中国有色金属学报(英文版)
Transactions of Nonferrous Metals Society of China
| Vol. 34 No. 10 October 2024 |
（1. School of Materials Science and Engineering, Central South University, Changsha 410083, China;
2. State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083, China;
3. Key Laboratory of Nonferrous Metal Materials Science and Engineering, Ministry of Education, Central South University, Changsha 410083, China;
4. Xi''an Sailong AM technologies Co., Ltd., Xi’an 710016, China;
5. Department of Materials Science and Engineering, Hong Kong Institute for Advanced Study, City University of Hong Kong, Kowloon 999077, Hong Kong, China）
Abstract:Microstructural evolution and dynamic recrystallization (DRX) mechanisms of a Ti-48Al-2Cr-2Nb (at.%) alloy prepared by selective electron beam melting (SEBM) during hot deformation at 1150 °C and 0.1 s-1 were investigated by hot compression tests, optical microscope (OM), scanning electron microscope (SEM), electron back-scattered diffraction (EBSD) and transmission electron microscope (TEM). The results show that the initial microstructure of the as-SEBMed alloy exhibits layers of coarse γ grains and fine γ+α2+(α2/γ) lamellar mixture grains alternately along the building direction. During the early stage of hot deformation, deformation twins tend to form within the coarse grains, facilitating subsequent deformation, and a small number of DRX grains appear in the fine-grained regions. With the increase of strain, extensive DRX grains are formed through different DRX mechanisms in both coarse and fine-grained regions, involving discontinuous dynamic recrystallization mechanism (DDRX) in the fine-grained regions and a coexistence of DDRX and continuous dynamic recrystallization (CDRX) in the coarse- grained regions.
Key words: TiAl alloy; selective electron beam melting; heterogeneous microstructure; discontinuous dynamic recrystallization (DDRX); continuous dynamic recrystallization (CDRX)
