Modification of primary α-Al, eutectic silicon and β-Al5FeSi phases in as-cast AlSi10Cu3 alloys with (La+Yb) addition

Abstract The study systematically investigated the effects of master alloy addition containing rare earth elements La and Yb on the microstructures characteristic and tensile properties of AlSi10Cu3 alloy. It was studied by means of optical microscopy, X-ray diffraction, scanning electron microscopy, energy diffraction spectrum and differential thermal analyzer. The results showed that the addition of (La+Yb) obviously reduced the sizes of the primary α-Al phase and eutectic Si particles as well as β-Al5FeSi phase and improved the morphology of the primary α-Al phase and eutectic Si particles. The optimum addition of (La+Yb) addition was 0.6 wt.%. Comparing the 0.6 wt.% (La+Yb) modified AlSi10Cu3 alloy with the unmodified alloy, it was found that the mean diameter, mean area and SADS of primary α-Al phase were decreased by 50.80%, 75.74% and 50.83% respectively; the aspect ratio, size (length) and mean area of eutectic Si particles were decreased by 66.30%, 81.78% and 78.99%, respectively, and the average size of the β-Al5FeSi phase was 16.4 μm. In addition, the addition of (La+Yb) greatly improved the tensile properties of AlSi10Cu3 alloy, especially in the ultimate tensile strength and elongation as a result of the significant improvement in microstructure.

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