Enhancement of in-situ NbC oxidation with size reduction and its effect on electrochemical corrosion resistance of Cu-matrix composites

More serious oxidations of in-situ NbC in Cu-matrix composites are induced not only by the reinforcement refinement due to the increase in its specific surface energy, but also by the depth increase from the surface to interior due to the existence of oxygen concentration cell. As NbC grains decrease from -5.14 to -1.64 mu m, the content of oxidation products (NbO2, Nb2O5) is increased by 1320%. It benefits the anti-corrosion properties of composites because of the protection effects of oxides on matrix phase, though NbC oxidation does not change the materials corrosion mechanism. Such novel findings may provide a potential strategy for improving the corrosion resistance of metal matrix composites.