Abstract
The crystallization kinetics of as-quenched and pre-annealed Fe 76Co 4B 20 glasses were studied by differential scanning calorimetry and thermomagnetic gravimetry. The standard Johnson-Mehl-Avrami analysis of the isothermal crystallization data yielded different Avrami exponents in the range 3–4, which showed a temperature dependence. Therefore it was rather difficult to attribute the kinetic results to a particular crystallization mechanism. A general model which combines growth of quenched-in nuclei and simultaneous nucleation with subsequent crystal growth was developed to describe the isothermal kinetic data. The rates of nucleation and linear growth as well as the activation energy for growth estimated on the basis of this model were physically reasonable and close to those obtained by means of direct microscopic measurements for similar glasses. The influence of the pre-existing crystalline centres and the effect of the pre-annealing treatment on the mechanism of crystallization and the crystallization kinetics were analysed.
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