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E. Kozeschnik, Y.V. Shan, F.D. Fischer, J. Svoboda:
"Thermo-kinetics of Mg-Si couples as a precursor to precipitation in Al-Mg-Si alloys";
Talk: EUROMAT 2015, Warszawa (invited); 2015-09-20 - 2015-09-24.

The paper presents a thermodynamic model for kinetics of Mg-Si couples formation in the Al-rich matrix. The model applies the trapping concept and assumes that Mg and Si atoms act as mutual traps. The overall concentrations of Mg and Si are considered as fixed input quantities and the concentration of Mg-Si couples is considered as free evolving variable. The Gibbs energy of the system evaluated as function of concentration of Mg-Si couples allows calculating both the driving force for formation of Mg-Si couples as well as their equilibrium concentration by minimizing the Gibbs energy with respect to concentration of Mg-Si couples. In the kinetic part of the model, the evolution equations describing the kinetics of couple formation based on the thermodynamic extremal principle are derived. The model provides an access to systematic studies of the very early stages of nucleation in systems with high supersaturation. The predictions of our model are first compared to similar equilibrium-based approaches in literature. A parameter study of the kinetics of couple formation is presented with an outlook of how to incorporate this new approach into complex thermo-kinetic modeling of precipitation in Al-alloys.