Microstructures and Mechanical Properties of Cu-Coated SiC Particles Reinforced AZ61 Alloy Composites

The pure Cu coating was plated on the surface of silicon carbide particles (SiCP) by two different methods, hydrazine hydrate direct reduction method and hydrazine with glucose pre-reduction method. The hydrazine with glucose pre-reduction method is more suitable for Cu plating on the surface of SiCP in terms of morphology and microstructure. AZ61 composites reinforced with different volume fractions (3-15%) uncoated and Cu-coated SiCP were prepared by powder metallurgy followed by hot extrusion. The effect of Cu coating on the morphology of SiCP/AZ61 composite was analyzed by optical microscope (OM), scanning electron microscopy (SEM), energy dispersive spectrometer (EDS), electronic probe micro-analyzer (EPMA) and X-ray diffractometer (XRD). The properties of the composite were characterized by Brinell hardness tester and mechanical testing machine. The effects of Cu coating on the micro-hardness, tensile strength and elongation of SiCP/AZ61 composite were analyzed. The tensile strength of AZ61 composite reinforced with Cu-coated SiCP increased by 3.5-6.3% and the elongation increased by 7.4-35.0% compared with AZ61 composite reinforced with uncoated SiCP. Therefore, the Cu coating can ameliorate the microstructure and properties of the SiCP/AZ61 composite effectively, reduce the defect rate in the composite, and improve the hardness, relative density, tensile strength, elongation of the composite.