Laser cladding of Al plus Ir powders on ZM5 magnesium base alloy

Laser cladding of preplaced Al+Ir powders on a ZM5 magnesium alloy was performed to enhance the corrosion resistance of the ZM5 magnesium alloy. A metallurgical bond was obtained at the coating/substrate interface. The corrosion potential (E-corr) of the laser cladded sample was 169 mV positive to that of the untreated ZM5 substrate, while the corrosion current (I-corr) was some one order of magnitude lower. The laser cladded sample, unlike the untreated ZM5 substrate, showed a passive region in the polarization plot. Immersion tests confirmed that the corrosion resistance of the laser cladded ZM5 sample was significantly enhanced in 3.5 wt.% NaCl solution. The Al-rich phases of AlIr, Mg17Al12, and Al formed in the cladding layer and the rapid solid characteristics were contributed to the improved corrosion behavior of the coating.