Thermal effects in crystallization of alloys with unrestricted and limited solubility of components

The processes of crystallization of two-component alloys with unrestricted and limited solubility of the constituent components were investigated by the method of differential high-resolution scanning calorimetry. It was found that in all cases a jump in the heat evolution of crystallization that is noticeable in magnitude and speed is recorded directly below the liquidus line. Traditional approaches in describing the development of crystallization processes in the intercritical temperature range do not provide an explanation for the observed phenomena. It is assumed that the observed effects are associated with the formation of a large number of local microvolumes (concentration fluctuations) enriched in the leading crystallization component. Their appearance precedes the beginning of processes of spontaneous formation of a large number of crystals in a noticeable volume of the liquid phase.