Structural and mechanical characteristics of the Al–23Si–8Fe–5Mn alloy prepared by combination of centrifugal spraying and hot die forging

The structure, mechanical properties and thermal stability of the hypereutectic Al–23Si–8Fe–5Mn (wt%) alloy were studied. The alloy was prepared by the unique method of combining centrifugal spraying and hot die forging. The rapidly solidified semiproduct was prepared by pouring the melt onto a rapidly rotating graphite disc. This semiproduct was then compacted by die forging at the temperature of 550 °C. It was shown that the preparation method led to a compact pore-free material with very good compressive mechanical properties. The results of thermal stability testing revealed that the mechanical properties do not change significantly at high temperature, even after 100 h of annealing at 400 °C. In addition, the Al–23Si–8Fe–5Mn alloy exhibited very good creep resistance. The structure contained a very fine intermetallic phase, which was identified as α-AlFeMnSi. This phase had a significant impact on the hardness and the yield strength of the material, but the primary impact of this phase was on the thermal stability of the material. The Al–23Si–8Fe–5Mn alloy was compared to a commercial casting Al–12Si–1Cu–1Mg–1Ni alloy, which is used in high temperature automotive applications. The room temperature mechanical properties of the two alloys were comparable, but the Al–23Si–8Fe–5Mn alloy exhibited considerably better thermal stability. Therefore, this alloy can be considered a promising alternative to conventional alloys. It was also demonstrated that the combination of centrifugal spraying and die forging is a suitable method for processing Al–Si based alloys with high iron contents.