Enhanced Surface Properties by Electroless Nickel Deposition on a Laser Surface Treated Magnesium Alloy
J. Sudagar, R. Dewen, J-S. Lian, B-J. Zheng and K. Venkateswarlu
Surface-dependent mechanical and corrosion resistance has been enhanced by electroless nickel (EN) deposition on laser surface treated (LST) AZ91D substrate (AZ91D/LST/EN). This proposed method enhanced the surface properties in a better way than conventional LST on EN deposited AZ91D substrate (AZ91D/EN/LST). Microhardness, drysliding wear and electrochemical polarization tests were used to study the hardness, wear and corrosion resistance of these modified surfaces and followed by microstructure, phase composition analysis. The conventional, AZ91D/EN/LST samples produced a relatively smooth, crack-free and hard layer consisting of Ni-Mg intermetallic particles; thereby offered a significant increase in hardness and wear resistance and shortcoming of this method is its significant decrease in corrosion resistance, due to the diffusion of Mg into re-melted layer and the formation of Ni-Mg intermetallic phases. On the other hand, this proposed method AZ91D/LST/EN samples produced an increase in surface hardness and wear resistance and maintains a similar and high corrosion resistance.
Keywords: Laser surface treatment, magnesium alloy, electroless nickel, wear, corrosion, microhardness