Phase transition in shock compressed high-entropy alloy FeNiCrCoCu

High-entropy alloys (HEAs) show promising prospects to be extensively applied as functional and structural applications. Nevertheless, due to technical limitations in real-timely detecting microstructural evolution at the atomic level, an in-depth understanding with regard to dynamic deformation mechanisms is still limited. In present work, nonequilibrium molecular dynamics simulations were performed to investigate the shock-induced phase transition for the equiatomic FeNiCrCoCu HEA in terms of the crystallographic direction and shock velocity. The face-centered cubic to body-centered cubic phase transition due to uniaxial compression and lattice rotation was demonstrated to be prone to appearing for shock along the [001] orientation. This behavior was conducive to activating dislocation nucleation to release shear stress. More importantly, a shift from a dislocation-dominated deformation to a phase-transition-dominated one with the increase in shock velocity was corroborated to facilitate the swift stress relaxation at higher strains, contributing to the attenuation of the shock wave and thereby weakening the shock damage. These outcomes render valuable insights into understanding the dynamic deformation behavior of the FeNiCrCoCu HEA.