Improved Recyclability of Cast Al-Alloys by Engineering β-Al₉Fe₂Si₂ Phase

Castability and tensile properties of recycled cast Al–Si alloys are affected by the presence of high iron content. The present study demonstrates a promising scope of better recyclability by engineering the intermetallic β-phase that present in cast Al–6 wt%Si model alloy systems with as high as 2 wt%Fe. Thermodynamic interplay between Si and Fe concentration on the formation of the β-phase and the solidification behaviour of this hypoeutectic Al–Si alloy has been explored. It has been demonstrated that suitable heat treatment alters the morphology of the β-phase and simultaneous addition of Cu improves the strength. Based on the experimental evidences, the mechanism behind the solid-state morphological changes of beta phase has been proposed. Experimental results and thermodynamic calculations suggest that Cu content of more than 2 wt% marginally increases the yield of beta phase; however, at 4 wt%Cu the solid solution strengthening improve the strength of solutionized alloy.