Microstructural evolution and elemental interdiffusion behaviour near the interface of NiAlTa alloy and single crystal superalloy DD5 at 1000 °C, 1050 °C, and 1100 °C

Abstract

The NiAlTa system has been identified as a possible candidate for a protective coating material for single crystal superalloy blade tips. The microstructural evolution and elemental interdiffusion behaviour of NiAlTa/DD5 diffusion couples at 1000 °C, 1050 °C, and 1100 °C were investigated. Significant elemental interdiffusion occurred between the NiAlTa alloy and DD5 alloy. γ'-Ni3Al, AlNi2Ta, and TCP phases were generated in the NiAlTa/DD5 diffusion couples. Ni had the highest average effective interdiffusion coefficient and the lowest diffusion activation energy, while the opposite was true for Ta. The precipitation of the TCP phase raised the potential for cracking in the substrate.