热等静压温度和粒度对粉末冶金TiAl合金组织和性能的影响

Effect of HIPing temperatures and powders particle size on microstructure and properties of PM TiAl alloy

摘要:

采用电极感应熔炼气雾化（EIGA）制粉和热等静压（HIP）固结成形制备Ti-43Al-9V-0.3Y合金。研究了热等静压温度和粉末粒度对TiAl合金显微组织和力学性能的影响。采用场发射扫描电子显微镜（FESEM）、能谱（EDS）、X射线衍射（XRD）、定量金相（OM）、质谱仪（MS）对样品进行了分析表征。结果表明，TiAl合金粉末主要相组成为β/B2相，经热等静压固结成形后合金主要由γ和β/B2相组成，此外两种状态的合金中都含有少量YAl2和Y2O3相。TiAl合金在1000℃～1260℃范围150MPa、3h条件下热等静压，组织均为近γ组织，随着温度的升高，γ相尺寸增大，室温和700℃拉伸强度有一定的降低，但伸长率显著升高。在0～250μm范围，粉末粒径越小，空心粉含量和Ar含量越低。将同炉3个粒度段（<53μm、53～105μm、105～250μm）的TiAl合金粉末分别经1200℃/150MPa/3h热等静压固结成形，合金显微组织和拉伸强度随粒度变化不明显，但合金高温拉伸伸长率随粉末粒度的减小而升高。

Abstract:

The Ti-43Al-9V-0.3Y alloy was manufactured by electrode induction melting gas atomization (EIGA) and hot isostatic pressing (HIPing). Effect of HIPing temperature and powders particle size on microstructure and properties of this alloy were investigated. The TiAl powders and HIPed samples were characterized by field emission scanning electron microscopy (FESEM), energy dispertive spectrum (EDS), X-ray diffraction (XRD), quantitative metallugraphy ( QM) and mass spectrometer (MS). The results indicate that the TiAl alloy powders mainly consist of β/B2 phase. After hot isostatic pressing, the alloy mainly consists of γ and β/B2 phases. In addition, the powder and HIPed state alloys both contain a small amount of YAl2 and Y2O3 phases. After 1000-1260℃/150MPa/3h HIPing, the TiAl alloy microstructure is near γ, which is mainly comprised of γ phase and β/B2 phase. With the HIPing temperature increasing, the size of γ phase as well as the tensile elongation increased, but the tensile strength decreased. The Ar content and hollow powder quantity reduced accompanied by the powder particle size decreased. The TiAl alloy powders were sieved into three particle size range (<53μm, 53-105μm, 105-250μm), and then consolidated by HIPing at 1200°C for 3hrs under 150MPa argon pressure followed by furnace cooling. The microstructure and tensile strength of the alloy did not change significantly with the particle size, but the high temperature tensile elongation of the alloy increased obviously with the decrease of the particle size.