Antiphase domains and superlattice spot splitting in Cu 3 Au. I

Lattice imaging by high‐resolution electron microscopy has been utilized in the study of antiphase boundaries and antiphase domains in Cu 3 AuI. A displacement of half the 100 fringe spacing characterizes the antiphase boundary and, by following the trace of 100 fringes from one ordered domain to another, the relative phase of adjacent domains may be established. The technique has shown that the discrete ordered domains formed in the early stages of ordering in Cu 3 AuI are in small groups in which adjacent domains are in antiphase, with good correlation between the antiphase domain separation and the splitting of superlattice reflections in the corresponding diffraction patterns. It has also provided direct evidence that small regions of relatively high local degree of order (microdomains) exist in the disordered alloy.