5 years an average of more than 650,000 tons of magnesium metal was produced each year. Most of this was used to alloy aluminum, and only 30% being used to produce magnesium alloys. Because of the lack of innovative manufacturing processes and novel alloy compositions, the mechanical and chemical properties of magnesium alloys are still inferior to those of aluminum alloys, and therefore the market for magnesium is still small compared with that enjoyed by aluminum. The global titanium metal sponge production reached 186,000 tons in 2011. Titanium alloys are mostly used in the aerospace industry, with increasing applications in the chemical and biomedical (implants) industries.

Jian-Feng Nie

2014-01-01T23:59:59.000Z

287

500 V/200 A fault current limiter modules made of large-area MOD-YBa2Cu3O7 thin films with high-resistivity Au–Ag alloy shunt layers  

Science Journals Connector (OSTI)

We developed 500 Vrms/ 200 Arms superconducting thin-film fault current limiter (FCL) modules that can withstand high electric fields (E>30 Vrms cm?1) by using large-area YBa2Cu3O7 (YBCO) thin films with high-resistivity Au–Ag alloy shunt layers. Au–Ag alloy films about 60 nm thick were sputter-deposited on YBCO/CeO2/sapphire films (2.7 cm ? 20 cm) prepared using a fluorine-free MOD method. Each 20 cm long Au–Ag/YBCO film was then divided into three segments (each ~5.7 cm long) by four Ag electrodes deposited on the Au–Ag layer, resulting in an effective length of 17 cm. The 500 V/200 A FCL modules were then fabricated by first connecting two of the segmented films in parallel using Ag-sheathed Bi-2223 superconducting tapes and then connecting in parallel an external resistor and a capacitor for each segment to protect the Au–Ag/YBCO film from hot spots. Switching tests using a short-circuit generator revealed that all the modules carried a superconducting ac current of ?237 Arms and that modules prepared with YBCO films having a relatively homogeneous critical current Ic distribution successfully withstood ?515 Vrms for five cycles without any damage. These results demonstrate that (a) the FCL modules fabricated here successfully achieved the rated current of 200 Arms and rated voltage of 500 Vrms and (b) total area of the YBCO films on sapphire substrates required for the 500 V/200 A (100 kV A) module was less than one-third that for conventional thin-film FCL modules that use gold shunt layers, leading to the significantly reduced cost of thin-film FCLs. Film damage due to hot spots depended on the difference in Ic between the two parallel-connected films and on the inhomogeneity of the Ic distribution in the film, and is most probably due to nonlinear current flows at the moment of quenching that cause local overheating.

H Yamasaki; K Arai; K Kaiho; Y Nakagawa; M Sohma; W Kondo; I Yamaguchi; H Matsui; T Kumagai; N Natori; N Higuchi

2009-01-01T23:59:59.000Z

288

Vehicle Technologies Office Merit Review 2014: High Performance Cast Aluminum Alloys for Next Generation Passenger Vehicle Engines 2012 FOA 648 Topic 3a  

Energy.gov (U.S. Department of Energy (DOE))

Presentation given by Oak Ridge National Laboratory at 2014 DOE Hydrogen and Fuel Cells Program and Vehicle Technologies Office Annual Merit Review and Peer Evaluation Meeting about high...

289

Localized Corrosion of a Neutron Absorbing Ni-Cr-Mo-Gd Alloy  

SciTech Connect

The National Spent Nuclear Fuel Program, located at the Idaho National Laboratory (INL), has developed a new nickel-chromium-molybdenum-gadolinium structural alloy for storage and long-term disposal of spent nuclear fuel (SNF). The new alloy will be used for SNF storage container inserts for nuclear criticality control. Gadolinium has been chosen as the neutron absorption alloying element due to its high thermal neutron absorption cross section. This alloy must be resistant to localized corrosion when exposed to postulated Yucca Mountain in-package chemistries. The corrosion resistance properties of three experimental heats of this alloy are presented. The alloys performance are be compared to Alloy 22 and borated stainless steel. The results show that initially the new Ni-Cr-Mo-Gd alloy is less resistant to corrosion as compared to another Ni-Cr-Mo-Gd alloy (Alloy 22); but when the secondary phase that contains gadolinium (gadolinide) is dissolved, the alloy surface becomes passive. The focus of this work is to qualify these gadolinium containing materials for ASME code qualification and acceptance in the Yucca Mountain Repository.

R.E. Mizia; T. E. Lister; P. J. Pinhero; T. L. Trowbridge

2005-04-01T23:59:59.000Z

290

Multi-range force sensors utilizing shape memory alloys  

DOE Patents (OSTI)

The present invention provides a multi-range force sensor comprising a load cell made of a shape memory alloy, a strain sensing system, a temperature modulating system, and a temperature monitoring system. The ability of the force sensor to measure contact forces in multiple ranges is effected by the change in temperature of the shape memory alloy. The heating and cooling system functions to place the shape memory alloy of the load cell in either a low temperature, low strength phase for measuring small contact forces, or a high temperature, high strength phase for measuring large contact forces. Once the load cell is in the desired phase, the strain sensing system is utilized to obtain the applied contact force. The temperature monitoring system is utilized to ensure that the shape memory alloy is in one phase or the other.

Varma, Venugopal K. (Knoxville, TN)

2003-04-15T23:59:59.000Z

291

Entropy in C12+Au197 at intermediate energies  

Science Journals Connector (OSTI)

Isotopically resolved yields of complex particles and fragments from the reaction C12 on Au197 at three bombarding energies EA=30,48, and 84 MeV were measured. Specific entropies SA were derived from the isotope yield ratios using a quantum statistical model. The entropy increases with the bombarding energy in the case of preequilibrium light particles but, for intermediate mass fragments, has an energy-independent value of SA?2.3.

R. Trockel; K. D. Hildenbrand; U. Lynen; W. F. J. Müller; H. J. Rabe; H. Sann; H. Stelzer; W. Trautmann; R. Wada; E. Eckert; J. Pochodzalla; N. Brummund

1988-07-01T23:59:59.000Z

292

Numerical estimation of the relative entropy of entanglement  

SciTech Connect

We propose a practical algorithm for the calculation of the relative entropy of entanglement (REE), defined as the minimum relative entropy between a state and the set of states with positive partial transpose. Our algorithm is based on a practical semidefinite cutting plane approach. In low dimensions the implementation of the algorithm in matlab provides an estimation for the REE with an absolute error smaller than 10{sup -3}.

Zinchenko, Yuriy [Department of Mathematics and Statistics, University of Calgary, 2500 University Drive NW, Calgary, Alberta T2N 1N4 (Canada); Friedland, Shmuel [Department of Mathematics, Statistics and Computer Science, University of Illinois at Chicago, 851 S. Morgan Street, Chicago, Illinois 60607-7045 (United States); Gour, Gilad [Department of Mathematics, Statistics and Computer Science, University of Illinois at Chicago, 851 S. Morgan Street, Chicago, Illinois 60607-7045 (United States); Institute for Quantum Information Science, University of Calgary, 2500 University Drive NW, Calgary, Alberta T2N 1N4 (Canada)

2010-11-15T23:59:59.000Z

293

Density operator and entropy of the damped quantum harmonic oscillator  

E-Print Network (OSTI)

The expression for the density operator of the damped harmonic oscillator is derived from the master equation in the framework of the Lindblad theory for open quantum systems. Then the von Neumann entropy and effective temperature of the system are obtained. The entropy for a state characterized by a Wigner distribution function which is Gaussian in form is found to depend only on the variance of the distribution function.

A. Isar

2005-08-18T23:59:59.000Z

294

Fractional entropy decay and the third law of thermodynamics  

Science Journals Connector (OSTI)

We report in this paper a theoretical study on the quantum thermodynamic properties of a fractional damping system. Through the analysis, few nontrivial characteristics are revealed, which include (1) a fractional power-law decay entropy function, which provides an evidence for the validity of the third law of thermodynamics in the quantum dissipative region and (2) the varying of the entropy from a nonlinear divergent function to a semilinear decay function with a fractional exponent as the temperature approaches absolute zero.

Chun-Yang Wang; Xue-Mei Zong; Hong Zhang; Ming Yi

2014-08-21T23:59:59.000Z

295

Quantum Algorithm for SAT Problem and Quantum Mutual Entropy  

E-Print Network (OSTI)

It is von Neumann who opened the window for today's Information epoch. He defined quantum entropy including Shannon's information more than 20 years ahead of Shannon, and he introduced a concept what computation means mathematically. In this paper I will report two works that we have recently done, one of which is on quantum algorithum in generalized sense solving the SAT problem (one of NP complete problems) and another is on quantum mutual entropy properly describing quantum communication processes.

Masanori Ohya

2004-06-29T23:59:59.000Z

296

EPR = ER and Scattering Amplitude as Entanglement Entropy Change  

E-Print Network (OSTI)

We study the causal structure of the minimal surface of the four-gluon scattering, and find a world-sheet wormhole parametrized by Mandelstam variables, thereby demonstrate the EPR = ER relation for gluon scattering. We also propose that scattering amplitude is the change of the entanglement entropy by generalizing the holographic entanglement entropy of Ryu-Takayanagi to the case where two regions are divided in space-time.

Shigenori Seki; Sang-Jin Sin

2014-04-03T23:59:59.000Z

297

Fireside corrosion testing of candidate superheater tube alloys, coatings, and claddings  

SciTech Connect

Fireside corrosion, caused by liquid alkali-iron trisulfates, has been an obstacle to higher steam temperatures and to efficient utilization of high-sulfur coals. Tests simulating the environment in the superheater bank of a pulverized-coal-fired boiler were conducted on several promising new alloys and claddings. Alloys were exposed to a variety of synthetic ash and simulated flue gas compositions at 650 and 700{degrees}C for times ranging up to 800 hours. Included in the testing program were new high-chromium/high-nickel alloys, modified commercial alloys, lean stainless steels (modified Type 316) clad with high-chromium/high-nickel alloys, and intermetallic aluminides. Thickness loss measurements indicated that resistance to attach improved with increasing chromium level. Silicon and aluminum were also helpful in resisting attack, while molybdenum was detrimental to the resistance of the alloys to attack. Three different attack modes were observed on the alloys tested. Alloys with low resistance to attack exhibited uniform wastage, while pitting was observed in more resistant alloys. In addition to surface fluxing by molten alkali-iron trisulfates, subsurface sulfur penetration and intergranular attack also occurred.

Van Weele, S. (Foster Wheeler Development Corp., Livingston, NJ (United States))

1991-08-01T23:59:59.000Z

298

Fireside corrosion testing of candidate superheater tube alloys, coatings, and claddings. Final report  

SciTech Connect

Fireside corrosion, caused by liquid alkali-iron trisulfates, has been an obstacle to higher steam temperatures and to efficient utilization of high-sulfur coals. Tests simulating the environment in the superheater bank of a pulverized-coal-fired boiler were conducted on several promising new alloys and claddings. Alloys were exposed to a variety of synthetic ash and simulated flue gas compositions at 650 and 700{degrees}C for times ranging up to 800 hours. Included in the testing program were new high-chromium/high-nickel alloys, modified commercial alloys, lean stainless steels (modified Type 316) clad with high-chromium/high-nickel alloys, and intermetallic aluminides. Thickness loss measurements indicated that resistance to attach improved with increasing chromium level. Silicon and aluminum were also helpful in resisting attack, while molybdenum was detrimental to the resistance of the alloys to attack. Three different attack modes were observed on the alloys tested. Alloys with low resistance to attack exhibited uniform wastage, while pitting was observed in more resistant alloys. In addition to surface fluxing by molten alkali-iron trisulfates, subsurface sulfur penetration and intergranular attack also occurred.

Van Weele, S. [Foster Wheeler Development Corp., Livingston, NJ (United States)

1991-08-01T23:59:59.000Z

299

Microstructural refinement of W-Ni-Fe heavy alloys by alloying additions  

SciTech Connect

This communication describes the effect of alloying additions on grain refinement in tungsten heavy alloys and the resulting changes in mechanical properties. The body-centered-cubic refractory metals, like molybdenum and tantalum, have total solubility in tungsten and a high solubility in the matrix. The solubility of the additive in tungsten provides a means to increase the strength by solid-solution hardening. Alternatively, the solubility of tungsten in the matrix is the key to grain growth and possible strengthening by a reduction in the grain-growth size.

German, R.M.

1988-12-01T23:59:59.000Z

300

Computations of entropy bounds: Multidimensional geometric methods  

SciTech Connect

The entropy bounds for constructive upper bound on the needed number-of-bits for solving a dichotomy is represented by the quotient of two multidimensional solid volumes. For minimization of this upper bound exact calculation of the volume of this quotient is needed. Three methods for exact computing of the volume of a given nD volume are presented: (1) general method for calculation any nD volume by slicing it into volumes of decreasing dimension is presented; (2) a method applying appropriate curvilinear coordinate system is described for volume bounded by symmetrical curvilinear hypersurfaces (spheres, cones, hyperboloids, ellipsoids, cylinders, etc.); and (3) an algorithm for dividing any nD complex into simplices and computing of the volume of the simplices is presented, supplemented by a general formula for calculation of volume of an nD simplex. These mathematical methods enable exact calculation of volume of any complicated multidimensional solids. The methods allow for the calculation of the minimal volume and lead to tighter bounds on the needed number-of-bits.

Makaruk, H.E.

1998-02-01T23:59:59.000Z

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301

Surface Engineering to Improve the Durability and Lubricity of Ti-6Al-4V Alloy  

SciTech Connect

Titanium alloys offer high strength, high corrosion resistance, and the opportunity to reduce the weight of heavy vehicle engine components, but they do not perform well as bearing surfaces without further treatments or coatings. This paper explores a series of surface engineering treatments to improve the friction and wear behavior of Ti-6Al-4V alloy under diesel engine oil-lubricated conditions.

Bansal, Dinesh G [ORNL; Eryilmaz, Osman L [Argonne National Laboratory (ANL); Blau, Peter Julian [ORNL

2011-01-01T23:59:59.000Z

302

Phase stability and elastic properties of Cr-V alloys  

SciTech Connect

V is the only element in the periodic table that forms a complete solid solution with Cr and thus is particularly important in alloying strategy to ductilize Cr. This study combines first-principles density functional theory calculations and experiments to investigate the phase stability and elastic properties of Cr–V binary alloys. The cluster expansion study reveals the formation of various ordered compounds at low temperatures that were not previously known. These compounds become unstable due to the configurational entropy of bcc solid solution as the temperature is increased. The elastic constants of ordered and disordered compounds are calculated at both T = 0 K and finite temperatures. The overall trends in elastic properties are in agreement with measurements using the resonant ultrasound spectroscopy method. The calculations predict that addition of V to Cr decreases both the bulk modulus and the shear modulus, and enhances the Poisson’s ratio, in agreement with experiments. Decrease in the bulk modulus is correlated to decrease in the valence electron density and increase in the lattice constant. An enhanced Poisson’s ratio for bcc Cr–V alloys (compared to pure Cr) is associated with an increased density of states at the Fermi level. Furthermore, the difference charge density in the bonding region in the (110) slip plane is highest for pure Cr and decreases gradually as V is added. The present calculation also predicts a negative Cauchy pressure for pure Cr, and it becomes positive upon alloying with V. The intrinsic ductilizing effect from V may contribute, at least partially, to the experimentally observed ductilizing phenomenon in the literature.

Gao, M. C.; Suzuki, Y.; Schweiger, H.; Do?an, Ö.N.; Hawk, J.; Widom M.

2013-02-20T23:59:59.000Z

303

Mold, flow, and economic considerations in high temperature precision casting  

E-Print Network (OSTI)

Casting high temperature alloys that solidify through a noticeable two phase region, specifically platinum-ruthenium alloys, is a particularly challenging task due to their high melting temperature and this necessitates ...

Humbert, Matthew S

2013-01-01T23:59:59.000Z

304

On the Modeling of Plastic Deformation of Magnesium Alloys  

SciTech Connect

Magnesium alloys are promising materials due to their low density and therefore high specific strength. However, the industrial application is not well established so far, especially for wrought products such as sheets or profiles. Due to its hexagonal crystallographic structure, deformation mechanisms observed in magnesium alloys are rather different from those in face centered cubic metals such as aluminum alloys. This leads not only to a mechanical anisotropy, but also to a tension-compression asymmetry, i.e. unequal compressive and tensile yield strength. The resulting complexity in the yielding behavior of such materials cannot be captured by conventional models of J2 plasticity. Cazacu and Barlat, therefore, proposed a phenomenological yield potential which accounts for the respective phenomena by introducing the third invariant of the stress tensor. Simulations based on this model are performed with ABAQUS/Explicit and a user defined routine VUMAT for validating the respective implementation. The application aims at simulating the extrusion process of magnesium alloys.

Ertuerk, S.; Steglich, D.; Bohlen, J.; Letzig, D.; Brocks, W. [GKSS Research Center, Institute of Materials Research, Max-Plank-Str., D-21502 Geesthacht (Germany)

2007-05-17T23:59:59.000Z

305

Thermal coatings for titanium-aluminum alloys  

SciTech Connect

Titanium aluminides and titanium alloys are candidate materials for use in hot structure and heat-shield components of hypersonic vehicles because of their good strength-to-weight characteristics at elevated temperature. However, in order to utilize their maximum temperature capability, they must be coated to resist oxidation and to have a high total remittance. Also, surface catalysis for recombination of dissociated species in the aerodynamic boundary layer must be minimized. Very thin chemical vapor deposition (CVD) coatings are attractive candidates for this application because of durability and very light weight. To demonstrate this concept, coatings of boron-silicon and aluminum-boron-silicon compositions were applied to the titanium-aluminides alpha2 (Ti-14Al-21Nb), super-alpha2 (Ti-14Al-23-Nb-2V), and gamma (Ti-33Al-6Nb-1Ta) and to the titanium alloy beta-21S (Ti-15Mo-3Al-3Nb-0.2Si). Coated specimens of each alloy were subjected to a set of simulated hypersonic vehicle environmental tests to determine their properties of oxidation resistance, surface catalysis, radiative emittance, and thermal shock resistance. Surface catalysis results should be viewed as relative performance only of the several coating-alloy combinations tested under the specific environmental conditions of the LaRC Hypersonic Materials Environmental Test System (HYMETS) arc-plasma-heated hypersonic wind tunnel. Tests were also conducted to evaluate the hydrogen transport properties of the coatings and any effects of the coating processing itself on fatigue life of the base alloys. Results are presented for three types of coatings, which are as follows: (1) a single layer boron silicon coating, (2) a single layer aluminum-boron-silicon coating, and (3) a multilayer coating consisting of an aluminum-boron-silicon sublayer with a boron-silicon outer layer.

Cunnington, G.R.; Clark, R.K.; Robinson, J.C.

1993-04-01T23:59:59.000Z

306

Entropy of Factorized Snapshot Data for Two-Dimensional Ising Model: Holographic Derivation of Entanglement Entropy Alternative to Ryu-Takayanagi Formula  

E-Print Network (OSTI)

We reexamine the snapshot entropy of two-dimensional square-lattice LxL Ising model. Focusing on factorization of the snapshot matrix, we find that the entropy at Tc scales asymptotically with S=(c/3)lnL consistent with the Calabrese-Cardy formula in one-dimensional quantum critical systems. This nontrivial consistency strongly supports that the snapshot entropy after the factorization really represents the holographic entanglement entropy. On the other hand, the anomalous scaling for the coarse-grained snpshot entropy is maintained even after the factorization.

Matsueda, Hiroaki

2014-01-01T23:59:59.000Z

307

Theoretical Studies of Hydrogen Storage Alloys.  

SciTech Connect

Theoretical calculations were carried out to search for lightweight alloys that can be used to reversibly store hydrogen in mobile applications, such as automobiles. Our primary focus was on magnesium based alloys. While MgH{sub 2} is in many respects a promising hydrogen storage material, there are two serious problems which need to be solved in order to make it useful: (i) the binding energy of the hydrogen atoms in the hydride is too large, causing the release temperature to be too high, and (ii) the diffusion of hydrogen through the hydride is so slow that loading of hydrogen into the metal takes much too long. In the first year of the project, we found that the addition of ca. 15% of aluminum decreases the binding energy to the hydrogen to the target value of 0.25 eV which corresponds to release of 1 bar hydrogen gas at 100 degrees C. Also, the addition of ca. 15% of transition metal atoms, such as Ti or V, reduces the formation energy of interstitial H-atoms making the diffusion of H-atoms through the hydride more than ten orders of magnitude faster at room temperature. In the second year of the project, several calculations of alloys of magnesium with various other transition metals were carried out and systematic trends in stability, hydrogen binding energy and diffusivity established. Some calculations of ternary alloys and their hydrides were also carried out, for example of Mg{sub 6}AlTiH{sub 16}. It was found that the binding energy reduction due to the addition of aluminum and increased diffusivity due to the addition of a transition metal are both effective at the same time. This material would in principle work well for hydrogen storage but it is, unfortunately, unstable with respect to phase separation. A search was made for a ternary alloy of this type where both the alloy and the corresponding hydride are stable. Promising results were obtained by including Zn in the alloy.

