DISSOCIATION OF A DISLOCATION INTO PARTIAL DISLOCATIONS BOUNDING AN UNSTABLE STACKING-FAULT

Though a stable stacking fault is usually assumed to exist for a dislo cation to dissociate into partial dislocations, we show in this paper that a dissociation can occur even when the stacking fault is unstable . In the case where both the undissociated and dissociated states are stable and the former state has the lower energy than the latter, a yi eld stress anomaly is expected to occur because the metastable state c an have much higher mobility than the stable state. (C) 1997 Elsevier Science S.A.