Kinetic simulation of primary transformations in glassy alloys

The kinetic processes of primary transformations have recently been modelled using the Avrami formalism and a mean field hypothesis [D. Crespo, T. Pradell, M.T. Clavaguera-Mora, N. Clavaguera, Phys. Rev. B 55 (1997) 3435]. However, the importance of several of the factors influencing the transformation has not been studied. In particular, the lack of randomness in the nucleation rate induced by the change in the untransformed matrix concentration has never been evaluated. This factor is of interest because non-random nucleation has been described in the literature as one of the main factors responsible for deviations from the Avrami kinetics. In this work, a kinetic Monte Carlo simulation of a primary transformation is presented. The simulation attempts to account for both the reduction in the nucleation and growth rates and the non-randomness in the nucleation protocol, due to the changes in the untransformed matrix along the transformation. The effects on the predicted time-dependent transformed fraction as well as on the microstructure are shown.