The Oxidation Mechanism of Ni-3, 6, 9wt.% Cr Alloy Containing Stable Oxide Dispersions

The isothermal oxidation behavior of Ni-3,6,9 wt. % Cr alloys with and without 10vol, % Al2O3 was studied in 1 atm of oxygen at 1000 and 1100 .deg. C. The presence of stable oxide dispersion markedly increased the isothermal oxidation resistance compared to the Ni-Cr alloy without dispersions and also promoted the formation of a continuous and protective layer of Cr2O3 at a quite low Cr concentration of about 6wt.%Cr. Furthermore, the types of oxide dispersoids (Y2O3, TiO2 and Al2O3) had no marked effect on the oxidation behavior of Ni-9wt.%Cr alloy containing oxide dispersion. It is suggested that the oxide dispersion in Ni-3,6,9wt.%Cr alloys improved the oxidation properties of these alloys by promoting the selective oxidation of Cr and increasing the selective diffusion paths of Cr such as interphase boundary as well as grain boundary in these alloys