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Title: The Effect of the Presence of 2 wt% Hafnium in T-111

Abstract

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 reduce creep strain (T-111). These tantalum alloys have demonstrated sufficient high-temperature toughness to survive prolonged exposure to the RTG's working environment. Due to the commercial unavailability of the tantalum alloy T-111, Ta-10%W is a possible candidate replacement material because of its high melting point (3037 deg. C), high elastic modulus (207 GPa), high yield, ultimate tensile strengths at both ambient and elevated temperatures, excellent ductility, and exceptional creep properties. Ta-10%W is also attractive due its commercial availability and low cost when compared to T-111. The objective of this paper is to compare and contrast Ta-10%W and T-111 for high-temperature nuclear based power conversion applications and to document research that must be conducted to fully characterize both materials.

Authors:
 [1];  [2];  [3]
  1. University of Dayton, 300 College Park Dayton OH 45469-0240 (United States)
  2. University of Dayton Research Institute, 300 College Park Dayton OH 45469-0102 (United States)
  3. Argonne National Laboratory, P.O. Box 2528, Idaho Falls, ID 83403-2528 (United States)
Publication Date:
OSTI Identifier:
20798016
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 813; Journal Issue: 1; Conference: 10. conference on thermophysics applications in microgravity; 23. symposium on space nuclear power and propulsion; 4. conference on human/robotic technology and the national vision for space exploration; 4. symposium on space colonization; 3. symposium on new frontiers and future concepts, Albuquerque, NM (United States), 12-16 Feb 2006; Other Information: DOI: 10.1063/1.2169256; (c) 2006 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS; 36 MATERIALS SCIENCE; COMPARATIVE EVALUATIONS; CORROSION RESISTANCE; CREEP; DUCTILITY; ENERGY CONVERSION; HAFNIUM; HAFNIUM ALLOYS; MELTING POINTS; NUCLEAR POWER; POWER GENERATION; PRESSURE RANGE GIGA PA; RADIOISOTOPES; REACTOR MATERIALS; SPACE VEHICLES; STRAINS; TANTALUM ALLOYS; TESTING; THERMAL CONDUCTIVITY; THERMOELECTRIC GENERATORS; WELDABILITY; NESDPS Office of Nuclear Energy Space and Defense Power Systems

