ATOMIC-STRUCTURE ANALYSIS OF THE (10-(1)OVER-BAR-2) TWIN IN ZINC BY HREM AND ENERGETICAL CALCULATIONS

The atomic structure of the (10 ($) over bar 12) twin boundary in zinc is investigated theoretically by atomistic calculations and experimentally by high resolution electron microscopy. For computer simulations, the atomic interactions are described by a many-body potential of the Finnis-Sinclair type and are applied to a h.c.p. structure with a large c/a ratio (1.856). Using this potential, only one planar atomic structure is found to exist for the (10 ($) over bar 12) twin. This is in agreement with the previous results for h.c.p. metals with c/a ratio close to the ideal value (1.633). In contrast, two atomic structures are observed experimentally: a planar and symmetric interface similar to the one obtained by calculations, and a microfaceted structure. The microfaceted structure is observed for the first time in the(10 ($) over bar 12) twin.