Molecular dynamics simulation on formation mechanism of grain boundary steps in micro-cutting of polycrystalline copper
Molecular dynamics simulation on formation mechanism of grain boundary steps in micro-cutting of polycrystalline copper
复制标题
多晶铜微切削晶界台阶形成机制的分子动力学模拟
DOI：
10.1016/j.commatsci.2016.10.001
复制
发表时间：
2017-01-01
影响因子：
3.3
通讯作者：
Rong, Yiming (Kevin)
中科院分区：
文献类型：
--
作者：
Liu, Dehao;Wang, Gang;Rong, Yiming (Kevin)
采用三维分子动力学方法研究了多晶铜微切削过程中晶界（GB）步骤的形成机理。研究了GB和取向角对表面质量的影响。模拟结果表明，由于晶界台阶的形成，多晶铜的表面最大峰谷高度大于单晶铜。在刀具-工件界面上连续形核的位错被停止并堆积在GB处。当位错在晶界处堆积时，位错排列并形成亚晶界，使系统总能量最小化。在多晶铜微切削过程中，由于切削刃的犁耕和晶体的旋转，在晶界处形成了具有过渡晶向的亚晶粒。亚晶与原晶在滑移方向上的错位导致了晶界台阶的产生。在多晶切削过程中，由于几何硬化效应，切削力在晶界处出现峰值。结果表明，在微切削过程中，GB对工件的表面质量有很大的影响。(C) 2016 Elsevier B.V.版权所有
Three-dimensional molecular dynamics (MD) simulations were performed to investigate the formation mechanism of grain boundary (GB) steps in the micro-cutting of polycrystalline copper. The effects of the GB and misorientation angle on the surface quality were studied. Based on the simulation results, the surface maximum peak-to-valley height of polycrystalline copper was greater than that of single crystal copper owing to the formation of grain boundary steps. The dislocations continuously nucleated on the tool-workpiece interface were stopped and piled up at the GB. As the dislocations piled up at the GB, the dislocations became aligned and formed the sub-grain boundary to minimize the total system energy. Sub-grains with transitional crystal orientations formed at the GB during the micro-cutting of polycrystalline copper for the plowing of the cutting edge and crystal rotation. The misalignment in the slip directions between sub-grains and original grain resulted in the grain boundary step. A peak cutting force appeared at the GB in the cutting of polycrystalline owing to the geometrical hardening effects. It is revealed that the GB has a strong effect on the surface quality of a workpiece during the micro-cutting process. (C) 2016 Elsevier B.V. All rights reserved.