热等静压法制备细晶γ-TiAl及可成形性研究

Study on Fabrication of Fine-Grained γ-TiAl by Hot Isostatic Pressing Method and Its Formability

采用低温高能球磨法和热等静压技术制备出细晶Ti-45Al-2Cr-2Nb-1B合金,采用XRD、TEM对热等静压烧结后组织形貌进行分析,采用INSTRON4200型拉伸试验机对热等静压后的材料进行拉伸性能测试。研究表明,在不同条件下烧结,其相组成为γ-TiAl和少量Ti3Al,晶粒尺寸为细晶结构(低于500nm)。对块体材料进行室温和高温拉伸试验,研究表明室温具有很低的塑性,认为粉末间没有很好的结合;850℃高温拉伸试验,强度为60～80MPa、延伸率为63%～101%,具有很好的塑性,表现出很好的高温可成形性。这表明,可以在800～900℃条件对钛铝烧结块进行二次加工(锻造或轧制)获得致密高强度的细晶钛铝块体或板材;对热等静压制备的TiAl的可成形性进行了讨论。

Fine-grained Ti-45Al-2Cr-2Nb-1B alloys were fabricated by low temperature high-energy ball milling and hot isostatic pressing （HIP）. The microstructures of the alloys after HIP sintered were observed by XRD and TEM. γ-TiAl and a small amount of Ti3Al phases were found under different sintering conditions. The grain size is characterized by fine-grained structure （lower than 500 nm）. Tensile tests were conducted by INSTRON 4200 at room temperature and high temperature. It is showed that the alloy at room temperature has lower ductility and there is poor bonding in the powders, but the alloy at 850 ℃ has good plasticity and good high temperature processing properties with tensile strength 60-80 MP and the elongation 63%-101%. It is indicated that fine-grained TiAI bulk or sheet with high-density and high strength can be obtained through secondary processing （forging or rolling）. The formability of the alloy was also discussed.