BOUNDARIES OF THERMAL STABILITY OF AN AMORPHOUS MATERIAL. I. INTERACTION OF PHASES IN THE MEAN-FIELD APPROXIMATION
With the use of the heating rate dependences of model parameters found earlier, the surface of crystallization is built, i.e. the plot of temperature and heating rate dependent volume fraction of crystallites. Thermal stability of an amorphous material is studied in the mean-field approximation. The existence of a «diffusive» spinodal (the spinodal of ordering) in the area of metastable phase states is shown. The existence of the spinodal is explained by instability of the metastable phase with respect to the change of the order parameter within a certain interval of values. Realization of self-assembly of phase areas as a result of «ascending» diffusion becomes possible. This fact is related to that the effective coefficient of diffusion can become negative. It is found that the mean-field approximation is insufficient to establish the type of the boundary of absolute instability.