Microstructural Optimization of Fe-Rich Intermetallic in Al–12 wt% Si–2 wt% Fe alloys by Adding Travelling Magnetic Fields

Iron can cause negative effects on the recycling and mechanical performance of Al–Si alloys, because it is difficult to remove, and easy to form Fe-rich intermetallic with large size. In this regard, travelling magnetic fields are performed to optimize Fe-rich intermetallic in Al–12 wt% Si–2 wt% Fe alloys; and experiments and simulations are conducted to study the related evolutions induced by different Fe content from 0.1 to 2 wt% and by travelling magnetic fields. Current findings conclude that the increase of Fe content changes the precipitation sequence, causing Fe-rich intermetallic to preferentially form and convert from α-Al₈Fe₂Si to β-Al₉Fe₂Si₂; accompanied by the increase of aspect ratio and max-length from 1.81 and 15.0 μm (wt% Fe) to 50.2 and 578.2 μm (2 wt% Fe) respectively, as well as the decrease of curvature from 0.079 μm⁻¹ (0.1 wt% Fe) to 0.001 μm⁻¹ (2 wt% Fe). Moreover, precipitates containing Cu shift from adhering to the (Al, Si) phases to Fe-rich intermetallic. In additionally, primary Si particles and Al–Si eutectic phases decrease. Noteworthily, travelling magnetic fields can reduce nucleate radius and generate intense long-range directional melt flows, further to distribute temperature and solute uniformly and break up Fe-rich intermetallic, so as to optimize them. Consequently, max-length and aspect ratio decrease by 43.7% and 44.6%, whereas curvature increases by 2.7 times.