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.