Atomic-scale investigations on the interaction mechanisms of dislocations with _1121 and _1122 twinning

H Zhang and K Rao and YHZ Li and HZ Cui and S Ni and FY Liu and J Xiong and J Gu and M Song, INTERNATIONAL JOURNAL OF PLASTICITY, 193, 104430 (2025).

DOI: 10.1016/j.ijplas.2025.104430

The interaction mechanisms of dislocations with (_)1121 and (_)1122 twin boundaries (TBs) were systematically investigated at the atomic-scale in pure Ti via molecular dynamics (MD) simulations and transmission electron microscopy (TEM) characterizations. Results reveal that under pure shear loading, dislocations dissociate into dislocations, twinning dislocations (TDs)b(2/2) ((_1121)), and an interfacial defect b(10/12)((_1121)), or into sessile dislocation with TDs b(1/1)((_1121)) and b(3/3) ((_1121))at migrating (_)1121 TBs, while interactions of dislocation with (_)1122 TBs produce dislocations and TDs b1/1((_1122)) and b(3/3)((_1122)). The introduction of normal stress perpendicular to TBs generates shear stress components in the basal slip system, promoting basal dislocation formation to alter interaction mechanisms. Stress evolution arises from localized stress transfer from dislocations to reaction products, where pure shear retains residual stresses in interfacial defects (increasing fracture risks), while normal stress mitigates stress concentration at TBs by modifying dissociation pathways. TEM characterization confirms the interface defect configurations, validating the proposed mechanisms. This work provides atomic-level insights into -TB interactions and establishes a theoretical foundation for regulating dislocation- twin dynamics in alpha-Ti alloys, emphasizing the critical role of stress- state control in optimizing the mechanical performance

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