Citation Formats

Barklay, Chadwick D., Kramer, Daniel P., and Miller, Roger G.. The Effect of the Presence of 2 wt% Hafnium in T-111. United States: N. p., 2006. Web. doi:10.1063/1.2169256.
Barklay, Chadwick D., Kramer, Daniel P., & Miller, Roger G.. The Effect of the Presence of 2 wt% Hafnium in T-111. United States. doi:10.1063/1.2169256.
Barklay, Chadwick D., Kramer, Daniel P., and Miller, Roger G.. Fri . "The Effect of the Presence of 2 wt% Hafnium in T-111". United States. doi:10.1063/1.2169256.
@article{osti_20798016,
title = {The Effect of the Presence of 2 wt% Hafnium in T-111},
author = {Barklay, Chadwick D. and Kramer, Daniel P. and Miller, Roger G.},
abstractNote = {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 reduce creep strain (T-111). These tantalum alloys have demonstrated sufficient high-temperature toughness to survive prolonged exposure to the RTG's working environment. Due to the commercial unavailability of the tantalum alloy T-111, Ta-10%W is a possible candidate replacement material because of its high melting point (3037 deg. C), high elastic modulus (207 GPa), high yield, ultimate tensile strengths at both ambient and elevated temperatures, excellent ductility, and exceptional creep properties. Ta-10%W is also attractive due its commercial availability and low cost when compared to T-111. The objective of this paper is to compare and contrast Ta-10%W and T-111 for high-temperature nuclear based power conversion applications and to document research that must be conducted to fully characterize both materials.},
doi = {10.1063/1.2169256},
journal = {AIP Conference Proceedings},
number = 1,
volume = 813,
place = {United States},
year = {Fri Jan 20 00:00:00 EST 2006},
month = {Fri Jan 20 00:00:00 EST 2006}
}
  • Fe{sub 3}Al–20 wt.%Al{sub 2}O{sub 3} ultrafine grained composites with 4 wt.% Cr were prepared by mechanical alloying inducing self propagating high temperature synthesis with subsequent plasma activated sintering. Microstructures of the composites were studied by X-ray diffraction, scanning electron microscopy, energy dispersive spectrum and transmission electron microscope. Then the relative density, room temperature hardness, static corrosion resistance and dry sliding wear behavior at a temperature range of 25 °C–800 °C of the sintered samples were tested and analyzed. The results showed that the composites had high hardness and a good microstructure with fine grain size, high relative density. The compositesmore » with 4 wt.% Cr amount also exhibited excellent comprehensive tribological properties at medium–high temperatures especially at a temperature above 500 °C, although the wear resistance did not be improved at 25 °C–500 °C. 4 wt.% Cr element addition improved the corrosion resistance of the composites significantly with the corrosion loss decreasing by 19.48%. - Highlights: ► In-situ Fe{sub 3}Al–20 wt.%Al{sub 2}O{sub 3} composites with 4 wt.% Cr was prepared by MA-PAS. ► Composites had good tribological properties at the temperature above 500 °C. ► Corrosion resistance was improved obviously by 4 wt.% Cr amount.« less
  • The addition of 3 equiv of methyl Grignard (MeMgCl) to the amidodiphosphine derivatives MCl{sub 3} [N-(SiMe{sub 2}CH{sub 2}PR{sub 2}){sub 2}] (M = Zr, Hf; R=Me, Pr{sup i}, Bu{sup t}) generates the corresponding trimethyl complexes MMe{sub 3}[N-(SiMe{sub 2}CH{sub 2}PR{sub 2}){sub 2}]. The solution structures and fluxional behavior of these molecules along with the X-ray structure of HfMe{sub 3}[N(SiMe{sub 2}CH{sub 2}PMe{sub 2}){sub 2}] are presented. 32 refs., 1 fig., 4 tabs.
  • Titanium, zirconium, and hafnium dialkyl complexes that contain the [(t-Bu-d{sub 6}-N-o-C{sub 6}H{sub 4}){sub 2}O]{sup 2{minus}} ([t-BuNON]{sup 2{minus}}) ligand have been prepared. Only [T-BuNON]TiMe{sub 2} could be isolated, but [t-BuNON]ZrR{sub 2} and [t-BuNON]HfR{sub 2} complexes could be isolated in which (for example) R = Me, Et, or i-Bu. X-ray studies showed [t-BuNON]MMe{sub 2} structures (M = Tk or Zr) to be of the twisted fac variety in which two amido nitrogens occupy equatorial positions in a distorted trigonal bypyramid. However, in solution all such species show equivalent alkyl groups on the NMR time scale as a consequence of formation of anmore » intermediate mer structure that contains a planar oxygen donor. In analogous complexes that contain the {l_brace}[Me(CD{sub 3}){sub 2}CNC{sub 6}H{sub 4}][Me(CD{sub 3}){sub 2}CN-2,4-Me{sub 