真空脱气对粉末冶金Ti2AlNb合金力学性能的影响

Effect of Vacuum Degassing on Mechanical Properties of Powder Metallurgy Ti2AlNb Alloy

摘要:

采用无坩埚感应熔炼超声气体雾化法制备了成分为Ti-22Al-24Nb-0.5Mo(原子分数，x/%)的预合金粉末，并对预合金粉末的化学成分、表面状态及流动性等进行了表征。通过包套热等静压工艺制备了粉末冶金Ti2AlNb合金，研究了真空脱气对粉末冶金Ti2AlNb合金力学性能的影响。结果表明，超声气体雾化法制备的Ti2AlNb合金粉末化学成分批次稳定性好；从粉末填充的工艺性能方面考虑，热等静压成形应选取粒度小于250 μm以下的全粒度分布预合金粉末；真空脱气处理可减少粉末冶金Ti2AlNb合金的孔隙缺陷，提升合金拉伸性能的稳定性和高温持久寿命。

Abstract:

In this work, a Ti2AlNb based intermetallic alloy with the composition of Ti-22Al-24Nb-0.5Mo(atomic fraction, x/%) pre-alloyed powder was produced by electrode induction melting gas atomization, and its chemical composition, surface state and fluidity were characterized. The powder metallurgy(PM) Ti2AlNb alloy was fabricated by hot isostatic pressing. The effect of vacuum degassing on mechanical properties of PM Ti2AlNb alloy was studied. The results show that the batch stability of chemical composition of Ti2AlNb alloy powder is good. Considering the process performance of powder filling, the principle of powder size selection is to select full size distribution pre-alloyed powder with particle size less than 250 μm. Vacuum degassing can reduce the pore defects of PM Ti2AlNb alloy. Vacuum degassing can improve the stability of tensile properties and rupture lifetime of PM Ti2AlNb alloy at elevated temperature.