MICROSTRUCTURAL EVOLUTION IN INHOMOGENEOUS ELASTIC MEDIA

We simulate the diffusional evolution of microstructures produced by s olid state diffusional transformations in elastically stressed binary alloys in two dimensions. The microstructure consists of arbitrarily s haped precipitates embedded coherently in an infinite matrix. The prec ipitate and matrix are taken to he elastically isotropic, although the y may have different elastic constants (elastically inhomogeneous). Bo th far-field applied strains and mismatch strains between the phases a re considered. The diffusion and elastic fields are calculated using t he boundary integral method, together with a small scale preconditione r to remove ill-conditioning. The precipitate-matrix interfaces are tr acked using a nonstiff time updating method. The numerical method is s pectrally accurate and efficient. Simulations of a single precipitate indicate that precipitate shapes depend strongly on the mass flux into the system as well as on the elastic fields, Growing shapes (positive mass flux) are dendritic while equilibrium shapes (zero mass flux) ar e squarish. Simulations of multiparticle systems show complicated inte ractions between precipitate morphology and the overall development of microstructure (i.e., precipitate alignment, translation, merging, an d coarsening), In both single and multiple particle simulations, the d etails of the microstructural evolution depend strongly on the elastic inhomogeneity, misfit strain, and applied fields. (C) 1997 Academic P ress.