Investigation of corrosion characteristics of Cu-10Ni-1.2Fe-xMn (x = 0.53, 0.87, 1.19) alloy in 3.5% NaCl solution

Cupronickel alloys have been broadly utilized in various fields due to their excellent properties. In this paper, electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PDP) curves were used to study the impact of different Mn contents on the corrosion resistance of 90/10 cupronickel alloy. Surface morphology, electronic structure, and phase composition of the film formed on different Mn content 90/10 cupronickel alloy immersed in 3.5% NaCl solution for 30 days were investigated using SEM, EDS, Mott–Schottky, XRD, XPS, etc., revealing that adding an appropriate amount of Mn to the 90/10 cupronickel alloy can change the corrosion resistance of the alloy. The corrosion resistance first increases and then decreases with the addition of Mn content. Among them, the sample with 0.87% Mn addition has the best corrosion resistance, the corrosion product film is more complete, no cracks appear, and the corrosion product binding force is stronger. The addition of Mn promotes the filling of cation vacancies by Ni and generates more NiO, which enhances the stability of the corrosion product film.