Simultaneous improving high temperature oxidation resistance and room temperature toughness of NbSi based alloy via appropriate Ta content addition strategy

• Published in: International journal of refractory metals & hard materials 2024-11, Vol.124, Article 106800
• Main Authors: Yu, Jingyue, Chen, Dezhi, Xu, Fangdong, Wang, Shu, Cui, Xiangyin, Gong, Wotai, Chen, Ruirun
• Format: Article
• Language: English
• Subjects: Alloying; Nb[sbnd]Si based alloy; Oxidation resistance; Room temperature fracture toughness
• ISSN: 0263-4368
• DOI: 10.1016/j.ijrmhm.2024.106800

NbSi based alloys are expected to become the application materials for high pressure turbine blades of aircraft engines. This paper investigates the impact of Ta addition on room temperature fracture toughness and isothermal oxidation behavior at 1250 °C of four NbSi based alloys with compositions of Nb-16Si-20Ti-8Zr-4Hf-1.5Al-xTa (x = 0, 1, 2, and 4 at.%) fabricated through vacuum non-consumable arc-melting. The results show that the room temperature fracture toughness and 1250 °C oxidation resistance of the alloys increase first and then decrease with the addition of Ta element. The room temperature fracture toughness of 1Ta alloy is the best, reaching 17.1 MPa·m1/2. Adding a moderate amount of Ta (1 at.%) significantly enhances the alloy's oxidation resistance, but an excessive Ta content diminishes this enhancement. This research has obtained a Nb-16Si-20Ti-8Zr-4Hf-1.5Al-1Ta alloy with high room temperature fracture toughness and excellent high temperature oxidation resistance simultaneously, which provide an ideal path for designing NbSi alloys with superior comprehensive properties. •Adding a lower concentration of Ta (1 at.%) can toughen the alloy, while higher Ta additions (2 and 4 at.%) decreased it.•The addition of Ta element promotes the formation of Ti vacancies, effectively inhibiting the outward diffusion of Ti and the inward diffusion of oxygen.•Excessive addition of Ta will cause the eutectic point to shift to the left, thereby deteriorating the room temperature fracture toughness and high temperature oxidation resistance of the alloy.•The addition of Ta reduces the Si content in the Nbss phase and has a certain refining effect on the alloy.•The Nb-16Si-20Ti-8Zr-4Hf-1.5Al-1Ta alloy exhibits excellent comprehensive performance.