The oxidation behavior of Y ₂O ₃-dispersed β-NiAl

Y ₂O ₃-dispersed NiAl was produced by a powder-metallurgy process. By adding Y as an oxide dispersion (OD), problems with NiY _x formation and internal oxidation were avoided. Short-term isothermal and cyclic-oxidation performance at 1200°-1500°C was compared to cast NiAl alloys with and without Zr. Results indicate that the Y ₂O ₃ addition was beneficial to scale adhesion and significantly modified the α-Al ₂ O ₃ scale microstructure, similar to a Zr alloy addition. However, at 1400 and 1500° C, neither the Y ₂O ₃ or Zr additions changed the scale-growth rate, eliminated the formation of voids at the metal-scale interface or prevented scale spallation. These similarities in performance suggest that similar mechanisms occur when the reactive element is added as either an OD or an alloy addition.