Inception of plasticity in copper single crystal in presence of stacking fault tetrahedra

Abstract

Atomistic simulations have been used to investigate the effect of a spatially distinct defect, i.e. stacking fault tetrahedron (SFT), on the inception of plastic deformation in a perfect copper single crystal during nanoindentation. An SFT positioned within a volume under significant stress from indentation lowers the stress required for dislocation nucleation by up to 50 from that of the perfect crystal when the nucleation event occurs at the SFT. The orientation of the SFT affects the required load for the initiation of plastic deformation and provides an envelope for the effect an SFT can have in weakening an otherwise perfect crystal. The weakening effect of the upward SFT vanishes faster than the downward SFT when it is lowered along the indentation axis. The load at the onset of plasticity changes with position, and the load drop after the inception of plastic deformation increases with SFT distance from the surface.