부산대학교 도서관

The present study presents the synergistic effects of casting thickness and various amounts of SiCp (0, 1, 3, 5, and 7 wt% SiC) on the microstructure, hardness, and tensile properties of Mg–Mg3Sb2 in-situ composite. Initially, Mg–Mg3Sb2–xSiC composite melts were made via the stir casting method which were poured into a modified green sand mold (with 6, 12, 18, and 24 mm section thicknesses). Then, the structural studies were performed by means of an optical microscope, a scanning electron microscope, and an X-ray diffraction for phase identification. It was found that the composites were comprised of primary Mg, Mg3Sb2 intermetallics, and SiCp. The addition of SiC particles to the Mg–5Sb in-situ composite did not change the average length of Mg3Sb2 phases significantly. The macrostructural studies revealed that average grain size decreased with the addition of SiC particles and increased when the casting section thickness was enlarged due to a lower cooling rate. Tensile and hardness tests were performed on all composites, and fracture surfaces of the tensile test specimens were examined via electron microscopy. As the amount of SiC increased, the hardness of the composites improved consistently, but the tensile strength and elongation of the samples showed an improvement first and then reduced. In the terms of tensile properties, the best results were observed in the Mg–5Sb–3SiC composite with a thickness of 6 mm and reached almost 151 MPa. The fracture surface observations showed that fracture mode in these composites formed of cleavage and semi-cleavage planes. [ABSTRACT FROM AUTHOR]