Ti45Al8.5Nb0.2W0.2B0.02Y合金热暴露组织及疲劳性能研究

Research on Thermal Exposure Microstructure and Fatigue Properties of Ti45Al8.5Nb0.2W0.2B0.02Y Alloy

在大气环境下,对Ti45Al8.5Nb0.2W0.2B0.02Y等温锻造合金分别在700℃进行1 000、3 000和5 000 h,900℃进行了100、500和1 000 h热暴露处理。采用光学显微镜和扫描电镜研究了热暴露对合金组织稳定性的影响,并进行了氧化性能和疲劳性能测试。结果发现,该合金等温锻造后为典型的双态组织,经过700℃×5 000 h和900℃×1 000 h热暴露处理后,在α_2+γ层片晶团内α_2层片通过α_2→γ相变发生了一定平行分解,使层片细化,有利于提高该合金的疲劳强度。在700℃和900℃条件下,初始氧化速度均较快,相对而言700℃抗氧化能力较好。热暴露处理后,合金的室温疲劳强度均较原始状态有所提高,疲劳行为相对比较稳定。

In atrnospheric environment, the Ti45AI8.5Nb0.2W0.2B0.02Y isothermal forging alloy at 700 ℃ for 1 000 h, 3 000 h, and 5 000 h, and at 900℃ for 100 h, 500 h and 1 000 h were carried out thermal exposure treatment, respectively. The effect of thermal exposure on microstructure stability of the alloy was studied by optical microscope and scanning electron microscope, and the oxidation and fatigue properties were investigated. The results show that the alloy is a typical double state structure after isothermal forging. After 700 ℃ for 5 000 h and 900 ℃ for 1 000 h thermal exposure processing, a parallel decomposition phase transformation has taken place in the α2＋γ lamellae, α2→γ, thus the lamellae are refined, and it is beneficial to improve the fatigue strength of the alloy. Under the thermal exposure condition of 700℃ and 900℃, the initial oxidation has a rapid speed, relatively have good oxidation resistance in 700℃. After thermal exposure treatment, the fatigue strength of the alloy at room temperature is higher than that of the original state, and the fatigue behavior is relatively stable.