Self-diffusion of iron in an α-γ interface compared with diffusion in grain boundaries

We have analysed the experimental conditions required to obtain a planar ferriteaustenite interface in stable equilibrium. It is shown that self-diffusion of iron in the interface is like that along grain boundaries only when the material is of very high purity. The Arrhenius plot of the interfacial diffusion parameter is given by P I = 1.75 × 10 −8 exp (− 155×10 3 RT ) cm 3 s −1 (activation energy in joules per mole). When the impurity level is increased the diffusivity increases as a result of changes in the structure (segregation, precipitation and interfacial instability).