NUMERICAL SIMULATIONS OF TRANSIENT-STAGE OSTWALD RIPENING AND COALESCENCE IN 2 DIMENSIONS

A new numerical method for tracking interface motion in microstructure s is described and used to simulate two-dimensional, transient-stage O stwald ripening at high volume fractions of coarsening phase. Two limi ting kinetic regimes are explicitly simulated, namely diffusion-contro lled mass transport and surface-attachment/detachment-limited kinetics (SALK). The simulations indicate important qualitative and quantitati ve differences between these two mechanisms at high volume fractions. These differences include: (1) The persistence of coalescence events u nder SALK that are completely absent under diffusion control; and (2) stable circular shapes for isolated domains under SALK; under diffusio n control, the morphology of an isolated domain is dependent on its ne arby surroundings, as reported by other investigators. Spatial correla tions amongst the coarsening domains are also investigated using two-p oint correlation functions and medium polarization functions. (C) 1997 Elsevier Science S.A.