Jonsson, Hannes

2012-03-22T23:59:59.000Z

308

Two phase titanium aluminide alloy  

DOE Patents (OSTI)

A two-phase titanic aluminide alloy having a lamellar microstructure with little intercolony structures. The alloy can include fine particles such as boride particles at colony boundaries and/or grain boundary equiaxed structures. The alloy can include alloying additions such as .ltoreq.10 at % W, Nb and/or Mo. The alloy can be free of Cr, V, Mn, Cu and/or Ni and can include, in atomic %, 45 to 55% Ti, 40 to 50% Al, 1 to 5% Nb, 0.3 to 2% W, up to 1% Mo and 0.1 to 0.3% B. In weight %, the alloy can include 57 to 60% Ti, 30 to 32% Al, 4 to 9% Nb, up to 2% Mo, 2 to 8% W and 0.02 to 0.08% B.

Deevi, Seetharama C. (Midlothian, VA); Liu, C. T. (Oak Ridge, TN)

2001-01-01T23:59:59.000Z

309

Immersion studies on candidate container alloys for the Tuff Repository  

SciTech Connect

Cortest Columbus Technologies (CC Technologies) is investigating the long-term performance of container materials used for high-level radioactive waste packages. This information is being developed for the Nuclear Regulatory Commission to aid in their assessment of the Department of Energy`s application to construct a geologic repository for disposal of high-level radioactive waste. This report summarizes the results of exposure studies performed on two copper-base and two Fe-Cr-Ni alloys in simulated Tuff Repository conditions. Testing was performed at 90{degrees}C in three environments; simulated J-13 well water, and two environments that simulated the chemical effects resulting from boiling and irradiation of the groundwater. Creviced specimens and U-bends were exposed to liquid, to vapor above the condensed phase, and to alternate immersion. A rod specimen was used to monitor corrosion at the vapor-liquid interface. The specimens were evaluated by electrochemical, gravimetric, and metallographic techniques following approximately 2000 hours of exposure. Results of the exposure tests indicated that all four alloys exhibited acceptable general corrosion rates in simulated J-13 well water. These rates decreased with time. Incipient pitting was observed under deposits on Alloy 825 and pitting was observed on both Alloy CDA 102 and Alloy CDA 715 in the simulated J-13 well water. No SCC was observed in U-bend specimens of any of the alloys in simulated J-13 well water. 33 refs., 48 figs., 23 tabs.

Beavers, J.A.; Durr, C.L. [Cortest Columbus Technologies, OH (USA)

1991-05-01T23:59:59.000Z

310

Method of making active magnetic refrigerant materials based on Gd-Si-Ge alloys  

DOE Patents (OSTI)

An alloy made of heat treated material represented by Gd.sub.5(Si.sub.xGe.sub.1-x).sub.4 where 0.47.ltoreq.x.ltoreq.0.56 that exhibits a magnetic entropy change (-.DELTA.S.sub.m) of at least 16 J/kg K, a magnetostriction of at least 2000 parts per million, and a magnetoresistance of at least 5 percent at a temperature of about 300K and below, and method of heat treating the material between 800 to 1600 degrees C. for a time to this end.

Pecharsky, Alexandra O. (Ames, IA); Gschneidner, Jr., Karl A. (Ames, IA); Pecharsky, Vitalij K. (Ames, IA)

2006-10-03T23:59:59.000Z

311

CHARACTERIZATION OF ELEVATED TEMPERATURE PROPERTIES OF HEAT EXCHANGER AND STEAM GENERATOR ALLOYS  

SciTech Connect

The Next Generation Nuclear Plant project is considering Alloy 800H and Alloy 617 for steam generator and intermediate heat exchangers. It is envisioned that a steam generator would operate with reactor outlet temperatures from 750 to 800 C, while an intermediate heat exchanger for primary to secondary helium would operate up to an outlet temperature of 950 C. Although both alloys are of interest due in part to their technical maturity, a number of specific properties require further characterization for design of nuclear components. Strain rate sensitivity of both alloys has been characterized and is found to be significant above 600 C. Both alloys also exhibit dynamic strain aging, characterized by serrated flow, over a wide range of temperatures and strain rates. High temperature tensile testing of Alloy 617 has been conducted over a range of temperatures. Dynamic strain aging is a concern for these materials since it is observed to result in reduced ductility for many solid solution alloys. Creep, fatigue, and creep-fatigue properties of Alloy 617 have been measured as well, with the goal of determining the influence of the temperature, strain rate and atmosphere on the creep fatigue life of Alloy 617. Elevated temperature properties and implications for codification of the alloys will be described.

J.K. Wright; L.J. Carroll; C.J. Cabet; T. Lillo; J.K. Benz; J.A. Simpson; A. Chapman; R.N. Wright

2012-10-01T23:59:59.000Z

312

Shape memory alloy actuator  

DOE Patents (OSTI)

An actuator for cycling between first and second positions includes a first shaped memory alloy (SMA) leg, a second SMA leg. At least one heating/cooling device is thermally connected to at least one of the legs, each heating/cooling device capable of simultaneously heating one leg while cooling the other leg. The heating/cooling devices can include thermoelectric and/or thermoionic elements.

Varma, Venugopal K. (Knoxville, TN)

2001-01-01T23:59:59.000Z

313

Universal viscosity to entropy density ratio from entanglement  

SciTech Connect

We present evidence that the universal Kovtun-Son-Starinets shear viscosity to entropy density ratio of 1/4{pi} can be associated with a Rindler causal horizon in flat spacetime. Since there is no known holographic (gauge/gravity) duality for this spacetime, a natural microscopic explanation for this viscosity is in the peculiar properties of quantum entanglement. In particular, it is well known that the Minkowski vacuum state is a thermal state and carries an area entanglement entropy density in the Rindler spacetime. Based on the fluctuation-dissipation theorem, we expect a similar notion of viscosity arising from vacuum fluctuations. Therefore, we propose a holographic Kubo formula in terms of a two-point function of the stress tensor of matter fields in the bulk. We calculate this viscosity assuming a minimally coupled scalar field theory and find that the ratio with respect to the entanglement entropy density is exactly 1/4{pi} in four dimensions. The issues that arise in extending this result to nonminimally coupled scalar fields, higher spins, and higher dimensions provide interesting hints about the relationship between entanglement entropy and black hole entropy.

Chirco, Goffredo; Eling, Christopher; Liberati, Stefano [SISSA, Via Bonomea 265, 34136 Trieste (Italy) and INFN Sezione di Trieste, Via Valerio 2, 34127 Trieste (Italy)

2010-07-15T23:59:59.000Z

314

The entropy distribution in clusters: evidence of feedback?  

E-Print Network (OSTI)

The entropy of the intracluster medium at large radii has been shown recently to deviate from the self-similar scaling with temperature. Using N-body/hydrodynamic simulations of the LCDM cosmology, we demonstrate that this deviation is evidence that feedback processes are important in generating excess entropy in clusters. While radiative cooling increases the entropy of intracluster gas, resulting in a good match to the data in the centres of clusters, it produces an entropy-temperature relation closer to the self-similar scaling at larger radii. A model that includes feedback from galaxies, however, not only stabilises the cooling rate in the simulation, but is capable of reproducing the observed scaling behaviour both in cluster cores and at large radii. Feedback modifies the entropy distribution in clusters due to its increasing ability at expelling gas from haloes with decreasing mass. The strength of the feedback required, as suggested from our simulations, is consistent with supernova energetics, providing a large fraction of the energy reaches low-density regions and is originally contained within a small mass of gas.

Scott T. Kay

2003-11-10T23:59:59.000Z

315

Renyi entropy, stationarity, and entanglement of the conformal scalar  

E-Print Network (OSTI)

We extend previous work on the perturbative expansion of the Renyi entropy, $S_q$, around $q=1$ for a spherical entangling surface in a general CFT. Applied to conformal scalar fields in various spacetime dimensions, the results appear to conflict with the known conformal scalar Renyi entropies. On the other hand, the perturbative results agree with known Renyi entropies in a variety of other theories, including theories of free fermions and vector fields and theories with Einstein gravity duals. We propose a resolution stemming from a careful consideration of boundary conditions near the entangling surface. This is equivalent to a proper treatment of total-derivative terms in the definition of the modular Hamiltonian. As a corollary, we are able to resolve an outstanding puzzle in the literature regarding the Renyi entropy of ${\\cal N}=4$ super-Yang-Mills near $q=1$. A related puzzle regards the question of stationarity of the renormalized entanglement entropy (REE) across a circle for a (2+1)-dimensional massive scalar field. We point out that the boundary contributions to the modular Hamiltonian shed light on the previously-observed non-stationarity. Moreover, IR divergences appear in perturbation theory about the massless fixed point that inhibit our ability to reliably calculate the REE at small non-zero mass.

Jeongseog Lee; Aitor Lewkowycz; Eric Perlmutter; Benjamin R. Safdi

2014-07-29T23:59:59.000Z

316

Renyi entropy, stationarity, and entanglement of the conformal scalar  

E-Print Network (OSTI)

We extend previous work on the perturbative expansion of the Renyi entropy, $S_q$, around $q=1$ for a spherical entangling surface in a general CFT. Applied to conformal scalar fields in various spacetime dimensions, the results appear to conflict with the known conformal scalar Renyi entropies. On the other hand, the perturbative results agree with known Renyi entropies in a variety of other theories, including theories of free fermions and vector fields and theories with Einstein gravity duals. We propose a resolution stemming from a careful consideration of boundary conditions near the entangling surface. This is equivalent to a proper treatment of total-derivative terms in the definition of the modular Hamiltonian. As a corollary, we are able to resolve an outstanding puzzle in the literature regarding the Renyi entropy of ${\\cal N}=4$ super-Yang-Mills near $q=1$. A related puzzle regards the question of stationarity of the renormalized entanglement entropy (REE) across a circle for a (2+1)-dimensional ma...

Lee, Jeongseog; Perlmutter, Eric; Safdi, Benjamin R

2014-01-01T23:59:59.000Z

317

Horizon entropy and higher curvature equations of state  

E-Print Network (OSTI)

The Clausius relation between entropy change and heat flux has previously been used to derive Einstein's field equations as an equation of state. In that derivation the entropy is proportional to the area of a local causal horizon, and the heat is the energy flux across the horizon, defined relative to an approximate boost Killing vector. We examine here whether a similar derivation can be given for extensions beyond Einstein gravity to include higher derivative and higher curvature terms. We review previous proposals which, in our opinion, are problematic or incomplete. Refining one of these, we assume that the horizon entropy depends on an approximate local Killing vector in a way that mimics the diffeomorphism Noether charge that yields the entropy of a stationary black hole. We show how this can be made to work if various restrictions are imposed on the nature of the horizon slices and the approximate Killing vector. Also, an integrability condition on the assumed horizon entropy density must hold. This can yield field equations of a Lagrangian constructed algebraically from the metric and Riemann tensor, but appears unlikely to allow for derivatives of curvature in the Lagrangian.

Raf Guedens; Ted Jacobson; Sudipta Sarkar

2012-01-02T23:59:59.000Z

318

WEAR RESISTANT ALLOYS FOR COAL HANDLING EQUIPMENT  

E-Print Network (OSTI)

Proceedings of the Conference on Coal Feeding Systems, HeldWear Resistant Alloys for Coal Handling Equipment", proposalWear Resistant Alloys for Coal Handling Equi pment". The

Bhat, M.S.

2011-01-01T23:59:59.000Z

319

High-Precision Thermodynamics and Hagedorn Density of States  

E-Print Network (OSTI)

We compute the entropy density of the confined phase of QCD without quarks on the lattice to very high accuracy. The results are compared to the entropy density of free glueballs, where we include all the known glueball states below the two-particle threshold. We find that an excellent, parameter-free description of the entropy density between 0.7Tc and Tc is obtained by extending the spectrum with the exponential spectrum of the closed bosonic string.

Harvey B. Meyer

2009-05-26T23:59:59.000Z

320

DENSITY-FUNCTIONAL STUDY OF U-Mo AND U-Zr ALLOYS  

SciTech Connect

Density-functional theory previously used to describe phase equilibria in U-Zr alloys [A. Landa, P. Soederlind, P.E.A. Turchi, J. Alloys Comp. 478 (2009) 103-110] is extended to investigate the ground-state properties of U-Mo solid solutions. We discuss how the heat of formation in both alloys correlates with the charge transfer between the alloy components, and how the specific behavior of the density of states in the vicinity of the Fermi level promotes the stabilization of the U{sub 2}Mo compound. Our calculations prove that, due to the existence of a single {gamma}-phase over the typical fuel operation temperatures, {gamma}-U-Mo alloys should indeed have much lower constituent redistribution than {gamma}-U-Zr alloys for which binodal decomposition causes a high degree of constituent redistribution.

Landa, A; Soderlind, P; Turchi, P A

2010-11-01T23:59:59.000Z

Note: This page contains sample records for the topic "high entropy alloy" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


321

E-Print Network 3.0 - al si alloys Sample Search Results  

NLE Websites -- All DOE Office Websites (Extended Search)

SiGe alloys to high-speed devices and circuits is given... , however, development in the growth tech- nology of high-quality SiGe ... Source: Rieh, Jae-Sung - School of Electrical...

322

Limits on classical communication from quantum entropy power inequalities  

E-Print Network (OSTI)

Almost all modern communication systems rely on electromagnetic fields as a means of information transmission, and finding the capacities of these systems is a problem of significant practical importance. The Additive White Gaussian Noise (AWGN) channel is often a good approximate description of such systems, and its capacity is given by a simple formula. However, when quantum effects are important, estimating the capacity becomes difficult: a lower bound is known, but a similar upper bound is missing. We present strong new upper bounds for the classical capacity of quantum additive noise channels, including quantum analogues of the AWGN channel. Our main technical tool is a quantum entropy power inequality that controls the entropy production as two quantum signals combine at a beam splitter. Its proof involves a new connection between entropy production rates and a quantum Fisher information, and uses a quantum diffusion that smooths arbitrary states towards gaussians.

Robert Koenig; Graeme Smith

2012-05-15T23:59:59.000Z

323

Comment on the law of entropy increase in thermodynamics  

Science Journals Connector (OSTI)

A common formulation of the law of increase of entropy, found in textbooks on thermodynamics, states that in a process taking place in a completely isolated system the entropy of the final equilibrium state cannot be smaller than that of the initial equilibrium state. This statement does not specify that thermal isolation is all that is needed for its validity, with no need for mechanical isolation. For the purpose of illustrating this situation, we exhibit examples of thermodynamic processes carried out with thermally isolated—although not mechanically isolated—systems, which we know to be allowed by the second law because the entropy of the system increases. We believe that the analysis presented in this paper may be useful in a first undergraduate course on thermodynamics.

Pier A Mello; Rosalío F Rodríguez

2013-01-01T23:59:59.000Z

324

A Guide to Entropy and the Second Law of Thermodynamics  

E-Print Network (OSTI)

This article is a short version of a longer article to appear in Physics Reports (cond-mat/9708200). The essential postulates of classical thermodynamics are formulated, from which the second law is deduced as the principle of increase of entropy in irreversible adiabatic processes that take one equilibrium state to another. The entropy constructed here is defined only for equilibrium states and no attempt is made to define it otherwise. Statistical mechanics does not enter these considerations. One of the main concepts that makes everything work is the comparison principle (which, in essence, states that any two states of the same chemical composition can be connected by an adiabatic process) and we show that it can be derived from some assumptions about the pressure and thermal equilibrium. Temperature is derived from entropy, but at the start not even the concept of `hotness' is assumed. Our formulation offers a certain clarity and rigor that goes beyond most textbook discussions of the second law.

Elliott H. Lieb; Jakob Yngvason

1998-05-06T23:59:59.000Z

325

Entropy Generation in Computation and the Second Law of Thermodynamics  

E-Print Network (OSTI)

Landauer discussed the minimum energy necessary for computation and stated that erasure of information is accompanied by heat generation to the amount of kT ln2/bit. Modifying the above statement, we claim that erasure of information is accompanied by entropy generation k ln2/bit. Some new concepts will be introduced in the field of thermodynamics that are implicitly included in our statement. The new concepts that we will introduce are ``partitioned state'', which corresponds to frozen state such as in ice, ``partitioning process'' and ``unifying process''. Developing our statement, i.e., our thermodynamics of computation, we will point out that the so-called ``residual entropy'' does not exist in the partitioned state. We then argue that a partioning process is an entropy decreasing process. Finally we reconsider the second law of thermodynamics especially when computational processes are involved.

Shunya Ishioka; Nobuko Fuchikami

1999-02-17T23:59:59.000Z

326

E-Print Network 3.0 - absolute configurational entropies Sample...  

NLE Websites -- All DOE Office Websites (Extended Search)

Collection: Engineering 27 typeset using JPSJ.sty Spin States and Entropy of Ising Spin Glasses Summary: . For this purpose, we introduce the entropy of bond...

327

Experimental design to determine the effect of temperature and Mach number on entropy noise  

E-Print Network (OSTI)

The Osney Laboratory sought to create an entropy noise test rig that could determine the relationship between entropy noise and the flow parameters of temperature change and nozzle Mach number. The apparatus simulates ...

Hake, Mariah I. (Mariah Inez)

2014-01-01T23:59:59.000Z

328

3D Flat Holography: Entropy and Logarithmic Corrections  

E-Print Network (OSTI)

We compute the leading corrections to the Bekenstein-Hawking entropy of the Flat Space Cosmological (FSC) solutions in 3D flat spacetimes, which are the flat analogues of the BTZ black holes in AdS3. The analysis is done by a computation of density of states in the dual 2D Galilean Conformal Field Theory and the answer obtained by this matches with the limiting value of the expected result for the BTZ inner horizon entropy as well as what is expected for a generic thermodynamic system. Along the way, we also develop other aspects of holography of 3D flat spacetimes.

Arjun Bagchi; Rudranil Basu

2013-12-19T23:59:59.000Z

329

Geodesic Distance in Fisher Information Space and Holographic Entropy Formula  

E-Print Network (OSTI)

In this short note, we examine geodesic distance in Fisher information space in which the metric is defined by the entanglement entropy in CFT_(1+1). It is obvious in this case that the geodesic distance at a constant time is a function of the entropy data embedded into the information space. In a special case, the geodesic equation can be solved analytically, and we find that the distance agrees well with the Ryu-Takayanagi formula. Then, we can understand how the distance looks at the embeded quantum information. The result suggests that the Fisher metric is an efficient tool for constructing the holographic spacetime.

Hiroaki Matsueda

2014-08-28T23:59:59.000Z

330

Radiation entropy bound from the second law of thermodynamics  

E-Print Network (OSTI)

It has been suggested heuristically by Unruh and Wald, and independently by Page, that among systems with given energy and volume, thermal radiation has the largest entropy. The suggestion leads to the corresponding universal bound on entropy of physical systems. Using a gedanken experiment we show that the bound follows from the second law of thermodynamics if the CPT symmetry is assumed and a certain general condition on matter holds. The experiment suggests that a wide class of Lorentz invariant local quantum field theories obeys a bound on the density of states.

Itzhak Fouxon

2008-06-14T23:59:59.000Z

331

Entropy Production in Non-Linear, Thermally Driven Hamiltonian Systems  

E-Print Network (OSTI)

We consider a finite chain of non-linear oscillators coupled at its ends to two infinite heat baths which are at different temperatures. Using our earlier results about the existence of a stationary state, we show rigorously that for arbitrary temperature differences and arbitrary couplings, such a system has a unique stationary state. (This extends our earlier results for small temperature differences.) In all these cases, any initial state will converge (at an unknown rate) to the stationary state. We show that this stationary state continually produces entropy. The rate of entropy production is strictly negative when the temperatures are unequal and is proportional to the mean energy flux through the system.

Jean-Pierre Eckmann; Claude-Alain Pillet; Luc Rey-Bellet

1998-10-30T23:59:59.000Z

332

Mechanical Flow Response and Anisotropy of Ultra-Fine Grained Magnesium and Zinc Alloys  

E-Print Network (OSTI)

asymmetry, and the mechanisms responsible for these phenomena in two hcp materials: AZ31B Mg alloy consisting of one phase and Zn-8wt.% Al that has an hcp matrix with a secondary facecentered cubic (fcc) phase. Mg and its alloys have high specific strength...

Al Maharbi, Majid H.

2011-02-22T23:59:59.000Z

333

Shape memory alloy thaw sensors  

DOE Patents (OSTI)

A sensor permanently indicates that it has been exposed to temperatures exceeding a critical temperature for a predetermined time period. An element of the sensor made from shape memory alloy changes shape when exposed, even temporarily, to temperatures above the Austenitic temperature of the shape memory alloy. The shape change of the SMA element causes the sensor to change between two readily distinguishable states.

Shahinpoor, Mohsen (Albuquerque, NM); Martinez, David R. (Albuquerque, NM)

1998-01-01T23:59:59.000Z

334

A maximum entropy theorem with applications to the measurement of biodiversity  

E-Print Network (OSTI)

This is a preliminary article stating and proving a new maximum entropy theorem. The entropies that we consider can be used as measures of biodiversity. In that context, the question is: for a given collection of species, which frequency distribution(s) maximize the diversity? The theorem provides the answer. The chief surprise is that although we are dealing not just with a single entropy, but a one-parameter family of entropies, there is a single distribution maximizing all of them simultaneously.

