Effect of thermal exposure on degradation of compressor blades in aero-jet engines

The environmental resistance of two single crystal nickel based superalloys, CMSX-4 and CMSX-10, used as blading materials in aero-jet engines has been studied at temperatures in the range of 800–1000°C, representative of that encountered in the high compression section of the engines. Mapping of residual stresses in ex-service blades using ruby luminescence provide an insight into the thermomechanical loading history of these blades. Comparison with laboratory test samples revealed higher compressive stresses in the blades due to extensive thermal cycling. Oxidation of CMSX-10 showed predominant NiO formation on the outer surface, whereas CMSX-4 displayed disparate oxidation regimes between the dendrite core and interdendritic regions.