The Influence of Sr Addition on the Microstructure of A380 Alloy

Whereas A380 series alloys are some of the most widely used aluminum alloys, iron can severely degrade the ductility of an Al–Si die-casting alloy because its presence leads to the precipitation of different AlFeSi intermetallic phases resulting in development of stress concentrations. Thus, controlling the fraction and morphology of AlFeSi phase, especially the β-AlFeSi phase, is an important way to refine the ductility of A380 die-casting alloys. This article describes how Sr element was added to A380 alloys to study the effect of Sr on the morphology change of the AlFeSi phase. The results show that high cooling rates and Sr addition can both change the morphology of β-AlFeSi and transfer β-AlFeSi to α-AlFeSi. In addition, both high cooling rates and Sr addition can modify the eutectic Al–Si phase. The study shows that the optimum Sr addition and cooling rate for the A380 series alloy are 0.1 wt% and 10 °C/s, respectively.