High temperature oxidation of an oxide-dispersion strengthened NiAl

The oxidation behavior of an oxide-dispersion strengthened (ODS) NiAl has b een studied between 900 and 1100 degrees C in air. The dispersoids of mostl y Al2O3 in fine-grained beta-NiAl were incorporated by mechanical alloying (MA) in an argon atmosphere and hot pressing. It was found that excessive a mounts of dispersoids and voids within the matrix had serious negative effe cts on the oxidation resistance of beta-NiAl, by allowing for a more rapid formation of oxide scales and by providing fast diffusion paths for oxygen. Below the thin surface oxide scales consisted of alpha-Al2O3, NiAl2O4 and Ni2O3, an internal oxidation zone was formed deep into the matrix. No metas table transient aluminas were formed during oxidation. The oxide ridge stru cture began to evolve after oxidation at 1100 degrees C at the oxide-gas in terface. (C) 1999 Elsevier Science Ltd. All rights reserved.