DIFFUSION IN THE B2-B.C.C. PHASE OF THE Al-Fe-Ni SYSTEM-APPLICATION OF A PHENOMENOLOGICAL MODEL

摘要

A phenomenological model for multicomponent diffusion in B2-b.c.c. ordered phases is applied to the Al-Fe-Ni system. In the model, the activation energy for diffusion is expressed as a function of the degree of ordering, which is evaluated from thermodynamic data. These data are also used to evaluate the thermodynamic factors for diffusion. A CALPHAD-like assessment procedure is applied to the experimen- tal data for diffusion in the B2-b.c.c. phase of the Al-Fe-Ni system. It is shown that the model is capable of representing the experimental data. The diffusivities from the model are used to simulate six different diffusion experiments. The results are compared with experimental data and it is concluded that the model yields satisfactory predictions.