Atomistic simulations on the dynamic properties of shock and release melting in single crystal Al

Molecular dynamics simulations are performed to investigate the dynamic properties of melting in single crystal Al under [0 0 1] shock loading and release. Our simulations suggest that the shock melting can be accompanied with shuffle mechanism and especially with collision cascade. The overheated interval and the relaxation of shear stress below and above shock melting pressure are presented by the microstructure and dynamic paths. The Hugoniot results can describe the shocked solid, liquid and also solid-liquid phases, and the range of shock melting pressure is about 125–155 GPa. From different release paths, we observe the transition from surface melting to sustained release meting. The shock pressure leading to melt at release is about 72 GPa. For higher shock pressure, the melting speed will keep some constant after the early nucleation. In fact, the release melting involve both the solid-liquid interface movement and the continuous nucleation in front of it. Finally, we present the different release P-T paths (solid-solid, solid-liquid and liquid-liquid) to show the difference of melting near and far away from the free surface.