Molecular dynamics simulation of plasticity in VN(001) crystals under nanoindentation with a spherical indenter

We perform molecular dynamics simulations of the nanoindentation on VN (001) films with a spherical indenter to elucidate the initial plastic deformation and the formation mechanisms of dislocation loops during nanoindentation. We find that the nucleation and movement of partial dislocations are the main mechanism of the inelastic deformation at the initial plastic stage of nanoindentation, when the dislocation-flower consisting of several {111} stacking fault planes and the (110) stair rod dislocation lines are observed. With the increase in indentation depth, the newly nucleated dislocations react with the existing ones, forming four kinds of dislocation loops. Moreover, we also conduct a systematic analysis of the formation process of the dislocation flower and the four kinds of dislocation loops. (C) 2016 Elsevier B.V. All rights reserved.