Effect of precipitate shape and orientation on Orowan strengthening of non-basal slip modes in hexagonal crystals, application to magnesium alloys

Orowan equations predicting the strengthening of non-basal slip systems in hexagonal crystals are derived for rationally distributed, shear resistant precipitates of typical morphologies and orientations. These equations may be employed for any hexagonal crystal, but application is made specifically to hexagonal close packed Mg, where alloy development is presently quite active. Particular focus is placed on discerning the effect on 〈c+a〉 dislocations, and generally speaking, 〈c+a〉 slip is most potently strengthened by prismatic plate shaped precipitates, as was shown previously for basal and prismatic slip. If strengthening is the primary goal, prismatic plate shaped precipitates appear ideal. Because the motion of 〈c+a〉 dislocations has been repeatedly emphasized as crucial for preserving ductility, it may be of interest to consider.