Formation mechanism of three-fold {101¯1}α twins during β to α phase transformation in titanium

The formation mechanism of three-fold twins during β to α phase transformation in titanium was investigated. Such twins were found to form by three α variants with the {101¯1}αtwin relationship. Three-fold twins have the lowest elastic interaction energy and are favored by the existence of screw dislocations. The present result reveals the stress and defect origins of three-fold twins and provides theoretical support for obtaining the microstructure containing intensive three-fold twins with high symmetry through stress-induced and dislocation-mediated α phase nucleation in titanium alloys.