Defect dynamics in γ-U, Mo, and their alloys

JOURNAL OF NUCLEAR MATERIALS

卷:549

Article

Jin, Miaomiao¹  Gao, Yipeng²  Jiang, Chao²  Gan, Jian² 

[1] Penn State Univ, Dept Nucl Engn, 205 Hallowell Bldg, University Pk, PA 16802 USA

[2] Idaho Natl Lab, 2525 Fremont Ave, Idaho Falls, ID 83402 USA

关键词: Defects;    radiation damage;    molecular dynamics;    uranium;    molybdenum;   

DOI  :  10.1016/j.jnucmat.2021.152893

来源: Elsevier

【 摘 要 】

Defect dynamics constitutes the foundation for describing microstructural evolution in any material sys-tems for nuclear applications, including body-centered cubic gamma-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 exam-ine 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 al-loys. 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 magni-tude 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 un-favorable 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 implica-tions towards explaining radiation effects influenced by the dimensionality and rates of defect diffusion. (C) 2021 Elsevier B.V. All rights reserved.

【 授权许可】

Free