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A. Falahati, E. Povoden-Karadeniz, P. Lang, P. Warczok, E. Kozeschnik:
"Thermo-kinetic Computer Simulation of Differential Scanning Calorimetry Curves of AlMgSi Alloys";
Talk: ICAA 12, Japan, Yokohama; 2010-09-05 - 2010-09-09; in: "Proceedings of the 12th International Conference on Aluminium Alloys", The Japan Institute of Light Metals, 1 (2010), ISBN: 978-4-905829-11-9; Paper ID 3B-13 - P.1077-1082, 6 pages.

The microstructure evolution in heat-treatable Al-alloys is characterized by a complex sequence of precipitation processes. These can be either endothermic or exothermic in nature and they can be investigated by thermal analysis. The individual peaks identified in a differential scanning calorimetry (DSC) analysis can be attributed to the nucleation, growth and dissolution of certain types of precipitates. Simultaneously, these data can also be obtained by thermo-kinetic simulation based on models implemented, for instance, in the software MatCalc. The simulations make use of information stored in thermodynamic databases commonly used for equilibrium phase diagram calculations. Since thermodynamic information for metastable phases is generally lacking in these databases, in the present work, we show that these data can be obtained from the combination of experimental investigation with DSC, thermo-kinetic computational analysis and implementation of lattice stability data from ab-initio modeling. On the example of the Al-Mg-Si system, we demonstrate that the comparison between experimentally observed DSC signals for precipitation and dissolution of metastable GP-zones,beta-dp, beta-p as well as stable beta-Mg2Si and Si precipitates with the kinetic simulation allows for an optimization of the thermodynamic data, particularly for the metastable phases. With the proposed methodology, consistent sets of parameters to describe the non-equilibrium thermodynamics and kinetics of complex systems can be obtained, which can finally aid in alloy and process development.

AlMgSi; metastable phases; DSC; thermo-kinetic simulation; lattice stability