A SIMPLE WAY OF DESCRIBING THE DIFFUSION PHASE GROWTH IN CYLINDRICAL AND SPHERICAL SAMPLES

It is shown that during diffusional growth of the intermediate phase between substances A and B for cylindrical and spherical samples, the total diffusion flux relative to the center, -S(r)D partial derivative c/partial derivative r, where S is the area of the interface, varies by a small amount in the radial direction, despite the concentration dependence of the interdiffusion coefficient D(c). In this context we propose a constant-flux method which allows the kinetics of the diffusional phase growth in cylindrical and spherical samples to be described in a rather simple way. Deviations from the parabolic law of phase growth in cylindrical and spherical samples are analyzed.