论文部分内容阅读
采用元素粉末经热压烧结法制备了新型Ti-43.5Al-4Nb-1Mo-0.3B合金,研究了热处理工艺对合金组织中β相转变行为及其力学性能的影响。结果表明,粉末冶金态Ti Al合金中β相呈条带状,与γ相形成块状组织。热处理能显著改善材料的组织均匀性,使B2/γ块状组织逐渐转变成α_2/γ层片组织,β相转变行为特征为吸收Ti、Al元素,排出Nb元素。温度是热处理过程中组织均匀化的主控因素,在共析温度Te附近热处理时(1100~1160℃/24 h),B2相逐渐溶解但不能完全消除,而在α相转变温度Tα以上短时热处理和稳定化低温热处理后,如1400℃/2 h/FC+850℃/6 h/AC,B2/γ块状组织可完全消除,且组织粗化不严重。初始态B2相纳米硬度为6.69 GPa,弹性模量为175.4 GPa,热处理导致其纳米硬度和弹性模量逐渐降低。
A novel Ti-43.5Al-4Nb-1Mo-0.3B alloy was prepared by hot pressing sintering with elemental powder. The effect of heat treatment on the β phase transformation behavior and mechanical properties of the alloy was investigated. The results show that the β phase in the powder metallurgy TiAl alloy is strip-like and forms the massive structure with γ phase. Heat treatment can significantly improve the homogeneity of the material, gradually transforming the B2 / γ massive structure into α_2 / γ lamellar structure, and the β phase transformation behavior is characterized by absorbing Ti and Al elements and discharging Nb elements. Temperature is the main controlling factor for the homogenization of the microstructure during the heat treatment. When heat treatment (1100-1160 ℃ / 24 h) near the eutectoid temperature Te, the B2 phase dissolves gradually but can not be completely eliminated. When the temperature is above the α phase transition temperature Tα After heat treatment and stabilization at low temperature, such as 1400 ℃ / 2 h / FC + 850 ℃ / 6 h / AC, the B2 / γ massive structure can be completely eliminated, and the coarsening of the tissue is not serious. The initial B2 phase nanohardness of 6.69 GPa, elastic modulus of 175.4 GPa, heat treatment led to the nano-hardness and elastic modulus decreased.