| Summary: | 碩士 === 國立臺灣科技大學 === 機械工程系 === 106 === In this study, 1, 3 and 5 wt.% of SiC particles with the size of 50 nm were added to Mg97Y2Zn1 alloy by a stir-casting method. The best distribution of the SiC nano-particles was obtained with the addition of 1 wt.% SiC. Magnesium-based composites were fabricated with three different particle sizes (50 nm, 1 μm and 10 μm) of 1 wt.% of SiC to study the effect of particle size. Then, the microstructure of the composites was investigated by optical microscopy, scanning electron microscope and X-ray diffractometer. Mechanical properties of the composites were also studied.
The results show that the phase composition of magnesium-based composites are α-Mg, Mg12Y1Zn1 and SiC. Microstructural characterization of the composites show that the highest degree of agglomeration of SiC particles occurred when 5 wt.% of SiC was added. The amount of Mg12Y1Zn1 precipitates along grain boundary decreases when the amount of SiC particles increases. The 0.2% yield strength, ultimate strength and elongation of the as-cast Mg97Y2Zn1 alloy are 66 MPa, 126 MPa and 6.9 %, respectively. The mechanical strength of the composites increase; however, the elongation of the composite with 5 wt.% of SiC decreases due to the agglomeration of SiC particles. The composite with 1 wt.% of SiC having a particle size of 50 nm shows the best overall performance because of the largest amount of Mg12Y1Zn1 and lowest agglomeration of SiC particles.
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