Oxidation behavior of a new wrought Ni-30Fe-20Cr based alloy at 750 °C in pure steam and the effects of alloyed yttrium

The oxidation behavior of a Ni-30Fe-20Cr base alloy with/without yttrium was studied in pure steam at 750 degrees C. Results showed that the oxide scale formed was equiaxed Cr2O3 and grew parabolically with time. Underneath the scale, Si, Ti and Al was internally oxidized into SiO2, TiO2 and Al2O3, respectively. Alloying 0.05-0.10 wt.% yttrium reduced the oxidation rate of the alloy by about 2 factors and improved the oxide adherence and also suppressed the internal oxidation. The reason for it probably lies in the decrease of the outward diffusion of chromium along grain boundaries.