Superlattice dislocations in L1 2 ordered alloys and in alloys containing L1 2 ordered precipitates

Abstract

In this paper we report the dislocation configurations in L1 2 ordered alloys and in alloys containing L1 2 ordered precipitates. The alloy system CuNiZn was chosen because, in the ordered alloy Cu 2NiZn, two structures (L1 0 and L1 2) are possible and these influence the mechanical behaviour. A rather random distribution of superlattice dislocations and superlattice dislocation dipoles is observed in the L1 2 ordered system, whereas planar dislocation arrays such as pile-ups and multipoles are present in the disordered alloy. Configurations of superdislocation dipoles and of superlattice dislocations on {111} were calculated and compared with transmission electron microscopy observations. Superlattice dislocation configurations on {111} and {100} planes were observed in nickel-base superalloys containing L1 2 ordered precipitates.