Dispersoid precipitation and process modelling in zirconium containing commercial aluminium alloys

Small dispersoid particles inhibit recrystallisation and are thus critical in controlling the grain structure of many high strength commercial aluminium alloys. A general, physical model has been developed for the precipitation of Al 3Zr dispersoids in aluminium alloys. The predictions of the model have been compared with results of an experimental investigation of Al 3Zr precipitation in 7050. The model has been shown to faithfully reproduce the distribution of dispersoids observed in this alloy, correctly predicting dispersoid free zones observed in interdendritic regions and at grain boundaries. Furthermore, the predicted precipitation kinetics agree well with experimental observation. The model has been used to study the effects of homogenisation conditions and alloy composition on dispersoid formation and has been shown to be a powerful tool for optimising the dispersoid distribution in 7xxx series aluminium alloys.