Gibbs energies databases provided by CALPHAD

Sara Catalina Pineda Heresi, Ruhr-Universität Bochum, Bochum, Germany
Suzana G. Fries, Ruhr-Universität Bochum, Bochum, Germany

The so-called “CALPHAD databases” are a set of Gibbs energies for individual phases of a system. By using Gibbs energy minimizers, many thermodynamic properties, inclusive phase diagrams for multicomponent (many phases, many elements) can be obtained. Quantities like entropy, enthalpy, heat capacity, thermal expansion among others, can be calculated by using software based on CALPHAD (CALculation of PHAse Diagrams) method [1]. The thermodynamic data for the generation of these datasets (for binary, ternary and multicomponent systems) is obtained from reliable experimental data and theoretical calculations (e.g. DFT including metastable phases). Also, it is possible to model the magnetism and other properties.

These databases can be encrypted in the case of commercial software (e.g. Thermo-Calc (TC) [2]) or they can be open-databases which can be read by other thermodynamic software, for example, OpenCalphad (OC) which is an open-source thermodynamic Gibbs minimizer [3].

It is quite important to improve and optimize these databases due to their capability to anticipate properties of materials useful for their design. The optimization of this thermodynamic information is possible by using the TC module called PARROT [2].

In this work, we present a set of open Gibbs energy and use OC to calculate thermodynamic properties. In this way, we try to let important thermodynamic information available to students and teachers.

[1] Lukas, H. L., Fries, S. G., and Sundman, B. (2007). Computational thermodynamics: the Calphad method (Vol. 131). Cambridge: Cambridge university press.

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