ON THE PRIMARY CREEP OF NI3AL

The primary creep stage in single-crystal Ni3Al(1 at.% Ta) at an inter mediate temperature of 520 degrees C and at a stress of 550 MPa has be en investigated. It is found that edge superdislocations in the [123] orientation dissociate on the octahedral plane while their counterpart s in the [1112] orientation, which is about 7 degrees off the [001] or ientation, climb-dissociate subject to the same duration of creep (7 h ). It is concluded that the climb-dissociation leads to the end of pri mary creep and that it occurs after the edge dislocations are halted b y forest interactions.