Atomic scale structural characterization of {10(1)over-bar2} twin boundaries in zinc

The structure and the migration mechanisms of {10 (1) over bar2} twin boundaries (TBs) of pure zinc deformed by rolling were studied using high-resolution transmission electron microscopy (HRTEM) at atomic scale. We found the presence of basal/prismatic (BP/PB) planes serrations on {10 (1) over bar2} TBs and the coexistence of two kinds of TBs with different structures in the same {10 (1) over bar2} twin: TBs composed of {10 (1) over bar2} coherent twin boundaries (CTBs) plus short BP/PB serrations, and TBs composed of successive BP/PB segments without {10 (1) over bar2} CTBs. The formation of BP/PB serrations has no relation to the cla ratio of hexagonal-close-packed (HCP) metals because the BP/PB serrations are energetically preferred and geometrically favored. Based on dislocation theory, we proposed the migration mechanisms of the TBs to be the glide of twinning dislocations (TDs) on the CTBs and the climb of interface dislocations (IDs) on the BP/PB segments.