Crystallization of amorphous materials and deformation mechanism of nanocrystalline materials under cutting loads: A molecular dynamics simulation approach

Abstract

The crystallization of amorphous and cutting process of nanocrystalline copper was investigated by the use of a molecular dynamics (MD) simulation. Stress-induced crystallization of amorphous in cutting process was observed. By the common neighbor analysis (CNA), it was found that nuclei were first formed in the larger stress region around the rake face and tip of the tool and then they grew quickly under stress. The growth and consolidation process of grains was analyzed, using relative atomic displacement vector method. When grains grew in contact with each other, a merger occurred. Grains were combined firstly in a local area, and rotated to discharge the excess free volume out of boundaries before the merging process completed. Through calculating the shear strain of atoms in the cutting process, the serrated chips and four shear bands were observed clearly. The radius distribution function (RDF) curve of the shear band shows that the cutting of crystalline was carried out in the amorphous state. The shear angle of less than 45° was observed in the simulation, which is consistent with the experiments reported and validates the simulation results in this paper.