Modelling of microstructure evolution during precipitation processes: a population balance approach of the KWN model

Abstract

In the present study a general kinetic model for phase transformations resulting in a second-phase particle precipitation in a matrix is presented. Such transformations involve simultaneous nucleation, growth and coarsening of particles resulting in a particle population that can be described from the particle size distribution (PSD). The material final mechanical properties strongly depend on particles volume fraction and radius and consequently on the shape of the PSD. A strength model was used taking into account the contributions of the lattice resistance, the solid solution hardening and the precipitation hardening, using the kinetic model results. The model can be applied to both isothermal and non-isothermal conditions. Finally, the model is validated using a variety of microstructure and hardness data for a 6XXX aluminium alloy series taken from the open literature. It is concluded that the model results are in reasonable agreement with experimental data and capable of predicting the age hardening response of aluminium alloys.