Anisotropy of interface characteristics between NiCoCrAlY coating and a hot corrosion resistant Ni-Based single crystal superalloy during thermal exposure at different temperatures

Effects of crystal orientations and service temperatures on microstructural evolution of a coated hot corrosion resistant Ni-Based single-crystal superalloy containing carbon were investigated. gamma' grains nucleated at the interdiffusion zone (IDZ) and secondary reaction zone (SRZ) with formation of M23C6 and a phases during thermal exposure at 900 degrees C. But for specimens exposed at 1000 degrees C, gamma grains nucleated at the IDZ with precipitation of secondary MC carbides and many needle-like a phases precipitated at the substrate-diffusion zone (SDZ). The interfacial microstructure stabilities exhibited opposite anisotropy during the thermal exposure at 900 degrees C and 1000 degrees C.