应变率诱发镍纳米丝的非晶化

采用镶嵌原子法(EAM)作用势对镍纳米丝的拉伸过程进行了分子动力学模拟. 体系施加应变率范围在5×10^7 - 1×10^10 s^-1, 观察体系的应力-应变曲线、平均原子能量、原子轨迹, 偶相关函数随应变率的变化. 发现当应变率低于1×10^8 s^-1时, 体系发生塑性变形, 最终颈缩断裂, 偶相关函数表明体系一直保持晶体结构; 而当应变率高于1×10^9 s^-1时, 体系发生了由晶体向非晶的持续转变, 偶相关函数出现了典型的非晶峰, 高应变率诱发了Ni纳米丝的非晶化.

Amorphization of Ni Nanowires Induced by Strain Rate

Molecular dynamics simulations were performed for studying mechanical properties of nickel nanowires subjected to uniaxial strain using embedded atommethod (EAM) potential. Strain rates applied in the simulations ranged from 5×10^7 s^-1 to 1×10^10 s^-1. The stress, the average atomic energy, the pair correlation function, as well as the transient atomic images of the systems were presented to explore the strain rate dependence of structure of nanowires. It was found that as the strain rates applied to the system were lower than 1×10^8 s^-1, the nanowires underwent plastic deformation and kept crystal structure before fracture during the process of tensioning state, which was testified clearly by the pair correlation function. While as strain rates were higher than 1×10^9 s^-1, the nanowires changed continuously from crystalline structure to amorphous phase and the pair correlation function also exhibited the characteristics of typical amorphous peaks. Amorphization of Ni nanowires was induced under high strain rates.