The radiation-induced order-disorder transformation in Cu₃Au

Abstract

A model for ordered alloys is presented which describes the combined effects of radiation disordering and radiation-enhanced ordering. The model uses the assumptions of Bragg-Williams ordering in a kinetic form in which the ordering energy is a linear function of order. Point-defect concentrations are introduced into the ordering kinetics so that the effect of the radiation (through enhancement of such concentrations) can be described. Both time-dependent and steady-state solutions to the resulting ordering rate equation are presented.

All the available data on irradiation of Cu₃Au with fast and thermal neutrons are reviewed and presented as functions of long-range order parameters (S) versus dose. All the curves at a wide variety of temperatures are fitted successfully with the model using the same diffusion parameters throughout. The implications and predictions of the model for future experiments are discussed.