Kinetic study on non-isothermal crystallization in glassy materials:: application to the Sb0.12As0.40Se0.48 alloy

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 formation and growth of nuclei. By means of this method, and considering the assumptions of extended volume and random nucleation, a general expression of the fraction crystallized has been obtained, as a function of the temperature in bulk crystallization. The kinetics parameters have been deduced, assuming that the crystal growth rate has an Arrhenius-type temperature dependence, and the nucleation frequency is either constant or negligible. The theoretical method described has been applied to the crystallization kinetics of glassy alloy Sb0.12As0.40Se0.48 with and without previous reheating. According to the study carried out, it is possible to state that the reheating did not cause the appearance of nuclei, but that the as-quenched material already contains a sufficient number of them. The phases at which the alloy crystallizes after the thermal process have been identified by X-ray diffraction. The diffractogram of the transformed material suggests the presence of microcrystallites of Sb2Se3 and AsSe, remaining in a residual amorphous matrix. (C) 1999 Elsevier Science S.A. All rights reserved.