Thermal Effects Due to Crystallization of Alloys with Unlimited and Limited Solubility of Components

Resumo

High-resolution differential scanning calorimetry has been used to study the crystallization of binary alloys with unlimited and limited solubility of their constituents. A sharp and intense emission of crystallization heat has been invariably observed immediately below the liquidus curve. Standard techniques to describe crystallization in the intercritical temperature range cannot explain the above phenomena. It is assumed that they may be associated with a large number of local microvolumes enriched with a crystallization-controlling component (concentration fluctuations) that appear in the liquid as approaching the liquidus curve. The appearance of such microvolumes precedes the spontaneous formation of many crystallites in a large volume of the liquid phase.