Effect of Electromagnetic Stirring on Shape of β-Al<sub>9</sub>Fe<sub>2</sub>Si<sub>2</sub> Intermetallic Compounds Formed During Solidification of Al–Si–Fe Alloys

Abstract

A rotating magnetic field was applied during the solidification of Al–Si–Fe alloys (Si = 5 mass% or 10 mass% and Fe = 0.5 mass% or 1 mass%) and the effect of electromagnetic stirring on the area and shape of the intermetallic compounds was studied. The phases formed during solidification of the alloys were not influenced by electromagnetic stirring. The alloys consisted of α-Al, Si and intermetallic β-Al9Fe2Si2. At coil current frequencies above 10 Hz, electromagnetic stirring induced fragmentation of dendritic α-Al, giving rise to coarsening of the β-Al9Fe2Si2 present between the fragmented α-Al grains. The application of electromagnetic stirring at coil current frequencies above 80 Hz decreased the aspect ratio of β-Al9Fe2Si2 in Al–10 mass%Si–1 mass%Fe, while no such decrease was identified in Al–5 mass%Si–0.5 mass%Fe, Al–5 mass%Si–1 mass%Fe or Al–10 mass%Si–0.5 mass%Fe. It was found that the shape of the β-Al9Fe2Si2 phase formed under forced flow of the melt depended significantly on the stirring intensity and the solid fraction of the melt at which intermetallic compounds were formed.