| This article discusses three hypereutectic Al-Si-Fe alloys' microstructures; electromagnetic stirring semi-solid extrusion solid extrusion and heat treatment make effect on these alloys. It mainly researches semi-solid extrusion alloys' microstructure and properties, and the thermo stability of the semi-solid extrusion alloy.Researches show: after stirring, dendritic ertectic silicon breaks size decreases, and its distribution becomes better. After extrusion, initial silicon becomes thinner, the most dendritic phases broke, and massive phase and needlelike phase turn into thin granulated. The bigger extrusion ratio alloys have thinner more symmetrical microstructure. In dry friction, semi-solid extrusion ratio 10:1 alloy, abrasive loss is 50.98% as much as casting Al-17Si with the loading time 60min. In lubricated condition, it is as 57.77% abrasive loss as that of casting Al-17Si alloy.Al-15 Si-5Fe-3Mn-4Cu-lMg-2Ni alloy after semi-solid extrusion heat treatment, Buchner hardness reaches 196; ultimate tensile strength reaches 192Mpa, extensibility reaches 2.5%.Semi-solid extrusion Al-15Si-5Fe-3Mn-4Cu-lMg-2Ni alloy phase II doesn't become bulky, microstructure has good thermal-stability as the heating temperature is 200℃ or 350℃. As it rises to 400℃, β-Si phase becomes thick rapidly, it grows to the biggest dimension, as it keeps heating, β-SI phase dimension keeps stable basically.
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