Thermally activated crystallization of two FeNiPSi alloys

Abstract

The crytsallization kinetics of two alloys in the Fe-Ni-P-Si quaternary system have been investigated, with both isothermal and continuous heating experiments, by means of differential scanning calorimetry. Both alloys present two separated crystallization processes. The Johnson-Mehl-Avrami-Erofeev equation with a rate constant following the Arrhenius behavior gives the best fit of the experimental data. In all processes the value of its JMAE kinetic exponent is not constant. In the nearly stages, n changes steeply revealing the transient nucleation effect to reach values corresponding to a three-dimensional volume growth controlled by diffusion in the central part (0.3<x<0.55). Latter in the transformation n continuously decreases reflecting the saturation of nucleation