Tracer and chemical diffusion in L12-ordered Pt3Fe

Abstract

The tracer diffusion coefficient of Fe and the chemical diffusion coefficient in L12-ordered Pt3Fe have been measured at temperatures below the order-disorder transition temperature. The tracer diffusion coefficient of Fe in a nearly stoichiometric alloy is curved upwards in the Arrhenius plot on approaching the order-disorder transition temperature. The chemical diffusion coefficient is about 10-30 times larger than the diffusion coefficient of Fe. The tracer diffusion coefficient is influenced by composition, namely, it increases with increasing the concentration of Fe through the stoichiometric composition, but this trend almost vanishes at higher temperatures. The chemical diffusion coefficient is virtually independent of composition. The tracer diffusion coefficient of Pt has been estimated from the Darken-Manning relation. At 1223 K, it is in between the chemical diffusion coefficient and the tracer diffusion coefficient of Fe.