Influences of Mn and Sr Contents on Iron Phase Morphology and Phases Composition of Cast Al-Si Alloy

The influences of Mn and Sr contents on the iron phase morphology and phases composition of cast Al-Si alloy were studied by optical microscopy and X-ray diffraction. The results show that, for the Al-Si alloy containing 0.02wt%Sr, with the increase of Mn content, needle-like β-Al9Fe2Si2 phase transformed into skeleton-like AlSiMnFe phase, but when the Mn content was above 0.5wt%, AlSiMnFe phase would appear in the form of polyhedral shape. For the Al-Si alloy containing 0.3wt%Mn, with the increase of Sr content, AlSiMnFe phase and β phase all would be broke, β phase even disappeared, and there was a tendency that MgSi2 transformed into Al8Mg3FeSi6 phase, but when Sr content was above 0.03wt%, AlSiMnFe phase would aggregate, when Sr content was above 0.05wt%, AlSiMnFe phases would appear in the form of polyhedral shape.