ABSTRACT
The oxidation of NbAl3 with additions of Cr and Y was studied to determine the mechanisms of the beneficial effects of these elements upon oxidation. Cr additions to the binary NbAl3 alloy of up to 6.8 at% reduced scale growth rates and promoted α-Al2O3 formation over much longer times relative to binary NbAl3. A major effect of Cr is to form a layer of AlNbCr at the metal/scale interface, which appears to be inherently more oxidation resistant than the matrix alloy. Yttrium additions to a Cr-containing alloy improved the scale growth rate and adherence, and changed the scale microstructure to mimic that of a typical protective Al2O3 scale.
