The effects of initial void and dislocation on the onset of plasticity in copper single crystals

Based on molecular dynamics, the effects of void and initial dislocation structure on incipient plasticity are investigated with single crystal copper samples. By introducing a void of different sizes and shapes and dislocations of different initial structures around the void in copper single crystals, we explore their effects on yielding as well as the dominated deformation mechanism. The main findings from this study are as follows: (1) for the samples with a void of the same size, the yield stress approaches to a specific value as the initial dislocation density increases; (2) for samples with a void of varying size, the yield stress becomes independent of the void size as it reaches a certain level, due to the saturation of preexisting dislocations around the void; and (3) as the strain rate increases, the effects of voids and preexisting dislocations on the yield stress become limited due to the response inertia, for which the phase transition from face-centered cubic to an amorphous phase occurs at an extremely high strain rate. Published under license by AIP Publishing