含钨/铌TiAl合金热稳定性研究

Thermal Stability of TiAl Alloys Containing Tungsten and Niobium

研究了700℃长期大气热暴露对含钨/铌铸态TiAl合金的组织和力学性能的影响。研究发现,在长期的高温热暴露过程中,晶团中的γ板条显示出相当稳定的特征,没有发现任何回复、再结晶和断开现象,而亚稳定的α2板条发生了α2→α2+γ的分解,并且导致合金的脆化。α2板条发生"平行分解"后,合金的抗拉和抗疲劳性能有提高的趋势,而发生"垂直分解"后,对合金的抗拉性能是有害的。钨/铌等重元素的添加会减缓α2板条的"垂直分解"。

The as-cast TiAl alloys containing tungsten and niobium were exposed to 700 °C air for a long term and effects of the exposure on microstructures and mechanical properties were investigated.Results show that the γ phase is stable and the phenomena of recovery,recrystallization and disconnection are never observed during the long-term thermal exposure.However,the metastable α2 lamellar decompose to α2＋γ phases,resulting in embrittlement of the alloys.The tensile and fatigue resistance of TiAl alloys are improved after ＂parallel decomposition＂ of α2 lamellar but the ＂perpendicular decomposition＂ of α2 lamellar is detrimental to tensile resistance.The heavy element additions can slow down the ＂perpendicular decomposition＂ of α2 lamellar.