Shock consolidation and the corresponding plasticity in nanopowdered Mg

Nanopowder consolidation under high strain rate shock compression is a potential method for synthesizing and processing bulk nanomaterials. A thorough investigation of the shock deformation of powder materials is of great engineering significance. Here we combine nonequilibrium molecular dynamics (NEMD) simulations and X-ray diffraction (XRD) simulation methods to investigate the deformation twinning and pore compaction in shock-compressed np-Mg. Significant anisotropy and strong dependence on crystallographic orientation are presented during shock-induced deformation twinning. During the shock stage, three typical types of twins were firstly induced, namely {11-21} twin (T1), {11-22} twin (T2) and {10-12} twin (T3). Most of them were generated in grains with a larger angle between the impact direction and the c-axis of the lattice. With the increase in strain rate, the types and quantities of twins continued to enrich, but they did not occur when the strain rate was too high. We also discussed the deformation mechanisms of the three types of twins and found that the coupling of slip and shuffle dominated twin deformation. In addition, void filling occurred due to the interaction of twinning and other plastic deformations, leading to the densification of np-Mg. During the release stage, an interesting reverse change was observed, where the twins produced by the impact receded, and twins were produced in grains that were previously difficult to produce.