High temperature cyclic oxidation of Ni based superalloys at different temperatures in air

In present study high temperature cyclic oxidation behavior of Ni-based superalloy (Inconel 617) was investigated. The cyclic oxidation test was carried out at various temperatures 750 degrees C, 850 degrees C, 950 degrees C and 1000 degrees C under cyclic conditions in the air for 96 h. Weight gain is measured discontinuously at different oxidation temperatures and times. Weight gain was used to determine the kinetics of oxidation. The oxidation kinetics of the alloys followed a parabolic rate law at 850 degrees C, 950 degrees C and 1000 degrees C. Field emission scanning electron microscopy/energy dispersive spectroscopic analysis (FESEM/EDAX) technique was used to analyze the oxidation products. X-Ray Diffraction (XRD) was used to analyze the formed scale. The protective oxides of Cr2O3, NiO, and NiCr2O4 were formed, which contributed to the better oxidation resistance. These oxide scales increased with time and temperature and they are compact, dense, distributed uniformly and adherent to the surface of Inconel 617 alloy. (C) 2017 Published by Elsevier B.V.