Stress induced microstructural evolution via discrete atom method

The shapes, sizes, and distribution of second phase precipitates are the principal factors determining the mechanical, electrical, and magnetic properties of a wide variety of high technology alloys and ceramics. In the initial processing, and also in high temperature applications, such as jet engine superalloys, the precipitate morphologies evolve in time and the properties change. An understanding of the elastic interactions between matrix and precipitates, among the precipitates, and between precipitates and dislocations is crucial for predicting and manipulating the properties of the crystalline materials. There has been a need for a computational technique, therefore, by which one can analyse the elastic state associated with arbitrarily shaped precipitates whose elastic constants are different from those of the matrix phase. This overview presents a new technique, termed the discrete atom method, which is predicated on the combination of statistical mechanics and linear elasticity. The problems treated are the elastic strain energy and morphology of a coherent precipitate, the elastic interaction between precipitates, coherency influenced coarsening, the effects of applied stresses, the elastic interaction between a precipitate and edge dislocations, and the instability of heteroepitaxial thin films.