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Title: Synthesis and Performance of Fe-based Amorphous Alloys for Nuclear Waste Applications

Abstract

Recent developments in multi-component Fe-based amorphous alloys have shown that these novel materials exhibit outstanding corrosion resistance compared to typical crystalline alloys such as high-performance stainless steels and Ni-based C-22 alloy. During the past decade, amorphous alloy synthesis has advanced to allow for the casting of bulk metallic glasses. In several Fe-based alloy systems it is possible to produce glasses with cooling rates as low as 100 K/s. At such low cooling rates, there is an opportunity to produce amorphous solids through industrial processes such as thermal spray-formed coatings. Moreover, since cooling rates in typical thermal spray processing exceed 1000 K/s, novel alloy compositions can be synthesized to maximize corrosion resistance (i.e. adding Cr and Mo) and to improve radiation compatibility (adding B) and still maintain glass forming ability. The applicability of Fe-based amorphous coatings in typical environments where corrosion resistance and thermal stability are critical issues has been examined in terms of amorphous phase stability and glass-forming ability through a coordinated computational analysis and experimental validation. For example, a wedge casting technique has been applied to examine bulk glass forming alloys by combining multiple thermal probes with a measurement based kinetics analysis and a computational thermodynamics evaluation to elucidatemore » the phase selection competition and critical cooling rate conditions. Based upon direct measurements and kinetics modeling it is evident that a critical cooling rate range should be considered to account for nucleation behavior and that the relative heat flow characteristics as well as nucleation kinetics are important in judging ease of glass formation. Similarly, a novel computational thermodynamics approach has been developed to explore the compositional sensitivity of glass-forming ability and thermal stability. Also, the synthesis and characterization of alloys with increased cross-section for thermal neutron capture will be outlined to demonstrate that through careful design of alloy composition it is possible to tailor the material properties of the thermally spray-formed amorphous coating to accommodate the challenges anticipated in typical nuclear waste storage applications over tens of thousands of years in a variety of corrosive environments.« less

Authors:
; ;
Publication Date:
Research Org.:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
908118
Report Number(s):
UCRL-CONF-227808
TRN: US0703634
DOE Contract Number:
W-7405-ENG-48
Resource Type:
Conference
Resource Relation:
Conference: Presented at: M&C+SNA 2007, Monterey, CA, United States, Apr 15 - Apr 19, 2007
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ALLOY SYSTEMS; ALLOYS; CORROSION RESISTANCE; GLASS; HEAT FLUX; KINETICS; METALLIC GLASSES; PERFORMANCE; PHASE STABILITY; RADIOACTIVE WASTES; STABILITY; STAINLESS STEELS; SYNTHESIS; THERMAL NEUTRONS

Citation Formats

Kaufman, L, Perepezko, J, and Hildal, K. Synthesis and Performance of Fe-based Amorphous Alloys for Nuclear Waste Applications. United States: N. p., 2007. Web.
Kaufman, L, Perepezko, J, & Hildal, K. Synthesis and Performance of Fe-based Amorphous Alloys for Nuclear Waste Applications. United States.
Kaufman, L, Perepezko, J, and Hildal, K. Tue . "Synthesis and Performance of Fe-based Amorphous Alloys for Nuclear Waste Applications". United States. doi:. https://www.osti.gov/servlets/purl/908118.
@article{osti_908118,
title = {Synthesis and Performance of Fe-based Amorphous Alloys for Nuclear Waste Applications},
author = {Kaufman, L and Perepezko, J and Hildal, K},
abstractNote = {Recent developments in multi-component Fe-based amorphous alloys have shown that these novel materials exhibit outstanding corrosion resistance compared to typical crystalline alloys such as high-performance stainless steels and Ni-based C-22 alloy. During the past decade, amorphous alloy synthesis has advanced to allow for the casting of bulk metallic glasses. In several Fe-based alloy systems it is possible to produce glasses with cooling rates as low as 100 K/s. At such low cooling rates, there is an opportunity to produce amorphous solids through industrial processes such as thermal spray-formed coatings. Moreover, since cooling rates in typical thermal spray processing exceed 1000 K/s, novel alloy compositions can be synthesized to maximize corrosion resistance (i.e. adding Cr and Mo) and to improve radiation compatibility (adding B) and still maintain glass forming ability. The applicability of Fe-based amorphous coatings in typical environments where corrosion resistance and thermal stability are critical issues has been examined in terms of amorphous phase stability and glass-forming ability through a coordinated computational analysis and experimental validation. For example, a wedge casting technique has been applied to examine bulk glass forming alloys by combining multiple thermal probes with a measurement based kinetics analysis and a computational thermodynamics evaluation to elucidate the phase selection competition and critical cooling rate conditions. Based upon direct measurements and kinetics modeling it is evident that a critical cooling rate range should be considered to account for nucleation behavior and that the relative heat flow characteristics as well as nucleation kinetics are important in judging ease of glass formation. Similarly, a novel computational thermodynamics approach has been developed to explore the compositional sensitivity of glass-forming ability and thermal stability. Also, the synthesis and characterization of alloys with increased cross-section for thermal neutron capture will be outlined to demonstrate that through careful design of alloy composition it is possible to tailor the material properties of the thermally spray-formed amorphous coating to accommodate the challenges anticipated in typical nuclear waste storage applications over tens of thousands of years in a variety of corrosive environments.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Tue Feb 06 00:00:00 EST 2007},
month = {Tue Feb 06 00:00:00 EST 2007}
}

