Effect of laser surface melting on corrosion and wear resistance of a commercial magnesium alloy

Among the light metals, Mg and its alloys occupy a prominent position due to its low density, excellent machinability, and high specific strength. However, a relatively poor resistance to corrosion and wear are serious impediments against wider application of Mg alloys. In the present study, an attempt was made to enhance pitting corrosion resistance and microhardness of a commercial Mg alloy, MEZ (Zn 0.5%, Mn 0.1%, Zr 0.1%, rare earth elements 2%, Mg remaining percentage) by laser surface melting. The study included a detailed characterization of laser surface melted zone in terms of microstructure, phase analysis and its correlation with process parameters to optimize the laser processing routine. Mechanical properties like microhardness, wear, and electrochemical properties like pitting corrosion resistance of the surface melted layer were studied in detail. Microhardness of the laser surface melted layer was improved to 85-100 VHN as compared to 35 VHN of the as-received MEZ. Pitting corrosion resistance of the laser surface melted MEZ, significantly improved in a 3.56 wt.% NaCl solution because of grain refinement and redistribution of the intermetallic phases following rapid quenching associated with the process. The wear resistance of laser surface melted layer was also improved as compared to as-received MEZ. (C) 2003 Elsevier B.V. All rights reserved.