Effect of predeformation on globularization of Ti-5Al-2Sn-2Zr-4Mo-4Cr during annealing  

预变形对Ti-5Al-2Sn-2Zr-4Mo-4Cr退火过程中球化的影响（英文）

作　　者：Lian LI Miao-quan LI 李莲;李淼泉(西北工业大学材料学院,西安710072)

机构地区：School of Materials Science and Engineering, Northwestern Polytechnical University, Xi＇an 710072, China

出　　处：《Transactions of Nonferrous Metals Society of China》2018年第5期912-919,共8页中国有色金属学报（英文版）

基　　金：Project(51275416)supported by the National Natural Science Foundation of China;Project(KP201513)supported by the Fund of the State Key Laboratory of Solidification Processing in NWPU,China

摘　　要：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 °C and 1.0 s^-1, deformation amount（height reduction） 20% and 50% and annealed at 810 °C, 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 °C, 0.01 s^-1, and then annealed at 810 °C, 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.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°C、1.0 s^(-1)条件下经20%和50%的压缩变形后再在810°C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°C、0.01 s^(-1)条件下经50%变形后再在810°C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。

关 键 词：Ti-5Al-2Sn-2Zr-4Mo-4Cr alloy ANNEALING thermal grooving globularization high-angle grain boundaries 

分 类 号：TG146.23[一般工业技术—材料科学与工程] TG166.5[金属学及工艺—金属材料]