Role of volatilization of molybdenum oxides during the cyclic oxidation of high-Mo containing Ni-based single crystal superalloys

The cyclic oxidation behavior of two high-Mo containing Ni-based single crystal superalloys with different Al contents at 1100 °C has been investigated. The higher formation tendency of the continuous and dense α-Al2O3 scales in the alloy with higher Al content can prevent the volatilization of MoO3 through decreasing the diffusion of Mo. Besides the spallation of oxide scales, the volatilization of refractory metal oxides can also result in the mass loss of the samples in the cyclic oxidation tests, especially in the Ni-based single crystal superalloys with high contents of refractory elements and weak formation tendency of continuous α-Al2O3 scales.