基于分子动力学的纳米压痕形变过程模拟

采用分子动力学方法模拟了金刚石压头压入Fe基体的纳米压痕全过程．研究了加载和卸载时基体的原子组态、载荷一位移曲线以及位错的发射和变化．分析了基体的塑性形变机理．发现压人深度为0．69nm时出现位错．随压入深度的增加位错长大成环，基体塑性形变加剧．卸载过程中位错环不断减小，当压头恢复到起始位置后，基体中心残留有位错环，产生了永久塑性形变，位错环的存在是基体产生永久塑性形变的关键因素．

Molecular dynamics simulation of plastic deformation during nanoindentation

Molecular dynamics simulation was performed to study the nanoindentation process of a hard diamond tip into an Fe substrate.The atomic configuration of the substrate,the load-displacement curve,and the emission and variation of dislocations during loading and unloading processes were investigated.The plastic deformation mechanism of the substrate was discussed.It is found that during the loading process,the dislocation occurs when the indentation depth is about 0.69 nm;with the indentation depth increasing,the dislocation grows up into a dislocation loop and the plastic deformation of the substrate becomes more severe.During the unloading process,with the decrease of indentation depth,the number of dislocation loops decreases continuously;when the indenter returns to its starting position,there are still a small amount of dislocation loops in the center of the substrate,and this is the main reason for the permanent plastic deformation of the substrate.