EFFECTS OF VARYING THE ZIRCONIUM CONCENTRATION AND 1 WT-PERCENT-Y ON HIGH-TEMPERATURE OXIDATION OF FE-15WT-PERCENT-CR-4WT-PERCENT-AL ALLOY UNDER ISOTHERMAL AND CYCLIC CONDITIONS

The effect of a 1 wt.%Zr on the oxidation behaviour of Fe-15wt.%Cr-4wt.%Al alloy under isothermal conditions in air, O2 and O2-10%H2O environments in the temperature range 1000-1150 °C was investigated. Also the effect of varying the zirconium concentration was studied at 1200 °C in air. Cyclic oxidation testing was carried out in the temperature range 1150-1300 °C in air. Under isothermal oxidation, 1 wt.% Zr has a deleterious effect in O2 and air, but it has a beneficial effect in the O2-10%H2O environment. 0.2 wt.% Zr is most effective in increasing the oxidation resistance of the Fe-15wt.%Cr-4wt.%Al alloy under both isothermal and cyclic oxidation conditions. X-ray diffraction showed the scale to be mainly α-Al2O3 with little Cr2O3 in the case of Fe-15wt.%Cr-4wt.%Al alloy. ZrO2 and YCrO3 were incorporated in the scale with α-Al2O3 in the alloys containing 1 wt.% Zr and 1 wt.% Y respectively. © 1990.