Simulation of crystallization processes in amorphous iron-based alloys

A theoretical approach to crystallization kinetics is proposed which takes into account the influence of microstructure and microstructural changes during crystallization on nucleation rate and growth of crystallites. An analytical model for random structures is introduced and used to simulate the geometrical arrangement of crystallites and of chemical fluctuations in the partially crystallized system. Slowly diffusing inhibitors are simulated by a random point field. The evolution of an individual crystallite is controlled by a critical radius, an intrinsic growth law, and the distributions of regions already transformed, fluctuations of chemical composition, and slowly diffusing inhibitors. Experimental data on crystallization of amorphous FeSiBCuNb alloys are interpreted in terms of the present theory. The Johnson-Mehl-Avrami-Kolmogorov model is shown to be an exact and lucid special solution of the used basic model.