THE OXIDATION BEHAVIOR OF OXIDE-DISPERSED BETA-NIAL - I - SHORT-TERM PERFORMANCE AT 1200-DEGREES-C

Oxide dispersions were added to beta-NiAl alloys using a powder-metall urgy technique. During 20, 2-hr cycles at 1200 degrees C, scale adhesi on of the external alpha-Al2O3 was improved by the addition of Y2O3 an d ZrO2. Relative to an undoped, cast NiAl alloy, no improvement was ob served for TiO2 and HfO2 additions and negative effects were observed for Al2O3 and La2O3 additions. The various cation additions also had d iffering effects on the scale morphology and isothermal growth rates a t 1200 degrees C. The effect of the dopants added as oxide dispersions was compared to similar alloy additions of the dopants to beta-NiAl.