TY - JOUR
T1 - Defect dynamics in γ-U, Mo, and their alloys
AU - Jin, Miaomiao
AU - Gao, Yipeng
AU - Jiang, Chao
AU - Gan, Jian
N1 - Publisher Copyright:
© 2021 Elsevier B.V.
PY - 2021/6
Y1 - 2021/6
N2 - Defect dynamics constitutes the foundation for describing microstructural evolution in any material systems for nuclear applications, including body-centered cubic γ-U, Mo, and their alloys. However, defect properties and evolution, and the impact of a large atomic size mismatch between U and Mo atoms on defect dynamics have not been elucidated. In this work, we use molecular dynamics to extensively examine composition-dependent defect behavior in U-Mo alloys and the pure metals. It has been found that point defect migration is strongly correlated and mediated by minor atoms via preferential paths in alloys. Interstitial dumbbells migrate three-dimensionally through the major atoms with a preferred 〈110〉 configuration. Vacancies are less mobile than interstitials, but become comparable (one order of magnitude difference in diffusivity) in U-rich systems. Overall, compared with the pure metals, defect diffusivity can be tuned up or down based on the alloy composition. Finally, interstitial clustering is found to be unfavorable in U-rich systems, as opposed to Mo which exhibits an efficient formation of interstitial-type dislocation loop with 1D diffusion mode. These findings not only provide necessary input to high-fidelity meso-scale simulations of microstructural evolution in these systems, but also have important implications towards explaining radiation effects influenced by the dimensionality and rates of defect diffusion.
AB - Defect dynamics constitutes the foundation for describing microstructural evolution in any material systems for nuclear applications, including body-centered cubic γ-U, Mo, and their alloys. However, defect properties and evolution, and the impact of a large atomic size mismatch between U and Mo atoms on defect dynamics have not been elucidated. In this work, we use molecular dynamics to extensively examine composition-dependent defect behavior in U-Mo alloys and the pure metals. It has been found that point defect migration is strongly correlated and mediated by minor atoms via preferential paths in alloys. Interstitial dumbbells migrate three-dimensionally through the major atoms with a preferred 〈110〉 configuration. Vacancies are less mobile than interstitials, but become comparable (one order of magnitude difference in diffusivity) in U-rich systems. Overall, compared with the pure metals, defect diffusivity can be tuned up or down based on the alloy composition. Finally, interstitial clustering is found to be unfavorable in U-rich systems, as opposed to Mo which exhibits an efficient formation of interstitial-type dislocation loop with 1D diffusion mode. These findings not only provide necessary input to high-fidelity meso-scale simulations of microstructural evolution in these systems, but also have important implications towards explaining radiation effects influenced by the dimensionality and rates of defect diffusion.
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U2 - 10.1016/j.jnucmat.2021.152893
DO - 10.1016/j.jnucmat.2021.152893
M3 - Article
AN - SCOPUS:85101797873
SN - 0022-3115
VL - 549
JO - Journal of Nuclear Materials
JF - Journal of Nuclear Materials
M1 - 152893
ER -