Generalization of the phase transformation equation for the analysis of non-isothermal crystallization kinetics. Application to the Cu0.10As0.40Se0.50 glassy alloy.

The techniques of differential thermal analysis are frequently employed to study the kinetics of the transformation reactions and, in particular, the crystallization of the glassy alloys. The corresponding thermal data can be analyzed by the Kissinger method, which was originally derived for the stu dy of homogeneous reactions. The consensus in the literature, in several de cades, was that such applications (i.e. to heterogeneous solid state transf ormations) of the Kissinger method are not valid. In the present work the p rincipal objections to the mentioned applications are addressed and alterna tive derivations of theoretical results are provided. These results demonst rate that the Kissinger method is valid for heterogeneous reactions of the type described by Johnson-Mehl-Avrami equation in the isothermal case. Also the isothermal and non-isothermal data on crystallization of the Cu0.10As0 .40Se0.50 glassy alloy are given. The experimental results and the discussi on carried out here, help to clarify the effects of incubation time in non- isothermal transformation kinetics and provide a further demonstration of v alidity of the generalized Johnson-Mehl-Avrami theory for the description o f heterogeneous solid state transformations.