Dendrite arm spacing and grain size prediction in directionally solidified Al-Cu alloy–modelling and experimental study

The microstructure in binary Al-4 wt% Cu alloy solidified directionally under precisely defined thermal conditions in aerogel based furnaces is analysed in detail metallographically and compared with a full 3D simulation of the whole solidification facility and microstructure evolution models. Features like primary stem spacing, secondary dendrite arm spacing and grain size were measured and quantitative relationships between cooling rate, dendrite spacings and grain size have been compared to predictions implemented in the casting simulation software package ProCAST© coupled with a 3D Cellular Automaton technique in the CAFE module of CALCOSOFT©. The comparison between the very precise experiments and predictions by the microstructure laws implemented in the software tools shows that a good agreement can be obtained if the thermal history of the solidification process and the parameters of grain nucleation and evolution are chosen properly