A STUDY OF (0(1)BAR12) TWIN DEVIATING FROM EXACT ORIENTATION IN MAGNESIUM

The (0112BAR) twin in magnesium containing a dense dislocation network has been studied by transmission electron microscopy. It does not have an exact twin orientation, and the deviation has a twist character. The Burgers vectors of the dislocations have been identified by contrast analysis and simulation. Using the Bollmann approach for the interpretation of secondary dislocations in non-cubic materials, dislocation networks have been predicted for the deviation from CSLs close to the twin orientation. By comparing the direction and spacing of the dislocations between the experimental and calculated networks, it is found that in this particular case of a twist deviation, the dislocations accommodate a deviation from the exact twin orientation rather than from a 3D-CSL.