Equations which described multi-phase binary diffusion were arranged in such an order that the unknowns in the equations could be expressed as 2 series of sequential functions of the corresponding 2 independent variables. The conditions which had to hold, between one series of functions and the other, were given and a numerical method was developed for the solution of this type of equation in 2 unknowns. For the purposes of the numerical calculation of the parabolic rate constants for the formation of product phases, data were required concerning the average interdiffusion coefficients, the partial molal volumes and the phase boundary compositions (for an infinite medium). In the case of a semi-infinite medium, information was also required concerning the equilibrium surface composition and the ratio of mole transfers of the 2 components at the surface.

S.Tsuji: Metallurgical and Materials Transactions A, 1994, 25[4], 753-61