晶体弹塑性接触的微观机制  

MICRO-MECHANISMS OF ELASTO-PLASTIC CONTACT FOR CRYSTALS

作　　者：冷永胜[1] 胡元中[1] 郑林庆[1] 杨桂萍[2] 

机构地区：[1]清华大学 [2]北方工业大学

出　　处：《材料研究学报》1997年第3期267-274,共8页Chinese Journal of Materials Research

基　　金：国家自然科学基金!59605005;清华大学摩擦学国家重点实验室开放基金

摘　　要：用分子动力学和金属固体的镶嵌原子模型（Embedded－atommethod）研究了fcc晶体Cu探针一基体微观接触的加载一卸载规律、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理论断裂强度当探针趋近量δ大于临界值δε后，材料出现塑性失稳．原子轨迹显示，（010）面原子发生［010］方向的穿层运动．探针与基体分离（卸载）时出现较大的粘着力，基体内部产生空洞，表面形成原子台阶.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.

关 键 词：分子动力学 镶嵌原子模型 弹塑性接触 晶体 

分 类 号：O76[理学—晶体学]