CALPHAD
Calphad originally stands for CALculation of PHAse Diagrams while nowadays has expanded as to Computer Coupling of Phase Diagrams and Thermochemistry. The histories, principles, methodology, software/database developments and applications have been extensively described in the recently published book of Computational Thermodynamics – The Calphad Method by H.L. Lukas, S.G. Fries and B. Sundman (2007, Cambridge). The Calphad approach was first generally described in the book of Computer Calculations of Phase Diagrams by L. Kaufman and H. Bernstein (1970), in which the important concept of lattice stability (that had been introduced earlier by L. Kaufman, 1959) for calculation of phase diagrams based on modeled Gibbs free energies was developed. They explained clearly how thermodynamic model parameters describing Gibbs free energies in multicomponent systems could be derived both from experimental phase diagrams and from the rudimentary first-principles techniques available at that time, and how they could be used for calculations of phase diagrams.
The Calphad approach has also been significantly extended into the field of Computational Kinetics since the early stages of its developments. Nowadays, it has been become a powerful method in a wide range of applications where modeled Gibbs free energies and derivatives of heterogeneous systems thereof are used for calculations of phase equilibria and phase properties and for simulations of phase transformations of real multicomponent materials. For instances, chemical potentials and chemical driving forces (i.e., the thermodynamic factors being as the second derivatives of Gibbs free energies) are used in simulations of diffusion-controlled and/or deformation-induced phase transformations in materials processes; chemical driving forces are also used in simulations of materials microstructures based on the Landu theory and phase-field methods; fractions of solid/liquid phases, segregations of components, and energies and chemical driving forces of metastable states are used in simulations of melt/slag solidifications and of precipitations; energies, chemical driving forces and other thermochemical/thermophysical properties are used in computational fluid dynamics (CFD) of materials processing.
In other words, wherever/whenever a sophistic thermodynamic/kinetic descriptions of heterogeneous interaction systems/processes are required, the Extended Calphad Approach can be comprehensively applied.
More details of the lattice stability concept can be also read from the paper of Hume-Rothery and Calphad Thermodynamics by L. Kaufman (2002; in Calphad and Alloy Thermodynamics, Eds. P.E. Turchi, A. Gonis and R.D. Shull, Warrendale, PA: TMS, pp. 3-19). The lattice stability concept was essential for the development of multicomponent thermodynamic databases. The method of extrapolating solubility lines into the metastable range to obtain a thermodynamic property (such as the melting temperature of metastable FCC Cr) shows one of the important advantages of combining phase diagrams and thermodynamics. Along the development histories of the Calphad techniques, of thermodynamic models, and of thermodynamic software, databases and application programming interfaces, more such combinations have been used in exploring various thermochemical and thermophysical properties of many systems using experimental and theoretical data in thermodynamic models, through important contributions made by Kubascheski et al. (1967), Hillert and Staffanson (1970), Eriksson (1971), Basebe and Nishizawa (1972), Ansara et al. (1973), Hillert and Sundman (1976, 1990), Sundman and Ågren (1981), Sundman et al. (1985, 1998, 1999), Fernández Guillermet (1982), Jansson (1983), Hillert et al. (1985), Andersson and Sundman (1987), Dinsdale (1991), Chase et al. (1995), Dupin (1995), Kattner (1997), Aldinger et al. (1995, 1997, 2000, 2001, 2007), Hillert (1997, 1998, 2001), Pelton et al. (2000, 2001), Andersson et al. (2002), Lukas et al. (1977, 2007), Shi et al. (2008), among many others.
More information about CALPHAD can be found at: www.calphad.org and on Wikipedia
