分子动力学模拟金属玻璃Cu应力晶化的应变率效应

采用Mishin镶嵌原子势，通过分子动力学方法模拟了零温下非晶金属Cu在不同应变率条件下的拉伸变形过程和应力晶化行为，分析了此过程中原子体系应力与结构组态的变化．结果表明：在应变率10^8s^-1-10^9s^-1范围内，金属玻璃Cu的塑性流动应力随着应变率的提高而增大，弹性模量约为55GPa．在塑性流动过程中发生应力晶化现象，伴随着明显的晶核形成与生长过程，晶化程度随着应变率的增加而加剧．应力效应和温度效应都是导致金属玻璃晶化的重要途径，形成的少量纳米晶粒是导致剪切带的形成和扩展的可能因素．

Molecular dynamics simulation of strain rate effect on stress induced crystallization for metallic glass Cu

The tensile deformation and stress induced crystallization behavior of metallic glass Cu was investigated under uniformly distributed strains with different rates at 0 K temperature using molecular dynamics simulations. The variation of the atomic stress and structure in the system during tensile process was analyzed. The results show that the Young modulus is about 55 GPa and the higher flow stress occurs at higher strain with the strain rate increasing in the range 10^8s^-1 to 10^9 s^-1. The metallic glass Cu sample shows transforms continuously from the amorphous phase to a crystalline phase during plastic flow. It was observed that the nucleation, growth processes of crystal were induced by stress and more crystal phase was found at lower strain rate. The stress effect is an important factor that induces metallic glass crystallization just like temperature effect. The formation of little nanocrystal is the possible reason of formation and development of shear bands.