研究Ti?5Al?2Sn?2Zr?4Mo?4Cr在退火过程中的显微组织演变.结果表明,合金在810 ℃、1.0 s?1条件下经20%和50%的压缩变形后再在810 ℃进行退火处理,在前20 min退火过程中,β相楔入形成热沟槽十分充分,球化率迅速增大;随退火时间延长,球化率继续增加.对经较大变形程度(50%)的合金进行4 h的退火处理获得了近似完全球化的组织.合金在810 ℃、0.01 s?1条件下经50%变形后再在810 ℃进行退火处理,在前20 min退火过程中,热沟槽作用并不明显,且保留了大量的大角度晶界.通过长时间退火,在大角度晶界、末端迁移和Ostwald熟化的共同作用下形成了项链状α相晶粒.因此,在Ti?5Al?2Sn?2Zr?4Mo?4Cr退火前应进行较高应变速率与较大程度的变形以获得等轴组织.%The microstructure evolution during annealing of Ti?5Al?2Sn?2Zr?4Mo?4Cr alloy was investigated. The results show that for the alloy compressed at 810 ℃ and 1.0 s?1, deformation amount (height reduction) 20% and 50% and annealed at 810 ℃, thermal grooving by penetration of β phase is sufficient during the first 20 min annealing, resulting in a sharp increase in globularization fraction. The globularization fraction continuously increases with the increase of annealing time, and a height reduction of 50% leads to a near globular microstructure after annealing for 4 h. For the alloy with deformation amount of 50% by compressing at 810 ℃, 0.01 s?1, and then annealed at 810 ℃, thermal grooving is limited during the first 20 min of annealing and large quantities of high-angle grain boundaries (HABs) remain. With long time annealing, the chain-like α grains are developed due to the HABs, termination migration and Ostwald ripening. The present results suggest that a higher strain rate and a larger height reduction are necessary before annealing to achieve a globular microstructure of Ti?5Al?2Sn?2Zr?4Mo?4Cr.
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