晶体弹塑性接触的微观机制

用分子动力学和金属固体的镶嵌原子模型研究了ｆｃｃ晶体Ｃｕ探针－基体微观接触的加载卸载规律、系统能量特性、基体微观应力场分布以及塑性失稳的缺陷形成机制。计算结果显示，在表面开始接触时，存在不稳定的突然粘着接触（ｊｕｍｐ－ｔｏ－ｃｏｎｔａｃｔ）。在压入状态（ｉｎｄｅｎｔａｔｉｏｎ）晶体的原子应力分布与宏观Ｈｅｒｔｚ理论的应力场相似。对弹性卸载，探针－基体分离的粘着拉应力接近Ｇｒｉｆｆｉｔｈ理论断裂强度

MICRO-MECHANISMS OF ELASTO-PLASTIC CONTACT FOR CRYSTALS

Molecular dynamics(MD) and the embedded atom method(EAM) were used to simulate(FCC) Cu tip-to-substrate (a 3.4nm crystal slab) contact at 0.1K via NVT ensemble. Both the load-ing-unloading cycle and the potential energy of the system vs the tip approach were investigated. The atomistic stress fields in elastic contact were calculated by the lattice dynamics theory. On the other hand, for plastic indentation, we observed the plastic instability of the substrate when the tip approach was beyond some critical value. The voids initiation mechanisms were depicted through the atomic trajectories and con-figurations. The crystal defects after plastic indentation incIuded substrqte cavities, atomic steps and plastic indent.