Modelling Al3Zr dispersoid precipitation in multicomponent aluminium alloys

An integrated modelling approach has been used to predict the precipitation of metastable L12 Al3Zr dispersoids in multicomponent aluminium alloys, during homogenization heat treatment. The Scheil–Gulliver method has been used to predict the segregation of the alloying elements after casting. A coupled model was then developed to predict the simultaneous precipitation of Al3Zr dispersoids and diffusional redistribution of the alloying elements during subsequent homogenization. The effect of the concentration of copper, magnesium and zinc solute on dispersoid precipitation has been predicted for 7xxx aluminium alloys. These elements are predicted to accelerate Al3Zr precipitation kinetics, with changes in magnesium concentration showing the strongest effect. The effect of the solute concentration on the width of the dispersoid free zone towards the edge of the dendrites has also been calculated. Increasing solute concentration is predicted to reduce this width, and the possible consequences of this on the fraction of recrystallization have been investigated.