Y2O3-reinforced Al-Si alloy coatings were prepared on the surface of a Mg alloy by the laser cladding technique. The microstructure, hardness, and wear resistance of the coatings were analyzed using an X-ray diffractometer, a scanning electron microscope, an energy spectrometer, a Vickers hardness tester, and a friction wear tester. The effect of different additions of Y2O3 on the microstructure and properties of the coatings was investigated. The results indicate that the addition of Y2O3 leads to a significant refinement of the grain size and a denser microstructure of the coatings. Coatings with a high Y2O3 content provide superior hardness and wear resistance. With a Y2O3 content of 7.5 wt.%, the coating exhibits the finest grain size, highest hardness, and smallest wear volume. Excessive amounts of Y2O3, however, cause a reduction in the surface properties of the coating.
Cu–Cr–Zr alloys reinforced in situ with TiCx nanoparticles were prepared via combustion synthesis and electromagnetic stirring casting. The microstructure of TiCx/Cu-Cr-Zr composites with various contents was analyzed. The microhardness and Brinell hardness of the composites were determined; the average volumetric abrasive wear rate and worn surface of the composites were investigated; and the electrical, thermal conductivity and thermal expansion coefficients of the materials were discussed. The results indicated that the addition of TiCx particles transformed the Cu–Cr–Zr matrix alloy microstructure from a dendritic to an equiaxed crystal, and the grain size was significantly refined as the amount added was increased. The composites with high TiCx content possessed higher hardness and abrasive wear resistance. The addition of TiCx particles reduced the electrical and thermal conductivity and thermal expansion coefficients of the materials.
In situ spherical TiCp-reinforced copper matrix composites were prepared via hot-pressing sintering assisted with copper plating. Brinell hardness and electrical conductivity of composites with various contents were investigated, room temperature compression properties and fractography of optimal TiCp/Cu composites and sintered pure copper were analysed. It was found that with the increase of TiCp content, Brinell hardness of composites was increased, while electrical conductivity decreased. When TiCp content was 1.0 wt-%, the Brinell hardness increased significantly and the conductivity was maintained at a high level. Compared with sintered pure copper, the yield strength and ultimate compressive strength of the composites were improved, while the fracture strain was reduced.
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