Crystallization kinetics by differential scanning calorimetry under non-isothermal regime in the case of "site saturation"

A procedure has been developed for analyzing the evolution with time of the volume fraction crystallized and for calculating the kinetic parameters at non-isothermal reactions in materials involving growth of nuclei. By means of this method, and considering the assumptions of extended volume and randomly located nuclei, a general expression of the fraction crystallized has been obtained, as a function of the temperature in bulk crystallization. The kinetic parameters have been deduced, assuming that the reaction rate constant is a time function through its Arrhenian temperature dependence. The theoretical method described has been applied to the crystallization kinetics of the Sb0.20As0.32Se0.48 glassy alloy with and without previous reheating. According to the study carried out, it is possible to state that in the considered alloy the nuclei were dominant before thermal analysis, and therefore the reheating did not appreciably change the number of pre-existing nuclei in the material, which constitutes a case of "site saturation". (C) 2003 Elsevier Science B.V. All rights reserved.