A review of ultra high temperature Nb-Si based superalloys

With high melting point, low density, and good high-temperature strength and processability, ultra high temperature Nb-Si intermetallic based superalloys are considered as the most promising materials for replacing the third generation of monocrystal Ni-based superalloys. This paper introduced a series of results regarding typical microstructure characteristics, composition optimization, microstructural control, and roles of constituent phases for Nb-Si based superalloys. Recently, some properties, such as room-temperature fracture toughness, high-temperature strength, and oxidation resistance, have met the application requirements of turbine airfoil materials. However, there is still a gap between the current comprehensive properties and application requirements. In the future, based on the optimization of alloy design, how to develop a more available process for microstructural control to achieve a comprehensive combination of room-temperature fracture toughness, high-temperature strength, and oxidation resistance, is important for the development of ultra high temperature Nb-Si intermetallic based superalloys.