Air oxidation of Cu-50Ni and Cu-70Ni alloys at 800 degrees C
The air oxidation of Cu-Ni alloys with 50% and 70% nickel (mole fraction) at 800 degreesC was studied. The kinetic curves for the oxidation of the two alloys are complex and deviate from the parabolic rate law. Typical double-layered scales are produced, which consist of a CuO outer layer and an inner layer containing a mixture of Cu2O and NiO with many pores. Cu-50Ni presents a small degree of internal oxidation of nickel, which is observed in many binary double-phase systems, but is quite rare in single phase systems.