High temperature oxidation of Ni3Al alloy containing Cr, Zr, Mo, and B

The oxidation behavior of a 74.028 Ni–16.004 Al–7.844 Cr–1.263 Zr–0.836 Mo–0.025 B at.% alloy, known as IC221M, has been studied at 900, 1000 and 1100 °C in air. Isothermal and cyclic weight gain measurements indicated that protective scales formed on the alloy at 900 and 1000 °C. At 1100 °C, massive scale spallation after 220 h of exposure was observed for cyclic oxidation conditions. The oxide scales consisted mainly of an outer NiO oxide layer, and inner, mixed oxides of α-Al2O3, NiAl2O4, and (monoclinic, tetragonal)-ZrO2. Some alumina and zirconia existed as internal oxide stringers. The oxide grains were frequently incorporated with dissolved, foreign cations such as Cr or Ni to a certain extent.