Effect of Rare Earth Element La Addition on the Corrosion Resistance of 90/10 Copper–Nickel Alloy

The corrosion behavior of 90/10 copper–nickel alloy with different rare earth La contents in 3.5 wt% NaCl solution was investigated by electrochemical impedance spectroscopy and polarization tests. The corrosion product films were characterized using scanning electron microscopy, energy dispersive spectrometer, and X‐ray diffraction, and the corrosion products on the sample surface were further analyzed using X‐ray photoelectron spectroscopy (XPS) to investigate the detailed layer structure. The results demonstrate that rare earth La enhances the corrosion resistance of 90/10 copper–nickel alloy in a 3.5 wt% NaCl solution, with its effect becoming more pronounced as the immersion time increases to 30 days. The corrosion resistance of the alloys increased initially and then decreased with increasing rare earth content, with the optimal corrosion resistance observed at 0.063 wt% rare earth La. Rare earth La can effectively improve the binding force and stability of the corrosion product film on the surface of 90/10 copper–nickel alloy with the substrate and reduce the generation of cracks in the corrosion products. XPS results indicate that the Ni content in the corrosion product film of 90/10 copper–nickel alloy with rare earth La added is higher. The La 2 O 3 formed in the corrosion product inhibits the cathodic reaction and enhances the dielectric properties of the surface film, thereby improving the corrosion resistance of 90/10 copper–nickel alloy.