Inversion anti-phase domains in Cu-rich γ-brasses i. The domain structures

Transmission electron microscopy has revealed the presence of inversion anti-phase domains (IAPD's) in Cu-rich γ-brass. The domains form regular arrays in two distinct configurations: a) triangular domains with boundaries parallel to {112} planes and b) ribbon domains parallel to {110}. Of these configurations, the ribbon IAPD structure corresponds to the long-period structure previously reported in γ-brass. Contrast experiments show that there is a displacement associated with the IAPD boundary and the displacement vector R is of the form 1/3〈110〉 and does not lie in the boundary plane. The transition from one IAPD configuration to the other is described and it is proposed that the IAPD boundaries accommodate changes in composition in these Cu-rich γ-brasses.