Effect of nanopores on plasticity and their collapse mechanism in magnesium single crystal under shock loading

Abstract

The influence of defects on the plastic properties of materials always captures much attention for ultrahigh strain-rate loading. By virtue of the planar shock compression in [0001], [101¯0], and [1¯21¯0] directions, our large-scale molecular dynamics simulations reveal that the prismatic nanopores facilitate the inelastic deformation, such as basal and prismatic glides, reorientation, and amorphization. And that, the nanopores with different center axial directions contribute to activation of various slip systems, such as basal and prismatic dislocation slip. The inelastic deformation induced nanopore collapse is an important mechanism of nanopore collapse at weak shock intensity. Three modes of collapse are obtained: a transverse and a longitudinal collapse from the basal glide, and an inclined collapse from the amorphization at the tip of the prismatic nanopore. The shear stress is highly concentrated at the elastic region about to be plastic deformation, and then attenuates mainly during inelastic deformation and nanopore collapse. The shock energy dissipation is correlated to the conversion between kinetic energy and internal energy, which leads to a higher local temperature around the prismatic nanopore.