Laser composite surfacing of a magnesium alloy with silicon carbide

The present study concerns an attempt to improve the wear resistance of a recently developed magnesium alloy (MEZ) by formation of a SiC reinforced composite layer on the surface by laser surface engineering. Laser processing was carried out with a 10 kW continuous wave CO2 laser by melting and subsequent feeding of SiC particles on the surface of MEZ. Following laser processing, detailed microstructural and phase analysis of the composite surfaced layer were carried out and correlated with the laser parameters. The microhardness of the surface layer was measured as a function of laser parameters and wear resistance was evaluated in details. Microstructure of the composite surfaced layer mainly consists of uniform dispersion of SiC particles in grain refined MEZ matrix. The volume fraction of SiC particles was found to vary with laser/process parameters. Microhardness of the surface layer was significantly improved to as high as 270 VHN as compared to 35 VHN of the substrate. The wear resistance of the composite surfaced samples was considerably improved as compared to the as-received specimen. (C) 2002 Elsevier Science Ltd. All rights reserved.