Abstract:The structure and the migration mechanisms of 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 TBs and the coexistence of two kinds of TBs with different structures in the same twin: TBs composed of coherent twin boundaries (CTBs) plus short BP/PB serrations, and TBs composed of successive BP/PB segments without CTBs. The formation of BP/PB serrations has no relation to the c/a 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.

Key words: zinc; twin boundaries; basal/prismatic BP/PB serrations; migration mechanism; high-resolution transmission electron microscopy (HRTEM)