Multiscale characterisation of AlSi9Cu3(Fe) die casting alloys after Cu, Mg, Zn and Sr addition

The Al-Si alloys are the most diffused foundry light alloys and now constitute 90% of the Al alloys used in the automotive sector. Among the industrial processes for the production of Al alloy components, the high pressure die casting is the most widespread technology. This paper presents the influence of different alloying elements such as Cu, Mg, Zn and Sr on the microstructure and mechanical properties of an AlSi9Cu3(Fe) die casting alloy. The metallographic analysis carried out by optical, scanning and transmission electron microscopy allowed to evaluate, at different scales, the size of the primary crystals of α-Al and the porosity too, as well as to identify the different intermetallic phases distributed in the microstructure. Hardness, microhardness and static tensile testing were also performed on the different alloys, and the experimental results were correlated with the different concentrations of the alloying elements.