Effects of Sn and Nb Additions on the Corrosion Resistance of Cu-Ni-Si-Mg Alloy

Abstract

The effects of Sn and Nb additions on the corrosion resistance of Cu-2.89Ni-0.61Si-0.14Mg alloy in 3.5 wt.% NaCl solution were investigated. The results show that the additions of Sn and Nb can improve the corrosion resistance of Cu-Ni-Si-Mg alloy. The sample with 0.2 wt.% Nb exhibits better corrosion resistance than the sample with 0.2 wt.% Sn. Compared with the dopant-free sample, for the 0.2Sn-doped sample and 0.2Nb-doped sample, the values of corrosion current densities decrease by 7 % and 21 %, and the values of polarization resistances increase by 5 % and 21 %, respectively. The corrosion film of Cu-Ni-Si-Mg alloy is a double-layer structure. The additions of Nb and Sn are helpful to improve the density of the outer layer of corrosion film and increase the charge transfer resistance of the inner layer of corrosion film. The additions of Sn and Nb can refine and uniform the microstructure of alloy, which is helpful to the formation of a more complete corrosion layer. The Cu2O and CuO are the corrosion products of alloys, and the content of Cu2O can be increased by the Sn and Nb additions.