Corrosion Behaviors of Supersaturated and Peak-Aged CuNiSiCr Alloys under Salt Spray Environment.

As promising substitutes for Cu-Be alloys, Cu-Ni-Si series alloys have been investigated intensively concerning their mechanical and electrical properties but without much attention on their corrosion performance. Herein corrosion behaviors and mechanisms of the supersaturated and peak-aged CuNiSiCr alloys are investigated using salt spray test, x-ray diffraction, scanning and transmission electron microscopes. The corrosion rate of the aged sample is lower than that of the supersaturated one due to forming a denser protective corrosion product, Cu₂O. Theoretical analyses indicate that the Cu₂O film grows by oxidization of the matrix and its granular size is greatly influenced by the precipitates. The second corrosion product Cu₂(OH)₃Cl/CuCl₂·3Cu(OH)₂ forms by consuming the oxide Cu₂O, which will induce pitting and deteriorate the corrosion resistance. Based on the obtained results, guidance concerning the composition and treatment optimization is provided for enhancing the anti-corrosion capability of the CuNiSiCr alloys. [ABSTRACT FROM AUTHOR]