Computer Simulation of Multiphase Binary Diffusion in Gas–Solid Type Couples

Abstract

Model 1 for describing multiphase diffusion and Model 2 for determining the interdiffusion coefficient of each phase in binary gas–solid couples were developed by modifying models previously presented. No restrictions on the number of phases, the values of interdiffusion coefficients, or the homogeneity ranges of phases were placed on the present models.
Composition profiles, mass changes per unit area of surface and dimensional changes normal to the surface for N–Cr, N–Fe, and N–Ti couples were numerically calculated from diffusivity and phase equilibrium data with Model 1. A good agreement between experimental and calculated results was found. It was confirmed that Model 1 is compatible with Model 2, which can be easily applied and is useful when no references are available for diffusivity data.