锻造对高铌γ-TiAl合金显微组织和织构的影响
Effect of forging on the microstructure and texture of a high Nb containing γ-TiAl alloy
陶慧 1李慧中 2王丽 3周睿 4车逸轩 1陈永辉 1梁霄鹏2
作者信息
- 1. School of Materials Science and Engineering,Central South University,Changsha 410083,China
- 2. School of Materials Science and Engineering,Central South University,Changsha 410083,China;State Key Laboratory of Powder Metallurgy,Central South University,Changsha 410083,China;Key Laboratory of Nonferrous Metal Materials Science and Engineering,Central South University,Changsha 410083,China
- 3. State Key Laboratory of Powder Metallurgy,Central South University,Changsha 410083,China
- 4. Department of Materials Science and Engineering,City University of Hong Kong,Kowloon 999077,Hong Kong,China
- 折叠
摘要
采用X射线衍射仪(XRD)、扫描电子显微镜(SEM)和透射电子显微镜(TEM)研究了锻造对高铌Ti-45Al-7Nb-0.3W(at.%)合金显微组织和织构演变的影响.结果表明:铸态合金主要由平均尺寸为70 μm的α2/γ层片组织组成,而热锻态合金则呈现近双态组织(DP).在热锻过程中,合金发生了层片结构的扭折和弯曲、变形孪晶和动态再结晶(DRX).同时,锻造后β相中密集的位错表明,具有无序结构的高温β相有利于改善合金的热加工性.与常见的TiAl铸造织构不同,本研究中高铌TiAl铸态合金的凝固过程由于完全通过β单相区而形成了<110>γ纤维织构,即<110>γ晶向与热流方向平行.而锻态合金则表现出较强的<001>纤维织构和较弱的<302>纤维织构,这可以归因于变形孪晶.退火后,在孪晶界和孪晶交叉处发生静态再结晶,使变形织构减弱.
Abstract
The effect of forging on the microstructure and texture evolution of a high Nb containing Ti-45Al-7Nb-0.3W(at.%)alloy was investigated by X-ray diffractometer(XRD),scanning electron microscopy(SEM),and transmission electron microscopy(TEM).The results show that the as-cast alloy is mainly composed of α2/γ lamellar colonies with a mean size of 70 μm,but the hot-forged pancake displays a near duplex microstructure(DP).Kinking and bending of lamellar colonies,deformation twinning and dynamic recrystallization(DRX)occur during hot forging.Meanwhile,dense dislocations in the β phase after forging suggest that the high-temperature β phase with a disordered structure is favorable for improving the hot-workability of the alloy.Unlike the common TiAl casting texture,the solidification process of the investigated as-cast alloy with high Nb content is completely via the β phase region,resulting in the formation of a<110>γ fiber texture where the<110>γ aligns parallel to the heat-flow direction.In comparison,the relatively strong<001>and weak<302>texture components in the as-forged alloy are attributed to the deformation twinning.After annealing,static recrystallization occurs at the twin boundary and intersections,which weakens the deformation texture.
关键词
高铌TiAl合金/锻造/显微组织/织构/β相Key words
high Nb containing γ-TiAl alloy/forging/microstructure/texture/β phase引用本文复制引用
基金项目
National Natural Science Foundation of China(52274402)
National Natural Science Foundation of China(52174381)
出版年
2024
NETL
NSTL
万方数据