Orientation effects on shock-induced plastic deformation in FeNiCoCu high entropy alloy

FeNiCoCu high-entropy alloys (HEAs) demonstrate promising potential for widespread use in structural and functional applications. However, a thorough understanding of dynamic deformation processes in FeNiCoCu HEA is limited due to technological constraints in detecting real-time microstructural developments at the atomic level. This study examines the shock-induced plastic deformations in the equiatomic FeNiCoCu HEA, focusing on crystallographic orientation and particle velocity, using nonequilibrium molecular dynamics simulations. We obtained the P-V/V0, P-T, P-Up, and Us-Up Hugoniot relations and evaluated their anisotropy. The shock velocity, stress, and shear stress exhibit orientation dependence due to the differences in the plastic deformation mechanism. For shock loading along [100] orientations, dislocation dominates at lower shock intensities. However, a phase transition from face-centered-cubic (FCC) to body-centered-cubic becomes the primary plastic deformation at high shock intensity. For shock loading along [ 11 2 <overline> ] and [111] orientations, the generation of disordered structures and dislocation activities is revealed to play an important role in the development of localized plastic deformation. Moreover, the competition of disordered and hexagonal-close-packed (HCP) atoms is observed. The transition from FCC to disordered atoms provides nucleation sites for dislocations, and the slip of dislocations around disordered atoms leads to the formation of HCP structures. These findings are very helpful for learning the dynamic deformation behavior of FeNCoCu HEA.