Effect of Vacancies on Dynamic Response and Spallation in Single-Crystal Magnesium by Molecular Dynamic Simulation

CY Jiang and ZY Jian and SF Xiao and XF Li and K Wang and HQ Deng and WY Hu, METALS, 12, 215 (2022).

DOI: 10.3390/met12020215

The effect of vacancies on dynamic response and spallation in single- crystal magnesium (Mg) is investigated by nonequilibrium molecular dynamics simulations. The initial vacancy concentration (C-v) ranges from 0% to 2.0%, and the shock loading is applied along 0001 and 10-10 directions. The simulation results show that the effects of vacancy defects are strongly dependent on the shock directions. For shock along the 0001 direction, vacancy defects have a negligible effect on compression-induced plasticity, but play a role in increasing spall damage. In contrast, for shock along the 10-10 orientation, vacancy defects not only provide the nucleation sites for compression- induced plasticity, which mainly involves crystallographic reorientation, phase transition, and stacking faults, but also significantly reduce spall damage. The degree of spall damage is probably determined by a competitive mechanism between energy absorption and stress attenuation induced by plastic deformation. Void evolution during spallation is mainly based on the emission mechanism of dislocations. The 11-22 pyramidal dislocation facilitates the nucleation of void in the 0001 shock, as well as the 1-100 prismatic dislocation in the 10-10 shock. We also investigated the variation of spall strength between perfect and defective Mg at different shock velocities. The relevant results can provide a reference for future investigations on spall damage.

Return to Publications page