Temperature-dependent mechanisms of dislocation–twin boundary interactions in Ni-based equiatomic alloys

Abstract

The high entropy alloy FeNiCoCrMn and its subsets have exhibited an unusual combination of strength and ductility dependance on temperature, showing a significant increase in ductility as temperature decreases. This phenomenon is intriguing, and the underlying mechanism is critical for understanding the mechanical properties of these materials. Here, we investigate the interaction between a screw dislocation and a coherent twin boundary in Ni-based equiatomic alloys using atomistic simulations. We find that the dominant mechanism for this interaction changes as a function of temperature, which could be one of the underlying causes of the enhanced ductility at cryogenic temperatures in these alloys. Further investigations reveal the interaction's temperature dependence arises from a critical parameter related to the stacking fault energy and the distance between the Shockley partial dislocations. The insights extracted herein contribute to a fundamental understanding of plastic deformation in Ni-based equiatomic alloys and can be utilized for developing design strategies to achieve superior strength and ductility in structural materials.