CALPHAD modeling of molar volume

Databases concerning basic physical properties of materials, such as molar volume, density, thermal expansion coefficient, elastic constants, thermal conductivity, etc., are essential parts of the underlying knowledge for materials design. While thermodynamic databases provide chemical driving forces and phase equilibrium data, physical property databases provide essential physical parameters, such as volume, lattice constant, lattice misfit, elastic energy, interfacial energy, etc., for phase transformation and microstructure simulations. Combined with thermodynamic databases, physical property databases established on the basis of the calculation of phase diagram (CALPHAD) method can be used to calculate physical properties together with phase equilibria, phase fractions, phase compositions, and thermodynamic properties for multi-component and multi-phase material systems and for the constituent phases. In this paper, we will discuss in detail various volume models based on the CALPHAD method which are capable of describing experimental data in a wide range from cryogenic temperatures to melting points, from the atmospheric pressure to high pressures for pure substances as well as multi-component and multi-phase materials.