DIFFUSION IN A REGULAR SOLID-SOLUTION

Diffusion in a regular solid solution was investigated. A thin plate o f isotropic solid of constant surface molal fraction was considered. T he regular solution is described by the parameter alpha. When alpha is positive, the attraction between unlike atoms is greater than the att raction between like atoms, and conversely. The depths of penetration and average molal fraction for a given period increase with increasing alpha. The separation of two curves for given alpha increase with inc reasing surface molal fraction. The diffusion coefficient is positive only if alpha is greater than -1/X(1 - X).