ON THE POSSIBLE MULTIPLICITY OF NEARLY EQUIVALENT COINCIDENCE SITE LATTICES FOR (0(1)OVER-BAR-12) TWIN IN HEXAGONAL CRYSTALS

Features of secondary dislocation networks lying in a near coincidence grain boundary may be predicted as a function of the misorientation, i.e. the deviation from exact coincidence orientation. This work was carried out for the (0112BAR) common twin in magnesium in case of deviations from several CSLs close to the twin orientation. The dislocation line direction and spacing associated with basis and combined DSC vectors are calculated for a range of deviations. It is shown that for small deviation angles, the dislocation networks associated with different CSLs may be distinguished which allows the CSL adopted by the grain boundary to be discriminated. By using the criterion of the lowest dislocation density, some CSLs are favoured as a function of the deviation.