Insight into crystallization paths in Au–Si eutectic alloy through the energy-temperature diagram

Abstract

An energy/temperature (E/T) diagram is a powerful representation of the stability relations between various solid-states with the same composition if they melt at a single temperature instead of a temperature range, such as eutectic microstructures in addition to allotropes and polymorphs. The characteristic melting point and melting enthalpies of two metastable eutectic microstructures and one metastable single phase in Au–18.6at%Si alloy have been measured using fast differential scanning calorimetry (FDSC) which is used as a phase identification technique. An E/T diagram for the eutectic Au–Si alloy has been prepared using these thermodynamic parameters, which gives all possible crystallization paths in this simple binary alloy. In the present contribution, we give a roadmap to understand FDSC curves that demonstrate the characteristics of different crystallization paths in this alloy. A strong phase competition between a rich variety of metastable and stable solid-states present in Au–Si eutectic alloy has been investigated using the E/T diagram. The stochastic nature of nucleation has also been demonstrated as a critical phenomenon on phase competition between metastable solids.