关键词: U-Mo alloy, molecular dynamics simulation, plastic deformation mechanism, dislocation slip, twin formation

Abstract: Uranium-molybdenum (U-Mo) alloys are critical for nuclear power generation and propulsion because of their superior thermal conductivity, irradiation stability, and anti-swelling properties. This study explores the plastic deformation mechanisms of $\gamma $-phase U-Mo alloys using molecular dynamics (MD) simulations. In the slip model, the generalized stacking fault energy (GSFE) and the modified Peierls-Nabarro (P-N) model are used to determine the competitive relationships among different slip systems. In the twinning model, the generalized plane fault energy (GPFE) is assessed to evaluate the competition between slip and twinning. The findings reveal that among the three slip systems, the {110}$\langle 111\rangle$ slip system is preferentially activated, while in the {112}$\langle 111\rangle$ system, twinning is favored over slip, as confirmed by MD tensile simulations conducted in various directions. Additionally, the impact of Mo content on deformation behavior is emphasized. Insights are provided for optimizing process conditions to avoid $\gamma \to \alpha''$ transitions, thereby maintaining a higher proportion of $\gamma $-phase U-Mo alloys for practical applications.

Key words: U-Mo alloy, molecular dynamics simulation, plastic deformation mechanism, dislocation slip, twin formation