The Effects of Curvature on the Dissolution Kinetics of Spherical Precipitates

Abstract

The effects of curvature on the dissolution kinetics of spherical precipitates is investigated. This is accomplished by using a modified Gibbs–Thompson equation to represent the composition in the matrix at the precipitate/matrix interface as a function of precipitate radius. In this way one can account for the increasing curvature of the dissolving precipitate. The range of physical parameters for which the effect of curvature may appreciably alter the kinetics of diffusion-controlled dissolution is discussed. The presence of curvature tends to speed up dissolution, being particularly important at long times (i.e., small precipitate sizes) and when the difference between the solute concentration at the precipitate/matrix interface (Cr I ) and in the depleted matrix (C M ) is small. It is shown, however, that curvature will, in general, not sensibly affect the dissolution kinetics even at long times unless the concentration difference (Cr I – C M ) is sufficiently small.