YAG laser cladding of an Al-Si alloy onto an Mg/SiC composite for the improvement of corrosion resistance

Magnesium metal-matrix composites (MMCs) show great potential for industrial applications. But galvanic corrosion between magnesium matrices and the reinforcing constituents is a major concern when using these materials. Laser cladding onto an Mg/SiC composite was carried out for the enhancement of corrosion resistance in the present study. Results show that laser parameters, especially scanning velocity, have significant influences on both the microstructure and the corrosion resistance. When laser power was kept at 500 W, the laser-clad coating at 8 mm s-1displayed three layers, i.e. the undiluted layer, the diffusive layer and the interfacial layer. Increasing scanning velocity to 10 mm s-1caused the elimination of the diffusive layer whilst decreasing scanning velocity to 5 mm s-1induced the absence of the undiluted layer. An increase of laser power to 600 W resulted in rough surface and porosity in the coating. The undiluted layer has a fine A1-Si eutectic structure and the diffusive layer consists of aluminum, A1-Si eutectic and Mg2Si phase. The corrosion resistance of the Mg/SiC composite has been significantly improved by using YAG laser cladding treatment, especially, at a scanning velocity of 10 mm s-1.