2}C{sub 6}H{sub 2}]O{r_brace}{sup 2{minus}} or {l_brace}[Me(CD{sub 3}){sub 2}CNC{sub 6}H{sub 4}][Me(CD{sub 3}){sub 2}-N-2-EtC{sub 6}H{sub 3}]O{r_brace}{sup 2{minus}} ligand the two metal alkyl groups are inequivalent on the NMR time scale. Addition of trimethylphosphine to [t-BuNON]Zr(CH{sub 2}CH{sub 3}){sub 2} yields structurally characterized pseudooctahedral [t-BuNON]Zr({eta}{sup 2}-C{sub 2}H{sub 4})(PMe{sub 3}){sub 2}. Addition of B(C{sub 6}F{sub 5}){sub 3} to [t-BuNON]ZrMe{sub 2} yields structurally characterized {l_brace}[t-BuNON]ZrMe{r_brace}[MeB(C{sub 6}F{sub 5}){sub 3}], while addition of [PhNMe{sub 2}H]-[B(C{sub 6}F{sub 4}){sub 4}] to [t-BuNON]ZrMe{sub 2} in bromobenzene-d{sub 5} generates {l_brace}[t-BuNON]ZrMe(PhNMe{sub 2}){r_brace}-[B(C{sub 6}F{sub 5}){sub 4}], which is an active catalyst for the polymerization of up to 500 equiv of 1-hexene in a living manner at 0 C. The analogous hafnium systems are not as well behaved, since the dimethylaniline is insufficiently labile. No polymerization activity is observed for activated titanium dialkyl complexes. Polymerization activity is quenched upon addition of THF or dimethoxyethane to the cationic complexes. An X-ray structure of {l_brace}[t-BuNON]ZrMe(THF){sub 2}{r_brace}-[B(C{sub 6}F{sub 5}){sub 4}] shows it to be a pseudooctahedral species in which the [t-BuNON]{sup 2{minus}} ligand adopts a twisted mer geometry, while the X-ray structure of [t-BuNON]ZrMe(MeOCH{sub 2}CH{sub 2}OMe)-[B(C{sub 6}F{sub 5}){sub 4}] was found to be of the twisted fac variety. In the case of hafnium, pseudooctahedral cationic bis-THF or DME complexes can be isolated even when the anion is [B(C{sub 6}H{sub 5}){sub 4}]{sup {minus}}; like all complexes that contain THF or DME they are essentially inactive for polymerization of 1-hexene.« less
  • Titanium, zirconium, and hafnium dialkyl complexes that contain the [(t-Bu-d[sub 6]-N-o-C[sub 6]H[sub 4])[sub 2]O][sup 2[minus]] ([t-BuNON][sup 2[minus]]) ligand have been prepared. Only [T-BuNON]TiMe[sub 2] could be isolated, but [t-BuNON]ZrR[sub 2] and [t-BuNON]HfR[sub 2] complexes could be isolated in which (for example) R = Me, Et, or i-Bu. X-ray studies showed [t-BuNON]MMe[sub 2] structures (M = Tk or Zr) to be of the twisted fac variety in which two amido nitrogens occupy equatorial positions in a distorted trigonal bypyramid. However, in solution all such species show equivalent alkyl groups on the NMR time scale as a consequence of formation of anmore » intermediate mer structure that contains a planar oxygen donor. In analogous complexes that contain the [l brace][Me(CD[sub 3])[sub 2]CNC[sub 6]H[sub 4]][Me(CD[sub 3])[sub 2]CN-2,4-Me[sub 2]C[sub 6]H[sub 2]]O[r brace][sup 2[minus]] or [l brace][Me(CD[sub 3])[sub 2]CNC[sub 6]H[sub 4]][Me(CD[sub 3])[sub 2]-N-2-EtC[sub 6]H[sub 3]]O[r brace][sup 2[minus]] ligand the two metal alkyl groups are inequivalent on the NMR time scale. Addition of trimethylphosphine to [t-BuNON]Zr(CH[sub 2]CH[sub 3])[sub 2] yields structurally characterized pseudooctahedral [t-BuNON]Zr([eta][sup 2]-C[sub 2]H[sub 4])(PMe[sub 3])[sub 2]. Addition of B(C[sub 6]F[sub 5])[sub 3] to [t-BuNON]ZrMe[sub 2] yields structurally characterized [l brace][t-BuNON]ZrMe[r brace][MeB(C[sub 6]F[sub 5])[sub 3]], while addition of [PhNMe[sub 2]H]-[B(C[sub 6]F[sub 4])[sub 4]] to [t-BuNON]ZrMe[sub 2] in bromobenzene-d[sub 5] generates [l brace][t-BuNON]ZrMe(PhNMe[sub 2])[r brace]-[B(C[sub 6]F[sub 5])[sub 4]], which is an active catalyst for the polymerization of up to 500 equiv of 1-hexene in a living manner at 0 C. The analogous hafnium systems are not as well behaved, since the dimethylaniline is insufficiently labile. No polymerization activity is observed for activated titanium dialkyl complexes. Polymerization activity is quenched upon addition of THF or dimethoxyethane to the cationic complexes. An X-ray structure of [l brace][t-BuNON]ZrMe(THF)[sub 2][r brace]-[B(C[sub 6]F[sub 5])[sub 4]] shows it to be a pseudooctahedral species in which the [t-BuNON][sup 2[minus]] ligand adopts a twisted mer geometry, while the X-ray structure of [t-BuNON]ZrMe(MeOCH[sub 2]CH[sub 2]OMe)-[B(C[sub 6]F[sub 5])[sub 4]] was found to be of the twisted fac variety. In the case of hafnium, pseudooctahedral cationic bis-THF or DME complexes can be isolated even when the anion is [B(C[sub 6]H[sub 5])[sub 4]][sup [minus]]; like all complexes that contain THF or DME they are essentially inactive for polymerization of 1-hexene.« less