@ARTICLE{Migas_D._The_2021, author={Migas, D. and Kierat, M. and Moskal, G.}, volume={vol. 66}, number={No 1}, journal={Archives of Metallurgy and Materials}, pages={5-14}, howpublished={online}, year={2021}, publisher={Institute of Metallurgy and Materials Science of Polish Academy of Sciences}, publisher={Committee of Materials Engineering and Metallurgy of Polish Academy of Sciences}, abstract={In this investigation, the formation of oxide scales on different Co-Ni based superalloys of γ–γ′ type was analyzed. Co-20Ni-7Al-7W (at. %) alloy as well as its W-free modifications based on Co-Ni-Al-Mo-Nb and Co-Ni-Al-Ta systems was analyzed under conditions of high temperature oxidation at 800 and 900°C. Therefore, the alloys were isothermally oxidized at selected temperatures for 100 h in laboratory furnace. Afterwards, the oxidation products were evaluated by means of X-ray diffraction (XRD), optical microscopy (OM) and scanning electron microscopy (SEM). The performed tests showed that W-free alloys exhibit worse oxidation resistance compared to those of Co-Ni-Al-W alloys. After oxidation at 900°C, all alloys were prone of oxide spallation. The scales characterized by oxide peeling were mostly composed of complex Co-based oxides, including CoWO4, CoTa2O6, Co2Mo3O8, CoNb2O6.}, type={Article}, title={The Oxide Scales Formed on Different Co-Ni Based Superalloys During Isothermal Oxidation at 800 and 900°C}, URL={http://journals.pan.pl/Content/117781/PDF/AMM-2021-1-01-Migas.pdf}, doi={10.24425/amm.2021.134752}, keywords={γ–γ′ cobalt-based superalloys, high temperature oxidation, Co-Ni superalloy, W-free cobalt superalloys}, }