Amorphization transformation in high-entropy alloy FeNiCrCoCu under shock compression

High-entropy alloys (HEAs) possess immense potential for structural applications due to their excellent mechanical properties. Deeply understanding underlying deformation mechanisms under extreme regimes is crucial but still limited, due to the restrictions of existing experimental techniques. In the present study, dynamic deformation behaviors in equiatomic FeNiCrCoCu HEAs were investigated in terms of various shock velocities through nonequilibrium molecular dynamics simulations. The amorphous atoms by amorphization transformation were corroborated to be conducive to dislocation nucleation and propagation. Also, the dominant plasticity pattern was confirmed to be taken over by amorphization under higher velocities, while dislocation slips merely prevailed for lower shock ones. More importantly, for a shock velocity of 1.4 km/s, multi-level deformation modes appearing in deformation, first amorphization and then a combination of amorphization and dislocation slip, was demonstrated to substantially contribute to the shock wave attenuation. These interesting findings provide important implications for the dynamic deformation behaviors and corresponding mechanisms of the FeNiCrCoCu HEA system.