The microstructure determines for the most part mechanical properties of castings. This is the case especially with age-hardening aluminum alloys. To predict the phase transformation in cast parts during and after solidification a sophisticated approach to a coupled modeling of various simulation phenomena is presented. This approach couples a diffusion equation solver which considers the online estimation of thermodynamic equilibria with a macroscopic model for temperature calculation. The coupled micro-model predicts the dendrite solidification of ternary alloys. To simulate the phase transformation in temperature zones below solidification a homogenization model is added. Permanent mould casting experiments with ternary aluminum alloys are used to validate these models.