nergy Landscape for Screw Dislocation in Body-Centered Cubic Binary and Ternary Subsystems of MoNbTaW

Refractory high-entropy alloys (RHEA) exhibit high strength and compressive ductility at elevated temperatures. However, their engineering application is limited by their brittle failure modes under tension. The plastic deformation behavior of RHEAs may be closely linked to the energetics of screw dislocation cores, which depend on local chemical environments. Recent work has shown that, in contrast to pure metals, chemically disordered MoNbTaW exhibits a rough landscape of screw dislocation core energies, but the energy fluctuations are decreased by the formation of local chemical order. It is unclear, however, the extent to which these effects are related to the “high-entropy” nature of the system. We thus compare the dislocation core energetics of MoNbTaW and its binary and ternary subsystems. Using a machine learning interatomic potential, we calculate the dislocation energy landscapes in random and equivalently short-range ordered alloys. Results suggest that the specifics of the ordering phase transition are more important than the number of components.