Leinster, Tom

2009-01-01T23:59:59.000Z

335

Interacting entropy-corrected agegraphic Chaplygin gas model of dark energy  

E-Print Network (OSTI)

In this work, we consider the interacting agegraphic dark energy models with entropy correction terms due to loop quantum gravity. We study the correspondence between the Chaplygin gas energy density with the interacting entropy-corrected agegraphic dark energy models in non-flat FRW universe. We reconstruct the potentials and the dynamics of the interacting entropy-corrected agegraphic scalar field models. This model is also extended to the interacting entropy-corrected agegraphic generalized Chaplygin gas dark energy.

M. Malekjani; A. Khodam-Mohammadi

2010-04-07T23:59:59.000Z

336

On energy and entropy influxes in the Green–Naghdi Type III theory of heat conduction  

Science Journals Connector (OSTI)

...1009 120 185 On energy and entropy influxes in the Green-Naghdi Type III...Rome, Italy The energy-influx/entropy-influx relation in the Green-Naghdi Type III...isotropic (that is, in Green-Naghdi's theory, when energy and entropy influxes...

2013-01-01T23:59:59.000Z

337

Energy 32 (2007) 335343 Minimizing the entropy production in a chemical process  

E-Print Network (OSTI)

Energy 32 (2007) 335­343 Minimizing the entropy production in a chemical process Ranheim, Norway Received 2 November 2005 Abstract We minimize the total entropy production of a process of selected units, which minimized the total entropy production of the process, were found. The most important

Kjelstrup, Signe

338

Entropy 2010, 12, 1145-1193; doi:10.3390/e12051145 OPEN ACCESS  

E-Print Network (OSTI)

production is always positive. Entropy was born as a daughter of energy. If a body gets heat Q at the temperature T then for this body dS = Q/T. The total entropy is the sum of entropies of all bodies. Heat goes and Information Technologies, Siberian Federal University, Krasnoyarsk, Russia 3 Department of Resource Economics

Gorban, Alexander N.

339

Frequency Moments Inverse Problem and Maximum (Shannon vs. R enyi-Tsallis) Entropy  

E-Print Network (OSTI)

) maximization of Shannon's entropy (MaxEnt), b) maximization of R#19;enyi-Tsallis entropy (maxTent). ConcerningEnt 4 1.2 Aims 5 2 Frequency moment constraints 5 2.1 Characteristics of MaxEnt choice 6 2.2 Maximum RFrequency Moments Inverse Problem and Maximum (Shannon vs. R#19;enyi-Tsallis) Entropy #3; A case

340

Wedlable nickel aluminide alloy  

DOE Patents (OSTI)

A Ni.sub.3 Al alloy with improved weldability is described. It contains about 6-12 wt % Al, about 6-12 wt % Cr, about 0-3 wt % Mo, about 1.5-6 wt % Zr, about 0-0.02 wt % B and at least one of about 0-0.15 wt % C, about 0-0.20 wt % Si, about 0-0.01 wt % S and about 0-0.30 wt % Fe with the balance being Ni.

Santella, Michael L. (Knoxville, TN); Sikka, Vinod K. (Oak Ridge, TN)

2002-11-19T23:59:59.000Z

Note: This page contains sample records for the topic "high entropy alloy" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


341

Alloy 45TM in waste incineration applications  

SciTech Connect

Industrial and municipal wastes produced in the western society are being increasingly destroyed and managed by controlled high temperature incineration. Depending on the chemical make-up of the waste stream and operational parameters of the incinerator, a variety of high temperature corrosive environments are generated. Typically most of the modern incineration systems consist of a high temperature incinerator chamber, a heat recovery system, a quench section to further reduce the temperature of the flue gas stream and a host of air pollution control equipment to scrub acidic gases and control the particulate emissions. This paper describes the development of a new nickel-base high chromium-high silicon alloy, which has shown good resistance to high temperature corrosion in incinerator environments. Some field test data are also presented.

Agarwal, D.C. [VDM Technologies, Houston, TX (United States); Kloewer, J.; Grossmann, G.K. [Krupp VDM GmbH, Werdohl (Germany)

1997-08-01T23:59:59.000Z

342

Automatic RNA virus classification using the Entropy-ANFIS method  

Science Journals Connector (OSTI)

Innovations in the fields of medicine and medical image processing are becoming increasingly important. Historically, RNA viruses produced in cell cultures have been identified using electron microscopy, in which virus identification is performed by ... Keywords: ANFIS, Center-edge change method, Classification, Clustering, DNA, Entropy, FCM, RNA, RNA virus images

Esin Dogantekin; Engin Avci; Oznur Erkus

2013-07-01T23:59:59.000Z

343

Entropy of Spacelike Two-Surfaces of Spacetime  

E-Print Network (OSTI)

We argue that every finite piecewise smooth spacelike two-surface of spacetime possesses an entropy which is, in natural units, one quarter of its area. However, the thermodynamical properties of a two-surface become apparent only to the observers having that two-surface as a horizon. Consequences of this result are discussed.

J. Makela; A. Peltola

2004-06-08T23:59:59.000Z

344

Maximum Entropy in Support of Semantically Annotated Datasets  

E-Print Network (OSTI)

Maximum Entropy in Support of Semantically Annotated Datasets Paulo Pinheiro da Silva, Vladik whether two datasets describe the same quantity. The existing solution to this problem is to use these datasets' ontologies to deduce that these datasets indeed represent the same quantity. However, even when

Kreinovich, Vladik

345

HAMILTON JACOBI EQUATIONS ON METRIC SPACES AND TRANSPORT ENTROPY INEQUALITIES  

E-Print Network (OSTI)

HAMILTON JACOBI EQUATIONS ON METRIC SPACES AND TRANSPORT ENTROPY INEQUALITIES N. GOZLAN, C. ROBERTO, P-M. SAMSON Abstract. We prove an Hopf-Lax-Oleinik formula for the solutions of some Hamilton that the log-Sobolev inequality is equivalent to an hypercontractivity property of the Hamilton-Jacobi semi

Boyer, Edmond

346

Review Article Aluminum-Induced Entropy in Biological Systems  

E-Print Network (OSTI)

Review Article Aluminum-Induced Entropy in Biological Systems: Implications for Neurological years, mining, smelting, and refining of aluminum (Al) in various forms have increasingly exposed living of the Al toxicants to which we are being exposed. 1. Introduction Aluminum (Al) is the most common metal

Seneff, Stephanie

347

Oxidation resistant alloys, method for producing oxidation resistant alloys  

DOE Patents (OSTI)

A method for producing oxidation-resistant austenitic alloys for use at temperatures below 800.degree. C. comprising of: providing an alloy comprising, by weight %: 14-18% chromium, 15-18% nickel, 1-3% manganese, 1-2% molybdenum, 2-4% silicon, 0% aluminum and the balance being iron; heating the alloy to 800.degree. C. for between 175-250 hours prior to use in order to form a continuous silicon oxide film and another oxide film. The method provides a means of producing stainless steels with superior oxidation resistance at temperatures above 700.degree. C. at a low cost

Dunning, John S. (Corvallis, OR); Alman, David E. (Salem, OR)

2002-11-05T23:59:59.000Z

348

Oxidation resistant alloys, method for producing oxidation resistant alloys  

DOE Patents (OSTI)

A method for producing oxidation-resistant austenitic alloys for use at temperatures below 800 C. comprising of: providing an alloy comprising, by weight %: 14-18% chromium, 15-18% nickel, 1-3% manganese, 1-2% molybdenum, 2-4% silicon, 0% aluminum and the balance being iron; heating the alloy to 800 C. for between 175-250 hours prior to use in order to form a continuous silicon oxide film and another oxide film. The method provides a means of producing stainless steels with superior oxidation resistance at temperatures above 700 C. at a low cost

Dunning, John S.; Alman, David E.

2002-11-05T23:59:59.000Z

349

Multiband GaNAsP Quaternary Alloys  

SciTech Connect

We have synthesized GaN{sub x}As{sub 1-y}P{sub y} alloys (x {approx} 0.3-1% and y = 0-0.4) using nitrogen N ion implantation into GaAsP epilayers followed by pulsed laser melting and rapid thermal annealing techniques. As predicted by the band anticrossing model, the incorporation of N splits the conduction band (E{sub M}) of the GaAs{sub 1-y}P{sub y} substrate, and strong optical transitions from the valence band to the lower (E{sub -}) and upper (E{sub +}) conduction subbands are observed. The relative strengths of the E{sub -} and E{sub +} transition change as the localized N level E{sub N} emerges from the conduction band forming narrow intermediate band for y > 0.3. The results show that GaN{sub x}As{sub 1-x-y}P{sub y} alloys with y > 0.3 is a three band semiconductor alloy with potential applications for high-efficiency intermediate band solar cells.

Yu, K.M.; Walukiewicz, W.; Ager III, J.W.; Bour, D.; Farshchi,R.; Dubon, O.D.; Li, S.X.; Sharp, I.D.; Haller, E.E.

2005-12-08T23:59:59.000Z

350

High Energy Novel Cathode / Alloy Automotive Cell  

Energy.gov (U.S. Department of Energy (DOE))

2012 DOE Hydrogen and Fuel Cells Program and Vehicle Technologies Program Annual Merit Review and Peer Evaluation Meeting

351

High Energy Novel Cathode / Alloy Automotive Cell  

Energy.gov (U.S. Department of Energy (DOE))

2013 DOE Hydrogen and Fuel Cells Program and Vehicle Technologies Program Annual Merit Review and Peer Evaluation Meeting

352

Thermodynamics of the solid solution of hydrogen in ?-titanium alloys: ?-TiMo and ?-TiRe  

Science Journals Connector (OSTI)

The solid solution of hydrogen has been investigated in a series of random ?-TiMo alloys ranging from 0–65 atom % Mo via determination of pressure-composition-temperature relationships; additionally, one (?-TiRe alloy (Ti37 atom % Re) was investigated. The thermodynamic parameters of hydrogen solution were generated from the p-c-T data. The relative partial molar enthalpy at infinite dilution, ?H?Ho, exhibited by ?-TiMo alloys were adjusted to conditions of fixed volume, that of pure ?-Ti. It was found that variations in the resulting ?E?Ho correlated roughly with variations in the electron density of states at the Fermi level. The relative partial molar entropy at infinite dilution was found to vary linearly with Mo content and it is suggested that this trend reflects a blocking of potentially available interstitial sites to hydrogen occupation by Mo atoms at small hydrogen contents. Examination of the excess free energy vs hydrogen content relationships indicates that effects resulting from accommodation of hydrogen electrons by the metal conduction band are significant even at small hydrogen contents in the TiMo alloys; thus, explicit determination of the H-H interaction is not possible in the alloys. By contrast, electronic effects in pure ?-Ti are negligible at small HM and under fixed volume conditions, the H-H interactions in ?-Ti are attractive.

J.F. Lynch; J. Tanaka

1981-01-01T23:59:59.000Z

353

Entropy production and wave packet dynamics in the Fock space of closed chaotic many-body systems  

E-Print Network (OSTI)

Highly excited many-particle states in quantum systems such as nuclei, atoms, quantum dots, spin systems, quantum computers etc., can be considered as ``chaotic'' superpositions of mean-field basis states (Slater determinants, products of spin or qubit states). This is due to a very high level density of many-body states that are easily mixed by a residual interaction between particles (quasi-particles). For such systems, we have derived simple analytical expressions for the time dependence of energy width of wave packets, as well as for the entropy, number of principal basis components and inverse participation ratio, and tested them in numerical experiments. It is shown that the energy width $\\Delta (t)$ increases linearly and very quickly saturates. The entropy of a system increases quadratically, $S(t) \\sim t^2$ at small times, and after, can grow linearly, $S(t) \\sim t$, before the saturation. Correspondingly, the number of principal components determined by the entropy, $N_{pc} \\sim exp{(S(t))}$, or by the inverse participation ratio, increases exponentially fast before the saturation. These results are explained in terms of a cascade model which describes the flow of excitation in the Fock space of basis components. Finally, a striking phenomenon of damped oscillations in the Fock space at the transition to an equilibrium is discussed.

V. V. Flambaum; F. M. Izrailev

2001-03-23T23:59:59.000Z

354

Study of Forming of Magnesium Alloy by Explosive Energy  

SciTech Connect

Magnesium alloy is an attractive next generation material due to its high specific strength with low weight. However, magnesium alloys has few slip lines with close-packed hexagonal lattice, and generally poor ductility at room temperature, therefore it is difficult to form this material by cold forging. It is well known that the speed of deformation of metallic materials rapidly changes at the high strain rate. For some metallic materials, it is reported that the ductility also increases at the high strain rate with this speed effect. In this study, a series of high speed impulsive compressive tests were carried. By using explosives for shock wave loading, the velocity in this experiment reached 100 m/s that can't be easily obtained in normal experiment. In this paper, the possibility of forming the AZ31 extrusion magnesium alloy using explosive-impulsive pressure is investigated. And improved ductility by the effect of high-rate deformation is observed with this alloy.

Ruan, Liqun; Hokamoto, Kazuyuki; Marumo, Yasuo [Kumamoto University Department of Mechanical Systems Engineering Graduate School of Science and Technology, Kurokami 2-39-1, Kumamoto-shi 860-8555 (Japan); Yahiro, Ititoku [Mitsui Engineering and Shipbuilding Co., Ltd. Nihonbasi 1-3-16, Toukyou 104-8439 (Japan)

2011-05-04T23:59:59.000Z

355

Protective nitride formation on stainless steel alloys for proton exchange membrane fuel cell bipolar plates  

SciTech Connect

Gas nitridation has shown excellent promise to form dense, electrically conductive and corrosion-resistant Cr-nitride surface layers on Ni-Cr base alloys for use as proton exchange membrane fuel cell (PEMFC) bipolar plates. Due to the high cost of nickel, Fe-base bipolar plate alloys are needed to meet the cost targets for many PEMFC applications. Unfortunately, nitridation of Fe-base stainless steel alloys typically leads to internal Cr-nitride precipitation rather than the desired protective surface nitride layer formation, due to the high permeability of nitrogen in these alloys. This paper reports the finding that it is possible to form a continuous, protective Cr-nitride (CrN and Cr{sub 2}N) surface layer through nitridation of Fe-base stainless steel alloys. The key to form a protective Cr-nitride surface layer was found to be the initial formation of oxide during nitridation, which prevented the internal nitridation typically observed for these alloys, and resulted in external Cr-nitride layer formation. The addition of V to the alloy, which resulted in the initial formation of V{sub 2}O{sub 3}-Cr{sub 2}O{sub 3}, was found to enhance this effect, by making the initially formed oxide more amenable to subsequent nitridation. The Cr-nitride surface layer formed on model V-modified Fe-27Cr alloys exhibited excellent corrosion resistance and low interfacial contact resistance under simulated PEMFC bipolar plate conditions.

Yang, Bing [ORNL; Brady, Michael P [ORNL; Wang, Heli [National Renewable Energy Laboratory (NREL); Turner, John [National Renewable Energy Laboratory (NREL); More, Karren Leslie [ORNL; Young, David J [ORNL; Tortorelli, Peter F [ORNL; Payzant, E Andrew [ORNL; Walker, Larry R [ORNL

2007-01-01T23:59:59.000Z

356

Design of Stable Nanocrystalline Alloys  

E-Print Network (OSTI)

Nanostructured metals are generally unstable; their grains grow rapidly even at low temperatures, rendering them difficult to process and often unsuitable for usage. Alloying has been found to improve stability, but only ...

Chookajorn, Tongjai

357

The Microstructure of Mechanically Alloyed Nanocrystalline Aluminium-Magnesium  

E-Print Network (OSTI)

The Microstructure of Mechanically Alloyed Nanocrystalline Aluminium-Magnesium Jen Gubicza1 analysis. Magnesium gradually goes into solid solution during ball milling and after 3 h almost all. Experimental A series of aluminium-magnesium samples were prepared from high purity aluminium (99.9%) powder

Gubicza, Jenõ

358

Fischer-Tropsch synthesis over iron-rhodium alloy catalysts  

SciTech Connect

To investigate the nature of iron-rhodium alloy catalysts during the Fischer-Tropsch synthesis, a combination of experimental techniques were applied. Infrared spectroscopy was mainly used to extract direct information on the surface of catalysts under the reaction conditions. In addition, Mossbauer spectroscopy was employed to study the iron alloy catalysts. Further characterization of the catalysts was performed by chemisorption measurements. Hydrocarbon products of the CO + H/sub 2/ synthesis reaction were analyzed by gas chromatography. The working surface of a silica-supported rhodium catalyst was found to be saturated with molecular carbon monoxide. The intensity of the linear carbonyl absorption band remained constant compared to that for room temperature CO adsorption, while that of the bridge-bonded carbonyl absorption band was drastically reduced during the Fischer-Tropsch synthesis. The bridge-bonded adsorption sites are assumed to be the active sites for dissociating carbon monoxide. The hydrogenation rate of the linearly adsorbed carbon monoxide was much slower than the steady state reaction rate. The alloy catalyst did not form a bulk carbide, but the presence of surface carbon was suggested by the large shift of the linear carbonyl absorption band. On the other hand, infrared spectra on an iron catalyst showed only weak bands, indicating a high degree of CO dissociation. On a silica-supported iron-rhodium alloy catalyst, surface analysis by infrared spectroscopy presents evidence of well-mixed alloy formation. Three models of carbon monoxide adsorption were identified.

Choi, S.

1983-01-01T23:59:59.000Z

359

E-Print Network 3.0 - akot ti alloy Sample Search Results  

NLE Websites -- All DOE Office Websites (Extended Search)

666670 Phase transformation and precipitation in aged TiNiHf Summary: in aged Ti-Ni-Hf high-temperature shape memory alloys X.L. Meng, W. Cai, Y.F. Zheng, L.C. Zhao...

360

Evaluation of Quasicrystal Al-Cu-Fe Alloys for Tribological Applications  

E-Print Network (OSTI)

This research investigated the tribological performance of a composite material, formed from an ultra high molecular weight polyethylene (UHMWPE) matrix and quasicrystalline Al-Cu-Fe alloy powders. An evaluation was conducted for the microstructure...

Nabelsi, Nezar

2013-07-22T23:59:59.000Z

Note: This page contains sample records for the topic "high entropy alloy" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


361

Formation of composite coatings based on titanium carbide via electrospark alloying  

Science Journals Connector (OSTI)

This work concerns studying the coatings prepared via electrospark alloying. To deposit the coatings, we used STIM-2/30 electrodes derived from a combination of self-propagating high-temperature synthesis (SHS...

F. I. Panteleenko; V. V. Sarantsev…

2011-08-01T23:59:59.000Z

362

Kretschmann Invariant and Relations Between Spacetime Singularities, Entropy and Information  

E-Print Network (OSTI)

Using a yukawa type of metric we derive the kretschmann scalar for a general static black hole of a certain mass. The scalar gives the curvature of the space time as a function of the radial distance in the vicinity as well as inside of the black hole. Furthermore, the kretschmann scalar helps us understand the appearance of the black hole as a whole entity. It can be applied in solar mass size black holes, neutron stars or super massive black holes at the center of various galaxies. In an effort to investigate the connection of geometry to entropy and information, the kretschmann scalar for a solar mass yukawa schwarzschild and simple schwarzschild black holes are derived. Moreover, the dependence of the curvature on the entropy and number of information in nats is derived.

Ioannis Gkigkitzis; Ioannis Haranas; Omiros Ragos

2014-06-06T23:59:59.000Z

363

Black Holes, Entropies, and Semiclassical Spacetime in Quantum Gravity  

E-Print Network (OSTI)

We present a coherent picture of the quantum mechanics of black holes. The picture does not require the introduction of any drastically new physical effect beyond what is already known; it arises mostly from synthesizing and (re)interpreting existing results in appropriate manners. We identify the Bekenstein-Hawking entropy as the entropy associated with coarse-graining performed to obtain semiclassical field theory from a fundamental microscopic theory of quantum gravity. This clarifies the issues around the unitary evolution, the existence of the interior spacetime, and the thermodynamic nature in black hole physics--any result in semiclassical field theory is a statement about the maximally mixed ensemble of microscopic quantum states consistent with the specified background, within the precision allowed by quantum mechanics. We present a detailed analysis of information transfer in Hawking emission and black hole mining processes, clarifying what aspects of the underlying dynamics are (not) visible in sem...

Nomura, Yasunori

2014-01-01T23:59:59.000Z

364

EPR = ER and Scattering Amplitude as Entanglement Entropy Change  

E-Print Network (OSTI)

Alday and Maldacena have found an exact minimal surface of open string world-sheet describing a gluon scattering. We study the causal structure of that minimal surface in AdS of position space, and find a world-sheet wormhole parametrized by Mandelstam variables. If we figure a gluon as an open string in AdS, the ribbon connecting the two strings always pass the world-sheet wormhole, demonstrating the EPR = ER for gluon scattering. Since entanglement is caused by an interaction, one can ask what is the relation between entanglement entropy and the scattering amplitude. We propose an answer by generalizing the holographic entanglement entropy (EE) of Ryu-Takayanagi to the case where two regions are divided in space-time and interpret the result as the change of EE.

Seki, Shigenori

2014-01-01T23:59:59.000Z

365

Improve the fatigue life of titanium alloys; Part 1  

SciTech Connect

Heat treatment and mechanical surface treatments of titanium alloys interact in unique ways to allow tailoring of surface microstructures for specific applications. Part 1 of this two-part review discusses the properties of titanium alloys in their various microstructural phases, and Part 2 will describe novel methods for improving fatigue performance by combining mechanical and thermal treatments. Microstructural modification by thermomechanical treatments is widely used to optimize the properties of high-strength titanium alloys for specific applications. However, because the surface of a mechanically loaded titanium part often experiences different conditions than the bulk, it makes sense in many applications to modify only the surface microstructure. By combining thermal treatments with mechanical working, stability of the resulting tailored surface is enhanced. Such stability is especially significant for resistance to fatigue crack nucleation and growth.

