Crystallographic characters of {11¯22} twin-twin junctions in titanium

(Formula presented.) contraction twins that are commonly activated in α-titanium interact to each other and form three types of twin–twin junctions (C^I _i,i+1, C^I _i,i+2, C^I _i,i+3 TTJs) corresponding to the crystallography of six twin variants C^I _i (i = 1,2, …, 6). We detected 243 (Formula presented.) TTJs in rolled pure α-titanium sheets. Electron backscatter diffraction analysis reveals that C^I _i,i+1 TTJs are profuse, 79.8% among three types while C^I _i,i+2 and C^I _i,i+3 TTJs take up 17.7 and 2.5%. Twin transmission does not occur. Consequently, boundaries associated with twin–twin interactions block twin propagation and influence twin growth. We explain structural features of TTJs according to the Schmid factor analysis and the reaction mechanism of twinning dislocations. The knowledge regarding TTJs provides insight for improving the predictive capability of meso/macro-scale crystal plasticity models for hexagonal metals.