Order-disorder transitions in alloys near Au3Cu

We applied diffractometry to the order-disorder transition in Cu-72.5 at.% Au alloy with a Ll₂ superlattice; the long-range order parameter and the lattice parameter have been measured in relation to annealing temperature. Disordering occurs through a two-phase Ll₂ + Al region; the upper bound to the phase-transition temperature is 208±3°C. A study has been made of the dimensions of the antiphase domains as defined by superlattice lines.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 3, pp. 70–74, March, 1980.