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

Abstract

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.