Laser surface engineering of a magnesium alloy with Al+Al₂O₃

Abstract

The present study concerns an attempt to improve the wear resistance of a commercial magnesium alloy, MEZ (rare earth 2 wt.%, Zn 0.5 wt.%, Mn 0.1 wt.%, Zr 0.1 wt.%) by dispersion of Al₂O₃ particles and alloying with aluminium 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 Al+Al₂O₃ particles (in the ratio of 3:1) on the surface of MEZ. Following laser processing, a detailed microstructural and phase analysis of the surface modified layer were carried out. The microhardness of the surface layer was measured as a function of laser parameters and wear resistance property was evaluated in details. Microhardness of the surface layer was significantly improved to as high as 350 VHN as compared to 35 VHN of the substrate. The optimum processing region for formation of a homogeneous microstructure and composition for laser surface modification of MEZ with Al+Al₂O₃ was established. The wear resistance of the laser surface modified samples was considerably improved as compared to the as-received specimen.