The 15th Global Conference on Materials Science and Engineering (CMSE 2026)

Abstract: Nb-Si-based ultrahigh temperature alloys, with their high melting point, low density, and excellent mechanical properties at both room and elevated temperatures, are promising candidates for next-generation high-temperature structural materials in aircraft engines. Alloying is a key approach to improving the overall performance of Nb-Si based ultrahigh temperature alloys, particularly their high temperature oxidation resistance. The effects of elements such as Ti, Cr, Al, Hf, B, V, Zr, and Mo, as well as their combined influences on microstructure and properties, have been clarified, leading to the development of novel multi-component Nb-Si based ultrahigh temperature alloys with superior comprehensive performance.

The integral directional solidification technique (IDS) significantly increases the axial temperature gradient, avoiding strong convection and skin effect in the melt ahead of the solid/liquid interface during zone melting directional solidification. This enables the fabrication of alloys with excellent directional growth and outstanding mechanical properties. As the withdrawing rate increases, the number of eutectic cells in the directional solidified microstructure increases, while the average diameter of eutectic cells and the interlamellar spacing within them decrease, enhancing the characteristics of eutectic coupled growth. The integral directional solidification markedly improves the alloy's room-temperature fracture toughness, high-temperature tensile strength, and creep resistance. After whole-body directional solidification, the average K_Q value reaches 26.8 MPa·m^1/2, the tensile creep life at 1200 °C/75 MPa reaches 216 hours, the tensile strength at 1400 °C reaches 191.7 MPa, and that at 1500 °C reaches 113.8 MPa. A shell mold suitable for investment casting of Nb-Si based ultrahigh temperature alloy turbine blades has been developed, and a directionally solidified turbine blade made from Nb-Si based ultrahigh temperature alloy was successfully produced under a molten metal temperature of 2000 °C.

Keywords: Nb-Si based alloy, Alloying effects, Directional solidification, Tensile stress rupture properties, Turbine blade

Biography: Prof Guo got his Ph. D in the field of Materials Science and Engineering at Northwestern Polytechnical University in 1992. He was promoted to a full professor in 2000 at Northwestern Polytechnical University. Prof. Guo is a member of the Materials Major Accreditation Committee of the China Engineering Education Accreditation Association. He was awarded the Program for New Century Excellent Talents in University by the Ministry of Education of China in 2004. He was awarded the title of “Excellent Backbone Teachers in National Higher Education Institutions” by the Ministry of Education of China in 2002. Prof. Guo’s main research interests are in the field of physical metallurgy of ultrahigh temperature structural metallic materials. His research focuses on compositional design, melting and integrally directional solidification techniques, and microstructure and property evaluation of the Nb-Si based ultrahigh temperature alloys. He has also developed silicide-based protective coatings for Nb-Si based alloys. He has published more than 210 SCI indexed academic papers. He has obtained 6 ministry-level science and technology progress awards and 15 authorized national invention patents of China.