Molecular dynamics simulation on formation mechanism of grain boundary steps in micro-cutting of polycrystalline copper

DH Liu and G Wang and JC Yu and Y Rong, COMPUTATIONAL MATERIALS SCIENCE, 126, 418-425 (2017).

DOI: 10.1016/j.commatsci.2016.10.001

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.

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