Microstructural evolution and dynamic recrystallization mechanisms of additively manufactured TiAl alloy with heterogeneous microstructure during hot compression

IF 4.7 1区材料科学 Q1 METALLURGY & METALLURGICAL ENGINEERING

Transactions of Nonferrous Metals Society of China Pub Date : 2024-10-01 DOI:10.1016/S1003-6326(24)66603-3

Hui TAO , Hui-zhong LI , Jia-hui LI , Li WANG , Wei-wei HE , Xiao-fen TAN , Rui ZHOU , Xiao-peng LIANG

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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.

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热压缩过程中具有异质微观结构的添加式制造钛铝合金的微观结构演变和动态再结晶机制

通过热压试验、光学显微镜（OM）、扫描电子显微镜（SEM）、电子背散射衍射（EBSD）和透射电子显微镜（TEM），研究了选择性电子束熔炼（SEBM）制备的 Ti-48Al-2Cr-2Nb (at.%) 合金在 1150 °C 和 0.1 s-1 热变形过程中的微观结构演变和动态再结晶（DRX）机制。结果表明，as-SEBMed 合金的初始微观结构沿构建方向交替出现粗γ晶粒层和细γ+α2+（α2/γ）层状混合晶粒层。在热变形的早期阶段，变形孪晶倾向于在粗晶粒内形成，从而促进了后续变形，而在细晶粒区域则出现了少量的 DRX 晶粒。随着应变的增加，粗粒区和细粒区都会通过不同的 DRX 机制形成大量 DRX 晶粒，其中细粒区涉及不连续动态再结晶机制（DDRX），而粗粒区则是 DDRX 和连续动态再结晶机制（CDRX）并存。

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来源期刊

Transactions of Nonferrous Metals Society of China 工程技术-冶金工程

CiteScore

7.40

自引率

17.80%

发文量

8456

审稿时长

3.6 months

期刊介绍： The Transactions of Nonferrous Metals Society of China (Trans. Nonferrous Met. Soc. China), founded in 1991 and sponsored by The Nonferrous Metals Society of China, is published monthly now and mainly contains reports of original research which reflect the new progresses in the field of nonferrous metals science and technology, including mineral processing, extraction metallurgy, metallic materials and heat treatments, metal working, physical metallurgy, powder metallurgy, with the emphasis on fundamental science. It is the unique preeminent publication in English for scientists, engineers, under/post-graduates on the field of nonferrous metals industry. This journal is covered by many famous abstract/index systems and databases such as SCI Expanded, Ei Compendex Plus, INSPEC, CA, METADEX, AJ and JICST.