Interaction between Dislocation and Twinning Boundary under Incremental Loading in α-Titanium**Supported by the National Key R&D Program of China under Grant No 2017YFA0303603, and the National Natural Science Foundation of China under Grant Nos 11474207 and 11774248.

Abstract

The lattice dislocation interacting with grain boundary in the polycrystal exerts an evident influence on the materials’ strength and toughness. A comprehensive study regarding the dislocation–twinning boundary (TB) interaction in α-titanium and TB migration is performed by employing molecular dynamic simulation. We analyze the interactions between dislocation and TB, under the conditions of plastic deformation and thermal stress, including the interaction between pure edge ⟨a⟩ dislocation and TB and the interaction between mixed type ⟨a⟩ dislocations and TB at 10 K/300 K. The ⟨c + a⟩ pyramidal transmitting slip mode is motivated in the case of edge dislocation– interaction at 300 K and then transforms into basal-dissociated dislocation after experiencing the complex dissociation and combination. The basal-dissociated pyramidal partial dislocation located in the second grain can be driven to penetrate through the second grain leaving the multiple stacking faults behind. Dissociation of incident basal dislocation on TB results in a nucleation of a twin embryo in twin crystals at room temperature. We determine the nature of the generated defects by means of the Burgers circuit analysis.