Laser cladding of Mg–Zn–Y–Zr alloy using Al with different ratios of micro- and nano-SiC powder

In this study, a Mg–Zn–Y–Zr alloy was laser cladded with Al–SiC powder using different weight percentages and different grain sizes of SiC to improve its surface properties. We observed that the laser-cladded layer primarily comprised α-Mg, Mg₂Si, Mg₁₇Al₁₂, Al₂Y and Al₃Y phases. Moreover, the cladded layer exhibited a progressive microstructure and composition, and the volume fraction and size of the Mg₁₇Al₁₂, Al₂Y and Al₃Y phases decreased with the increase in depth. Because of the formation of these hardened phases, the average hardness of the sample with 10% of nSiCp was 4.06 times that of the substrate. In comparison with four laser-cladded samples, the sample cladded with 5% of nSiCp had the lowest friction coefficient and the highest wear resistance. The potentio-dynamic polarisation curves, measured in an aqueous NaCl (3.5 wt%) solution, demonstrated that for samples with a cladding of 10% nm, the corrosion potential increased from − 1.63 V for the untreated Mg–Zn–Y–Zr alloy to − 1.32 V for the laser-cladded alloy. The corrosion current density significantly decreased from 3.60 × 10⁻⁵ to 4.03 × 10⁻⁶ A cm⁻². These results demonstrate that laser cladding with nano-SiC is an effective method to significantly improve the surface properties of Mg-rare earth alloys.