EVALUATION OF TIME-DEPENDENT GRAIN-SIZE POPULATIONS FOR NUCLEATION AND GROWTH-KINETICS

A theoretical calculation of time-dependent grain-size populations of an emerging phase driven by nucleation and growth kinetics is performe d. A statistical mean-field model is presented for a completely degene rated system, based on the same assumptions as the Kolmogorov-Johnson- Mehl-Avrami (KJMA) model, that is to say, randomly distributed active nucleation sites which grow isotropically and collision resulting in a growth stop at the interface. Dependence of the kinetic parameters (n ucleation and growth rates) on macroscopic and/or microscopic variable s and on time is considered. The differential form of the KJMA model i s applied to each grain-size population, providing a detailed microstr ucture development. As a result of this calculation, grain-size distri butions are obtained. The validity of the model is tested by comparing the grain-size distributions obtained for a kinetically controlled pr ocess with a numerical Monte Carlo simulation. Imaging of the microstr ucture obtained by Monte Carlo is also shown. Finally, the model is co mputed with different kinetic conditions and the results are presented .