The dynamics of precipitate evolution in elastically stressed solids .1. Inverse coarsening

The effects of elastic stress generated by a misfit between a particle and matrix on the morphological evolution of a two-phase microstructure have been investigated. The particles were allowed to evolve by the flow of mass through the matrix with the interfacial concentrations given by the elastic stress-modified Gibbs-Thompson equation. We find that neither the total elastic nor the total interfacial energy must decrease with time during the evolution of the particles. Two misfitting particles were never observed to be stable with respect to coarsening, in contrast to the predictions of energetic calculations using particles of fixed morphology. However, inverse coarsening, wherein a small particle grows at the expense of a large particle, was quite common in systems with more than two particles. This inverse coarsening process can, in some cases, be accompanied by a decrease in the total interfacial energy in the system. We also find that particles which are aligned along the elastically soft directions of the crystal can evolve by the flow of mass through the thin regions of matrix separating these particles.