Background


The Calphad (Calculation of phase diagrams) technique has reached maturity. It is widely used to model thermodynamic properties for each phase and simulate multicomponent multi-phase behavior in complex systems. It started from a vision of combining data from thermodynamics, phase diagrams and atomistic properties such as magnetism into a unified and consistent methodology. It has become now a powerful method for a wide range of applications where modeled Gibbs energies and their derivatives are used to calculate properties and simulate phase transformations in real multicomponent materials. Diffusion and solidification simulations can be carried out by using the second derivatives of Gibbs energy and data from laboratory experiments such as rapid solidification process. Whenever the thermodynamic description of a system is required, the Calphad technique can be applied.

The successful use of Calphad in these applications relies on the development of multicomponent databases, which describe many different kinds of thermodynamic functions in a consistent way, all checked to be consistent with experimental data. The construction of these databases is still a very demanding task, requiring expertise and experience. Furthermore, the growing range of applications of these databases increases the feedback but also the demand for updates and improvements. The development of new models and the rapid advance of first-principles (Latin: ab-initio) calculations make the assessment techniques very dynamic and challenging.

The OpenCalphad project was initiated to create an open-source code implementing the Calphad technique.

Reference:
H. L. Lukas, S. G. Fries and B. Sundman (2007). Computational Thermodynamics: The Calphad Method. Cambridge University Press, United Kingdom.