Effects of shear strain on shock response in single crystal iron

Abstract

With large-scale non-equilibrium molecular dynamics simulations and in situ x-ray diffraction analysis, we conducted a systematic investigation into the effects of pre-existing shear strain (γxy) on the shock response of single crystal iron. Our findings reveal significant effects of γxy on the deformation of the crystal structure during shock loading, leading to noticeable alterations in the propagation of shock waves. Specifically, during the elastic stage, the presence of γxy results in a reduction of shock strength, consequently diminishing the magnitude of elastic lattice strain (εe). In the plastic stage, γxy stimulates the α–ε phase transformation, and structure deformation undergoes a transition from the sequential activity of dislocation-to-transformation to the synchronous activity of dislocation and transformation. This transition inhibits the propagation of plastic waves and consequently broadens the elastic regime. Additionally, the introduction of γxy activates different slip systems, as it alters the corresponding resolved shear stress. Concurrently, the presence of γxy triggers the activation of different high-pressure phase variants. Our investigation sheds light on the fundamental physics of iron under shock compression and the influence of pre-existing shear strain on its behavior.