CRYSTALLIZATION OF AL23TE77 GLASSES

The crystallization of Al23Te77 glasses has been studied by DSC techniques. Two peaks occur, showing an earlier excess Te crystallization and a later one of the remaining amorphous matrix. Isothermal determination of the kinetics is only possible for the second process, so a model for non-isothermic crystallization is developed on the basis of the Avrami theory, which is in agreement with isothermic results. The shift of the crystallization peaks with the scan rate allows knowledge of the activation energy for both processes. Those are found to be 1.9 and 2.8 eV respectively. Fitting of the experimental data with this model also indicates a diffusion mechanism for the Te crystallization and a homogeneous nucleation and growth process for the second stage. Re-scanning of the sample after the completion of the first peak shows a second Tg commonly associated with phase separation. Results are discussed in terms of the studies of structure recently reported. © 1979.