Basal Stacking-Fault Induced Twin Boundary Gliding and Twin Growth in Ti from the First Principles

First-principles calculations were performed to investigate the structures and energetics of {10-1n} coherent twin boundaries (CTBs) and glide twin boundaries (GTBs) in hexagonal close-packed Ti, to explore the formation mechanism of GTBs and its correlation with twin growth. Results suggested GTBs can form from the gliding of CTBs, induced by basal stacking fault. The gliding can eventually restore the CTB structures with newly formed pairs of single-layer twinning dislocations. Further movement of the twinning dislocations promotes twin growth. Possible effects of various alloying solutes on pinning twin boundaries were also evaluated, to guide the strengthening design of Ti alloys.