Thermodynamic evaluation of the Al-Si-Mg-Cu phase diagram, including molar volumes

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The global goal of this project, as laid out in the initial proposal, remains the development of an accurate and reliable thermodynamic description of the entire quaternary Al-Si-Mg-Cu system using the Calphad method. With the input of data from focused experimental investigations and ab initio calculations from our partners in this bundled project it will be possible to reach a new level of quality of the thermodynamic description. In the proposed second period of this project we plan to focus our work on the modeling of the Cu-Si and Al-Cu-Si systems, and on a thermodynamic model for the quaternary Q-phase. The modeling will be based on new experimental data from the projects “Thermochemical and constitutional properties” (TUC) and “Critical solidification experiments” (FSU) and on ab initio calculations from the project “Ab initio prediction of thermodynamic data” (MPIE). Based on the ab initio data a model for thermal vacancies in fcc-Al will be developed. Density measurements of the liquid phase from the project “Thermophysical properties of Al-Si-Mg-Cu melts” (DLR) will be used to model molar volumes of the entire systems, so enabling pressure dependent calculations and calculation of volume changes during solidification and cooling.