Spalling Characteristics Associated with Shock-Induced Microstructure Based on Molecular Dynamics Simulation of Single-Crystal Aluminum

This Letter reports an anomalous discontinuous variation in spall strength associated with shock-induced microstructure. It is known that elastic deformation, dislocation and stacking fault, and shock FCC-BCC phase transition will appear in turn with the increase of shock intensity. Our molecular dynamics simulations of single-crystal aluminum reveal that the damage evolution during release process may show an evident dependence on the shock-induced microstructure. The nanovoids nucleate homogeneously in the region of elastic deformation or phase transition, resulting in higher spall strength. However, the nanovoids nucleate heterogeneously in the region of dislocation and stacking fault, which leads to a sudden decrease in spall strength. This anomalous change is accompanied by a higher temperature rise, and we find that both homogeneous and heterogeneous nucleation satisfy the same spall strength-spall temperature relationship.