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 1100DGC in air. Isothermal and cyclic weight gain measurements indicated that protective scales formed on the alloy at 900 and 1000DGC. At 1100DGC, 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 *a-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.