Corrosion Behavior of Ni₃Al Intermetallic Compound Synthesized by Laser Cladding

Single Ni₃Al intermetallic compound phase coating was successfully synthesized by laser cladding with preplaced Ni and Al mixed powders.Corrosion behaviors,corrosion resistance properties and corrosion mechanism of Ni₃Al in Na Cl solution were investigated by electrochemical and salt spray tests.It was found that the protective passive film could be formed on the Ni₃Al surface in various concentration of Na Cl solution and the passie film has a better stabilization and protection property in the Na Cl solution below 2%.However,the passive film activated dissolved and its stability decrease,which leads to the formation of corrosion pits on the surface of Ni₃Al in Na Cl solution above 3.5% and the corrosion become more serious with increasing the concentration of Na Cl solution.It is interested that the corrosion morphologies and boundaries around the corrosion pits are regular and clear with no corroded micro-cracks and destructive defects formed on the surface of Ni₃Al,The corrosion mechanism of laser cladding Ni₃Al intermetallic compound is the typical intragranular corrosion.which means that the laser cladding Ni₃Al has a potential application in the hot and humid salt spray coastal environment.