Rotational outward solidification casting: An innovative single step process to produce a functionally graded aluminum reinforced with quasicrystal approximant phases

Abstract A secondary AlSi7.5Cu3-(Fe,Mn) alloy with small additions of Mn and Fe was processed by an innovative rotational outward solidification casting process to produce a functionally graded aluminum (FGA). A cylinder was produced in a single step presenting two well-defined metallurgically bonded layers (A and B) with distinct chemical composition, structure and mechanical properties. Both layers were deeply characterized through different techniques. Layer A microstructure has more than 50%vol. of the primary α-Al12(Fe,Mn,Cr)3Si quasicrystal approximant phase embedded in an Al-FCC matrix. On the other hand, layer B presents the typical hypoeutectic microstructure of the conventional AlSi7.5Cu3 alloy. Microhardness of the primary α-Al12(Fe,Mn,Cr)3Si phase and macro-hardness profile of the FGA were measured. It was found that the hardness of layer A is approximately 1.6 times higher than layer B. This new FGA may be an alternative for producing parts that require gradient properties such as, for instance, automobile engine blocks.