Microstructure and corrosion resistance of laser clad coating of Ni ₂Si/Ni₂Si₂ silicide alloy

A corrosion resistant Ni₂Si/Ni₃Si₂ silicide alloy coating was fabricated on a substrate of low carbon steel A3 by laser cladding of the Ni76Si24 alloy powders. The laser clad silicide alloy coating has a rapidly solidified homogeneous microstructure consisting of plate-like Ni₂Si primary phase and minor amount of Ni ₂Si/Ni₃Si₂ eutectics and is metallurgically bonded to the steel substrate. The corrosion resistances of the silicide alloy coating in the water solutions of 0.5mol/I H₂SO₄ and 3.5% NaCl were evaluated utilizing the electrochemical polarization corrosion-test method. Because of the inherent excellent corrosion-resisting properties of the constituting phases Ni₂Si and Ni₃Si₂, and the rapidly solidified homogeneous microstructure, the laser clad Ni ₂Si/Ni₃Si₂ silicide alloy coating exhibits excellent corrosion resistance.