The dislocation structure of polycrystalline material which had been deformed at room temperature was studied by means of transmission electron microscopy. It was found that the structure consisted mainly of <110> screw dislocations and partial dislocations which were linked by superlattice intrinsic stacking faults. A few dislocations were present as partials which were linked by antiphase boundaries. Two types of stacking fault-coupled partial dislocations were observed. One type consisted of pairs with dissimilar Burgers vectors, and the other type consisted of pairs with anti-parallel Burgers vectors. The energies of antiphase boundaries on {111} and {001} planes were estimated to be 169 and 148mJ/m2, respectively, and the superlattice intrinsic stacking fault energy was found to be between 15 and 30mJ/m2. Dissimilar superlattice intrinsic stacking faults appeared to be formed by the dissociation of a segment of a perfect dislocation. This confirmed a mechanism which had first been proposed in 1976. An anomalous yield stress behavior below room temperature was attributed mainly to mechanisms which involved superlattice intrinsic stacking faults.

The Dislocation Structure in L12 Ordered Alloy Ni3Ge. J.Fang, E.M.Schulson, I.Baker: Philosophical Magazine A, 1994, 70[6], 1013-25