Unveiling mechanisms of self-healing in CoCrFeMnNi/HfNbTaTiZr dual-phase high-entropy alloys: A molecular dynamics simulation study

Abstract

This study investigates the mechanical properties and self-healing behavior of FCC CoCrFeMnNi/BCC HfNbTaTiZr dual-phase high-entropy alloy (DP-HEA) multilayers using molecular dynamics simulations. The relaxed DP-HEA multilayers have low hexagonal close-packed (HCP) percentages and decreasing "Other" fractions with increasing thickness. DP-HEA multilayers exhibit ductile behavior under uniaxial tensile loading, with stress increasing linearly until the yield strain and then gradually decreasing. Dislocation motion, twinning in the FCC phase, and BCC to HCP local structural transformation contribute to this behavior. Single crystal FCC CoCrFeMnNi and BCC HfNbTaTiZr alloys show different stress-strain responses, while DP-HEAs exhibit no significant stress drop beyond the ultimate strain. Self-healing is observed in DP-HEAs with 5 and 10 nm thickness, with a transformation from HCP to BCC structures. The DP-HEA with 15 nm thickness shows less pronounced self-healing. The interlayer distance between BCC/FCC interfaces influences the self-healing ability of the BCC phase. These findings enhance our understanding of the mechanical behavior and self-healing mechanisms in DP-HEA multilayers, facilitating the design of advanced materials with improved properties.