Mechanism of interaction between dislocation and {112¯1} twin boundary upon shear loading

•The -{112¯1} interaction is the dissociation of M dislocation into M, T dislocations and steps.•High shear strain forms at the step/ dislocation and TB junction region in the twin.•High energy immobile step and dislocation pinning cause the strain concentration. In this work, the -{112¯1} TB interaction mechanism and the interaction induced strain localization are investigated via molecular dynamics (MD) simulations. Results show that the interaction mechanism is sessile dislocation in the matrix dissociating into mobile dislocation, mobile twinning dislocation (TD) b⇀2/2112¯1, new dislocation within the twin, and immobile high-level step pairs. The immobility of the dislocation and the high potential energy of the immobile steps pairs cause the high shear strain banding region within the twin, which acts as the source of strain localization. This work provides an in-depth understanding of the interaction mechanisms between dislocation and {112¯1} twins in Ti alloys, and offers several potential approaches for the weakening of strain concentration.