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 industria l applications. But galvanic corrosion between magnesium matrices and the r einforcing constituents is a major concern when using these materials. Lase r cladding onto an Mg/SiC composite was carried out for the enhancement of corrosion resistance in the present study. Results show that laser paramete rs, especially scanning velocity, have significant influences on both the m icrostructure and the corrosion resistance. When laser power was kept at 50 0 W, the laser-clad coating at 8 mm s(-1) displayed three layers, i.e. the undiluted layer, the diffusive layer and the interfacial layer. Increasing scanning velocity to 10 mm s(-1) caused the elimination of the diffusive la yer whilst decreasing scanning velocity to 5 mm s(-1) induced the absence o f the undiluted layer. An increase of laser power to 600 W resulted in roug h surface and porosity in the coating. The undiluted layer has a fine Al-Si eutectic structure and the diffusive layer consists of aluminium, Al-Si eu tectic and Mg2Si phase. The corrosion resistance of the Mg/SiC composite ha s been significantly improved by using YAG laser cladding treatment, especi ally, at a scanning velocity of 10 mm s(-1). (C) 2001 Elsevier Science Ltd. All rights reserved.