Laser cladding of Mg20Al80 powder on ZM5 magnesium alloy

Laser surface engineering can be used to alter the surface of alloys and produce a fine microstructure, usually improving the corrosion resistance and wear resistance. In the present paper, a CO2 laser was used to melt preplaced Mg20Al80 powder with the objective of improving the corrosion resistance of ZM5 magnesium alloy in sea water solution. The corrosion behaviour of the ZM5 substrate and the laser cladding Mg20Al80 sample was studied with relating to their microstructures. Corrosion was studied in a 3·5 wt-%NaCl solution at pH 7 by observing the corrosion morphology. The results showed that the Mg17Al12 acted as galvanic cathode in both the ZM5 substrate and the cladding layer. The enhanced corrosion resistance was attributed to the fine dispersion of intermetallic phases and extended Al solid solutions by laser rapid solidification.