Kinetics of the apparent isothermal and non-isothermal crystallization of the α-Fe phase within the amorphous Fe81B13Si4C2 alloy

Kinetics of the apparent isothermal and the non-isothermal crystallization of alpha-Fe phase within the amorphous Fe81B13Si4C2 alloy were investigated by an X-ray diffraction (XRD) and by a differential scanning calorimetry (DSC). It was established that the apparent isothermal crystallization of alpha-Fe phase within amorphous Fe81B13Si4C2 alloy could be described by the Johnson-Mehl-Avrami (JMA) kinetic model (with parameter n(iso)=4.0). The apparent isothermal crystallization process includes a constant rate of nucleation and three-dimensional growth of nuclei. The results of X-ray diffraction (XRD) data of the isothermally crystallized samples confirmed the above established kinetic model. From the kinetic analysis of the non-isothermal crystallization of the alpha-Fe phase within this amorphous alloy, it was concluded that the autocatalytic two-parameter 'Sestak-Berggren (SB) reaction model (with kinetic exponents M=0.72 and N=1.02) describes well the studied process under the given conditions. The non-isothermal crystallization process involves the constant nucleation rate of stable nuclei with additional secondary two-dimensional (surface) nucleation and overlapping of the growing nuclei on account of the non-isothermal activation. (C) 2010 Published by Elsevier Ltd.