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MM: Fachverband Metall- und Materialphysik

MM 18: Poster Session I

MM 18.19: Poster

Montag, 16. März 2020, 18:15–20:00, P4

Computational prediction of solubility limits in selected solid solutions — •Ondřej Fikar and Martin Zelený — Faculty of Mechanical Engineering, Brno University of Technoloty, Brno, Czech Republic

We provide a theoretical study of the phase stability of solid solutions in Al-Ge, Al-Pb, Ag-Au, Ag-Ge and Ag-Pb alloys, in which there are no intermediate phases across the whole composition range. Solubilities of Au, Ge and Pb in Ag and Al were determined using temperature-dependent free energies of pure elements and corresponding Al- and Ag-rich solid solutions obtained from ab initio calculations based on density functional theory. Contributions of vibrational free energy calculated from phonons, electron free energy and configuration entropy were considered. The temperature, at which a solid solution become stable, was estimated from the free energy difference between solid solution and mixture of pure elements. In case of the Al-Ge alloy, quasi-harmonic approximation was employed to include also the effect of volume expansion. For this system we employed more precise approach where mixture of Ge and Al-rich solid solution with maximum solubility were considered instead of mixture of pure elements. Predicted solubilities were compared with experimental ones in phase diagrams provided by the CALPHAD method. The results qualitatively agree with experimental observations. However, the exact temperatures at which the solid solutions become stable are underestimated.