RADIATION-ENHANCED DIFFUSION IN CU3AU - EFFECTS OF LONG-RANGE ORDER

Direct measurements of thermal and radiation-enhanced diffusion were performed above and below the ordering temperature on a metal having the Ll(2) structure, specifically Cu3Au, for the first time. Ni and Pd impurity tracers were employed to simulate the diffusion of Cu and Au respectively. Apparent activation enthalpies were obtained for these two tracers above and below the ordering temperature. Both diffusion coefficients were found to decrease significantly on ordering, by factors of two and four for thermal and radiation-enhanced diffusion respectively. The results indicate that the contribution of interstitial atoms to the radiation-enhanced diffusion of Ni and Pd may be negligible.