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  • In several Fe-based alloy systems it is possible to produce glasses with cooling rates as low as 100 K/s that exhibit outstanding corrosion resistance compared to typical crystalline alloys such as high-performance stainless steels and Ni-based C-22 alloy. Moreover, novel alloy compositions can be synthesized to maximize corrosion resistance (i.e. adding Cr and Mo) and to improve radiation compatibility (adding B) and still maintain glass forming ability. The applicability of Fe-based amorphous coatings in typical environments where corrosion resistance and thermal stability are critical issues has been examined in terms of amorphous phase stability and glass-forming ability through a coordinatedmore » computational analysis and experimental validation. Similarly, a novel computational thermodynamics approach has been developed to explore the compositional sensitivity of glass-forming ability and thermal stability. Also, the synthesis and characterization of alloys with increased cross-section for thermal neutron capture will be outlined to demonstrate that through careful design of alloy composition it is possible to tailor the material properties of the thermally spray-formed amorphous coating to accommodate the challenges anticipated in typical nuclear waste storage applications over tens of thousands of years in a variety of corrosive environments.« less
  • Understanding the basic mechanisms that determine microstructure changes in neutron irradiated steels is vital for a safe lifetime management of existing nuclear reactors and a safe design of future nuclear options. Low-alloyed ferritic steels containing Cu, Ni, Mn and Si as principal solute atoms are used as structural materials for current reactor vessels. The microstructural evolution under irradiation in alloys is decided by the interplay between defect formation and thermodynamic driving forces, together determining the appearance of phase transformations (precipitation, segregation,...) and favouring or delaying the nucleation and growth of point-defect clusters, their diffusion and their mutual recombination or removalmore » at sinks. A reliable description of the production, evolution and accumulation of radiation damage must therefore start from the atomic level and requires being able to describe multicomponent systems for timescales ranging from few picoseconds to years. This goal demands firstly the fabrication of interatomic potentials for alloys that must be both consistent with the thermodynamic properties of the system and capable of reproducing correctly the characteristic solute-point defect interactions, versus ab initio or experimental data. Secondly the performance of extensive molecular dynamics (MD) simulations, to grasp the main mechanisms of defect production, diffusion, mutual interaction, and interaction with solute atoms and impurities. Thirdly, the development of simulation tools capable of describing the microstructure evolution beyond the time-frame and length-scale of MD, while reproducing as much as possible the atomic-level origin of the mechanisms governing the evolution of the system, including phase changes. In this presentation the results of recent efforts made in this direction in the case of Fe-Cu, Fe-Cr and Fe-Ni alloys, as basic model alloys for the description of steels of technological relevance, are highlighted. In particular, advanced techniques to fit interatomic potentials consistent with thermodynamics are proposed and the results of their application to the mentioned alloys are presented. Next, the development of advanced methods, based on the use of artificial intelligence, to improve both the physical reliability and the computational efficiency of kinetic Monte Carlo codes for the study of point-defect clustering and phase changes beyond the scale of MD, is reported. These recent progresses bear the promise of being able, in the near future, of producing reliable tools for the description of the microstructure evolution of realistic model alloys under irradiation. (author)« less
  • Limited experimental data exists for the specific core loss and dynamic B-H loops for soft magnetic materials for the combined conditions of high frequency and high temperature. This experimental study investigates the specific core loss and dynamic B-H characteristics of a nickel-iron crystalline magnetic alloy (Supermalloy) and two-iron-based amorphous magnetic materials (Metglas 2605S-3A and Metglas 2605SC) over the frequency range of 1--50 kHz and temperature range of 23--300 C under sinusoidal voltage excitation. The effects of maximum magnetic flux density, frequency, and temperature on the specific core loss and on the size and shape of the B-H loops are examined.more » The Supermalloy and Metglas 2605S-3A and 2605SC data are used to compare the core loss of transformers with identical kVA and voltage ratings.« less
  • The availability of experimental data that characterizes the performance of soft magnetic materials for the combined conditions of high temperature and high frequency is almost non-existent. An experimental investigation was conducted over the temperature range of 23 to 300 C and frequency range of 1 to 50 kHz to determine the effects of temperature and frequency on the core loss and dynamic B-H loops of three different soft magnetic materials; an oriented-grain 50Ni-50Fe alloy, a nonoriented-grain 50Ni-50Fe alloy, and an iron-based amorphous material (Metglas 2605SC). A comparison of these materials show that the nonoriented-grain 50Ni-50Fe alloy tends to have eithermore » the lowest or next lowest core loss for all temperatures and frequencies investigated.« less
  • This paper describes a method of obtaining linear permeability characteristics from Fe-B based amorphous alloys, suitable for choke and inductor applications. The properties are developed by heat treatment at temperatures above those conventionally used to develop the optimum low or high frequency magnetic properties in these alloys. Within a narrow heat treatment temperature range it is possible to develop permeabilities of between 200 and 700, linear up to high flux density levels. D.C. Energy Storage Curves are presented for Fe /sub 77.5/ B/sub 13/ Si /sub 9.5/ alloy, toroidal tape wound cores, heat treated in this manner. These curves indicatemore » the potential advantages of these cores over powder cores and gapped ferrites in D.C. choke applications.« less