Solute segregation and coherent nucleation and growth near a dislocation -A phase-field model integrating defect and phase microstructures

A diffuse-interface field model is proposed for describing diffusional proc esses in coherent systems with arbitrary microstructures and arbitrary spat ial distribution of structural defects such as dislocations. It takes into account the effect of both the coherency elastic energy of a microstructure and the elastic coupling between the coherency strains and defect strains. In this model, any arbitrary spatial distribution of defects ii described using the micromechanics concept of space-dependent "stress-free" or "eigen " strains. As examples, the solute segregation as well as the nucleation an d diffusional growth of a coherent precipitate around an edge dislocation a re considered. It is shown that coherent nucleation may become barrierless under the influence of the local elastic field of a dislocation. (C) 2001 A cta Materialia Inc. Published by Elsevier Science Ltd. All rights reserved.