First-Principles Study of Tritium Trapping by Point Defects in Fe-Al Aluminide Coating Phases

Technical Report · Thu Sep 01 04:00:00 EDT 2022

DOI:https://doi.org/10.2172/1986035· OSTI ID:1986035

Sassi, Michel ^[1]; Chaka, Anne M. ^[1]; Senor, David J. ^[1]; Casella, Andrew M. ^[1]

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1. Pacific Northwest National Laboratory (PNNL), Richland, WA (United States)

Density functional theory simulations have been carried out to investigate the potential for tritium trapping by metal vacancies in five different Fe-Al aluminide coating phases. It was found that tritiation of Fe and Ni vacancies is generally less favorable than the tritiation of Al vacancies. However, for the first tritiation, a trend in the defect formation energy can be obtained such that metal defects in the Fe₂Al_x family of materials (i.e., Fe₂Al₄, Fe₂Al₅, and Fe₂Al₆) trap tritium species more favorably than metal vacancies in Fe₄Al₁₃ and FeNiAl₅. Further investigations using ab initio thermodynamics calculations confirmed that trend for a range of tritium partial pressure at a temperature of 700 K. Especially, it was shown that the energy difference between tritiated and non-tritiated metal vacancies is smaller and more favorable for the Fe₂Al_x family, followed by Fe₄Al₁₃, and FeNiAl₅. While this study shows that tritium interacts differently in the various Fe-Al aluminide phases, it also suggests that tritium trapping and retention could be more efficient if metal defects are present in some Fe-Al phases.

• Research Organization: Pacific Northwest National Laboratory (PNNL), Richland, WA (United States)
• Sponsoring Organization: USDOE National Nuclear Security Administration (NNSA)
• DOE Contract Number: AC05-76RL01830
• OSTI ID: 1986035
• Report Number(s): PNNL--33519
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE