The effect of yttrium addition on the isothermal oxidation behavior of sputtered K38 nanocrystalline coating at 1273 K in air

The influence of various amounts of Y addition on the isothermal oxidation behavior of sputtered Ni-based superalloy K38 nanocrystalline coating at 1273 K was investigated. The result indicated that the addition of 0.05 and 0.1 wt.% Y in nanocrystalline coating enhanced the selective oxidation of Al, reduced scale growth rate and retarded the phase transformation from metastable to stable alumina. In contrast, 0.5 wt.% Y addition significantly increased the oxidation rate of the coating, the incorporation of Ti in the external alumina scale accelerated the phase transformation to stable alumina.