• Diffuse γ/γ′ interfaces lower the critical stress for paired dislocation transmission; • Nonlinear GSF coupling introduces jerky glide and new interfacial energy barriers; • 2CSF + APB superdislocations form when stress highly outweighs interfacial GSF barrier; • Dislocation pile-ups and transmission are governed by elastic, GSF and load interplay. Compositional and structural heterogeneities at interphase interfaces modify the local generalized stacking fault (GSF) energy, thereby influencing the slip behavior of dislocations across these interfaces. Phase-field dislocation dynamics simulations reveal that in nickel-based superalloys dislocations in the γ matrix traverse the γ / γ ′ interface in paired configurations once a critical applied stress is reached. This critical stress decreases with increasing interfacial width, corresponding to a more diffuse interface characterized by a smoother gradient in GSF landscape. Introducing a nonlinear coupling term into the interfacial GSF energy creates an additional energy barrier that alters the local displacement transmission pathway, leading to a distinctive jerky dislocation glide across the interface. With continuous dislocation emission from the matrix, long-range elastic interactions, interfacial energy barriers and external loading govern dislocation pile-ups at and transmission across the interface, resulting in the formation of various dislocation configurations within the γ ′ phase. A relatively high applied stress combined with a low interfacial barrier promotes the formation of a 2CSF (complex stacking fault) + APB (antiphase boundary) superdislocation, whereas the opposite conditions favor isolated APBs. These results underscore the potential of interface engineering to control dislocation behavior in γ ′ -strengthened superalloys through precise tailoring of the local interfacial GSF landscape.
Qiu et al. (Sat,) studied this question.