Atomic-scale insight into interaction mechanism between screw dislocation and HCP phase in high-entropy alloy

Abstract

The face-centered cubic (FCC)/hexagonal close-packed (HCP) dual-phase structure is a new design strategy proposed in recent years to achieve high strength and excellent plasticity of high-entropy alloys (HEAs). Here, the effect of HCP phase thickness, strain rate, and temperature on the interaction mechanism between screw dislocation and the HCP phase in the FCC structured CoCrFeMnNi HEAs is investigated by molecular dynamics simulation. The results show that there are two types of interaction modes between dislocations and the HCP phase: one is the dislocation passing through the HCP phase, that is, the penetration mechanism, and the other is the dislocation being absorbed by the HCP phase, that is, the absorption mechanism. The generation of these two mechanisms mainly depends on the relative ability of the HCP phase to prevent dislocation slip, which is closely related to the HCP phase thickness, strain rate, and temperature. When the relative ability of the HCP phase to block dislocation is large, the interaction between dislocations and the HCP phase presents an absorption mechanism; otherwise, it presents a penetration mechanism. The research can provide theoretical guidance for the development and design of new high-performance HEAs to achieve high strength and high ductility of materials.