Studies on the Microstructure Modification and Tribological Characteristics of Cast Al-Si Eutectic Alloys

The focused of this investigation is on the modification of Fe-rich intermetallics morphology and wear and friction properties of eutectic Al-Si alloys. Eutectic Al-Si specimens were fabricated by tilt casting technique after addition of different amounts of iron and manganese to the melt alloy. Dry sliding tribological behavior of the samples were investigated using a reciprocating wear tester at the room temperature in atmospheric environment. It is found that the addition of iron up to 1.5 wt.pct to the alloy decreased the wear resistance of alloy owing to the formation of brittle plate-like β-Al5FeSi intermetallic compounds. As Manganese is added to the β-containing alloy up to the half of iron content (corresponding to a Mn/Fe ratio of 0.5), the platelet phases are completely replaced by the star-like α-Al15(Fe,Mn)3Si2 intermetallics resulting in improved wear resistance of the alloy. Introducing 0.8 wt.pct Mn to the alloy containing 1.6 wt.pct Fe did not convert the plate-like beta intermetallics to the modified alpha compounds completely and had no impressive impact on the wear rate of the alloy.