Molecular Insight into the Deformation of Single Crystal Copper Loaded by High-Speed Shock Wave

Abstract

Molecular dynamics simulations were performed to study the evolution of single crystal copper with and without a nanovoid (located at the middle of crystal with a diameter of ~2.9 nm) when loaded with shock waves of different velocities. The simulation results show that the average particle velocity of single crystal copper linearly relates to the velocity of the loaded shock wave for both the systems (crystal with and without a nanovoid). When loaded by the shock wave, the equilibrated temperature and pressure of the system with a nanovoid are found to be slightly larger than those of the system without the nanovoid, while the volume of the system with the nanovoid is found to be lower than that of the void-free system. The single crystal copper undergoes a phase transition from face-centered cubic (FCC) to hexagonal-close packed (HCP) and a dislocation structure forms around the nanovoid. The existence of a nanovoid can induce the rearrangement and deformation of the crystalline structure and eventually lead to the plastic deformation of the system. This work provides molecular-level insight into the effect of nanovoids on the shock plasticity of metals, which can aid in the ultimate application of the control of material structure damage in shock-wave propagation.