Laser cladding Al/Ni composite coating and its tribology performance

Al/Ni coating was prepared on Al substrate by laser cladding technology. The effects of Al/Ni ratio on the morphology, phase composition, hardness and wear resistance of the coating were investigated. The results showed that the coating formed a strong metallurgical bond with 7075 aluminum alloy substrate. With the increase of Ni content, the microstructure at the top of the coating changes from plate dendrites to equiaxial dendrites. When the Ni content reaches 50%, the top of the AlNi50 coating is a sheet of Al-Ni intermetallic compounds and locally precipitated Al-Ni intermetallic compounds with high aluminum content. The intermediate structure of the coating is dominated by columnar dendrites, and the heat-affected zone (HAZ) is characterized by transverse equiaxial dendrite structure. With the increase of Ni powder in composite powder, the hardness and wear resistance of the coating increases correspondingly. In particular, the maximum hardness of the AlNi50 coating is 1050 HV 2 , which is about 7 times the average hardness of the substrate. The wear surface of the AlNi50 coating has a shallow gully, the friction coefficient is only 0.305, and the wear amount is only 4.5 mg within 60 min. The corrosion potential of AlNi50 is −1.0838 V, the corrosion current density is 3.672 × 10 −5 A/cm 2 , and the corrosion resistance is better than that of the substrate.