Wagner, L. (TU Hamburg-Harburg (Germany)); Gregory, J.K. (GKSS Research Center, Geesthacht (Germany))

1994-03-01T23:59:59.000Z

366

Survey of physical property data for several alloys. [Nitronic 33; copper C10400; copper C17510  

SciTech Connect

This report summarizes an examination of physical property data available in the literature for six alloys of potential interest to the Toroidal Fusion Core Experiment in the Fusion Energy Program. The properties of thermal expansion, density, specific heat, electrical resistivity, and thermal conductivity were compiled for six alloys: Nitronic 33, a low-nickel, high manganese stainless steel; nickel-base Inconnel Alloys 625, 718, and X-750; and copper alloys C10400 and C17510. The temperatures of interest were 4-500 K for the Nitronic 33 and the Inconels, and 250-400 K for the copper alloys. Where data were lacking, estimates were made based on theory or comparisons with similar materials.

Pawel, R.E.; Williams, R.K.

1985-08-01T23:59:59.000Z

367

When are microcircuits well-modeled by maximum entropy methods?  

E-Print Network (OSTI)

and fire. The inputs are chosen from distributions that are either gaussian, uniform, skewed, or bimodal. For each circuit, we compute the distribution on output spiking states either analytically or by sampling, approximate by a maximum entropy fit... generation is characterized by a simple static nonlinearity, or by integrate-and-fire (LIF) threshold-crossing dynamics. However, this circuit does generate substantial higher-order correlations if the common input to the three cells is bimodal. This approach...

2010-07-20T23:59:59.000Z

368

Decoherence and entropy production in relativistic nuclear collisions  

E-Print Network (OSTI)

, the anisotropic collective transverse flow may be generated, in part, by interactions of minijets with the bulk medium [14] or by anisotropies in the initial gluon field [15]. Hydrodynamic calculations with viscous corrections describing small deviations from... then extract information on the original wave function. In heavy-ion collisions each Lorentz contracted ion acts like such a foil for the other. That the loss of information due to decoherence can generate a rapid increase in entropy in early phases...

Fries, Rainer J.; Mueller, Berndt; Schaefer, Andreas.

2009-01-01T23:59:59.000Z

369

Identifying delayed directional couplings with symbolic transfer entropy  

Science Journals Connector (OSTI)

We propose a straightforward extension of symbolic transfer entropy to enable the investigation of delayed directional relationships between coupled dynamical systems from time series. Analyzing time series from chaotic model systems, we demonstrate the applicability and limitations of our approach. Our findings obtained from applying our method to infer delayed directed interactions in the human epileptic brain underline the importance of our approach for improving the construction of functional network structures from data.

Henning Dickten and Klaus Lehnertz

2014-12-08T23:59:59.000Z

370

Cosmic dynamics with entropy corrected holographic dark energy  

E-Print Network (OSTI)

We investigate the model of holographic dark energy with logarithmic correction to its energy density. This modification is motivated from the loop quantum gravity corrections to the entropy-area law. We also consider an interaction between dark energy and dark matter. The behavior of the Hubble parameter (specially in the late time) is studied. Besides, conditions under which an accelerated universe can decelerate and also successive acceleration-deceleration phases can be occurred in the evolution of the universe is investigated.

Sadjadi, H Mohseni

2010-01-01T23:59:59.000Z

371

Gravitational Entropy and the Second Law of Thermodynamics  

E-Print Network (OSTI)

The spontaneous violation of Lorentz and diffeomorphism invariance in a phase near the big bang lowers the entropy, allowing for an arrow of time and the second law of thermodynamics. The spontaneous symmetry breaking leads to $O(3,1)\\rightarrow O(3)\\times R$, where $O(3)$ is the rotational symmetry of the Friedmann-Lema\\^{i}tre-Robertson-Walker spacetime. The Weyl curvature tensor $C_{\\mu\

Moffat, J W

2014-01-01T23:59:59.000Z

372

Maximum entropy method for reconstruction of the CMB images  

E-Print Network (OSTI)

We propose a new approach for the accurate reconstruction of cosmic microwave background distributions from observations containing in addition to the primary fluctuations the radiation from unresolved extragalactic point sources and pixel noise. The approach uses some effective realizations of the well-known maximum entropy method and principally takes into account {\\it a priori} information about finiteness and spherical symmetry of the power spectrum of the CMB satisfying the Gaussian statistics.

A. T. Bajkova

2002-05-21T23:59:59.000Z

373

Entropy and equilibrium state of free market models  

E-Print Network (OSTI)

Many recent models of trade dynamics use the simple idea of wealth exchanges among economic agents in order to obtain a stable or equilibrium distribution of wealth among the agents. In particular, a plain analogy compares the wealth in a society with the energy in a physical system, and the trade between agents to the energy exchange between molecules during collisions. In physical systems, the energy exchange among molecules leads to a state of equipartition of the energy and to an equilibrium situation where the entropy is a maximum. On the other hand, in the majority of exchange models, the system converges to a very unequal condensed state, where one or a few agents concentrate all the wealth of the society while the wide majority of agents shares zero or almost zero fraction of the wealth. So, in those economic systems a minimum entropy state is attained. We propose here an analytical model where we investigate the effects of a particular class of economic exchanges that minimize the entropy. By solving...

Iglesias, J R

2011-01-01T23:59:59.000Z

374

Dynamical horizon entropy and equilibrium thermodynamics of generalized gravity theories  

SciTech Connect

We study the relation between the thermodynamics and field equations of generalized gravity theories on the dynamical trapping horizon with sphere symmetry. We assume the entropy of a dynamical horizon as the Noether charge associated with the Kodama vector and point out that it satisfies the second law when a Gibbs equation holds. We generalize two kinds of Gibbs equations to Gauss-Bonnet gravity on any trapping horizon. Based on the quasilocal gravitational energy found recently for f(R) gravity and scalar-tensor gravity in some special cases, we also build up the Gibbs equations, where the nonequilibrium entropy production, which is usually invoked to balance the energy conservation, is just absorbed into the modified Wald entropy in the Friedmann-Robertson-Walker spacetime with slowly varying horizon. Moreover, the equilibrium thermodynamic identity remains valid for f(R) gravity in a static spacetime. Our work provides an alternative treatment to reinterpret the nonequilibrium correction and supports the idea that the horizon thermodynamics is universal for generalized gravity theories.

Wu Shaofeng; Ge Xianhui; Yang Guohong [Department of Physics, Shanghai University, Shanghai, 200444 (China); Shanghai Key Lab of Astrophysics, Shanghai, 200234 (China); Zhang Pengming [Center of Theoretical Nuclear Physics, National Laboratory of Heavy Ion Accelerator, Lanzhou 730000 (China); Institute of Modern Physics, Lanzhou, 730000 (China)

2010-02-15T23:59:59.000Z

375

Material synthesis and hydrogen storage of palladium-rhodium alloy.  

SciTech Connect

Pd and Pd alloys are candidate material systems for Tr or H storage. We have actively engaged in material synthesis and studied the material science of hydrogen storage for Pd-Rh alloys. In collaboration with UC Davis, we successfully developed/optimized a supersonic gas atomization system, including its processing parameters, for Pd-Rh-based alloy powders. This optimized system and processing enable us to produce {le} 50-{mu}m powders with suitable metallurgical properties for H-storage R&D. In addition, we studied hydrogen absorption-desorption pressure-composition-temperature (PCT) behavior using these gas-atomized Pd-Rh alloy powders. The study shows that the pressure-composition-temperature (PCT) behavior of Pd-Rh alloys is strongly influenced by its metallurgy. The plateau pressure, slope, and H/metal capacity are highly dependent on alloy composition and its chemical distribution. For the gas-atomized Pd-10 wt% Rh, the absorption plateau pressure is relatively high and consistent. However, the absorption-desorption PCT exhibits a significant hysteresis loop that is not seen from the 30-nm nanopowders produced by chemical precipitation. In addition, we observed that the presence of hydrogen introduces strong lattice strain, plastic deformation, and dislocation networking that lead to material hardening, lattice distortions, and volume expansion. The above observations suggest that the H-induced dislocation networking is responsible for the hysteresis loop seen in the current atomized Pd-10 wt% Rh powders. This conclusion is consistent with the hypothesis suggested by Flanagan and others (Ref 1) that plastic deformation or dislocations control the hysteresis loop.

Lavernia, Enrique J. (University of California, Davis); Yang, Nancy Y. C.; Ong, Markus D. (Whithworth University, Spokane, WA)

2011-08-01T23:59:59.000Z

376

CREEP AND CREEP-FATIGUE OF ALLOY 617 WELDMENTS  

SciTech Connect

The Very High Temperature Reactor (VHTR) Intermediate Heat Exchanger (IHX) may be joined to piping or other components by welding. Creep-fatigue deformation is expected to be a predominant failure mechanism of the IHX1 and thus weldments used in its fabrication will experience varying cyclic stresses interrupted by periods of elevated temperature deformation. These periods of elevated temperature deformation are greatly influenced by a materials’ creep behavior. The nickel-base solid solution strengthened alloy, Alloy 617, is the primary material candidate for a VHTR-type IHX, and it is expected that Alloy 617 filler metal will be used for welds. Alloy 617 is not yet been integrated into Section III of the Boiler and Pressure Vessel Code, however, nuclear component design with Alloy 617 requires ASME (American Society of Mechanical Engineers) Code qualification. The Code will dictate design for welded construction through significant performance reductions. Despite the similar compositions of the weldment and base material, significantly different microstructures and mechanical properties are inevitable. Experience of nickel alloy welds in structural applications suggests that most high temperature failures occur at the weldments or in the heat-affected zone. Reliably guarding against this type of failure is particularly challenging at high temperatures due to the variations in the inelastic response of the constituent parts of the weldment (i.e., weld metal, heat-affected zone, and base metal) [ref]. This work focuses on the creep-fatigue behavior of nickel-based weldments, a need noted during the development of the draft Alloy 617 ASME Code Case. An understanding of Alloy 617 weldments when subjected to this important deformation mode will enable determination of the appropriate design parameters associated with their use. Specifically, the three main areas emphasized are the performance reduction due to a weld discontinuity in terms of the reduced number of the cycles to failure and whether a saturation in reduced cycle life with increased hold times is observed, the microstructural stability over long cycle times, and finally, the location of the generated weldment data on a creep-fatigue damage diagram (D-diagram).

Wright, Jill; Carroll, Laura; Wright, Richard

2014-08-01T23:59:59.000Z

377

Thermodynamic Prediction of Compositional Phases Confirmed by Transmission Electron Microscopy on Tantalum-Based Alloy Weldments  

SciTech Connect

Tantalum alloys have been used by the U.S. Department of Energy as structural alloys for radioisotope based thermal to electrical power systems since the 1960s. Tantalum alloys are attractive for high temperature structural applications due to their high melting point, excellent formability, good thermal conductivity, good ductility (even at low temperatures), corrosion resistance, and weldability. Tantalum alloys have demonstrated sufficient high-temperature toughness to survive prolonged exposure to the radioisotope power-system working environment. Typically, the fabrication of power systems requires the welding of various components including the structural members made of tantalum alloys. Issues such as thermodynamics, lattice structure, weld pool dynamics, material purity and contamination, and welding atmosphere purity all potentially confound the understanding of the differences between the weldment properties of the different tantalum-based alloys. The objective of this paper is to outline the thermodynamically favorable material phases in tantalum alloys, with and without small amounts of hafnium, during and following solidification, based on the results derived from the FactSage(c) Integrated Thermodynamic Databank. In addition, Transition Electron Microscopy (TEM) data will show for the first time, the changes occurring in the HfC before and after welding, and the data will elucidate the role HfC plays in pinning grain boundaries.

Moddeman, William E.; Birkbeck, Janine C. [BWXT Pantex, Amarillo, Texas 79120-0020 (United States); Barklay, Chadwick D.; Kramer, Daniel P. [University of Dayton Research Institute, Dayton OH 45469-0102 (United States); Miller, Roger G.; Allard, Lawrence F. [Oak Ridge National Laboratory, Oak Ridge, TN 37831-6064 (United States)

2007-01-30T23:59:59.000Z

378

Microstructural Development and Mechanical Properties for Reactive Air Brazing of ZTA to Ni Alloys using Ag-CuO Braze Alloys  

SciTech Connect

Reactive air brazing (RAB) is a potential joining technique to join metal alloys to ceramics for a variety of applications. In the current study, nickel (Ni) alloys were heat treated to form an oxide layer prior to RAB joining to zirconia toughened alumina (ZTA). The Ni alloys evaluated were Nicrofer 6025 HT, Inconel 600, Inconel 693, Haynes 214 and Inconel 601. The ZTA studied had compositions of 0 to 15 wt% zirconia and 0 to 14 wt% glass. Four point-bend tests were performed to evaluate the joint strength of ZTA/ZTA and ZTA/nickel alloys brazed with Ag-2wt% CuO braze alloys. It was determined that the joint strength is not a function of the ZTA composition, but that the strength is a strong function of the chemistry and microstructure of the oxide layer formed on the nickel alloy. It was determined that an increase in the aluminum content of the Ni alloy resulted in an increase of the thickness of alumina in the oxide layer and was directly proportional to the bond strength with the exception of Inconel 601 which exhibited relatively high joint strengths even though it had a relatively low aluminum content.

Prevost, Erica; DeMarco, A.Joseph; MacMichael, Beth; Joshi, Vineet V.; Meier, Alan; Hoffman, John W.; Walker, William J.

2014-12-01T23:59:59.000Z

379

High Temperature coatings based on {beta}-NiAI  

SciTech Connect

High temperature alloys are reviewed, focusing on current superalloys and their coatings. The synthesis, characerization, and oxidation performance of a NiAl–TiB{sub 2} composite are explained. A novel coating process for Mo–Ni–Al alloys for improved oxidation performance is examined. The cyclic oxidation performance of coated and uncoated Mo–Ni–Al alloys is discussed.

Severs, Kevin

2012-07-10T23:59:59.000Z

380

Design of Ferromagnetic Shape Memory Alloy Composites  

E-Print Network (OSTI)

, superelasticity, bending plate, coil spring. INTRODUCTION RECENTLY, FERROMAGNETIC SHAPE memory alloys (FSMAs torque actuator (bending of FSMA composite plate) and spring actuator (torsion of helical FSMA composite spring). KEY WORDS: shape memory alloy, ferromagnetic material, stress-induced martensite transformation

Taya, Minoru

Note: This page contains sample records for the topic "high entropy alloy" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


381

Non-equilibrium thermodynamics of dark energy on the power-law entropy corrected apparent horizon  

E-Print Network (OSTI)

We investigate the Friedmann-Robertson-Walker (FRW) universe (containing dark energy) as a non-equilibrium (irreversible) thermodynamical system by considering the power-law correction to the horizon entropy. By taking power-law entropy area law which appear in dealing with the entanglement of quantum fields in and out the horizon, we determine the power-law entropy corrected apparent horizon of the FRW universe.

M. Umar Farooq; Mubasher Jamil

2011-11-24T23:59:59.000Z

382

Electrochemistry properties of multilayer TiN/Ti coatings on NiTi alloy for cardiac occluder application  

E-Print Network (OSTI)

-elasticity, thermal shape memory, high corrosion and fatigue resistance, make NiTi alloy especially suitableTi alloy is a subject of numerous recent studies to improve the material's corrosion resistance as well,b , D.Y. Zhang e a Center for Biomedical Materials and Tissue Engineering, Academy for Advanced

Zheng, Yufeng

383

Low-temperature magnetization in Ni-rich gamma-Ni100-x-yFexVy alloys  

E-Print Network (OSTI)

is antiferromagnetic) suppresses the ferromagnetic order in the NiFe binary alloys. The magnetization of the alloys with low V (y less than or equal to 11 at. %) has shown a good fit to only the spin-wave T-3/2 term whereas the data for the high V (gamma greater than...

Chakraborty, S.; Mukherjee, GD; Rathnayaka, KDD; Naugle, Donald G.; Majumdar, AK.

2000-01-01T23:59:59.000Z

384

Comprehensive Investigation of the Uranium-Zirconium Alloy System: Thermophysical Properties, Phase Characterization and Ion Implantation Effects  

E-Print Network (OSTI)

Uranium-zirconium (U-Zr) alloys comprise a class of metallic nuclear fuel that is regularly considered for application in fast nuclear energy systems. The U-10wt%Zr alloy has been demonstrated to very high burnup without cladding breach...

Ahn, Sangjoon

2013-07-31T23:59:59.000Z

385

Journal of Power Sources 155 (2006) 253263 Stability of platinum based alloy cathode catalysts in PEM fuel cells  

E-Print Network (OSTI)

on a conductive support that has a high surface area, such as carbon black, is used as electrocatalyst to the development of binary and ternary Pt-alloys [3­5]. Studies of ORR on Pt-alloys supported on carbon black­16]. The acid environment in the PEMFC is different from that of PAFCs because the anions of the perfluorinated

Popov, Branko N.

386

Oxidation Behavior of Mo-Si-B Alloys in Wet Air  

SciTech Connect

Multiphase composite alloys based on the Mo-Si-B system are candidate materials for ultra-high temperature applications. In non load-bearing uses such as thermal barrier coatings or heat exchangers in fossil fuel burners, these materials may be ideally suited. The present work investigated the effect of water vapor on the oxidation behavior of Mo-Si-B phase assemblages. Three alloys were studied: Alloy 1 = Mo{sub 5}Si{sub 3}B{sub x} (T1)- MoSi{sub 2}- MoB, Alloy 2 = T1- Mo{sub 5}SiB{sub 2} (T2)- Mo{sub 3}Si, and Alloy 3 = Mo- T2- Mo{sub 3}Si. Tests were conducted at 1000 and 1100C in controlled atmospheres of dry air and wet air nominally containing 18, 55, and 150 Torr H{sub 2}O. The initial mass loss of each alloy was approximately independent of the test temperature and moisture content of the atmosphere. The magnitude of these initial losses varied according to the Mo content of the alloys. All alloys formed a continuous, external silica scale that protected against further mass change after volatilization of the initially formed MoO{sub 3}. All alloys experienced a small steady state mass change, but the calculated rates cannot be quantitatively compared due to statistical uncertainty in the individual mass measurements. Of particular interest is that Alloy 3, which contains a significant volume fraction of Mo metal, formed a protective scale. All alloys formed varying amounts of subscale Mo and MoO{sub 2}. This implies that oxygen transport through the external silica scale has been significantly reduced. For all alloys, water vapor accelerated the growth of a multiphase interlayer at the silica scale/unoxidized alloy interface. This interlayer is likely composed of fine Mo and MoO{sub 2} that is dispersed within a thin silica matrix. Alloy 3 was particularly sensitive to water accelerated growth of this interlayer. At 1100 C, the scale thickness after 300 hours increased from about 20 mm in dry air to nearly 100 mm in wet air.

M. Kramer; A. Thom; O. Degirmen; V. Behrani; M. Akinc

2002-04-22T23:59:59.000Z

387

Stress-corrosion-cracking studies on candidate container alloys for the Tuff Repository  

SciTech Connect

Cortest Columbus Technologies, Inc. (CC Technologies) investigated the long-term performance of container materials used for high-level waste package as part of the information needed by the Nuclear Regulatory Commission (NRC) to assess the Department of Energy`s application to construct to geologic repository for high-level radioactive waste. At the direction of the NRC, the program focused on the Tuff Repository. This report summarizes the results of Stress-Corrosion-Cracking (SCC) studies performed in Tasks 3, 5, and 7 of the program. Two test techniques were used; U-bend exposures and Slow-Strain-Rate (SSR) tests. The testing was performed on two copper-base alloys (Alloy CDA 102 and Alloy CDA 175) and two Fe-Cr-Ni alloys (Alloy 304L and Alloy 825) in simulated J-13 groundwater and other simulated solutions for the Tuff Repository. These solutions were designed to simulate the effects of concentration and irradiation on the groundwater composition. All SCC testing on the Fe-Cr-Ni Alloys was performed on solution-annealed specimens and thus issues such as the effect of sensitization on SCC were not addressed.

Beavers, J.A.; Durr, C.L. [Cortest Columbus Technologies, Inc., OH (United States)

1992-05-01T23:59:59.000Z

388

Neutron scattering studies of spin?glass alloys  

Science Journals Connector (OSTI)

Neutron diffraction investigations of binary alloys such as Cu?Mn beginning with the earliest reported measurements in 1957 show no evidence of any long range magnetic order except for the broad short range order peaks at the (1 1/2 0) type positions attributed to both atomic and magnetic short range ordering in alloys containing more than about 10–15 at.% Mn. The current interest in spin glasses is focused on the theoretical possibility of a magnetic phase transition to the spin glass state in the dilute random substitutional alloys. Recently neutron scatteringmeasurements have been attempted to study the dynamics of spins in the alloys with a view to understanding the nature of the processes leading to the spin glass state. Small angle neutron scatteringmeasurements on Au?Fe alloys with Fe concentrations below the percolation threshold for ferromagnetism show a series of q?dependent maxima in the total scattering intensity suggesting a continuum of freezing temperatures. Other measurements employing energy analysis by the time?of?flight technique at somewhat larger q’s on the same and other alloys such as Cu?Mn Pd?Mn show a broad quasi?elastic paramagnetic spectrum at high temperatures whose energy width decreases with decreasing temperature apparently goes through a minimum especially at the higher q’s but always remains finite as T?0 K. The intensity of the quasi?elastic scattering however diminishes progressively below some temperature with a simultaneous continuous increase of the elastic peak intensity. Although the implications of the recent phase transition theories of spin glasses to the dynamics of spins at finite scattering vectors are not entirely clear the present neutron scattering results appear not inconsistent with the alternative picture of a continuous process of freezing of spins occurring at least over a finite temperature range.

