Abstract
•Crystallization kinetics of As37.5Se37.5Ag25 glasses were studied.•Two overlapped crystallization peaks at all heating rates are observed.•Volume nucleation with two- and three-dimensional growth is shown.•The crystallization activation energy was calculated by model-free and model-fitting.•The SB(M, N) model is suitable for describing the crystallization process.
The kinetic transformation parameters of the overlapped crystalline peaks of As37.5Se37.5Ag25 glass were examined through the model-fitting and model-free approaches. The analysis of the crystallization kinetic parameters of the studied glass utilizing the model-free approaches showed that the activation energy of crystallization is not constant but change with the conversion fraction. These results reflect the changes of the reaction mechanism and reveal that the free model is more realistic than model-fitting approach which assumes a constant mechanism. Furthermore, the present results showed that the conversion process of the first and second crystallization peak of As37.5Se37.5Ag25 glass may be described by Avrami-Erofeev model An (g(χ) = [−ln(1−χ)]1/n) with n = 2 and 3, respectively. Comparing the experimental differential scanning calorimetry data with calculated ones indicated that Sestak-Berggren (SB) model is more realistic for describing the crystallization mechanism of both crystallization peaks of the studied composition.