Effect of Aging Time on the Corrosion Behavior of a Cu-Ni-Si Alloy in 3.5 wt% NaCl Solution

Effect of aging time on corrosion behavior of a Cu-6.0Ni-1.0Si-0.5Al-0.15Mg-0.1Cr alloy immersed in a 3.5 wt% NaCl solution was investigated. The studied alloy exhibited good corrosion resistance compared with other super high-strength Cu-based alloys, and its corrosion resistance increased with the aging time. The purity of the copper matrix increased with precipitation and precipitates coarsening, resulting in the corrosion resistance increasing. Impedance spectra and equivalent circuit analysis confirmed that a multi-layer protective film formed on sample surface. Typical uniform corrosion appeared in this alloy, and the film density increased with the days of immersion and the aging treatment time. X-ray photoelectron spectra results showed that the main corrosion products were CuO, Cu2O, Al2O3, and Al(OH)3.