Investigation into the effect of adjacent crystallographic orientations on corrosion behavior in single-phase copper-nickel alloys by quasi-in-situ method

Abstract

In this study, the corrosion process of Cu-30 %Ni alloys in acidic NaCl solution was investigated by a quasi-in-situ method. The grain boundaries and twinned regions were two preferentially corroded sites. The adjacent grains of the preferentially corroded grain boundaries generally formed non-Σ3 high-angle grain boundaries. Their lattice misorientation angle rather than the surface orientation determined the intergranular corrosion susceptibility. By comparison, the preferentially corroded twinned regions were governed by the surface orientation of the twin and adjacent matrix. The large surface crystal planes deviation angle resulted in high corrosion susceptibility. Based on these observations, the corrosion behavior of polycrystalline material is predicted by computational models. The results showed that the intergranular corrosion susceptibility is similar for different matrix textures, but a high intragranular corrosion susceptibility is found in the twin-containing {100} grains. Thus, dominant twin-containing {100} grains should be avoided in Cu-Ni alloys in order to obtain high corrosion resistance.