Abstract:
Pure aluminum powder was mixed with aluminum-coated Ni5Al alloy powder according to aluminum mass fraction (5%, 10%, 20%). Atmospheric plasma spraying technology was used to prepare Ni5Al, Ni10Al and Ni20Al alloy coatings with different aluminum content on the surface of GH4169 nickel-based superalloy. The phase composition, microstructure, microhardness, bonding strength, and electrochemical properties of three kinds of nickel aluminum alloy coatings were studied. The results indicate that nickel aluminum alloy coatings with different aluminum content were mainly composed of nickel solid solution, accompanied by the formation of NiAl and NiAl
3 phases. With the increase of aluminum content, the number of diffraction peaks of NiAl
3 and NiAl phases increased, and the intensity of diffraction peaks of nickel solid solution phase decreased. Al
2O
3 phase was still present in both Ni10Al and Ni20Al alloy coatings, and Ni
3Al phase was also present in Ni5Al alloy coating. With the increase of aluminum content, the oxides in the nickel aluminum alloy coatings decreased, the aluminum phase dispersed in the entire coating microstructure, the number of intermetallic compounds in nickel aluminum alloy coatings increased, and the coating microhardness, bonding strength, self-corrosion potential increased, and the corrosion resistance improved. There were a large number of cleavage planes and cleavage steps in the nickel aluminum alloy coating fracture, and the fracture mode was mainly brittle fracture, among which the Ni5Al alloy coating fracture had a "rock sugar" shape, and the Ni10Al alloy coating fracture had a small number of dimples.