Computer simulation model for coupled grain growth and Ostwald ripening-application to Al2O3-ZrO2 two-phase systems

A kinetic model based on generalized continuum time-dependent Ginzburg-Landau (TDGL) equations is proposed for studying coupled grain growth and Ostwald ripening in multiphase systems. In this model, an arbitrary multiphase microstructure is described by many orientation field variables which represent crystallographic orientations of grains in each phase and by n - 1 composition field variables which distinguish the compositional differences among n phases. Microstructural development during simultaneous grain growth and Ostwald ripening is predicted by the temporal evolution of these field variables by numerically solving the TDGL equations. A particular example, Al2O3-ZrO2 particulate composite, was considered. The effects of the volume fraction of ZrO2 on the microstructural features and their evolution were studied and compared to experimental observations and previous thermodynamic analysis.