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 nu clei. By means of this method, and considering the assumptions of extended volume and random nucleation, a general expression of the fraction crystall ized has been obtained, as a function of the temperature in bulk crystalliz ation. The kinetics parameters have been deduced, assuming that the crystal growth rate has an Arrhenius-type temperature dependence, and the nucleati on frequency is either constant or negligible. The theoretical method descr ibed has been applied to the crystallization kinetics of glassy alloy Sb0.1 2As0.40Se0.48 with and without previous reheating. According to the study c arried out, it is possible to state that the reheating did not cause the ap pearance of nuclei, but that the as-quenched material already contains a su fficient number of them. The phases at which the alloy crystallizes after t he thermal process have been identified by X-ray diffraction. The diffracto gram of the transformed material suggests the presence of microcrystallites of Sb2Se3 and AsSe, remaining in a residual amorphous matrix. (C) 1999 Els evier Science S.A. All rights reserved.