A. P. Murani

1978-01-01T23:59:59.000Z

389

Bridge recognition of median-resolution SAR images using pun histogram entropy  

Science Journals Connector (OSTI)

A novel algorithm for bridge recognition of median synthetic aperture radar (SAR) images using histogram entropy presented by Pun is proposed. Firstly, Lee filter and histogram...

Wu, Wenyu; Yin, Dong; Zhang, Rong; Liu, Yan; Pan, Jia

2009-01-01T23:59:59.000Z

390

Research on Entropy-TOPSIS in External Environment Evaluation of Power Grid Corporation  

Science Journals Connector (OSTI)

This paper developed external environment impact assessment index system based on the asset management process of power grid Corporation. It established an entropy-TOPSIS environment...

Qingyou Yan; Xiaoya Wang; Siqi He; Lili Zhu

2011-01-01T23:59:59.000Z

391

Extra entropy production due to nonequilibrium phase transitions in relativistic heavy ion reactions  

Science Journals Connector (OSTI)

In a fluid-dynamical model, the extra entropy production which arises from a nonequilibrium phase transition from nuclear to quark-gluon matter is calculated.

H. W. Barz; B. Kämpfer; B. Lukács; L. P. Csernai

1985-01-01T23:59:59.000Z

392

A definition of thermodynamic entropy valid for non-equilibrium states and few-particle systems  

E-Print Network (OSTI)

From a new rigorous formulation of the general axiomatic foundations of thermodynamics we derive an operational definition of entropy that responds to the emergent need in many technological frameworks to understand and deploy thermodynamic entropy well beyond the traditional realm of equilibrium states of macroscopic systems. The new definition is achieved by avoiding to resort to the traditional concepts of "heat" (which restricts $a$ $priori$ the traditional definitions of entropy to the equilibrium domain) and of "thermal reservoir" (which restricts $in$ $practice$ our previous definitions of non-equilibrium entropy to the many-particle domain). The measurement procedure that defines entropy is free from intrinsic limitations and can be applied, $in$ $principle$, even to non-equilibrium states of few-particle systems, provided they are separable and uncorrelated. The construction starts from a previously developed set of carefully worded operational definitions for all the basic concepts. Then, through a new set of fully spelled-out fundamental hypotheses (four postulates and five assumptions) we derive the definitions of energy and entropy of any state, and of temperature of any stable equilibrium state. Finally, we prove the principle of entropy non-decrease, the additivity of entropy differences, the maximum entropy principle, and the impossibility of existence of a thermal reservoir.

Gian Paolo Beretta; Enzo Zanchini

2014-11-19T23:59:59.000Z

393

E-Print Network 3.0 - absolute single-molecule entropies Sample...  

NLE Websites -- All DOE Office Websites (Extended Search)

of Technology (MIT) Collection: Chemistry 7 The Backbone Conformational Entropy of Protein Folding: Experimental Measures from Atomic Summary: corre- sponds to the absolute...

394

Maximum Entropy and Bayesian Statistics in Crystallography: a Review of Practical Applications  

Science Journals Connector (OSTI)

The applications of the maximum entropy and Bayesian methods to problems in X-ray, neutron and electron crystallography are reviewed.

Gilmore, C.J.

1996-07-01T23:59:59.000Z

395

Investigation of Effects of Neutron Irradiation on Tantalum Alloys for Radioisotope Power System Applications  

SciTech Connect

Tantalum alloys have been used by the U.S. Department of Energy as structural alloys for space nuclear power systems such as Radioisotopic Thermoelectric Generators (RTG) since the 1960s. Tantalum alloys are attractive for high temperature structural applications due to their high melting point, excellent formability, good thermal conductivity, good ductility (even at low temperatures), corrosion resistance, and weldability. A number of tantalum alloys have been developed over the years to increase high-temperature strength (Ta-10%W) and to reduce creep strain (T-111). These tantalum alloys have demonstrated sufficient high-temperature toughness to survive the increasing high pressures of the RTG's operating environment resulting from the alpha decay of the 238-plutonium dioxide fuel. However, 238-plutonium is also a powerful neutron source. Therefore, the RTG operating environment produces large amounts of 3-helium and neutron displacement damage over the 30 year life of the RTG. The literature to date shows that there has been very little work focused on the mechanical properties of irradiated tantalum and tantalum alloys and none at the fluence levels associated with a RTG operating environment. The minimum, reactor related, work that has been reported shows that these alloys tend to follow trends seen in the behavior of other BCC alloys under irradiation. An understanding of these mechanisms is important for the confident extrapolation of mechanical-property trends to the higher doses and gas levels corresponding to actual service lifetimes. When comparing the radiation effects between samples of Ta-10%W and T-111 (Ta-8%W-2%Hf) subjected to identical neutron fluences and environmental conditions at temperatures <0.3Tm ({approx}700 deg. C), evidence suggests the possibility that T-111 will exhibit higher levels of internal damage accumulation and degradation of mechanical properties compared to Ta-10%W.

Barklay, Chadwick D.; Kramer, Daniel P. [University of Dayton Research Institute, 300 College Park Dayton OH 45469-0102 (United States); Talnagi, Joseph [Ohio State University Research Reactor, 1298 Kinnear Road, Columbus, OH 43212 (United States)

2007-01-30T23:59:59.000Z

396

Nd:YAG laser welding aluminum alloys  

SciTech Connect

Autogenous Nd:YAG laser welding wrought 4047, 1100, 3003, 2219, 5052, 5086, 5456, and 6061 and cast A356 aluminum alloys to cast A356 aluminum alloy in restrained annular weld joints was investigated. The welds were 12.7 mm (0.375 in.) and 9.5 mm (0.375 in.) diameter with approximately 0.30 mm (0.012 in.) penetration. This investigation determined 4047 aluminum alloy to be the optimum alloy for autogenous Nd:YAG laser welding to cast A356 aluminum alloy. This report describes the investigation and its results.

Jimenez, E. Jr.

1992-02-01T23:59:59.000Z

397

Microstructure and Corrosion Behavior of the Cu-Pd-X Ternary Alloys for Hydrogen Separation Membranes  

SciTech Connect

CuPd alloys are among the most promising candidate materials for hydrogen separation membranes and membrane reactor applications due to their high hydrogen permeability and better sulfur resistance. In order to reduce the Pd content and, therefore, the cost of the membrane materials, efforts have been initiated to develop CuPdM ternary alloys having a bcc structure. The advantages of having Pd as a hydrogen separation membrane are: (1) high hydrogen selectivity; and (2) high hydrogen permeability. The disadvantages are: (1) high cost; (2) hydrogen embrittlement ({alpha} {yields} {beta} Pd hydride); and (3) sulfur poisoning. Experiments (XRD, SEM/EDS) verified that Mg, Al, La, Y and Ti are promising alloying elements to expand the B2 phase region in Cu-Pd binary system. HT-XRD showed that the B2 to FCC transition temperatures for Cu-Pd-X (X = Mg, Al, La, Y and Ti) are higher than that of Cu-Pd binary alloys. While the Cu-50Pd alloy had the highest corrosion resistance to the H2S containing syngas, the Cu-Pd-Mg alloy had a comparable resistance.

O.N. Dogan; M.C. Gao; B.H. Howard

2012-02-26T23:59:59.000Z

398

Removing the Entropy Screen- To Let the Second Law Show  

E-Print Network (OSTI)

the second 'law' in terms of work; rathel' than entropy, , REFERENCES 1. Steinmeyer, D., "Process Energy Conservation"" I in Kirk-Qtbmer: Encyclopedia of Chemical Technology; supplement volume, third edition, John Wiley, 1984 pp 669-697. 2. Kenney, W... for a given step. For example, the work used (including the lost work) by a distillation column is simply the difference in Wp of the heat supplied to the reboiler and taken out in the condenser: W =Q'To[l/T - 1/'1' ] (9) condenser reboiler where...

Steinmeyer, D.

399

Entropy production rate as a constraint for collisionless fluid closures  

SciTech Connect

A novel method is proposed to construct collisionless fluid closures accounting for some kinetic properties. The first dropped fluid moment is assumed to be a linear function of the lower order ones. Optimizing the agreement between the fluid and kinetic entropy production rates is used to constrain the coefficients of the linear development. This procedure is applied to a reduced version of the interchange instability. The closure, involving the absolute value of the wave vector, is non-local in real space. In this case, the linear instability thresholds are the same, and the linear growth rates exhibit similar characteristics. Such a method is applicable to other models and classes of instabilities.

Fleurence, E.; Sarazin, Y.; Garbet, X.; Dif-Pradalier, G.; Ghendrih, Ph.; Grandgirard, V.; Ottaviani, M. [Association Euratom-CEA, CEA/DSM/DRFC Cadarache, 13108 Saint-Paul-Lez-Durance (France)

2006-11-30T23:59:59.000Z

400

Lattice constant and substitutional composition of GeSn alloys grown by molecular beam epitaxy  

SciTech Connect

Single crystal epitaxial Ge{sub 1?x}Sn{sub x} alloys with atomic fractions of tin up to x = 0.145 were grown by solid source molecular beam epitaxy on Ge (001) substrates. The Ge{sub 1?x}Sn{sub x} alloys formed high quality, coherent, strained layers at growth temperatures below 250 °C, as shown by high resolution X-ray diffraction. The amount of Sn that was on lattice sites, as determined by Rutherford backscattering spectrometry channeling, was found to be above 90% substitutional in all alloys. The degree of strain and the dependence of the effective unstrained bulk lattice constant of Ge{sub 1?x}Sn{sub x} alloys versus the composition of Sn have been determined.

Bhargava, Nupur; Coppinger, Matthew; Prakash Gupta, Jay; Kolodzey, James [Department of Electrical and Computer Engineering, University of Delaware, Newark, Delaware 19716 (United States)] [Department of Electrical and Computer Engineering, University of Delaware, Newark, Delaware 19716 (United States); Wielunski, Leszek [Department of Physics and Astronomy, Rutgers University, Piscataway, New Jersey 08854 (United States)] [Department of Physics and Astronomy, Rutgers University, Piscataway, New Jersey 08854 (United States)

2013-07-22T23:59:59.000Z

Note: This page contains sample records for the topic "high entropy alloy" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


401

Laser fusing of HVOF thermal sprayed alloy 625 on nickel-aluminum bronze  

SciTech Connect

A preliminary study has been conducted to determine the feasibility of laser fusing alloy 625 onto nickel-aluminum-bronze base metal. Laser fusing was performed by melting a pre-coated surface of alloy 625 that had been applied by the high velocity oxyfuel (HVOF) thermal spray process. The laser fusing was successful in producing a metallurigical bond between alloy 625 and the substrate. Minor modification to the heat-affected zone of the base metal was observed by microhardness measurements, and defect-free interfaces were produced between alloy 625 and nickel-aluminum-bronze by the process. The laser is a high energy density source that can be used for precise thermal processing of materials including surface modification. Laser fusing is the full or partial melting of a coating material that has been previously applied in some fashion to the substrate. Thermal spray coating of nickel-aluminum-bronze material with alloy 625 was conducted at the David Taylor Research Center. Nickel-aluminum-bronze specimens 2 x 3-in. by 1/2-in. thick were coated with alloy 25 utilizing the HVOF equipment. Coating thicknesses of approximately 0.014-in. (0.3 mm) were produced for subsequent laser fusing experiments. A preliminary study has been conducted to determine the feasibility of laser fusing a HVOF thermal sprayed alloy 625 coating onto nickel-aluminum-bronze base metal. Conclusions of this investigation were as follows: (1) Laser fusing was successful in producing a metallurgical bond between HVOF thermal sprayed alloy 625 and the nickel-aluminum-bronze. (2) Only minor microstructural modification to the heat-affected zone of the base metal ws observed by microhardness measurements. (3) Defect-free interfaces were produced between thermal sprayed alloy 625 and nickel-aluminum-bronze by laser fusing.

Brenna, R.T.; Pugh, J.L.; Denney, P.E. [and others

1994-12-31T23:59:59.000Z

402

A history of tungsten- and molybdenum-base alloys  

SciTech Connect

The development of tungsten and molybdenum alloys was initiated in the early 1900s in search of a better electric lamp filament with tantalum, tungsten, rhenium, and osmium being the prime candidates. The efforts required for accomplishment of the task led to refining oxides to high purity, reduction of the oxides to metal powders, forming green product forms by extrusion or pressing, and finally sintering by electric furnace and self-heating by direct current almost to the melting point. The technology required for producing lamp filaments led to the development of the powder metallurgy field and early research on high-melting-temperature metals. During the period 1909 through 1959, most of the tungsten-molybdenum, high-melting-temperature element alloys were developed and produced in almost any product form required.

Heestand, R.L.

1993-05-01T23:59:59.000Z

403

A history of tungsten- and molybdenum-base alloys  

SciTech Connect

The development of tungsten and molybdenum alloys was initiated in the early 1900s in search of a better electric lamp filament with tantalum, tungsten, rhenium, and osmium being the prime candidates. The efforts required for accomplishment of the task led to refining oxides to high purity, reduction of the oxides to metal powders, forming green product forms by extrusion or pressing, and finally sintering by electric furnace and self-heating by direct current almost to the melting point. The technology required for producing lamp filaments led to the development of the powder metallurgy field and early research on high-melting-temperature metals. During the period 1909 through 1959, most of the tungsten-molybdenum, high-melting-temperature element alloys were developed and produced in almost any product form required.

Heestand, R.L.

1993-01-01T23:59:59.000Z

404

Hydrogenated amorphous silicon-germanium alloys  

SciTech Connect

This report describes the effects of the germanium fraction in hydrogenated amorphous silicon-germanium alloys on various parameters, especially those that are indicators of film quality, and the impact of deposition methods, feedgas mixtures, and other deposition parameters on a SiGe:H and a-SiGe:H:F film characteristics and quality. Literature data show the relationship between germanium content, hydrogen content, deposition method (various glow discharges and CVD), feedgas lmixture, and other parameters and properties, such as optical band gap, dark and photoconductivities, photosensitivity, activation energy, Urbach parameter, and spin density. Some of these are convenient quality indicators; another is the absence of microstructure. Examining RF glow discharge with both a diode and triode geometry, DC proximity glow discharge, microwave glow discharge, and photo-CVD, using gas mixtures such as hydrogen-diluted and undiluted mixtures of silane/germane, disilane/germane, silane/germaniumtetrafluoride, and others, it was observed that hydrogen dilution (or inert gas dilution) is essential in achieving high photosensitivity in silicon-germanium alloys (in contradistinction to amorphous hydrogenated silicon). Hydrogen dilution results in a higher photosensitivity than do undiluted gas mixtures. 81 refs., 42 figs., 7 tabs.

Luft, W.

1988-02-01T23:59:59.000Z

405

Eutectic structures in friction spot welding joint of aluminum alloy to copper  

SciTech Connect

A dissimilar joint of AA5083 Al alloy and copper was produced by friction spot welding. The Al-MgCuAl{sub 2} eutectic in both coupled and divorced manners were found in the weld. At a relatively high temperature, mass transport of Cu due to plastic deformation, material flow, and atomic diffusion, combined with the alloy system of AA5083 are responsible for the ternary eutectic melting.

Shen, Junjun, E-mail: junjun.shen@hzg.de; Suhuddin, Uceu F. H.; Cardillo, Maria E. B.; Santos, Jorge F. dos [Helmholtz-Zentrum Geesthacht, Institute of Materials Research, Materials Mechanics, Solid-State Joining Processes, Max-Planck-Str. 1, 21502 Geesthacht (Germany)

2014-05-12T23:59:59.000Z

406

Introduction to hydrogen in alloys  

SciTech Connect

Substitutional alloys, both those that form hydrides and those that do not, are discussed, but with more emphasis on the former than the latter. This overview includes the following closely related subjects: (1) the significant effects of substitutional solutes on the pressure-composition-temperature (PCT) equilibria of metal-hydrogen systems, (2) the changes in thermodynamic properties resulting from differences in atom size and from modifications of electronic structure, (3) attractive and repulsive interactions between H and solute atoms and the effects of such interactions on the pressure dependent solubility for H, (4) H trapping in alloys of Group V metals and its effect on the terminal solubility for H (TSH), (5) some other mechanisms invoked to explain the enhancement (due to alloying) of the (TSH) in Group V metals, and (6) H-impurity complexes in alloys of the metals Ni, Co, and Fe. Some results showing that an enhanced TSH may ameliorate the resistance of a metal to hydrogen embrittlement are presented.

Westlake, D.G.

1980-01-01T23:59:59.000Z

407

A REVIEW OF THE OXIDATION BEHAVIOR OF STRUCTURAL ALLOYS IN STEAM  

SciTech Connect

The focus of this review is the state of knowledge of the oxidation behavior in steam of alloys with potential for use as pressure parts in steam boilers. Growth of steam-side oxides has implications for scale exfoliation, tube blockage and overheating, and turbine erosion. Mitigation of such problems requires mechanistic understanding of the influences of alloy composition and microstructure as well as time, temperature, and boiler operating parameters on the evolution of specific scale structures. The oxidation behavior in steam of three classes of alloys is addressed: ferritic steels (particularly the 9-12 wt% Cr alloys), austenitic steels, and high-temperature nickel-based alloys. Understanding the interplay among compositional and microstructural requirements for strengthening and oxidation resistance, and their influence on the rate and mode of scale evolution is key to the most effective application of these alloy classes. Underlying these interests is the apparently different mode of oxide growth in steam than in air, especially contributions from inward transport of oxidant species. The particular species involved and their roles in the oxidation process are expected to exert a large influence on the oxide morphologies developed, while the fate of any hydrogen released in the alloy is a further topic of particular interest.

Wright, Ian G [ORNL; Dooley, Barry [Electric Power Research Institute (EPRI)

2010-01-01T23:59:59.000Z

408

The Third Law of Thermodynamics and the residual entropy of ice: "Stillwater" or ?SH2Of,T=0 = 0  

Science Journals Connector (OSTI)

The Third Law of Thermodynamics and the residual entropy of ice: "Stillwater" or ?SH2Of,T=0 = 0 ... This paper will explore the connection between the third law of thermodynamics and the residual entropy of ice. ... Thermodynamics ...

Maureen M. Julian; Frank H. Stillinger; Roger R. Festa

1983-01-01T23:59:59.000Z

409

Diversity, Entropy and Thermodynamics http://math.ucr.edu/home/baez/biodiversity/  

E-Print Network (OSTI)

Diversity, Entropy and Thermodynamics John Baez http://math.ucr.edu/home/baez/biodiversity/ July 5, 2012 The Mathematics of Biodiversity CRM #12;The Shannon entropy S(p) = - n i=1 pi ln(pi) appears in thermodynamics and information theory, but it can also be used to measure biodiversity. Is this a coincidence

Baez, John

410

Biodiversity, Entropy and Thermodynamics http://math.ucr.edu/home/baez/bio info/  

E-Print Network (OSTI)

Biodiversity, Entropy and Thermodynamics John Baez http://math.ucr.edu/home/baez/bio info/ October(pi ) is fundamental to thermodynamics and information theory. But it's also used to measure biodiversity, where pi. In biodiversity studies, the entropy of an ecosystem is the expected amount of information we gain about

Baez, John

411

Entropy production and self-organized (sub)criticality in earthquake dynamics  

Science Journals Connector (OSTI)

...the entropy-production rate for the OFC model for...boundary stress and strain rate at steady state, the...entropy-production (EP) rate as a function of the conservation...at 2 km depth, Cajon Pass, California:implications...phenomena, universal physics at large length scales...

2010-01-01T23:59:59.000Z

412

Adaptive change of basis in entropy-based moment closures for linear kinetic equations  

Science Journals Connector (OSTI)

Entropy-based (M"N) moment closures for kinetic equations are defined by a constrained optimization problem that must be solved at every point in a space-time mesh, making it important to solve these optimization problems accurately and efficiently. ... Keywords: Convex optimization, Entropy-based closures, Kinetic theory, Moment equations, Realizability, Transport

Graham W. Alldredge; Cory D. Hauck; Dianne P. Oleary; André L. Tits

2014-02-01T23:59:59.000Z

413

A parametric sensitivity study of entropy production and kinetic energy dissipation using the FAMOUS AOGCM  

E-Print Network (OSTI)

A parametric sensitivity study of entropy production and kinetic energy dissipation using of APE and entropy production associated with kinetic energy dissipation, with the standard FAMOUS values of the conjecture of maximum APE production (or equivalently maximum dissipation of kinetic energy). Keywords

Ambaum, Maarten

414

An adaptive bacterial foraging algorithm for fuzzy entropy based image segmentation  

Science Journals Connector (OSTI)

In this paper an Adaptive Bacterial Foraging is proposed for fuzzy entropy optimization when it is applied to the segmentation of gray images. The proposed algorithm represents the improved version of classical bacterial foraging algorithm which is a ... Keywords: Bacterial foraging algorithm, Bi level thresholding, Chemotaxis, Fuzzy entropy, Image segmentation

Nandita Sanyal; Amitava Chatterjee; Sugata Munshi

2011-11-01T23:59:59.000Z

415

On exact identity between thermodynamic and informatic entropies in a unitary model of friction  

E-Print Network (OSTI)

An elementary collision model of a molecular reservoir is considered upon which an external field is applied and the work is dissipated into heat. To realize macroscopic irreversibility at the microscopic level, we introduce a ``graceful'' irreversible map which randomly mixes the identities of the molecules. This map is expected to generate informatic entropy exactly equal to the independently calculable irreversible thermodynamic entropy.

