A mathematical model coupled to CALPHAD to predict precipitation kinetics for multicomponent aluminum alloys

A mathematical model was developed to simulate the precipitation kinetics during heat treatment of multicomponent aluminum alloys. The model is based on the general numerical framework proposed by Kampmann and Wagner, and features a full coupling with CALPHAD software for the evaluation of the Gibbs–Thomson effect. It also does not rely on the assumption that precipitate phase composition is stoichiometric or uniform, and is therefore applicable for predicting complex precipitation kinetics encountered in industrial practices. Applications of the model to various aging treatments of binary Al–Sc alloys and a ternary Al–Sc–Zr alloy were conducted. It was found that the model predictions for extended time coarsening kinetics are in good agreement with the analytical Lifshitz–Slyozov–Wagner coarsening theory. Its ability to reproduce the complex precipitation pathways in multicomponent alloys was demonstrated by simulation of the precipitation kinetics for an Al–0.09 at.% Sc–0.03 at.% Zr alloy. Comparison of the simulation results with experimental measurement has also highlighted research directions that require further effort.