Effect of thermo-mechanical treatments on corrosion behavior of Cu-15Ni-8Sn alloy in 3.5 wt% NaCl solution

The microstructure and corrosion behavior of the Cu-15Ni-8Sn-1.0Zn- 0.8Al-02Si alloy treated with different thermo-mechanical processes in 3.5 wt% NaCl solution was investigated by electrochemical test, electron microscopy and XPS analysis. Compared with single-stage thermo-mechanical treatment (cold rolling by 60% reduction and then aging at 450 °C for 0.5 h), the alloy with two-stage treatment (pre-aging at 400 °C for 0.5 h, cold rolling by 60% reduction and then aging at 450 °C for 0.5 h) had finer ordered precipitates and less coarse, discontinuous precipitates, resulting in better corrosion resistance performance. The corrosion product layer was mainly a mixture of Cu2O, CuO, NiO, Ni(OH)2, SnO, SnO2, ZnO and Al2O3, with a transition from Cu2O to CuO and Cu(OH)2 occurring during the corrosion process.