Effect of rare earth element Y addition on the corrosion resistance of Cu-12.5Ni-5Sn alloy after aging

Cu-12.5Ni-5Sn-xY alloy with different rare earth Y contents was prepared by spark plasma sintering (SPS). The samples underwent aging at approximately 400 degrees C degrees C for 4 hours in an energy-saving box furnace. The effect of trace Y addition on the microstructure and corrosion behavior of aging treated Cu-12.5Ni-5Sn-xY alloy were investigated by electrochemical test, and the corrosion mechanism of the alloy was discussed. The results indicated that the addition of rare earth Y improved the uniformity of microstructure and grain size of the alloy, and improved the corrosion resistance of the alloy. When the Y content changed between 0 wt% and 1.0 wt%, the corrosion resistance of the Cu-12.5Ni-5Sn-xY alloy gradually improved. The Cu-12.5Ni-5Sn-1.0Y alloy had a lower self-corrosion current density (1.490x10-- 5 A/cm 2 ) and a lower corrosion rate (0.178 mm/a). Compared to the Cu-12.5Ni-5Sn alloy without Y addition, the maximum corrosion depth was reduced by about 44.6% and the corrosion resistance was improved. Rare earth Y promoted the uniform distribution of Ni elements, inhibited the conversion of Cu2O 2 O to Cu2(OH)3Cl, 2 (OH) 3 Cl, enhanced the layer density and stability. The internal corrosion layer mainly consisted of NiO, the intermediate layer mainly consisted of SnO, and the surface layer mainly comprised of CuO, Cu2O, 2 O, and Cu2(OH)3Cl. 2 (OH) 3 Cl. Additionally, Y2O3 2 O 3 formed on the alloy's surface, effectively prevented corrosive ion attack and enhanced the corrosion resistance of Cu-12.5Ni-5Sn alloy.