Molecular dynamics simulation on burst and arrest of stacking faults in nanocrystalline Cu under nanoindentation

Nanoindentation induces versatile deformation mechanisms. The situation is examined here for the case of nanocrystalline Cu by means of parallel molecular dynamics simulations. The indenter is applied to the grain boundary (GB) or to the grain interior. The inter-atomic interaction of Cu is modelled by both the Lennard-Jones potential and the embedded atom method potential. The burst and arrest of stacking faults hold the key for the plastic deformation of nanocrystalline Cu under nanoindentation, in clear contrast to the case of nanoindentation on single-crystal Cu. The following descending order of indentation resistance is found: single crystal (or polycrystal of large grain size), nanocrystal when indented on the grain interior, and nanocrystal indented on the GB.