INTERDIFFUSION IN R-COMPONENT (R-GREATER-THAN-OR-EQUAL-TO-2) ONE-DIMENSIONAL MIXTURE SHOWING CONSTANT CONCENTRATION

Darken's idea of separation of diffusional and drift flows and the pos tulate that the total mass flow is a sum of diffusion and translation only, are applied to the general diffusional transport in r-component system (process defined as chemical interdiffusion in unidimensional m ixture). Continuity equations, Darken's flux formulas, the postulate o f constant molar volume of the mixture (valid e.g. in solid solutions) and the initial and boundary conditions form a self-consistent interd iffusion problem. This problem is analyzed in open as well as closed s ystems and with diffusivities dependent on composition. The variationa l form of the interdiffusion problem is derived. It has been proved th at in a closed system the gradients of density of each mixture compone nt vanish at the mixture boundaries. Results of numerical simulation o f interdiffusion in binary alloys are presented.