Lajos Diósi; Tova Feldmann; Ronnie Kosloff

2005-05-30T23:59:59.000Z

416

Granular computing, rough entropy and object extraction Sankar K. Pal a,1  

E-Print Network (OSTI)

of image object extraction in the framework of rough sets and granular computing is addressed. A mea- sure of rough entropy are described. Ã? 2005 Elsevier B.V. All rights reserved. Keywords: Rough sets; Entropy in the process of prob- lem solving. Recently, rough set theory (Pawlak, 1991) has become a popular mathematical

Mitra, Pabitra

417

THE DEVIL’S STAIRCASE DIMENSIONS AND MEASURE-THEORETICAL ENTROPY OF MAPS WITH HORIZONTAL GAP  

E-Print Network (OSTI)

Abstract. This work elucidates the measure-theoretical entropy and dimensions of a unimodal map with a horizontal gap. The measure-theoretical entropy and dimensions of the Ft (which is defined later)are shown to form a devil’s staircase structure with respect to the gap size t. Pesin’s formula for gap maps is also considered. 1.

Jung-chao Ban; Song-sun Lin

418

Shear Viscosity to Entropy Density Ratio in Six Derivative Gravity  

E-Print Network (OSTI)

We calculate shear viscosity to entropy density ratio in presence of four derivative (with coefficient $\\alpha'$) and six derivative (with coefficient $\\alpha'^2$) terms in bulk action. In general, there can be three possible four derivative terms and ten possible six derivative terms in the Lagrangian. Among them two four derivative and eight six derivative terms are ambiguous, i.e., these terms can be removed from the action by suitable field redefinitions. Rest are unambiguous. According to the AdS/CFT correspondence all the unambiguous coefficients (coefficients of unambiguous terms) can be fixed in terms of field theory parameters. Therefore, any measurable quantities of boundary theory, for example shear viscosity to entropy density ratio, when calculated holographically can be expressed in terms of unambiguous coefficients in the bulk theory (or equivalently in terms of boundary parameters). We calculate $\\eta/s$ for generic six derivative gravity and find that apparently it depends on few ambiguous coefficients at order $\\alpha'^2$. We calculate six derivative corrections to central charges $a$ and $c$ and express $\\eta/s$ in terms of these central charges and unambiguous coefficients in the bulk theory.

Nabamita Banerjee; Suvankar Dutta

2009-03-23T23:59:59.000Z

419

Entanglement entropy and D1-D5 geometries  

Science Journals Connector (OSTI)

In conformal field theories (CFTs) with a gravitational anti–de Sitter (AdS) dual it is possible to calculate the entanglement entropy of a region A holographically by using the Ryu-Takayanagi formula. In this work we consider systems that are in a pure state that is not the vacuum. We study in particular the two-dimensional conformal field theory dual to type IIB string theory on AdS3×S3×T4 and focus on the 1/4-BPS states described holographically by the two-charge microstate geometries. We discuss a general prescription for the calculation of the entanglement entropy in these geometries that are asymptotically AdS3×S3. In particular we study analytically the perturbative expansion for a single, short interval: we show that the first nontrivial terms in this expansion are consistent with the expected CFT structure and with previous results on the vacuum expectation values of chiral primary operators for the 1/4-BPS configurations.

Stefano Giusto and Rodolfo Russo

2014-09-04T23:59:59.000Z

420

Increase of Black Hole Entropy in Higher Curvature Gravity  

E-Print Network (OSTI)

We examine the Zeroth Law and the Second Law of black hole thermodynamics within the context of effective gravitational actions including higher curvature interactions. We show that entropy can never decrease for quasi-stationary processes in which a black hole accretes positive energy matter, independent of the details of the gravitational action. Within a class of higher curvature theories where the Lagrangian consists of a polynomial in the Ricci scalar, we use a conformally equivalent theory to establish that stationary black hole solutions with a Killing horizon satisfy the Zeroth Law, and that the Second Law holds in general for any dynamical process. We also introduce a new method for establishing the Second Law based on a generalization of the area theorem, which may prove useful for a wider class of Lagrangians. Finally, we show how one can infer the form of the black hole entropy, at least for the Ricci polynomial theories, by integrating the changes of mass and angular momentum in a quasistationary accretion process.

Ted Jacobson; Gungwon Kang; Robert C. Myers

1995-03-11T23:59:59.000Z

Note: This page contains sample records for the topic "high entropy alloy" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


421

Insulator coating for high temperature alloys method for producing insulator coating for high temperature alloys  

DOE Patents (OSTI)

A method for fabricating an electrically insulating coating on a surface is disclosed comprising coating the surface with a metal, and reacting the metal coated surface with a nonmetal so as to create a film on the metal-coated surface. Alternatively, the invention provides for a method for producing a noncorrosive, electrically insulating coating on a surface saturated with a nonmetal comprising supplying a molten fluid, dissolving a metal in the molten fluid to create a mixture, and contacting the mixture with the saturated surface. Lastly, the invention provides an electrically insulative coating comprising an underlying structural substrate coated with an oxide or nitride compound. 2 figs.

Park, J.H.

1998-06-23T23:59:59.000Z

422

Oxide Film Aging on Alloy 22 in Halide Containing Solutions  

SciTech Connect

Passive and corrosion behaviors of Alloy 22 in chloride and fluoride containing solutions, changing the heat treatment of the alloy, the halide concentration and the pH of the solutions at 90 deg. C, was investigated. The study was implemented using electrochemical techniques, which included open circuit potential monitoring over time, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) measurements carried out at open circuit and at passivity potentials. Corrosion rates obtained by EIS measurements after 24 h immersion in naturally aerated solutions were below 0.5 {mu}m/year. The corrosion rates were practically independent of solution pH, alloy heat treatment and halide ion nature and concentration. EIS low frequency resistance values increased with applied potential in the passive domain and with polarization time in pH 6 - 1 M NaCl at 90 deg. C. This effect was attributed to an increase in the oxide film thickness and oxide film aging. High frequency capacitance measurements indicated that passive oxide on Alloy 22 presented a double n-type/p-type semiconductor behavior in the passive potential range. (authors)

Rodriguez, Martin A.; Carranza, Ricardo M. [Dept. Materiales, Comision Nacional de Energia Atomica, Av. Gral. Paz 1499, Villa Maipu, 1650 (Argentina); Rebak, Raul B. [Lawrence Livermore National Laboratory, 7000 East Ave, L-631, Livermore, CA, 94550-9698 (United States)

2007-07-01T23:59:59.000Z

423

Metallic glass alloys of Zr, Ti, Cu and Ni  

DOE Patents (OSTI)

At least quaternary alloys form metallic glass upon cooling below the glass transition temperature at a rate less than 10.sup.3 K/s. Such alloys comprise titanium from 19 to 41 atomic percent, an early transition metal (ETM) from 4 to 21 atomic percent and copper plus a late transition metal (LTM) from 49 to 64 atomic percent. The ETM comprises zirconium and/or hafnium. The LTM comprises cobalt and/or nickel. The composition is further constrained such that the product of the copper plus LTM times the atomic proportion of LTM relative to the copper is from 2 to 14. The atomic percentage of ETM is less than 10 when the atomic percentage of titanium is as high as 41, and may be as large as 21 when the atomic percentage of titanium is as low as 24. Furthermore, when the total of copper and LTM are low, the amount of LTM present must be further limited. Another group of glass forming alloys has the formula (ETM.sub.1-x Ti.sub.x).sub.a Cu.sub.b (Ni.sub.1-y Co.sub.y).sub.c wherein x is from 0.1 to 0.3, y.cndot.c is from 0 to 18, a is from 47 to 67, b is from 8 to 42, and c is from 4 to 37. This definition of the alloys has additional constraints on the range of copper content, b.

Lin, Xianghong (Pasadena, CA); Peker, Atakan (Pasadena, CA); Johnson, William L. (Pasadena, CA)

1997-01-01T23:59:59.000Z

424

Low-cycle fatigue deformation characteristics of Haynes {reg{underscore}sign} HR-120{reg{underscore}sign} alloy  

SciTech Connect

Low-cycle fatigue deformation characteristics of HAYNES HR-120 alloy at room and high temperatures were studied under axial strain control. Test results show that there is a significant effect of test temperature on the low-cycle fatigue behavior of HAYNES HR-120 alloy. It was found that the alloy could cyclically harden at moderately high temperatures (649 C and 871 C), but generally cyclically soften at room temperature (24 C) and high temperature (982 C). However, the variation of the stress amplitude with cycles at the temperatures of 24 C and 982 C depended on the total strain range. The significant cyclic hardening of the alloy occurred at the high total strain ranges of 1.5% and 2.0% during the beginning state of the test at both 24C and 982 C. Microstructural analyses indicated that the cyclic hardening behavior of the alloy at the test temperature of 649 C could be related to the formation of a number of deformation bands. Nevertheless, increasing the test temperature to 871 C, cyclic hardening was attributed to the precipitation of secondary-phase particles. Furthermore, it was also found that the coarsening of secondary-phase particles brought about cyclic softening of the alloy at the high temperature of 982 C. Coffin-Manson equations and Holloman equations were given for HAYNES HR-120 alloy at different temperatures.

Liaw, P.K.; He, Y.H.; Miller, L.; Huang, M.; Brooks, C.R.; Seeley, R.R.; Klarstrom, D.L.

1999-07-01T23:59:59.000Z

425

high  

Gasoline and Diesel Fuel Update (EIA)

0 0 Summary Our short-term outlook for a wide array of energy prices has been adjusted upward as international and domestic energy supply conditions have tightened. We think that crude oil prices are as likely as not to end the year $2 to $3 per barrel higher than our previous projections. Thus, we think that the probability of West Texas Intermediate costing an average of $30 per barrel or more at midwinter is about 50 percent. On their current track, heating oil prices are likely to be about 30 percent above year-ago levels in the fourth quarter. Prices for Q1 2001 seem more likely now to match or exceed the high level seen in Q1 2000. Tight oil markets this year and an inherent propensity for high gas utilization in incremental power supply have resulted in rising North American natural gas

426

Formation behavior of Be{sub x}Zn{sub 1-x}O alloys grown by plasma-assisted molecular beam epitaxy  

SciTech Connect

We report the phase formation behavior of Be{sub x}Zn{sub 1-x}O alloys grown by plasma-assisted molecular beam epitaxy. We find the alloy with low- and high-Be contents could be obtained by alloying BeO into ZnO films. X-ray diffraction measurements shows the c lattice constant value shrinks, and room temperature absorption shows the energy band-gap widens after Be incorporated. However, the alloy with intermediate Be composition are unstable and segregated into low- and high-Be contents BeZnO alloys. We demonstrate the phase segregation of Be{sub x}Zn{sub 1-x}O alloys with intermediate Be composition resulted from large internal strain induced by large lattice mismatch between BeO and ZnO.

Chen, Mingming; Zhu, Yuan; Su, Longxing; Zhang, Quanlin; Chen, Anqi; Ji, Xu; Xiang, Rong; Gui, Xuchun; Wu, Tianzhun [State Key Laboratory of Optoelectronic Materials and Technologies, School of Physics and Engineering, Sun Yat-sen University, Guangzhou 510275 (China)] [State Key Laboratory of Optoelectronic Materials and Technologies, School of Physics and Engineering, Sun Yat-sen University, Guangzhou 510275 (China); Pan, Bicai [Department of Physics and Hefei National Laboratory for Physical Sciences at Microscale, University of Science and Technology of China, Hefei, Anhui 230026 (China)] [Department of Physics and Hefei National Laboratory for Physical Sciences at Microscale, University of Science and Technology of China, Hefei, Anhui 230026 (China); Tang, Zikang [State Key Laboratory of Optoelectronic Materials and Technologies, School of Physics and Engineering, Sun Yat-sen University, Guangzhou 510275 (China) [State Key Laboratory of Optoelectronic Materials and Technologies, School of Physics and Engineering, Sun Yat-sen University, Guangzhou 510275 (China); Department of Physics, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong (China)

2013-05-20T23:59:59.000Z

427

Coarse-grained entropy and causal holographic information in AdS/CFT  

E-Print Network (OSTI)

We propose bulk duals for certain coarse-grained entropies of boundary regions. The `one-point entropy' is defined in the conformal field theory by maximizing the entropy in a domain of dependence while fixing the one-point functions. We conjecture that this is dual to the area of the edge of the region causally accessible to the domain of dependence (i.e. the `causal holographic information' of Hubeny and Rangamani). The `future one-point entropy' is defined by generalizing this conjecture to future domains of dependence and their corresponding bulk regions. We show that the future one-point entropy obeys a nontrivial second law. If our conjecture is true, this answers the question "What is the field theory dual of Hawking's area theorem?"

William R. Kelly; Aron C. Wall

2014-04-01T23:59:59.000Z

428

The generalized second law of thermodynamics and the nature of the Entropy Function  

E-Print Network (OSTI)

In black hole physics, the second law of thermodynamics is generally valid whether the black hole is a static or a non-static one. Considering the universe as a thermodynamical system the second law of black hole dynamics extends to the non-negativity of the sum of the entropy of the matter and the horizon, known as generalized second law of thermodynamics(GSLT). Here, we have assumed the universe to be bounded by the event-horizon where Bekenstein entropy-area relation and Hawking-temperature are not applicable. Thus considering entropy to be an arbitrary function of the area of the event-horizon, we have tried to find the nature of the entropy-function for the validity of the GSLT both in quintessence-era and in phantom-era. Finally, some graphical representation of the entropy-function has been presented.

Subenoy Chakraborty; Nairwita Mazumder; Ritabrata Biswas

2010-09-15T23:59:59.000Z

429

Gamma ray-induced embrittlement of pressure vessel alloys  

SciTech Connect

High-energy gamma rays emitted from the core of a nuclear reactor produce displacement damage in the reactor pressure vessel (RPV). The contribution of gamma damage to RPV embrittlement has in the past been largely ignored. However, in certain reactor designs the gamma flux at the RPV is sufficiently large that its contribution to displacement damage can be substantial. For example, gamma rays have been implicated in the accelerated RPV embrittlement observed in the High Flux Isotope Reactor (HFIR) at Oak Ridge National Laboratory. In the present study, mechanical property changes induced by 10-MeV electron irradiation of a model Fe alloy and an RPV alloy of interest to the HFIR were examined. Mini-tensile specimens were irradiated with high-energy electrons to reproduce damage characteristic of the Compton recoil-electrons induced by gamma bombardment. Substantial increases in yield and ultimate stress were observed in the alloys after irradiation to doses up to 5.3x10{sup {minus}3} dpa at temperatures ({approximately}50{degrees}C) characteristic of the HFIR pressure vessel. These measured increases were similar to those previously obtained following neutron irradiation, despite the highly disparate nature of the damage generated during electron and neutron irradiation.

Alexander, D.E.; Rehn, L.E. [Argonne National Lab., IL (United States); Farrell, K.; Stoller, R.E. [Oak Ridge National Lab., TN (United States)

1994-11-01T23:59:59.000Z

430

Microstructural characterization of as-cast biocompatible Co-Cr-Mo alloys  

SciTech Connect

The microstructure of a cobalt-base alloy (Co-Cr-Mo) obtained by the investment casting process was studied. This alloy complies with the ASTM F75 standard and is widely used in the manufacturing of orthopedic implants because of its high strength, good corrosion resistance and excellent biocompatibility properties. This work focuses on the resulting microstructures arising from samples poured under industrial environment conditions, of three different Co-Cr-Mo alloys. For this purpose, we used: 1) an alloy built up from commercial purity constituents, 2) a remelted alloy and 3) a certified alloy for comparison. The characterization of the samples was achieved by using optical microscopy (OM) with a colorant etchant to identify the present phases and scanning electron microscopy (SE-SEM) and energy dispersion spectrometry (EDS) techniques for a better identification. In general the as-cast microstructure is a Co-fcc dendritic matrix with the presence of a secondary phase, such as the M{sub 23}C{sub 6} carbides precipitated at grain boundaries and interdendritic zones. These precipitates are the main strengthening mechanism in this type of alloys. Other minority phases were also reported and their presence could be linked to the cooling rate and the manufacturing process variables and environment. - Research Highlights: {yields}The solidification microstructure of an ASTM-F75 type alloy were studied. {yields}The alloys were poured under an industrial environment. {yields}Carbides and sigma phase identified by color metallography and scanning microscopy (SEM and EDS). {yields}Two carbide morphologies were detected 'blocky type' and 'pearlite type'. {yields}Minority phases were also detected.

Giacchi, J.V., E-mail: jgiacchi@exa.unicen.edu.ar [Consejo Nacional de Investigaciones Cientificas y Tecnicas (CONICET), Av. Rivadavia 1917, C1033AAJ Buenos Aires (Argentina); Instituto de Fisica de Materiales Tandil (IFIMAT-FCE-CICPBA) Facultad de Ciencias Exactas, Universidad Nacional del Centro de la Provincia de Buenos Aires, Pinto 399 B7000GHG Tandil (Argentina); Morando, C.N.; Fornaro, O. [Consejo Nacional de Investigaciones Cientificas y Tecnicas (CONICET), Av. Rivadavia 1917, C1033AAJ Buenos Aires (Argentina); Instituto de Fisica de Materiales Tandil (IFIMAT-FCE-CICPBA) Facultad de Ciencias Exactas, Universidad Nacional del Centro de la Provincia de Buenos Aires, Pinto 399 B7000GHG Tandil (Argentina); Palacio, H.A. [Comision de Investigaciones Cientificas de la Provincia de Buenos Aires (CICPBA), Calle 526 e/10 y 11 B1096APP La Plata (Argentina); Instituto de Fisica de Materiales Tandil (IFIMAT-FCE-CICPBA) Facultad de Ciencias Exactas, Universidad Nacional del Centro de la Provincia de Buenos Aires, Pinto 399 B7000GHG Tandil (Argentina)

2011-01-15T23:59:59.000Z

431

Banados-Teitelboim-Zanelli black hole with gravitational Chern-Simons term: Thermodynamics and statistical entropy  

SciTech Connect

Recently, the Banados-Teitelboim-Zanelli (BTZ) black hole in the presence of the gravitational Chern-Simons term has been studied, and it is found that the usual thermodynamic quantities, like the black hole mass, angular momentum, and entropy, are modified. But, for large values of the gravitational Chern-Simons coupling where the modification terms dominate the original terms some exotic behaviors occur, like the roles of the mass and angular momentum are interchanged and the entropy depends more on the inner horizon area than the outer one. A basic physical problem of this system is that the form of entropy does not guarantee the second law of thermodynamics, in contrast to the Bekenstein-Hawking entropy. Moreover, this entropy does not agree with the statistical entropy, in contrast to a good agreement for small values of the gravitational Chern-Simons coupling. Here I find that there is another entropy formula where the usual Bekenstein-Hawking form dominates the inner-horizon term again, as in the small gravitational Chern-Simons coupling case, such that the second law of thermodynamics can be guaranteed. I also find that the new entropy formula agrees with the statistical entropy based on the holographic anomalies for the whole range of the gravitational Chern-Simons coupling. This reproduces, in the limit of a vanishing Einstein-Hilbert term, the recent result about the exotic BTZ black holes, where their masses and angular momenta are completely interchanged and the entropies depend only on the area of the inner horizon. I compare the result of the holographic approach with the classical-symmetry-algebra-based approach, and I find exact agreements even with the higher-derivative corrections of the gravitational Chern-Simons term. This provides a nontrivial check of the AdS/CFT correspondence, in the presence of higher-derivative terms in the gravity action.

