Multiphase binary diffusion in infinite and semi-infinite media: Part I. On the determination of interdiffusion coefficients

Abstract

Mathematical relationships describing the multiphase binary diffusions are deduced under the condition that$\tilde D_j \ne \tilde D_{j + 1} ,\bar V_i^j \ne \bar V_i^{j + 1} ,and\bar V_A^j \ne \bar V_B^j$ in an infinite medium, and also under the condition that$\tilde D_j \ne \tilde D_{j + 1} ,\bar V_i^j = \bar V_i^{j + 1} ,\bar V_A^j \ne \bar V_B^j$ and the fluxes of both the species occur in each other’s opposite direction through the surface in a semi-infinite medium, where$\tilde D_j and\bar V_i^j$ are the interdiffusion coefficient and the partial molal volume of componenti in phasej, respectively, and are composition independent. Two graphical evaluation methods for obtaining the interdiffusion coefficients for all the phases present in the diffusion zone have been developed in infinite and semi-infinite media. Concentration-distance curves of both the components for an infinite medium and those curves and also mass change of the couple per unit area of the surface before and after the diffusion anneal for a semi-infinite medium must be prepared to calculate an interdiffusion coefficient for each phase.