Thermo-kinetic computer simulation of differential scanning calorimetry curves of AlMgSi alloys

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 correlated 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, including stable and metastable phases. In the present work, a thermo-kinetic computational analysis of Al-Mg-Si DSC curves is carried out. The comparison with experimentally observed DSC signals for precipitation and dissolution of metastable GP-zones, beta '', beta ', as well as stable beta-Mg2Si and Si precipitates provides a quantitative insight into the kinetics and sequence of precipitation during DSC probing. The combination of thermo-kinetic and experimental DSC analysis offers new possibilities in interpretation of DSC peaks with multiple metastable phases. In the present paper, we discuss the linking of the simulated precipitation sequence with the measured DSC signal. In addition, with the proposed methodology, a consistent set of parameters to describe the non-equilibrium kinetic parameters of a specific alloy system can be obtained, which can substantially aid in alloy and process development.