Short-term isothermal oxidation of hot extruded GH3536 Ni-based superalloy in solid and semi-solid temperature ranges

The short-term isothermal oxidation process of hot extruded GH3536 alloy in solid and semi-solid temperature ranges was investigated. The solid oxidation rates at 1200 degrees C, 1250 degrees C, 1300 degrees C were 0.049 mg(2)cm(-4)s(-1), 0.125 mg(2)cm(-4)s(-1), 0.133 mg(2)cm(-4)s(-1) respectively, while semi-solid oxidation rates at 1350 degrees C, 1360 degrees C, 1367 degrees C were 0.168 mg(2)cm(-4)s(-1), 0.259 mg(2)cm(-4)s(-1), 0.549 mg(2)cm(-4)s(-1) respectively. Oxide scales formation and spallation were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM) with energy dispersion spectroscopy (EDS). The outer diffusion of Cr3+ and Fe3+ resulted in formation of Fe2O3 and Cr2O3 granular oxides. Diffusion of Ni2+ promoted spinel formation. NiO intermediate oxidation layer was formed beyond 1300 degrees C, which was conducive to continuous Cr2O3 inner oxidation layer formation. The growth and spallation of oxide scales were significantly accelerated during semi-solid oxidation. The liquid film in the semi-solid microstructure provided a diffusion channel. The inner oxidation layer was destroyed due to thermal stress and severe deformation of the interface between oxide scales and base alloy, which led to a sharp increase in oxidation rate. (c) 2022 The Author(s). Published by Elsevier B.V.