Microstructure and Wear Resistance of Laser Clad Al-Si+SiC Coatings 35 on an AZ91D Alloy
R-L. Sun, W. Niu and Y-W. Lei
Laser cladding was carried out on AZ91D magnesium alloys using Al-Si+SiC mixture powders as clad materials. Microstructure, composition and phase constituents of the laser clad coating were examined by optical microscope (OM), scanning electronic microscope (SEM), energy dispersive spectroscopy (EDS) and X-ray diffractometer (XRD). Microhardness and wear resistance of the laser clad coating were also investigated. The results show that the laser clad coating consists of Al12Mg17, Mg2Si, Al3Mg2 and SiC phase, and good metallurgical bond was obtained between the coating and substrate. The microhardness of the laser clad coating is 5 to 6 times that of the AZ91D substrate. Wear resistance of the coating is significantly improved as comparing with the substrate.
Keywords: Magnesium alloy, CO2 laser, laser cladding, composite coatings, microstructure, wear resistance