Analytic Model for Equation of State and Liquidus Curve of a Mixture

Self-consistent thermodynamic description of a mixture (a compound, an alloy, etc.) including both its equation of state (EOS) and solidus and liquidus boundaries is a challenging problem. We will review several standard approaches with the associated mixing rules and discuss their shortcomings. We will propose a new thermodynamics-based analytic model for the equation of state of a N-component mixture, N ≥ 2. The model uses N - 1 free parameters the values of which can be easily determined from the available experimental data. The calculation of the liquidus curve of a binary mixture, which the model also suggests, requires the knowledge of the melting curves of both pure constituents, but no other thermodynamic information such as their EOSs is needed. We will show several examples of the comparison of both model EOSs and model liquidi to the corresponding experimental data.