Solid-liquid phase transitions in single crystal Cu under shock and release conditions

Abstract

Solid-liquid phase transitions in single crystal Cu during shock and subsequent release are studied with large-scale classical molecular dynamics simulations. During shock compression, although the equilibrium states far behind shock front converge to the same Hugoniot, the pathways from metastable states right behind the shock front to the final equilibrium states and the resulting microstructures are orientation-dependent. Premelting is followed by recrystallization of supercooled melt into a polycrystalline solid for the [110] and [111] shocks, and a superheated, more ordered, solid is observed prior to shock melting for the [100] shock. The differences in the microstructure in the behind-shock region in turn give rise to different release melting behaviors (including premelting and superheating) along different release paths for these loading orientations.