Effect of cooling slope and manganese on the microstructure of hypereutectic Al-Si alloy with 2 %Fe

Abstract

The effect of cooling slope (CS) on the microstructure of hypereutectic Al-22Si-2Fe (% w/w) alloys with 0%, 0.99%, and 1.36% Mn were studied. The results showed that primary Si particles (PSPs), needle-like Fe phases, coarse fishbone-shaped α-Al 15 (Fe, Mn) 3 Si 2 phases, and eutectic Si could be refined. With such a CS process, the intermetallic compounds in the alloys with different Mn/Fe ratios were examined with an optical microscope, scanning electron microscope, and X-ray diffraction. Moreover, the acicular δ-Al 4 (Fe, Mn)Si 2 and blocky α-Al 15 (Fe, Mn) 3 Si 2 phases were analyzed by transmission electron microscopy.