Influence of Nb addition on the oxidation behavior of novel Ni-base superalloy

Highlights: • Influence of Nb on oxidation of superalloy was investigated. • Nb enhanced the formation of compact TiO₂ on Cr₂O₃ layer. • Nb enhanced the formation of continuous CrTaO₄ beneath the Cr₂O₃. • Nb enhanced the oxidation resistance of alloy. Influence of Nb on oxidation behavior of novel Ni-base superalloy was investigated in detail at 1000 °C. Although alloy with 2 wt%Nb (2Nb) exhibits significantly higher weight gain than alloy without Nb (0Nb), oxide scale of 2Nb was more continuous and compact. In contrast, 0Nb underwent severe vaporization and spallation in oxide scale. Nb was found to accelerate the formation of compact TiO₂ on Cr₂O₃ layer, leading to inhibited vaporization and spallation in oxide scale. Nb also accelerated the formation of continuous CrTaO₄ layer beneath the Cr₂O₃, enhancing the oxidation resistance via inhibiting the interdiffusion of oxygen, nitrogen and metallic elements.