Exploring NbSi based alloys with excellent fracture toughness and oxidation resistance

• Published in: Materials characterization 2024-09, Vol.215, Article 114220
• Main Authors: Xu, Fangdong, Chen, Dezhi, Chen, Ruirun, Cao, Wenquan, Gong, Wotai, Yu, Jingyue
• Format: Article
• Language: English
• Subjects: Fracture toughness; Nb-Si; Oxidation resistance; Oxides; Silicides
• ISSN: 1044-5803
• DOI: 10.1016/j.matchar.2024.114220

The main objective of this paper is to give a comprehensive discussion of the fracture toughness and oxidation resistance of Nb-16Si-20Ti-3Al-5Cr-xSn-yZr (x=0.5, 1.5; y=2, 4, 6) alloys, based on experimental evidence, phase formation and diffusion theory. Results demonstrate that the microstructure of Sn0.5Zr2 and Sn1.5Zr2 alloys consist of Nbss and α-Nb5Si3, and the other four alloys are composed of Nbss, α-Nb5Si3 and γ-Nb5Si3. At the same time, the area fraction of γ-Nb5Si3 increases with the increase of Zr content. The coarsening of silicides increases with the addition of Sn. The KQ value of the Sn0.5Zr4 alloy reaches the highest with the mean of 12.64 MPa·m1/2. After oxidation at 800 °C for 24 h, Sn0.5Zr4 alloy alloy did not undergo pest oxidation. Sn0.5Zr4 alloy forms a continuous and dense TiO2 oxide layer oxidized at 1200 °C, which makes it have the best high temperature oxidation resistance. Sn0.5Zr4 alloy has excellent fracture toughness, medium temperature and high temperature oxidation resistance. •The regulation of co-doping Sn and Zr affects the type and morphology of silicides.•The Sn0.5Zr4 alloy shows the best fracture toughness and its KQ value is 12.64 MPa·m1/2.•A continuous and dense TiO2 oxide layer in Sn0.5Zr4 alloy improves oxidation resistance.