Park, Mu-In [Center for Quantum Spacetime, Sogang University, Seoul 121-742 (Korea, Republic of)

2008-01-15T23:59:59.000Z

432

Entropy and Free Energy of a Mobile Protein Loop in Explicit Water Srinath Cheluvaraja, Mihail Mihailescu, and Hagai Meirovitch*  

E-Print Network (OSTI)

Entropy and Free Energy of a Mobile Protein Loop in Explicit Water Srinath Cheluvaraja, Mihail of the absolute entropy, S (hence the absolute free energy F) is difficult because it depends on the entire at 300 K. As in paper I, we are mainly interested in entropy and free energy differences between the free

Meirovitch, Hagai

433

Entropy production in irreversible systems described by a Fokker-Planck equation Tnia Tom and Mrio J. de Oliveira  

E-Print Network (OSTI)

Entropy production in irreversible systems described by a Fokker-Planck equation Tânia Tomé and the entropy production in nonequilibrium interacting particle systems described by a Fokker-Planck equation equilibrium there will be no production of entropy. A non- equilibrium thermodynamic system in the stationary

de Oliveira, Mário José

434

High pressure oxygen furnace  

DOE Patents (OSTI)

A high temperature high pressure oxygen furnace having a hybrid partially externally heated construction is disclosed. A metallic bar fabricated from an alloy having a composition of at least 45% nickel, 15% chrome, and 10% tungsten is utilized, the preferred alloy including 55% nickel, 22% chrome, 14% tungsten, 2% molybdenum, 3% iron (maximum) and 5% cobalt (maximum). The disclosed alloy is fabricated into 11/4 inch bar stock and has a length of about 17 inches. This bar stock is gun drilled for over 16 inches of its length with 0.400 inch aperture to define a closed high temperature, high pressure oxygen chamber. The opposite and closed end of the bar is provided with a small support aperture into which both a support and a thermocouple can be inserted. The closed end of the gun drilled bar is inserted into an oven, preferably heated by standard nickel chrome electrical elements and having a heavily insulated exterior. 5 figs.

Morris, D.E.

1992-07-14T23:59:59.000Z

435

High pressure oxygen furnace  

DOE Patents (OSTI)

A high temperature high pressure oxygen furnace having a hybrid partially externally heated construction is disclosed. A metallic bar fabricated from an alloy having a composition of at least 45% nickel, 15% chrome, and 10% tungsten is utilized (the preferred alloy including 55% nickel, 22% chrome, 14% tungsten, 2% molybdenum, 3% iron (maximum) and 5% cobalt (maximum). The disclosed alloy is fabricated into 11/4 inch bar stock and has a length of about 17 inches. This bar stock is gun drilled for over 16 inches of its length with 0.400 inch aperture to define a closed high temperature, high pressure oxygen chamber. The opposite and closed end of the bar is provided with a small support aperture into which both a support and a thermocouple can be inserted. The closed end of the gun drilled bar is inserted into an oven, preferably heated by standard nickel chrome electrical elements and having a heavily insulated exterior.

Morris, Donald E. (Kensington, CA)

1992-01-01T23:59:59.000Z

436

Alloy substantially free of dendrites and method of forming the same  

DOE Patents (OSTI)

Described herein are alloys substantially free of dendrites. A method includes forming an alloy substantially free of dendrites. A superheated alloy is cooled to form a nucleated alloy. The temperature of the nucleated alloy is controlled to prevent the nuclei from melting. The nucleated alloy is mixed to distribute the nuclei throughout the alloy. The nucleated alloy is cooled with nuclei distributed throughout.

de Figueredo, Anacleto M. (West Newton, MA); Apelian, Diran (West Boylston, MA); Findon, Matt M. (Monson, MA); Saddock, Nicholas (S. Windson, CT)

2009-04-07T23:59:59.000Z

437

Modular Process Equipment for Low Cost Manufacturing of High...  

Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

Manufacturing of High Capacity Prismatic Li-Ion Cell Alloy Anodes 2012 DOE Hydrogen and Fuel Cells Program and Vehicle Technologies Program Annual Merit Review and Peer...

438

GRAIN REFINEMENT OF PERMANENT MOLD CAST COPPER BASE ALLOYS  

SciTech Connect

Grain refinement behavior of copper alloys cast in permanent molds was investigated. This is one of the least studied subjects in copper alloy castings. Grain refinement is not widely practiced for leaded copper alloys cast in sand molds. Aluminum bronzes and high strength yellow brasses, cast in sand and permanent molds, were usually fine grained due to the presence of more than 2% iron. Grain refinement of the most common permanent mold casting alloys, leaded yellow brass and its lead-free replacement EnviroBrass III, is not universally accepted due to the perceived problem of hard spots in finished castings and for the same reason these alloys contain very low amounts of iron. The yellow brasses and Cu-Si alloys are gaining popularity in North America due to their low lead content and amenability for permanent mold casting. These alloys are prone to hot tearing in permanent mold casting. Grain refinement is one of the solutions for reducing this problem. However, to use this technique it is necessary to understand the mechanism of grain refinement and other issues involved in the process. The following issues were studied during this three year project funded by the US Department of Energy and the copper casting industry: (1) Effect of alloying additions on the grain size of Cu-Zn alloys and their interaction with grain refiners; (2) Effect of two grain refining elements, boron and zirconium, on the grain size of four copper alloys, yellow brass, EnviroBrass II, silicon brass and silicon bronze and the duration of their effect (fading); (3) Prediction of grain refinement using cooling curve analysis and use of this method as an on-line quality control tool; (4) Hard spot formation in yellow brass and EnviroBrass due to grain refinement; (5) Corrosion resistance of the grain refined alloys; (6) Transfer the technology to permanent mold casting foundries; It was found that alloying elements such as tin and zinc do not change the grain size of Cu-Zn alloys. Aluminum promoted b phase formation and modified the grain structure from dendritic to equiaxed. Lead or bismuth reduces the size of grains, but not change the morphology of the structure in Cu-Zn alloys. The grain size of the Cu-Zn-alloy can be reduced from 3000 mm to 300 mm after the addition of aluminum and lead. Similar effects were observed in EnviroBrass III after the addition of aluminum and bismuth. Boron refined the structure of yellow brasses in the presence of iron. At least 50 ppm of iron and 3 ppm of boron are necessary to cause grain refinement in these alloys. Precipitation of iron from the melt is identified as the cause of grain refinement. Boron initiates the precipitation of iron which could not be explained at this time. On the other hand zirconium causes some reduction in grain size in all four alloys investigated. The critical limit for the zirconium was found to be around 100 ppm below which not much refinement could be observed. The mechanism of grain refinement in the presence of zirconium could not be explained. Grain refinement by boron and iron can remain over a long period of time, at least for 72 hours of holding or after remelting few times. It is necessary to have the iron and boron contents above the critical limits mentioned earlier. On the other hand, refinement by zirconium is lost quite rapidly, some times within one hour of holding, mostly due to the loss of zirconium, most probably by oxidation, from the melt. In all the cases it is possible to revive the refinement by adding more of the appropriate refining element. Cooling curve analysis (thermal analysis) can be used successfully to predict the grain refinement in yellow brasses. The precipitation of iron in the liquid metal causes the metal to solidify without undercooling. Absence of this reaction, as indicated by the time-temperature (t-T) and its first derivative (dt/dT) curves, proved to be an indicator of refinement. The viability of the technique as an on-line quality control tool was proved in two foundries. The method can also correctly predict the onset of fading. Th

M. SADAYAPPAN, J.P. THOMSON, M.ELBOUJDAINI, G. PING GU, M. SAHOO

2004-04-29T23:59:59.000Z

439

Effect of CeO{sub 2} addition on the properties of FeAl based alloy produced by mechanical alloying technique  

SciTech Connect

Iron aluminides based on FeAl is notable for their low materials cost, ease of fabrication and good corrosion, suffixation and oxidation resistance. However, the application based on these unique properties still require the development of Fe-Al based alloy since it shows some drawbacks such as a lack of high temperature strength and low ductility. To improve the mechanical properties of FeAl based alloy, ceria (CeO{sub 2}) will be added to this compound. FeAl based alloy produced by the mechanical alloying (MA) technique. The developed specimens then assessed with respect to oxidation behaviour in high temperature, scale microstructure and hardness. The surface morphologies of the alloy evaluated and observed using scanning electron microscopy (SEM) with an energy dispersive X-ray spectroscopy (EDX). The phase structures of oxide scale formed on them were identified by X-ray diffraction (XRD). The results found that the FeAl intermetallic compound containing CeO{sub 2} 0.5 wt.% is less pores and CeO{sub 2} 1.0 wt.% is more homogen in powder and solid form, higher hardness and increase in their resistance to oxidation behaviour in high temperature compared with another percentage of CeO{sub 2}.

Khaerudini, Deni S.; Muljadi,; Sardjono, P.; Tetuko, Anggito P.; Sebayang, P.; Ginting, M. [Research Center for Physics, Indonesian Institute of Sciences (LIPI) Gd. 440, Kawasan Puspiptek Serpong Tangerang 15314 Banten (Indonesia)] [Research Center for Physics, Indonesian Institute of Sciences (LIPI) Gd. 440, Kawasan Puspiptek Serpong Tangerang 15314 Banten (Indonesia)

2013-09-03T23:59:59.000Z

440

Solid State Phase Transformations in Uranium-Zirconium Alloys  

E-Print Network (OSTI)

not only is economical but also reduces the amount of waste generated from spent nuclear fuel. However, the major limita- tion to reach high burn-ups comes from swelling of the fuel which leads to fuel-clad mechanical interactions (FCMI) and fuel...%Zr alloy at 5 at% burnup with superimposed microprobe scans : : : : : : : : : : : : : : : : : : : : 3 2.1 Schematic of crystal structures: Relationship between b.c.c (4 unit cells) and o (left) and orthorhombic phase (right...

Irukuvarghula, Sandeep

2013-08-06T23:59:59.000Z

Note: This page contains sample records for the topic "high entropy alloy" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


441

Oxidation of alloys targeted for advanced steam turbines  

SciTech Connect

Ultra supercritical (USC) power plants offer the promise of higher efficiencies and lower emissions. Current goals of the U.S. Department of Energy’s Advanced Power Systems Initiatives include coal generation at 60% efficiency, which would require steam temperatures of up to 760°C. This research examines the steamside oxidation of alloys for use in USC systems, with emphasis placed on applications in high- and intermediate-pressure turbines.

Holcomb, G.R.; Covino, B.S., Jr.; Bullard, S.J.; Ziomek-Moroz, M.; Alman, D.E.

2006-03-12T23:59:59.000Z

442

Oxidation of zirconium alloys in 2.5 kPa water vapor for tritium readiness.  

SciTech Connect

A more reactive liner material is needed for use as liner and cruciform material in tritium producing burnable absorber rods (TPBAR) in commercial light water nuclear reactors (CLWR). The function of these components is to convert any water that is released from the Li-6 enriched lithium aluminate breeder material to oxide and hydrogen that can be gettered, thus minimizing the permeation of tritium into the reactor coolant. Fourteen zirconium alloys were exposed to 2.5 kPa water vapor in a helium stream at 300 C over a period of up to 35 days. Experimental alloys with aluminum, yttrium, vanadium, titanium, and scandium, some of which also included ternaries with nickel, were included along with a high nitrogen impurity alloy and the commercial alloy Zircaloy-2. They displayed a reactivity range of almost 500, with Zircaloy-2 being the least reactive.

Mills, Bernice E.

2007-11-01T23:59:59.000Z

443

Surface modification of ferritic and Ni based alloys for improved oxidation resistance of SOFC interconnect applications  

SciTech Connect

This research is aimed at evaluating a surface modification of ferritic stainless steels (Type-430 and Crofer 22APU) and nickel-base alloys (Haynes 230) for use in the SOFC temperature range of 700 to 800°C. A surface treatment was devised to enhance the stability of the base metal oxide that forms and to reduce the oxidation rate of the materials at high temperature. Oxidation tests (in wet air; treated and untreated) were conducted at 800°C to evaulate the corrosion resistance of the alloys. It was found that the surface treatment improved the oxidation resistance of all the alloys tested. However, the treatment improved the performance of 430SS more than that of the other alloys.

Jablonski, Paul D.; Alman, David E.; Kung, Steven C. (SOFCo-EFS, Alliance, OH)

2005-08-01T23:59:59.000Z

444

Grain Growth Behavior, Tensile Impact Ductility, and Weldability of Cerium-Doped Iridium Alloys  

SciTech Connect

An iridium alloy doped with small amounts of cerium and thorium is being developed as a potential replacement for the iridium-based DOP-26 alloy (doped with thorium only) that is currently used by the National Aeronautics and Space Administration (NASA) for cladding and post-impact containment of the radioactive fuel in radioisotope thermoelectric generator (RTG) heat sources which provide electric power for interplanetary spacecraft. This report summarizes results of studies conducted to date under the Iridium Alloy Characterization and Development subtask of the Radioisotope Power System Materials Production and Technology Program to characterize the properties of the iridium-based alloy (designated as DOP-40) containing both cerium and thorium. Included within this report are data on grain growth of sheet material in vacuum and low-pressure oxygen environments, grain growth in vacuum of the clad vent set cup material, weldability, and the effect of grain size and test temperature on tensile properties. Where applicable, data for the DOP-26 alloy are included for comparison. Both grain size and grain-boundary cohesion affect the ductility of iridium alloys. In this study it was found that cerium and thorium, when added together, refine grain size more effectively than when thorium is added by itself (especially at high temperatures). In addition, the effect of cerium additions on grain-boundary cohesion is similar to that of thorium. Mechanical testing at both low ({approx} 10{sup -3}s{sup -1}) and high ({approx} 10{sup -3}s{sup -1}) strain rates showed that the Ce/Th-doped alloys have tensile ductilities that are as good or better than the DOP-26 alloy. The general conclusion from these studies is that cerium can be used to replace some of the radioactive thorium currently used in DOP-26 while maintaining or improving its metallurgical properties. The current DOP-26 alloy meets all requirements for cladding the radioactive fuel in the RTG heat source, but the new DOP-40 alloy could serve as a back-up alloy to be used if the costs of refining, handling, and transporting DOP-26 become prohibitively high.

McKamey, C.G.

2002-05-28T23:59:59.000Z

445

high  

Gasoline and Diesel Fuel Update (EIA)

0 0 Highlights International Oil Markets Prices. We have raised our world oil price projection by about $2 per barrel for this month because of assumed greater compliance by OPEC to targeted cuts, especially for the second quarter of 2000 (Figure 1). The expected decline in world petroleum inventories continues (Figure 2), and, given the generally stiff resolve of OPEC members to maintain production cuts, any sign of a turnaround in stocks may be postponed until later this year than previously assumed (Q3 instead of Q2). Our current estimate for the average import cost this past January is now $25 per barrel, a nearly $15-per-barrel increase from January 1999. Crude oil prices are expected to remain at relatively high levels for the first half of 2000, but

446

Erosion-Corrosion of Iron and Nickel Alloys at Elevated Temperature in a Combustion Gas Environment  

SciTech Connect

This paper reports on the results of a study that compares the erosion-corrosion behavior of a variety of alloys (Fe- 2¼Cr 1Mo, 304 SS, 310 SS, Incoloy 800, Haynes 230 and a Fe3Al) in a combustion environment. Advanced coal combustion environments, with higher temperatures, are driving re-examination of traditional and examination of new alloys in these hostile environments. In order to simulate conditions in advanced coal combustion boilers, a special erosion apparatus was used to allow for impingement of particles under a low abrasive flux in a gaseous environment comprised of 20 % CO2, 0.05 % HCl, 77 % N2, 3 % O2, and 0.1 % SO2. Tests were conducted at room temperature and 700 °C with ~ 270 ?m silica, using an impact velocity of 20 m/s in both air and the simulated combustion gas environment. The erosion-corrosion behavior was characterized by gravimetric measurements and by examination of the degraded surfaces optically and by scanning electron microscopy (SEM). At room temperature most of the alloys had similar loss rates. Not surprisingly, at 700 °C the lower chrome-iron alloy had a very high loss rate. The nickel alloys tended to have higher loss rates than the high chrome austenitic alloys.

Tylczak, Joseph [NETL] [NETL

2014-05-02T23:59:59.000Z

447

Refractory metal alloys and composites for space nuclear power systems  

SciTech Connect

Space power requirements for future NASA and other United States missions will range from a few kilowatts to megawatts of electricity. Maximum efficiency is a key goal of any power system in order to minimize weight and size so that the space shuttle may be used a minimum number of times to put the power supply into orbit. Nuclear power has been identified as the primary power source to meet these high levels of electrical demand. One method to achieve maximum efficiency is to operate the power supply, energy conversion system, and related components at relatively high temperatures. For systems now in the planning stages, design temperatures range from 1300 K for the immediate future to as high as 1700 K for the advanced systems. NASA Lewis Research Center has undertaken a research program on advanced technology of refractory metal alloys and composites that will provide base line information for space power systems in the 1900's and the 21st century. Special emphasis is focused on the refractory metal alloys of niobium and on the refractory metal composites which utilize tungsten alloy wire for reinforcement. Basic research on the creep and creep-rupture properties of wires, matrices, and composites will be discussed. 20 refs., 27 figs., 1 tab.

Titran, R.H.; Stephens, J.R.; Petrasek, D.W.

1988-01-01T23:59:59.000Z

448

Amorphous Alloy Membranes Prepared by Melt-Spin methods for Long-Term use in Hydrogen Separation Applications  

SciTech Connect

Amorphous Ni-based alloy membranes show great promise as inexpensive, hydrogenselective membrane materials. In this study, we developed membranes based on nonprecious Ni-Nb-Zr alloys by adjusting the alloying content and using additives. Several studies on crystallization of the amorphous ribbons, in-situ x-ray diffraction, SEM and TEM, hydrogen permeation, hydrogen solubility, hydrogen deuterium exchange, and electrochemical studies were conducted. An important part of the study was to completely eliminate Palladium coatings of the NiNbZr alloys by hydrogen heattreatment. The amorphous alloy (Ni0.6Nb0.4)80Zr20 membrane appears to be the best with high hydrogen permeability and good thermal stability.

Chandra, Dhanesh; Kim, Sang-Mun; Adibhatla, Anasuya; Dolan, Michael; Paglieri, Steve; Flanagan, Ted; Chien, Wen-Ming; Talekar, Anjali; Wermer, Joseph

2013-02-28T23:59:59.000Z

449

Fe-Cr-Mo based ODS alloys via spark plasma sintering: A combinational characterization study by TEM and APT  

SciTech Connect

Nanoscale oxides play an important role in oxide dispersion strengthened (ODS) alloys for improved high temperature creep resistance and enhanced radiation damage tolerance. In this study, transmission electron microscopy (TEM) and atom probe tomography (APT) were combined to investigate two novel Fe-16Cr-3Mo (wt.%) based ODS alloys. Spark plasma sintering (SPS) was used to consolidate the ODS alloys from powders that were milled with 0.5 wt.% Y2O3 powder only or with Y2O3 powder and 1 wt.% Ti. TEM characterization revealed that both alloys have a bimodal structure of nanometer-size (~ 100 – 500 nm) and micron-size grains with nanostructured oxide precipitates formed along and close to grain boundaries with diameters ranging from five to tens of nanometers. APT provides further quantitative analyses of the oxide precipitates, and also reveals Mo segregation at grain boundaries next to oxide precipitates. The alloys with and without Ti are compared based on their microstructures.

Y. Q. Wu; K. N. Allahar; J. Burns; B. Jacques; I Charit; D. P. Butt; J. I. Cole

2013-08-01T23:59:59.000Z

450

Effect of the strain-induced melt activation (SIMA) process on the tensile properties of a new developed super high strength aluminum alloy modified by Al-5Ti-1B grain refiner  

SciTech Connect

In this study, the effect of Al-5Ti-1B grain refiners and modified strain-induced melt activation process on an Al-Zn-Mg-Cu alloy was studied. The optimum level of Ti was found to be 0.1 wt.%. The specimens subjected to deformation ratio of 40% (at 300 Degree-Sign C) and various heat treatment times (10-40 min) and temperature (550-600 Degree-Sign C) regimes were characterized in this study. Reheating condition to obtain a fine globular microstructure was optimized. Microstructural examinations were conducted by optical and scanning electron microscopy coupled with an energy dispersive spectrometry. The optimum temperature and time in strain-induced melt activation process are 575 Degree-Sign C and 20 min, respectively. T6 heat treatment including quenching to room temperature and aging at 120 Degree-Sign C for 24 h was employed to reach to the maximum strength. Significant improvements in mechanical properties were obtained with the addition of grain refiner combined with T6 heat treatment. After the T6 heat treatment, the average tensile strength increased from 283 MPa to 587 and 332 MPa to 617 for samples refined with 2 wt.% Al-5Ti-1B before and after strain-induced melt activation process and extrusion process, respectively. Ultimate strength of Ti-refined specimens without SIMA process has a lower value than globular microstructure specimens after SIMA and extrusion process. - Highlights: Black-Right-Pointing-Pointer The effect of Al-5Ti-1B on the aluminum alloy produced by SIMA process was studied. Black-Right-Pointing-Pointer Al-5Ti-1B is an effective in reducing the grain and reagent fine microstructure. Black-Right-Pointing-Pointer Reheating condition to obtain a fine globular microstructure was optimized. Black-Right-Pointing-Pointer The optimum temperature and time in SIMA process are 575 Degree-Sign C and 20 min respectively. Black-Right-Pointing-Pointer UTS of globular structure specimens have a more value than Ti-refined specimens.

