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对Ti-45Al-8Nb-0.2Si-0.3B(原子分数,%)合金进行热压缩实验,采用基于动态材料模型建立的加工图研究了在变形温度为950—1300℃,应变速率为0.001—10 s~(-1)条件下的热变形行为.结果表明:在热压缩过程中,高Nb-TiAl合金在不同变形温度和应变速率下表现出不同的流变行为.该合金在温度为950—1200℃,应变速率为1 10 s~(-1)和温度为1250—1300℃,应变速率为10 s~(-1)两个区域内易产生流变失稳现象.在温度为950 1100℃,应变速率为0.1—0.001 s~(-1)的区域和温度为1250—1300℃,应变速率为0.001—1s~(-1)的区域内合金发生了动态再结晶.在动态再结晶区域内功率耗散效率在40%—55%之间,热变形后组织细小均匀.该合金的功率耗散效率的峰值区为1150—1200℃,应变速率为0.001 s~(-1),峰值效率为64%,在此区间内合金发生超塑性变形.
The hot compression experiments of Ti-45Al-8Nb-0.2Si-0.3B (atomic fraction,%) alloy were carried out. The working diagrams based on the dynamic material model were used to study the thermal deformation behavior of Ti- s ~ (-1) .The results show that the high Nb-TiAl alloy has different rheological behaviors under different deformation temperature and strain rate during the hot compression.The results show that when the temperature is 950- At 1200 ℃, the strain rate of 1 10 s ~ (-1) and the temperature of 1250 ~ 1300 ℃, the strain rate of 10 s ~ (-1) two regions prone to rheological instability at 950 1100 ℃ , The dynamic recrystallization occurred in the region of strain rate of 0.1-0.001 s -1 and in the region of temperature of 1250-1300 ℃ and the strain rate of 0.001-1 s -1.In the dynamic recrystallization region The power dissipation efficiency is between 40% -55%, and the microstructure is fine and uniform after hot deformation.The peak power dissipation efficiency of the alloy is 1150-1200 ℃ and the strain rate is 0.001 s ~ (-1), the peak efficiency is 64%, superplastic deformation occurred in this range alloy.