Influence of Ni content on the oxidation behavior of alumina-forming Co-based oxide dispersion strengthened superalloys at 900 °C

Abstract

This work systematically investigated the effect of Ni additions of 10, 20 and 30 at% on the oxidation behavior of oxide dispersion-strengthened (ODS) Co-20Cr-15Al (at%) superalloys at 900 °C in air. Alumina scale with a duplex structure consisting of outer θ-alumina and inner α-alumina was formed on all tested Co-based ODS superalloys. Ni addition reduced the oxidation rate by inhibiting the growth of the outer θ-alumina during initial oxidation and the inner α-alumina during prolonged exposure. Cr2O3 formation between the interface of the θ- and α-alumina layers was confirmed with the increase of Ni content.