CALPHAD modeling has become a mature technique in developing thermodynamic databases of multicomponent systems in the past three decades. It has also been extended to the development of other databases such as atomic mobility and lattice parameters. In the CALPHAD modeling of thermodynamics, the modeling of Gibbs energy of individual phases and the coupling of phase equilibria and thermochemistry are the key in developing internally consistent thermodynamic descriptions of multi-component materials with sound fundamentals and predictive power because these two sets of data are deduced from the Gibbs energy of individual phases under given constraints.
One issue in CALPHAD modeling is the lack of experimental data, particularly for new materials. For CALPHAD modeling to be in the forefront of materials research and development, we have to develop efficient routes both in generating data needed for database development and in updating existing databases when new data become available.
Experimentally, it is relatively easier to obtain phase equilibrium data in comparison with thermochemical data. On the other hand, first-principles calculations predict thermochemical data better than phase equilibrium data. More and more researchers are using enthalpy of formation from first-principles calculations. What more can we do to integrate experimental and first-principles data into CALPHAD modeling?
In current practice of CALPHAD modeling, experimental data collected for modeling are typically not available in electronic format after thermodynamic databases are developed. This is not only a great lose of value, but also makes the database updating more daunting. Can the advanced information technology help to improve this situation?
In this presentation, the recent research activities at our Phases Research Lab at Penn State will be presented with the following issues addressed
1. A framework for storage of CALPHAD modeling input data for upgrading database
2. Lattice stability of pure elements: CALPHAD and first-principles calculations
3. First-principles calculations of enthalpy and entropy of formation of compounds
4. First-principles calculations of enthalpy and entropy of mixing in solution phases