挤压开坯后TiAl合金高温变形过程中的微观组织演变

Microstructure evolution of extruded TiAl alloy in hot working

采用Gleeble-1500热模拟机对经挤压开坯后的TiAl合金进行热压缩变形,研究热变形参数对合金微观组织的影响。结果表明,随着变形量的增加,γ相首先在晶界处发生再结晶并长大,α2相发生拉长、分解和球化,组织得到了细化;变形温度和应变速率对组织影响显著,提高变形温度和降低应变速率,可有效提高组织均匀性。对微观组织进行定量金相统计分析,得到了TiAl合金动态再结晶组织演化模型。

The effects of deformation parameters（including deformation temperature,strain rate and strain） on the microstructure of the extruded TiAl alloy were investigated through isothermal compression experiments and metallographic tests.The results indicate that the dynamic recrystallization is occurred first at the grain boundary of γ phase,elongating,cracking and globularization occurred at α2 phase with microstructure being refined.The uniformity of microstructure can be improved by increasing deformation temperature and decreasing strain rate.The model of microstructure evolution during dynamic recrystallization for the TiAl alloy is obtained.