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The use of secondary aluminum for structural components in the automotive industry is limited by the high Fe contents in recycled alloys which often result in the formation of brittle β-Al₅FeSi phase which reduces the ductility of aluminum castings. In this study, a new secondary Al–Si–Mg alloy with high Fe content (about 0.44 wt pct) was developed for die casting applications. Based on thermodynamic modeling, manganese was added to obtain a designed Fe-to-Mn ratio of 2 which successfully suppressed the formation of β-Al₅FeSi phase, by forming α-Al₁₅(Fe,Mn)₃Si₂ phase with rounded or hexagonal morphology. Additionally, a fine needle-like π-Al₈FeMg₃Si₂ phase was also formed within the eutectic regions. The new recycled alloy showed comparable mechanical properties in the as-cast and heat-treated (T5 and T6) conditions to three major primary die cast alloys (≤ 0.2 wt pct Fe) with similar composition …