عنوان مقاله [English]
The most important drawback of hyper-eutectic Al-Si alloys is the presence of coarse, primary, irregular and brittle silicon phases, which strongly weakens the material. Therefore, modifying the morphology, decreasing the size and uniforming the distribution of primary silicon phases are essential. The aim of this paper is to use friction stir processing (FSP) for modification of surface microstructure of hyper-eutectic Al-Si alloy. Also, the effect of processing parameters on microstructure and tribological properties was investigated by the light microscopy and microhardness measurements. For this reason, several plate-shaped samples were prepared by casting in both metallic and sand molds. It was observed that microstructure is uniformed, porosities are removed and silicon phases are finely distributed by friction stir processing, leading to improvement of microstructure and mechanical properties of the alloy. The results also showed when Mg added and cooling rate increased, particles’ size changes from 33.09 to 21.05 µm, micro hardness increased from 53 to 69 HV, and microstructure morphology is modified.
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