High temperature oxidation behavior of Ni‐based superalloy GH586 in air

In this paper, the isothermal oxidation kinetics and oxidation behavior of GH586 superalloy from 800 to 1000 °C were investigated. The oxide scale morphologies of the surfaces and the cross sections after oxidation were characterized by means of X‐ray diffraction (XRD) and scanning electron microscope (SEM) equipped with energy‐dispersive spectroscopy (EDS). The results show that the growth of the oxide scales on the surface of superalloy GH586 obeys a parabolic law with the activation energy of 241.4 kJ·mol −1 from 800 to 1000 °C. The dense oxide scale formed at 800 °C is mainly composed of Cr 2 O 3 , NiCr 2 O 4 and a small amount of TiO 2 . At 900 °C, the oxide scale is divided into two layers: the outer layer with multiple cracks is mainly composed of Cr 2 O 3 and TiO 2 , while the inner is a layer of dense Cr 2 O 3 . Under the oxide scale, aluminum‐rich oxides along the grain boundaries are generated by the internal oxidation. At 1000 °C for 100 h, cracks throughout the whole oxide film accelerate the oxidation rate of Ni‐based superalloy GH586 and large blocks of TiO 2 in the oxide scale are generated, resulting in the spallation of oxide scale.