Microstructure and Corrosion Behavior of Selective Laser‐Melted Al–Ti–Ni Coating on 90/10 Copper–Nickel Alloy

Abstract

Al–Ti–Ni composite coatings with different Ti contents (wt% = 20, 25, 30, 35) are prepared on the surface of 90/10 copper–nickel alloy using selective laser melting. The microstructure and phase composition of the coatings are characterized by scanning electron microscopy, X‐ray diffraction, and energy‐dispersive spectrometry, and the corrosion resistance of the four coatings and the 90/10 copper–nickel alloy in 3.5 wt% NaCl solution is investigated. The coatings exhibit a good metallurgical bonding with the substrate, and passive films are formed on the surfaces of the coatings after 6 h of potentiostatic polarization. The coating with a Ti content of 30% has the most compact passive film and the best corrosion protection performance due to the minimal Ti2O3 content in the passive film, which greatly improves the stability of the passive film. The immersion corrosion mechanism of the coating is pitting corrosion. Electrochemical tests show that the corrosion current density of all four coatings is one order of magnitude lower than that of the substrate, and the coating with a Ti content of 30% has the lowest corrosion current density, indicating that this coating could significantly improve the corrosion resistance of the substrate.