Development of AGAT, a Third-Generation Nickel-Based Superalloy for Single Crystal Turbine Blade Applications

Abstract

The new third-generation single crystal superalloy AGAT has been developed for aircraft engine turbine blade applications. Alloy design procedure is described and AGAT alloy properties are presented and compared with those of, respectively, first-, second-, and third-generation AM1, CMSX-4 and CMSX-10 alloys. AGAT alloy exhibits high creep resistance at very high temperature (1200 °C) compared with first- and second-generation superalloys while maintaining moderate density (8870 kg m−3) and stable microstructure unlike the third-generation superalloy. High cycle fatigue (HCF) and low cycle fatigue (LCF) properties of AGAT alloy are similar to second-generation CMSX-4 alloy. AGAT solution heat treatment allows suppressing the γ/γ′ interdendritic eutectic pools at a temperature 30 °C lower than for CMSX-10 with a shorter duration. Oxidation resistance of AGAT alloy at 1150 °C is lower than that of second but higher than that of third-generation reference superalloys. AGAT shows low sensitivity to secondary reaction zone (SRZ) formation under β-NiPtAl bond coat (BC) and great spallation resistance of YPSZ EB-PVD thermal barrier coating (TBC) compared with reference alloys. Finally, single crystal turbine blades were successfully manufactured through industrial processes to be tested in engine conditions.