Modeling of Thermodynamic Behavior of Systems with Low Departure to Ideality: Application to Au-Pb

A novel regular solution model has been developed to explain the thermodynamic behavior of systems presenting a low departure to ideality. The model is an extension of the regular solution model that discriminates between two forms of one component of binary alloy. The change of enthalpy of formation versus temperature is due to the transformation of one form into another when the temperature varies. The application of the model to the system Au-Pb allows us to explain its thermodynamic behavior by the existence of two forms of lead.