Multiscale simulation of grain growth in nanocrystalline materials

Abstract

In this chapter, grain growth is used as a simple case study to illustrate a novel multiscale approach for the simulation of microstructural evolution in poly crystalline materials. By linking atomic-level, mesoscale, and continuum simulation methods, all the relevant length and time scales of the problem are incorporated. For the simple model case of grain growth, it illustrates a rigorous computational and theoretical framework that permits physical insights gained from atomic-level simulations to be transferred into the mesoscale and then linked to the continuum level. This transfer requires quantification of the results of the atomic-level simulations by formulation of a theoretical model. This then enables examination of the statistical mechanics of the process in a realistic system. It describes the way the effects of applied stress are incorporated into multiscale approach. By meshing the grain interiors in a way that the grain-interior nodes link up with the already discretized grain-boundary (GBs) and grain junctions delimiting each grain, the inhomogeneous stress distribution arising from some externally applied stress can be computed using the finite-element approach. In an elastically anisotropic system, these stresses provide a driving force for GB migration, in addition to or acting against the driving force because of the GB curvature.