Diffusion of Copper in Iron

Using 64copper and the residual-activity technique, diffusion of copper in iron has been studied in both the paramagnetic and the ferromagnetic phases. The diffusivities (cm2/sec) can be described as follows: DCu/Fe=0.57 exp(−57 000/RT) (800°–1050°C, paramagnetic phase), DCu/Fe=0.47 exp(−58 380/RT) (650°–750°C ferromagnetic phase). The decrease in the diffusivity at the Curie temperature has been discussed in light of the theories of spin-ordering and the temperature dependence of the elastic constants. The results do not show a change in activation energy at the transition temperature.