Atomistic simulations reveal slip selection in B2-type intermetallic alloys

Abstract

Slip system selection in B2 intermetallics remains poorly understood, despite its critical role in governing their ductility—an essential property in shape memory and refractory high-entropy alloys. In this work, we investigate the atomistic mechanisms controlling slip activation in B2 phases by combining density functional theory with molecular dynamics simulations. First, we benchmark several interatomic potentials against DFT calculations to ensure accurate modelling of dislocation behaviour. Using the validated potentials, we analyse dislocation core structures and their mobility at both T=0 K and finite temperatures in three representative B2 alloys: NiAl, CoTi, and FeAl. Our results reveal that slip system activation is governed by a competition between dislocation core energy and critical resolved shear stress. Based on these findings, we propose a slip selection criterion grounded in minimising the plastic work. This framework captures the observed slip behaviour and aligns with experimental trends, offering a pathway to design B2 alloys with improved ductility.