Mechanical properties and corrosion resistance of Cu-Ni-Al alloy

In order to improve the mechanical and corrosion resistance of Cu-10Ni alloy, the Cu-Ni-Al alloy with high strength and corrosion resistance was prepared by vacuum induction melting. SEM, XRD, universal testing machine, static immersion and electrochemical station were used to explore the effects of Al on the microstructure, mechanical properties and corrosion resistance of Cu-Ni alloy system. The results show that the hardness, tensile strength and yield strength of alloy significantly increased after the addition of Al element. Although the plasticity of the alloy decreases, its elongation is still greater than 40%, and the plasticity is good. The double-layer film structure of Cu2O and Cu2(OH)3Cl can form on the surface of the alloy in NaCl solution, which can prevent the corrosive medium from further corroding the surface of matrix. The corrosion rates of Cu-10Ni and Cu-9Ni-1Al alloys are 0.005 8 mm/a and 0.006 8 mm/a, respectively, when the corrosion cycle is 72 h. At 336 h, the corrosion rate of the alloys decreased to 0.003 5 mm/a and 0.001 8 mm/a, which shows that adding Al element can decrease corrosion rate to a great extent. The corrosion rate of Cu-9Ni-1Al is slower after the protective film stabilization, so the corrosion resistance is better than that of Cu-10Ni alloy.