Grain Boundary Dislocations in Noncubic Crystals. II. The GBD Model Applied to Grain Boundary Facets in <1010>Tilt Boundaries in Zinc.

摘要

Observations of faceting of <1010>tilt grain boundaries in zinc and a coincidence structural unit model were reported in earlier papers. The facet inclinations were found to be monotonic functions of boundary misorientation in certain misorientation ranges. In this paper,the grain boundary dislocation (GBD) model developed earlier is used to describe the structure of these faceted boundaries. The model,which assumes the Burgers vector of the GBD's to be lattice vectors of the complete-pattern-shift or DSC lattice derived from near-coincidence arrays in hcp crystals,is able to account for the experimentally observed changes in boundary inclination with misorientation. Observed facet morphologies are obtained with only certain GBD's,the core structures of which are shown to be equivalent to the stuctural units in the previously suggested structural unit model. Thus,the application of the GBD model to more general boundaries in noncubic crystals is illustrated,and thereby,the general equivalence of the GBD and coincidence structural unit models is clearly demonstrated. (Author)