Twin junctions with geometric compatibility and mobility in titanium and magnesium

The mechanical response of {12¯11} and {12¯12} coherency twin boundaries (CTB) under external loading was investigated with molecular dynamics simulations in titanium and magnesium. Mutual transformation between {12¯11} and {12¯12} CTB was revealed, i.e., {12¯12} CTB can transform into two co-zone {12¯11} CTBs, forming a twin junction, while reversibly {12¯11} CTB can transform into {12¯12} CTB and the other co-zone {12¯11} CTB, forming another twin junction. The simulation result thus well explains the experimental observation of twin junctions. Moreover, owing to the geometric compatibility and mobility of the two junctions, the mutual transformation between {12¯11} CTB and {12¯12} CTB produces {12¯12}/{12¯11} twin networks with perceivable plastic strain accommodation.