Kinetic simulation of primary transformations in glassy alloys

The kinetic processes of primary transformations have recently been modelle d using the Avrami formalism and a mean field hypothesis [D. Crespo, T. Pra dell, M.T. Clavaguera-Mora, N. Clavaguera, Phys. Rev. B 55 (1997) 3435], Ho wever, the importance of several of the factors influencing the transformat ion has not been studied. In particular, the lack of randomness in the nucl eation rate induced by the change in the untransformed matrix concentration has never been evaluated. This factor is of interest because non-random nu cleation has been described in the literature as one of the main factors re sponsible for deviations from the Avrami kinetics. In this work, a kinetic Monte Carlo simulation of a primary transformation is presented. The simula tion attempts to account for both the reduction in the nucleation and growt h rates and the non-randomness in the nucleation protocol, due to the chang es in the untransformed matrix along the transformation. The effects on the predicted time-dependent transformed fraction as well as on the microstruc ture are shown. (C) 2001 Elsevier Science B.V. All rights reserved.