基于分子动力学方法模拟研究了含氦泡 Cu/Nb 层状材料的界面拉伸屈服强度, 考察了氦泡内压、氦泡尺寸和层厚对界面拉伸屈服强度及其变形机理的影响. 研究结果发现, 界面氦泡可以诱导界面位错成核, 改变层状材料微观演化过程, 显著降低了 Cu/Nb 层状材料的界面拉伸屈服强度. 界面拉伸屈服强度随氦泡直径增大而减小, 表现出明显的尺寸效应. 典型的 3 nm 直径的平衡氦泡使得界面拉伸屈服强度 (上屈服极限) 相对于无氦泡情况降低约 12%, 而直径为 6 nm 的平衡氦泡使得界面拉伸屈服强度下降约 33%. 研究还发现, 层厚对 Cu/Nb 层状材料的上屈服极限影响甚微, 而对下屈服极限影响显著. 前者归因于 Cu/Nb 界面的结构对称性和加载方式的对称性, 使得界面应力及位错成核应力对层厚不敏感; 后者则归因于层厚的增加给位错运动和演化提供了更大的空间, 导致应力在屈服阶段的快速下降.

The interfacial tensile yield strengths of Cu/Nb layered materials containing helium bubbles are investigated via molecular dynamics simulations. Specifically, the effects of helium bubble internal pressure, bubble size, and layer thickness on the interface tensile yield strength and deformation mechanism of Cu/Nb layered materials are investigated. Results show that interface helium bubbles can induce interface dislocation nucleation, change the microstructural evolution, and significantly reduce the interface tensile yield strength of Cu/Nb layered materials. The effect of helium bubbles on the interface tensile yield strength weakens as the helium bubble size increases resulting in apparent size effect. Compared with the case without helium bubbles, the interface tensile yield strength reduced by approximately 12% and 33% for the models containing 3 and 6 nm helium bubbles, respectively. Additionally, the layer thickness minimally affects the upper yield stress of the Cu/Nb-layered materials, whereas it significantly affects the lower yield stress. The former is attributed to the structure symmetry of the Cu/Nb interface and the loading symmetry, which render the interface stress and dislocation nucleation stress insensitive to the layer thickness. The latter is due to the increased layer thickness, which provides more space for dislocation motion and evolution, thus resulting in rapid stress reduction during the yield period.