H.V.E.M. study of ordering and disordering in Cu3Au

Abstract

Cu₃Au has been irradiated with 600 kV electrons, and the rate of ordering and disordering determined between 140 and 400 K. The degree of order has been measured from the ratio of the intensities of the superlattice and fundamental reflections in electron diffraction patterns, these ratios having been calibrated under appropriate conditions using specimens of a known degree of order. At all irradiation temperatures a steady-state degree of order is developed. The results have been interpreted in terms of a model due to Zee and Wilkes (1980) with minor modifications. It has been found on this basis that the energy of migration of the defect responsible for ordering during irradiation is ∼0–62 eV, and this same value can be used to match the limited earlier data from neutron-damage studies.