Weak beam observation of dissociated dislocations in an L12ordered alloy deformed at the temperature of strength anomaly

Abstract

The dissociation properties of dislocations resulting from the compression of polycrystalline Ni₃Al at 620°C and 800°C have been studied using the weak beam technique. The dissociation of screw dislocations on {001} is confirmed. However, it is shown that the non-screw segments are neither dissociated in the same plane as the screw parts, nor are they dissociated by a pure glide process. It is shown in several-examples that climb has played an extensive role during the dissociation event, a fact which should have an importance in the interpretation of the anomalous temperature dependence of the strength of L1₂ ordered alloys.