An Alternative to the Recycling of Fe-Contaminated Al

Iron is considered an unavoidable impurity in Al–Si alloys, adversely impacting their mechanical properties due to the formation of Fe-bearing intermetallic particles. This study investigates Fe- and Fe/Ni-containing Al–9 wt% Si alloys to establish the effect of Ni addition on the microstructure and solidification conditions of these alloys. Two directionally solidified alloys are examined: Al–9 wt% Si–0.5 wt% Fe (non-modified) and Al–9 wt% Si–0.5 wt% Fe–0.5 wt% Ni (Ni-modified). The research focuses on determining the solidification cooling rate and growth rate parameters necessary to achieve specific volume fractions, sizes, and shapes of Fe-bearing intermetallics. Results indicate that the ultimate tensile strength of the Al–9Si–Fe–Ni alloy is higher than that of the Al–9Si–Fe alloy, with performance nearing that of the pure Al–9Si alloy. This improvement is attributed to the more compacted Fe-bearing intermetallics caused by the Ni addition, which mitigates the detrimental effects of Fe contamination. The elongation-to-fracture also improves under certain solidification conditions, approaching that of the pure Al–9Si alloy.