LASER CLADDING OF ZIRCONIUM ON MAGNESIUM FOR IMPROVED CORROSION PROPERTIES

Laser cladding of Mg-2 wt% Zr, and Mg-5 wt% Zr powder mixture onto magnesium was carried out. The microstructure of the laser clad was studied. From the microstructural study, the epitaxial regrowth of the clad region on the underlying substrate was observed. Martensite plates of different size were observed in transmission electron microscope for Mg-2 wt% Zr and Mg-5 wt% Zr laser clad. The corrosion properties of the laser clad were evaluated in seawater (3.5% NaCI). The position of the laser claddings in the galvanic series of metals in seawater, the anodic polarization characteristics of the laser claddings and the protective nature and the stability of the passivating film formed have been determined. The formation of pitting on the surface of the laser clad subjected to corrosion has been reported. The corrosion properties of the laser claddings have been compared with that of the commercially used magnesium alloy AZ91B.