Haghparast, Amin [School of Mechanical Engineering, College of Engineering, University of Tehran, Tehran (Iran, Islamic Republic of)] [School of Mechanical Engineering, College of Engineering, University of Tehran, Tehran (Iran, Islamic Republic of); Nourimotlagh, Masoud [Young Researchers Club, Dareshahr Branch, Islamic Azad university (Iran, Islamic Republic of)] [Young Researchers Club, Dareshahr Branch, Islamic Azad university (Iran, Islamic Republic of); Alipour, Mohammad, E-mail: Alipourmo@ut.ac.ir [School of Metallurgy and Materials Engineering, University of Tehran, Tehran (Iran, Islamic Republic of)] [School of Metallurgy and Materials Engineering, University of Tehran, Tehran (Iran, Islamic Republic of)

2012-09-15T23:59:59.000Z

451

QCD Viscosity to Entropy Density Ratio in the Hadronic Phase  

E-Print Network (OSTI)

Shear viscosity (eta) of QCD in the hadronic phase is computed by the coupled Boltzmann equations of pions and nucleons in low temperatures and low baryon number densities. The eta to entropy density ratio eta/s maps out the nuclear gas-liquid phase transition by forming a valley tracing the phase transition line in the temperature-chemical potential plane. When the phase transition turns into a crossover, the eta/s valley gradually disappears. We suspect the general feature for a first-order phase transition is that eta/s has a discontinuity in the bottom of the eta/s valley. The discontinuity coincides with the phase transition line and ends at the critical point. Beyond the critical point, a smooth eta/s valley is seen. However, the valley could disappear further away from the critical point. The eta/s measurements might provide an alternative to identify the critical points.

Jiunn-Wei Chen; Yen-Han Li; Yen-Fu Liu; Eiji Nakano

2007-03-21T23:59:59.000Z

452

Hall viscosity to entropy ratio in higher derivative theories  

E-Print Network (OSTI)

In this paper based on the basic principles of gauge/gravity duality we compute the hall viscosity to entropy ratio in the presence of various higher derivative corrections to the dual gravitational description embedded in an asymptotically $ AdS_{4} $ space time. As the first step of our analysis, considering the back reaction we impose higher derivative corrections to the abelian gauge sector of the theory where we notice that the ratio indeed gets corrected at the leading order in the coupling. Considering the probe limit as a special case we compute this leading order correction over the fixed background of the charged black brane solution. Finally we consider higher derivative ($ R^{2} $) correction to the gravity sector of the theory where we notice that the above ratio might get corrected at the sixth derivative level.

Dibakar Roychowdhury

2014-08-21T23:59:59.000Z

453

On Holographic Entanglement Entropy with Second Order Excitations  

E-Print Network (OSTI)

We study the low-energy quantum excitation corrections to the holographic entanglement entropy of the boundary CFT from the bulk gravitational perturbations up to second order. By focusing on the case when the boundary subsystem is a strip, we show that the bulk minimal surface can be expanded in terms of the conserved charges such as the mass, angular momentum and electric charge of the bulk AdS black brane when the black brane is a slightly perturbed geometry deviates from the pure AdS spacetime. We also calculate the energy of the subsystem in the CFT and argue that the first law-like relation for the subsystem should be satisfied at second order when the bulk geometry is stable under fluctuations at the same order.

Song He; Jia-Rui Sun; Hai-Qing Zhang

2014-11-23T23:59:59.000Z

454

Temperature–entropy diagram for an irreversible absorption refrigeration cycle  

Science Journals Connector (OSTI)

This article develops the theoretical foundation for the temperature–entropy (T–s) diagram for irreversible absorption chillers that employ either a volatile or nonvolatile working pair. The representation of a real absorption refrigeration cycle on a T–s diagram can directly depict the energetic superiority of one design over another. For practical usage this diagrammatic approach only requires as inputs the inlet and outlet state points that can be computed based on the corresponding temperatures pressures and component concentrations of each of the heat-and-mass exchanger modules within a chiller system and can therefore also be employed as a useful tool for system analysis and diagnosis. The same method is also applicable to any continuously operating thermodynamic system that is wholly or partially driven by thermal power.

H. T. Chua; H. K. Toh; K. C. Ng

2000-01-01T23:59:59.000Z

455

Markov Entropy Decomposition: A Variational Dual for Quantum Belief Propagation  

Science Journals Connector (OSTI)

We present a lower bound for the free energy of a quantum many-body system at finite temperature. This lower bound is expressed as a convex optimization problem with linear constraints, and is derived using strong subadditivity of von Neumann entropy and a relaxation of the consistency condition of local density operators. The dual to this minimization problem leads to a set of quantum belief propagation equations, thus providing a firm theoretical foundation to that approach. The minimization problem is numerically tractable, and we find good agreement with quantum Monte Carlo calculations for spin-12 Heisenberg antiferromagnet in two dimensions. This lower bound complements other variational upper bounds. We discuss applications to Hamiltonian complexity theory and give a generalization of the structure theorem of [P. Hayden et al., Commun. Math. Phys. 246, 359 (2004).] to trees in an appendix.

David Poulin and Matthew B. Hastings

2011-02-24T23:59:59.000Z

456

Maximum Entropy Principle and the Higgs boson mass  

Science Journals Connector (OSTI)

Abstract A successful connection between Higgs boson decays and the Maximum Entropy Principle is presented. Based on the information theory inference approach we determine the Higgs boson mass as M H = 125.04 ± 0.25 GeV , a value fully compatible to the LHC measurement. This is straightforwardly obtained by taking the Higgs boson branching ratios as the target probability distributions of the inference, without any extra assumptions beyond the Standard Model. Yet, the principle can be a powerful tool in the construction of any model affecting the Higgs sector. We give, as an example, the case where the Higgs boson has an extra invisible decay channel within a Higgs portal model.

Alexandre Alves; Alex G. Dias; Roberto da Silva

2014-01-01T23:59:59.000Z

457

A maximum entropy framework for non-exponential distributions  

E-Print Network (OSTI)

Probability distributions having power-law tails are observed in a broad range of social, economic, and biological systems. We describe here a potentially useful common framework. We derive distribution functions $\\{p_k\\}$ for situations in which a `joiner particle' $k$ pays some form of price to enter a `community' of size $k-1$, where costs are subject to economies-of-scale (EOS). Maximizing the Boltzmann-Gibbs-Shannon entropy subject to this energy-like constraint predicts a distribution having a power-law tail; it reduces to the Boltzmann distribution in the absence of EOS. We show that the predicted function gives excellent fits to 13 different distribution functions, ranging from friendship links in social networks, to protein-protein interactions, to the severity of terrorist attacks. This approach may give useful insights into when to expect power-law distributions in the natural and social sciences.

Peterson, Jack; Dill, Ken A

2015-01-01T23:59:59.000Z

458

Relative Entropy and Proximity of Quantum Field Theories  

E-Print Network (OSTI)

We study the question of how reliably one can distinguish two quantum field theories (QFTs). Each QFT defines a probability distribution on the space of fields. The relative entropy provides a notion of proximity between these distributions and quantifies the number of measurements required to distinguish between them. In the case of nearby conformal field theories, this reduces to the Zamolodchikov metric on the space of couplings. Our formulation quantifies the information lost under renormalization group flow from the UV to the IR and leads us to a quantification of fine-tuning. This formalism also leads us to a criterion for distinguishability of low energy effective field theories generated by the string theory landscape.

Balasubramanian, Vijay; Maloney, Alexander

2014-01-01T23:59:59.000Z

459

Relative Entropy and Proximity of Quantum Field Theories  

E-Print Network (OSTI)

We study the question of how reliably one can distinguish two quantum field theories (QFTs). Each QFT defines a probability distribution on the space of fields. The relative entropy provides a notion of proximity between these distributions and quantifies the number of measurements required to distinguish between them. In the case of nearby conformal field theories, this reduces to the Zamolodchikov metric on the space of couplings. Our formulation quantifies the information lost under renormalization group flow from the UV to the IR and leads us to a quantification of fine-tuning. This formalism also leads us to a criterion for distinguishability of low energy effective field theories generated by the string theory landscape.

Vijay Balasubramanian; Jonathan J. Heckman; Alexander Maloney

2014-10-24T23:59:59.000Z

460

Entropy solutions of the Euler equations for isothermal relativistic fluids  

Science Journals Connector (OSTI)

We investigate the initial-value problem for the relativistic Euler equations of isothermal perfect fluids, and generalise an existence result due to LeFloch and Shelukhin for the non-relativistic setting. We establish the existence of globally defined, bounded measurable, entropy solutions with arbitrary large amplitude. An earlier result by Smoller and Temple covered solutions with bounded variation that avoid the vacuum state. Our new framework provides solutions in a larger function space and allows for the mass density to vanish and the velocity field to approach the light speed. The relativistic Euler equations become strongly degenerate in both regimes, as the conservative or the flux variables vanish or blow up. Our proof is based on the method of compensated compactness and takes advantage of a scaling invariance property of the Euler equations.

Philippe G. LeFloch; Mitsuru Yamazaki

2007-01-01T23:59:59.000Z

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461

Molybdenum disilicide alloy matrix composite  

DOE Patents (OSTI)

Compositions of matter consisting of matrix materials having silicon carbide dispersed throughout them and methods of making the compositions. A matrix material is an alloy of an intermetallic compound, molybdenum disilicide, and at least one secondary component which is a refractory silicide. The silicon carbide dispersant may be in the form of VLS whiskers, VS whiskers, or submicron powder or a mixture of these forms.

Petrovic, John J. (Los Alamos, NM); Honnell, Richard E. (Los Alamos, NM); Gibbs, W. Scott (Los Alamos, NM)

1991-01-01T23:59:59.000Z

462

Molybdenum disilicide alloy matrix composite  

DOE Patents (OSTI)

Compositions of matter consisting of matrix matrials having silicon carbide dispersed throughout them and methods of making the compositions. A matrix material is an alloy of an intermetallic compound, molybdenum disilicide, and at least one secondary component which is a refractory silicide. The silicon carbide dispersant may be in the form of VLS whiskers, VS whiskers, or submicron powder or a mixture of these forms.

Petrovic, John J. (Los Alamos, NM); Honnell, Richard E. (Los Alamos, NM); Gibbs, W. Scott (Los Alamos, NM)

1990-01-01T23:59:59.000Z

463

Laser Cladding of Low Melting Point Alloys  

Science Journals Connector (OSTI)

Laser cladding has been used for some years as ... hardfacing method [1]. The two main laser cladding (and alloying) techniques are: i) ...

M. Ellis; D. C. Xiao; W. M. Steen; C. Lee…

1996-01-01T23:59:59.000Z

464

12 - Laser surface modification of titanium alloys  

Science Journals Connector (OSTI)

Abstract: The laser surface engineering of titanium alloys has been developed over the past thirty years to produce a modified layer up to 1 mm in depth, thicker than alternative techniques. Continuous wave CO2 lasers have been the main lasers used for both surface cladding and alloying. Much of the early work was based on laser nitriding forming titanium nitrides throughout the molten pool. Subsequent alloying developments have included the incorporation of carbides, nitrides, oxides and silicides; and also intermetallics and rare earths, added as powders. Laser processing can now tailor surfaces with superior tribological and erosion resistant properties, compared with the untreated titanium alloys.

T.N. Baker

2010-01-01T23:59:59.000Z

465

Magnetic Alloys in Nanoscale Biomaterials  

SciTech Connect

Fe-Co composition gradient and Fe-Pt multilayer alloy films were tested as catalysts for growing vertically aligned carbon nanofibers (VACNFs) by plasma-enhanced chemical vapor deposition (PECVD). The Fe-Co film yielded nanofibers with alloy tips in a wide compositional range varying from 8.15 pct Fe at the Co-rich end to 46.29 pct Fe in the middle of the wafer as determined by energy-dispersive X-ray analysis. Two Fe-Co cubic phases (SG Pm3m, Pm{bar 3}m) were identified by preliminary X-ray diffraction (XRD) measurements. Magnetic measurements showed a substantially greater hysteresis loop area and coercivity in Fe-Co catalyst nanoparticles as compared to the as deposited Fe-Co film. The Fe-Pt film did not break into FePt alloy nanoparticles under the applied processing parameters and thus the utility of FePt as a VACNF catalyst has been inconclusive.

Leventouri, T. H. [Florida Atlantic University; Melechko, Anatoli Vasilievich [ORNL; Sorge, Korey D. [Florida Atlantic University; Klein, Kate L [ORNL; Fowlkes, Jason Davidson [ORNL; Rack, P. D. [University of Tennessee, Knoxville (UTK); Anderson, Ian M [ORNL; Thompson, James R [ORNL; McKnight, Timothy E [ORNL; Simpson, Michael L [ORNL

2006-01-01T23:59:59.000Z

466

Low-Cost Titanium Alloy Production | Department of Energy  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

Cost Titanium Alloy Production Low-Cost Titanium Alloy Production titaniumalloyproduction.pdf More Documents & Publications Low Cost Titanium Propulsion Applications Low Cost...

467

Alloy Foam Diesel Emissions Control School Bus Implementation...  

Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

Alloy Foam Diesel Emissions Control School Bus Implementation Alloy Foam Diesel Emissions Control School Bus Implementation Poster presentation from the 2007 Diesel...

468

Alloys as Anode Materials in Magnesium Ion Batteries.  

E-Print Network (OSTI)

?? This thesis is a feasibility study of the possible application of magnesium alloys forfuture magnesium-ion batteries. It investigates dierent alloys and characterizesthem with respect… (more)

Syvertsen, Alf Petter

2012-01-01T23:59:59.000Z

469

Bimetallic and Ternary Alloys for Improved Oxygen Reduction Catalysis...  

NLE Websites -- All DOE Office Websites (Extended Search)

Bimetallic and Ternary Alloys for Improved Oxygen Reduction Catalysis . Bimetallic and Ternary Alloys for Improved Oxygen Reduction Catalysis . Abstract: The research described in...

470

PREDICTION OF LOW-CYCLE FATIGUE-LIFE BY ACOUSTIC EMISSION. PART 1: 2024-T3 ALUMINUM ALLOY PART 2: ALCLAD 7075-T6/ ALUMINUM ALLOY  

E-Print Network (OSTI)

low-cycle fatigue life of Aluminum sheet alloys by acoustictoughness of structural aluminum alloys. Fracture . Fracturetoughness of structural aluminum alloys, Eng. Fracture Mech.

Baram, J.

2013-01-01T23:59:59.000Z

471

On the preparation of TiAl alloy by direct reduction of the oxide mixtures in calcium chloride melt  

SciTech Connect

In recent years, TiAl-based intermetallic alloys are being increasingly considered for application in areas such as (i) automobile/transport sector (passenger cars, trucks and ships) (ii) aerospace industry (jet engines and High Speed Civil Transport propulsion system) and (iii) industrial gas turbines. These materials offer excellent (i) high temperature properties (at higher than 6000C) (ii) mechanical strength and (iii) resistance to corrosion and as a result have raised renewed interest. The combination of these properties make them possible replacement materials for traditional nickel-based super-alloys, which are nearly as twice as dense (than TiAl based alloys). Since the microstructures of these intermetallic alloys affect, to a significant extent, their ultimate performance, further improvements (by way of alteration/modification of these microstructures), have been the subject matter of intense research investigations. It has now been established that the presence of alloy additives, such as niobium, tantalum, manganese, boron, chromium, silicon, nickel and yttrium etc, in specific quantities, impart marked improvement to the properties, viz. fatigue strength, fracture toughness, oxidation resistance and room temperature ductility, of these alloys. From a number of possible alloy compositions, {gamma}-TiAl and Ti-Al-Nb-Cr have, of late, emerged as two promising engineering alloys/materials. . The conventional fabrication process of these alloys include steps such as melting, forging and heat treatment/annealing of the alloy compositions. However, an electrochemical process offers an attractive proposition to prepare these alloys, directly from the mixture of the respective oxides, in just one step. The experimental approach, in this new process, was, therefore, to try to electrochemically reduce the (mixed) oxide pellet to an alloy phase. The removal of oxygen, from the (mixed) oxide pellet, was effected by polarizing the oxide pellet against a graphite electrode in a pool of molten calcium chloride at a temperature of 9000C. The dominant mechanism of the oxygen removal was the ionization of oxygen followed by its subsequent discharge, as CO2/CO, at the anode surface. The removal of oxygen from the oxide mixture helped form the alloy in situ. The presentation shall cover the detailed experimental results pertaining to the preparation, evaluation and characterization of Ti-47Al-2Nb-2Cr (atom%) alloy.

Prabhat K. Tripathy; Derek J. Fray

2011-11-01T23:59:59.000Z

472

Neutron Absorbing Alloys  

DOE Patents (OSTI)

A process for making homogeneous copolymers of vinylpyrrolidone (VP) and vinyl acetate (VA) which form clear aqueous solutions and have high cloud points. The process involves precharging VP and VA monomers in a predetermined ratio, and then feeding VP and VA at a predetermined rate, the ratio of the components in the initial charge and the feeding rates for the monomer being selected in accordance with the reactivity rates of the monomers towards copolymerization as opposed to homopolymerization.

Zhong, Yuanzhen (Wayne, NJ), Parikh, Hemant (Harriman, NY); Smith, Terry E. (Murray, KY)

2002-05-28T23:59:59.000Z

473

Zirconium vanadium chromium alloy  

DOE Patents (OSTI)

A ternary intermetallic compound having the formula Zr(V/sub 1-x/Cr/sub x/)/sub 2/ where x is in the range of 0.01 to 0.90 is capable of reversibly sorbing hydrogen at temperatures ranging from room temperature to 200/sup 0/C, at pressures down to 10/sup -6/ torr. The compound is suitable for use as a hydrogen getter in low pressure, high temperature applications such as magnetic confinement fusion devices.

Mendelsohn, M.H.; Gruen, D.M.

1980-10-14T23:59:59.000Z

474

On the entropy devil's staircase in a family of gap-tent maps  

E-Print Network (OSTI)

We analyze dynamical properties of a "gap-tent map" - a family of 1D maps with a symmetric gap, which mimics the presence of noise in physical realizations of chaotic systems. We demonstrate that the dependence of the topological entropy on the size of the gap has a structure of the devil's staircase. By integrating over a fractal measure, we obtain analytical, piece-wise differentiable approximations of this dependence. Applying concepts of the kneading theory we find the position and the values of the entropy for all leading entropy plateaus. Similar properties hold also for the dependence of the fractal dimension of the invariant set and the escape rate.

Karol Zyczkowski; Erik M. Bollt

1998-07-07T23:59:59.000Z

475

Degradation mode survey of titanium-base alloys  

SciTech Connect

Of the materials reviewed, commercially pure titanium, Ti Gr 2, is the most susceptible to crevice corrosion. Ti Gr 7, 12, and 16 are likely to be resistant to crevice corrosion under the current expected Yucca Mountain repository conditions. Although Grade 7 has the greatest resistance to crevice corrosion it is also the most expensive. Although the possibility of sustained loads cracking exists, it has not yet been observed in a Ti alloys. For hydride precipitation to occur 100{degrees}C, the hydrogen concentration would need to be relatively high, much higher than the maximum amount of hydrogen allowed during the manufacture of ({alpha} Ti alloys (0.0 15 wt%). A large amount of (SCC) stress corrosion cracking data accumulated at SNL and BNL for the WIPP program and by the Canadian Waste Management Program on titanium grades 2 and 12 indicates that there is no SCC at naturally occurring potentials in various brines. Hydride-induced cracking of titanium is a possibility and therefore, further investigation of this phenomenon under credible repository conditions is warranted. One disadvantage of titanium and its alloys is that their strengths decrease rather rapidly with temperature. This is due to the strong temperature dependence of interstitial solute strengthening mechanisms. Ti Gr 12 and 16 are recommended for further consideration as candidate materials for high level nuclear waste containers.

Gdowski, G.E. [Lawrence Livermore National Lab., CA (United States); Ahluwalia, H.S. [Science and Engineering Associates, Inc., Livermore, CA (United States)

1995-01-30T23:59:59.000Z

476

Alloy decomposition and surface instabilities in thin films  

Science Journals Connector (OSTI)

We show that in the presence of substrate misfit and compositional stresses, static or growing films that undergo surface spinodal decomposition are always unstable to perturbations around the planar surface. For sufficiently rapid deposition processes, the planar surface can be stabilized due to a suppression of the alloy decomposition. Films grown outside of the miscibility gap can become unstable due to the mismatch with the substrate and compositionally generated stresses. We also demonstrate that the instability is independent of the sign of the misfit when the elastic moduli of the alloy constituents are equal, and the existence of a maximum misfit above which the film is always unstable, even at high growth rates. The symmetry under sign reversal of the misfit can be broken by composition-dependent elastic constants.

François Léonard and Rashmi C. Desai

1998-02-15T23:59:59.000Z

477

A modified electrospark alloying method for low surface roughness  

Science Journals Connector (OSTI)

A modified electrospark alloying method has been developed. The method allows the formation of deposits with low surface roughness compared to that of the conventional electrospark alloying method. It is based on the employment of a sequence of identical pulse groups. The process of electrospark deposition and the process of electrospark grinding were combined by forming pulse groups consisting of a high energy pulse for mass transfer from treating electrode to substrate and low energy pulses for grinding during deposition. Low as-deposited surface roughness was succeeded by properly selecting parameters of the pulses in a group and pauses between them. Experimental results revealed that the proposed method is useful in forming one–two layers of deposition.

Alexander V. Ribalko; Orhan Sahin; Kemal Korkmaz

2009-01-01T23:59:59.000Z

478

Method to Improve Steel Creep Strength by Alloy Design  

NLE Websites -- All DOE Office Websites (Extended Search)

to Improve Steel Creep Strength by Alloy Design to Improve Steel Creep Strength by Alloy Design and Heat Treatment Opportunity Research is active on the patent pending technology, titled "Creep Resistant High Temperature Martensitic Steel." This technology is available for licensing and/or further collaborative research from the U.S. Department of Energy's National Energy Technology Laboratory. Overview The operating efficiency of coal-fired power plants is directly related to combustion system temperature and pressure. Incorporation of