Ostwald ripening in multicomponent alloys

Abstract

A general theory of coarsening in a multicomponent alloy is developed, accounting for off-diagonal terms in the diffusion tensor. The analysis is valid for a non-ideal and non-dilute solution. The asymptotic analysis reveals that the temporal exponents for the average particle radius, number of particles per volume and both the precipitate and matrix compositions are identical to the binary limit. However, the amplitudes are different. It is found that the vector representing the matrix supersaturations coincides with the equilibrium tie-line, but in most alloys this is not the case with the precipitate compositions. It is also shown that considering only a low mobility species does not yield a description of the temporal evolution of the matrix and precipitate compositions, even though this can be the case for the average particle size and the number density of precipitates.