| Summary: | Iron is a common impurity present in commercial Al-Si alloys [1-3] and has consistently emerged as the impurity element that may be the most detrimental to the mechanical properties of these alloys [4]. When this element is combined with the aluminum and other alloying elements, iron intermetallic compounds are formed. The iron-bearing compounds that form during solidifi cation appear in a great variety of shapes and sizes and can generally be divided into three different morphologies: β-Al5FeSi-needles, α-Al15(Fe,Mn)3Si2-Chinese scripts and polyhedral and/or star-like crystals. The amount, size and shape of these iron compounds depend largely on the cooling conditions and on the chemical composition, especially the level of iron in the melt [5]. β-Al5FeSi-needles iron compounds have usually
been considered most detrimental to the mechanical properties of Al-Si alloys because of the brittle features
and stress concentration caused by the needle-like morphology. This kind of intermetallics
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