单晶铜纳米黏着接触与分离过程的接触力分析

Analysis the Nano Contact Force of Single Crystal Copper in Contact and Separation Processes

在考虑黏附力和单晶铜弹塑性变形基础上,基于EAM和Morse势函数和Verlet算法动态模拟了金刚石压头与单晶铜纳米黏着接触与分离过程。研究表明:压头尚未接触基体时,压头与基体之间作用力主要表现为引力,基体最上层原子易与压头原子发生"突跳"黏着接触现象;继续下移时,接触力随压头位移增大而呈增加趋势,且基体被压正下方不断发生位错原子堆积现象;压头与基体分离中,接触力与压头位移曲线呈锯齿状减小趋势,并且分离过程位移对应于黏着下压接触位移发生明显的黏着滞后现象;分离后,部分原子被黏附于压头底表面,基体已发生明显的塑性变形。

On the basis of considering the adhesive force and copper substrate elastic-plastic deformation, the contact and separation processes between diamond indenter and copper substrate are simulated based on EAM and Morse potentials and Verlet algorithm. The results show that, when diamond indenter approaches slowly to copper substrate during the contact process, some atoms at the top level of substrate happened 'snap back' phenomenon significantly due to the gravity became the main interaction force. Furthermore, it can be seen that the contact force and the accumulation phenomenon of dislocation atoms increase gradually with the increment of diamond displacements. During in separation process, the contact force decreases continuously with the declines of diamond indenter, the adhesive hysteresis phenomenon and some atoms adhered to the surface of diamond indenter can be seen obviously after separation absolutely.