Transportation of dislocation plasticity in a dual-phase TiMo alloy.

Understanding the coordinated deformation of multiple phases under applied stress is crucial for the structural design of dual-phase or multiphase advanced alloys. In this study, in-situ transmission electron microscope tensile tests were performed to investigate the dislocation behaviors and the transportation of dislocation plasticity during the deformation of a dual-phase Ti-10(wt.%) Mo alloy having hexagonal close-packed α phase and body-centered cubic β phase. We demonstrated that the dislocation plasticity preferred to transmit from alpha to alpha phase along the longitudinal axis of each plate, regardless of where dislocations were formed. The intersections of different α plates provided local stress concentration that facilitated the initiation of dislocation activities from there. Dislocations then migrated along the longitudinal axis of α plates and carried dislocation plasticity from one plate to another through these intersections as well. Since the α plates distributed in various orientations, dislocation slips occurred in multiple directions, which is beneficial for uniform plastic deformation of the material. Our micropillar mechanical testing further quantitatively demonstrated that the distribution of α plates and the α-α plates' intersections plays important role in tuning the mechanical properties of the material.