Progress in Nb-Si ultra-high temperature structural materials: A review

Nb-Si based alloys have the greatest potential to replace nickel-based superalloys and become a new generation ultra-high temperature structural material with service temperature of 1200-1400 °C due to their high melting point, high stiffness, low density, and attractive specific mechanical properties at elevated temperatures. This article reviewed the recent progress in the development of Nb-Si based refractory alloys. Special attention was paid to the property characteristics, preparation techniques, alloying effects, oxidation resistance and fabrication of Nb-Si based alloy components. Thereafter, the trend of development in the future was forecasted, including: Optimization of the composition and microstructure of Nb-Si based alloys to achieve a balance of mechanical properties; Comprehensive properties evaluation for Nb-Si based alloys to accumulate sufficient data for engineering applications; Development of practical preparation technology for Nb-Si based alloy components with complex shapes; New multilayer composite coatings for Nb-Si based alloy; Joining technology of Nb-Si alloy to itself and to superalloy.