Microstructural and mechanical property changes in the Ta-base T-111 alloy following thermal aging

Keith J. Leonard; Jeremy T. Busby; Steven J. Zinkle

doi:10.1016/j.jnucmat.2007.03.026

Microstructural and mechanical property changes in the Ta-base T-111 alloy following thermal aging

Keith J. Leonard, Jeremy T. Busby, Steven J. Zinkle

Isotope Sci & Eng Directorate

Research output: Contribution to journal › Article › peer-review

10 Scopus citations

Abstract

The microstructural changes occurring in the Ta-base T-111 (Ta-8W-2Hf) alloy during 1100 h thermal aging at 1098, 1248 and 1398 K under inert atmosphere and the influence on mechanical properties are reported. Electrical resistivity, hardness and tensile properties are compared between the as-annealed and aged conditions. Microstructural evaluations were performed by optical, scanning electron microscopy and transmission electron microscopy. An increase in the amount of grain boundary precipitation with increasing aging temperature was found to decrease the electrical resistivity and material strength. Precipitation at the grain boundaries was found to be a mixture of monoclinic and cubic structures, suggesting the development of mixed Hf oxides, carbides and nitrides. Precipitate development caused pronounced embrittlement of the alloy following aging at 1398 K.

Original language	English
Pages (from-to)	353-368
Number of pages	16
Journal	Journal of Nuclear Materials
Volume	366
Issue number	3
DOIs	https://doi.org/10.1016/j.jnucmat.2007.03.026
State	Published - Jul 1 2007

Funding

The authors thank J. Hack, R. Baranwal, T.M. Angeliu and Y. Ballout of the Naval Reactors Prime Contractor Team for many helpful technical discussions and guidance. The authors thank Marie Williams, Mike Pershing and Cliff Davison for help in acid cleaning and annealing of the specimens prior to thermal aging; Jeffrey McNabb and Bob Sitterson for welding and leak testing the Alloy 600 aging cans; Brian Sparks and David Harper for thermal aging the encapsulated materials; Kathy Thomas and Jackie Mayotte for their help in preparing samples for microscopy. The authors thank Chad Duty and Bill Wiffen for their helpful discussions. This work was performed under the sponsorship of NASA’s Project Prometheus and directed by DOE/NNSA Naval Reactors. Opinions and conclusions drawn by the authors are not endorsed by DOE/NNSA Naval Reactors. Research at the Oak Ridge National Laboratory SHaRE User Center was sponsored by the Division of Materials Sciences and Engineering, US Department of Energy. ORNL is managed for DOE by UT-Battelle, LLC, under contract DE-AC-05-00OR22725.

Funders	Funder number
US Department of Energy
UT-Battelle, LLC	DE-AC-05-00OR22725
Division of Materials Sciences and Engineering

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title = "Microstructural and mechanical property changes in the Ta-base T-111 alloy following thermal aging",

abstract = "The microstructural changes occurring in the Ta-base T-111 (Ta-8W-2Hf) alloy during 1100 h thermal aging at 1098, 1248 and 1398 K under inert atmosphere and the influence on mechanical properties are reported. Electrical resistivity, hardness and tensile properties are compared between the as-annealed and aged conditions. Microstructural evaluations were performed by optical, scanning electron microscopy and transmission electron microscopy. An increase in the amount of grain boundary precipitation with increasing aging temperature was found to decrease the electrical resistivity and material strength. Precipitation at the grain boundaries was found to be a mixture of monoclinic and cubic structures, suggesting the development of mixed Hf oxides, carbides and nitrides. Precipitate development caused pronounced embrittlement of the alloy following aging at 1398 K.",

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AU - Zinkle, Steven J.

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N2 - The microstructural changes occurring in the Ta-base T-111 (Ta-8W-2Hf) alloy during 1100 h thermal aging at 1098, 1248 and 1398 K under inert atmosphere and the influence on mechanical properties are reported. Electrical resistivity, hardness and tensile properties are compared between the as-annealed and aged conditions. Microstructural evaluations were performed by optical, scanning electron microscopy and transmission electron microscopy. An increase in the amount of grain boundary precipitation with increasing aging temperature was found to decrease the electrical resistivity and material strength. Precipitation at the grain boundaries was found to be a mixture of monoclinic and cubic structures, suggesting the development of mixed Hf oxides, carbides and nitrides. Precipitate development caused pronounced embrittlement of the alloy following aging at 1398 K.

AB - The microstructural changes occurring in the Ta-base T-111 (Ta-8W-2Hf) alloy during 1100 h thermal aging at 1098, 1248 and 1398 K under inert atmosphere and the influence on mechanical properties are reported. Electrical resistivity, hardness and tensile properties are compared between the as-annealed and aged conditions. Microstructural evaluations were performed by optical, scanning electron microscopy and transmission electron microscopy. An increase in the amount of grain boundary precipitation with increasing aging temperature was found to decrease the electrical resistivity and material strength. Precipitation at the grain boundaries was found to be a mixture of monoclinic and cubic structures, suggesting the development of mixed Hf oxides, carbides and nitrides. Precipitate development caused pronounced embrittlement of the alloy following aging at 1398 K.

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Microstructural and mechanical property changes in the Ta-base T-111 alloy following thermal aging

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