Anisotropic effects in elastic and incipient plastic deformation under (001), (110), and (111) nanoindentation of Al and Cu

Atomistic simulations of (001), (110), and (111) nanoindentation are performed to investigate anisotropic effects in elastic and incipient plastic behavior under nanoindentation. We compared two materials, single-crystalline Al and Cu, focusing on the large difference between their anisotropic properties. The indent load-depth behavior of Al during elastic deformation exhibits slight anisotropy, while that of Cu varies greatly according to the indentation axis. In addition, incipient plastic deformation, that is, dislocation nucleation, depends largely on the predicted slip system. While dislocations are emitted on the surface when indented by a spherical indenter with small radius, collective dislocation emission occurs from within the material. In the case of dislocation emission within the material, the critical mean pressure, which is an important indicator of dislocation nucleation, is inherent to the indentation axis in both materials.