Crystallization Kinetics by Thermal Analysis

Thermal Analysis techniques are widely used to study the crystallization kinetics in amorphous solids. Such experimental data are frequently interpreted in terms of the Johnson-Mehl-Avrami (JMA) nucleation-growth model. This paper discusses the limits of such approach. A simple method is proposed to verify the applicability of the JMA model as well as the basic assumptions in kinetic analysis. It is shown that the autocatalytic model includes the JMA model and it is a plausible description of the crystallization kinetics. The main advantage of the autocatalytic model is the possibility to describe quantitatively the kinetics of complex crystallization processes. The experimental data for crystallization of a chalcogenide glass analyzed in this paper clearly demonstrate rather complex nature of these processes. As a consequence it is very difficult to explore real kinetic mechanism of the crystallization process unless some complementary studies are made.