Cyclic oxidation behavior of Ni3Al-7.8% Cr-1.3% Zr-0.8% Mo-0.025% B between 900 and 1100°C

Abstract

A Ni3Al-based alloy, the composition of which was Ni-16.0% Al-7.8% Cr-1.3% Zr-0.8% Mo-0.025%B, was cyclically oxidized in the temperature range of 900 to 1100°C in air for up to 500 hr. The alloy displayed good cyclic oxidation resistance up to 1000°C, with little scale spallation. It, however, lost cyclic oxidation resistance during oxidation at 1100°C after about 200 hr, displaying large weight losses due to serious scale spallation. NiO, α-Al2O3, NiAl2O4 and ZrO2 were formed. The oxide scales consisted primarily of an outer Ni-rich layer which was prone to spallation, and (Al, Cr, Zr, Mo, Ni)-containing internal oxides which were adherent due mainly to the formation of (Al2O3, ZrO2)-containing oxides that keyed the oxide scale to the matrix alloy.