In this study, single crystal superalloy René N5 was exposed in air at 1150 °C for up to 16 hours to evaluate the alloy’s short-term oxidation behaviour and the potential for developing a no-bond coat TBC system. The results showed that after 1 hour of exposure, a three layered oxide developed on the surface, consisting of spinel, Ta-containing oxide and alumina just above the substrate. After 4 hours of exposure, oxide spallation occurred; this became more pronounced after 16 hours. The oxide spallation took place between the top spinel layer and alumina layer, where Ta-rich oxide was more abundant. All samples tested for 0.5, 1, 2, 4 and 16 hours developed alumina near the substrate while the occurrence of NiO, spinel and Ta-oxides varied, depending upon the exposure time.

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