The effects of Escaig stress and solution concentration on the interaction between screw dislocation and coherent twin boundary in random alloys

Abstract

The effect of Escaig stress as well as the solution concentration on the interaction between screw dislocation and coherent twin boundary (CTB) in random Ni–Co alloys is investigated using molecular dynamics (MD) simulations. Our results show that Co concentration would promote the screw dislocation-CTB reaction from absorption to transmission. And Escaig stress can influence the critical interaction shear stress (CISS) depending on its magnitude and direction, even changing the mode from transmission to absorption, which is not recognized before. Such phenomenon is well interpreted by modifying the traditional criterion through considering the differences between the average stacking fault energy (SFE) and elastic repulsion within the dislocation, which suggests that the repulsion under specific Escaig stress can better assess the reaction mechanism. Our results provide new insights in understanding the high-strength properties of nanotwinned face-centered cubic (FCC) metals or alloys.