A general solution to the diffusion equation was obtained for the compositions of 2 phases, in the situation where one phase dissolved and the other grew, at a constant temperature. The derivation was relevant of the case of melting. The exact solution was used to examine the conditions under which diffusion could be considered to occur in only one phase. It was demonstrated that the analysis could be used to measure solute diffusion coefficients in liquids. The method relied upon interface displacement measurements, and did not require the composition to be measured as a function of position.

A Diffusion Solution for the Melting/Dissolution of a Solid at Constant Temperature and Its Use for Measuring the Diffusion Coefficient in Liquids X.Wan, Q.Han, J.D.Hunt: Metallurgical and Materials Transactions A, 1998, 29[3], 751-8