Phenomenological Consideration on the Compositional Deviation from Equilibrium at the bcc ⁄ fcc Interface in Fe: Cr Diffusion Couples

interface in Fe:Cr diffusion couples is not equal to the equilibrium value even if the coupies are heated for a long time more than 100 hr. In a diffusion experiment Eifert et al.(2) reported a systematic deviation from the equilibrium composition at the bcclfcc interface in Cu:Al diffusion couples. Such deviations have also been detected in the two-phase diffusion couples of Au:Co by Braun et al.(3) and those of Ni:Cr by the present authors(4). Furthermore, Oikawa et al.(5) suggested the occurrence of a deviation in carbon concentra-