Abstract
Branches of the generalized stacking-fault energy surfaces for {013} and {110} planes in molybdenum disilicide are calculated by first-principles density functional methods. The possible antiphase-boundary faults are found to be unstable, but stable stacking faults which permit (331) dislocations to lower their energy by dissociation are found on both planes. Based on the properties of the predicted dissociated dislocations, a qualitative model is advanced to account for the observed features of {013}(331) slip in molybdenum disilicide, including the ductile-to-brittle transition.
