Electron Diffraction Study on CuAu at Temperatures Above the Transition Point of Order-Disorder

Abstract

Using a high temperature electron diffraction camera and thin oriented, evaporated films, the structure of CuAu has been investigated mainly at temperatures above the transition point of order-disorder. When the temperature exceeds the transition point, strong superlattice reflections of CuAu (II) vanish and weak, diffuse maxima appear at superlattice reflection positions, those at {110} positions showing peculiar shape characteristic of anti-phase domains, over the temperature range of about 50°C above the transition point. It is inferred that short chains of domains with the anti-phase character which is the same as the character in CuAu (II) but much more degenerate than this are present sporadically in the lattice in the equilibrium state in this temperature range.