Microstructure evolution and dynamic recrystallization behavior of a powder metallurgy Ti-22Al-25Nb alloy during hot compression

Journal Article · Sun Jan 15 00:00:00 EST 2017 · Materials Characterization

DOI:https://doi.org/10.1016/J.MATCHAR.2016.11.033· OSTI ID:22689692

Jia, Jianbo ^[1]; Yang, Yue ^[1]; Xu, Yan ^[1]; Xu, Bo ^[2]; Luo, Junting ^[1]; Zhang, Kaifeng ^[3]

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1. Education Ministry Key Laboratory of Advanced Forging & Stamping Technology and Science, Yanshan University, Qinhuangdao 066004 (China)
2. Institute of Petrochemistry Heilongjiang Academy of Sciences, Harbin 150040, (China)
3. National Key Laboratory for Precision Hot Processing of Metals, Harbin Institute of Technology, Harbin 150001 (China)

The flow behavior of a powder metallurgy (P/M) Ti-22Al-25Nb alloy during hot compression tests has been investigated at a strain rate of 0.01 s{sup −1} and a temperature range of 980–1100 °C up to various true strains from 0.1 to 0.9. The effects of deformation temperature and strain on microstructure characterization and nucleation mechanisms of dynamic recrystallization (DRX) were assessed by means of Optical microscope (OM), electron backscatter diffraction (EBSD) and transmission electron microscope (TEM) techniques, respectively. The results indicated that the process of DRX was promoted by increasing deformation temperature and strain. By regression analysis, a power exponent relationship between peak stresses and sizes of stable DRX grains was developed. In addition, it is suggested that the discontinuous dynamic recrystallization (DDRX) and continuous dynamic recrystallization (CDRX) controlled nucleation mechanisms for DRX grains operated simultaneously during the whole hot process, and which played the leading role varied with hot process parameters of temperature and strain. It was further demonstrated that the CDRX featured by progressive subgrain rotation was weakened by elevating deformation temperatures. - Highlights: •Flow behavior of a P/M Ti-22Al-25Nb is studied by hot compression tests. •Microstructure evolution of alloy is affected by deformation temperature and strain. •The relationship between peak stress and stable DRX grain size was developed. •The process of DRX was promoted by increasing deformation temperature and strain. •Nucleation mechanisms of DRX were identified by EBSD analysis and TEM observation.

• OSTI ID: 22689692
• Journal Information: Materials Characterization, Vol. 123; Other Information: Copyright (c) 2016 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA); ISSN 1044-5803
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALUMINIUM ALLOYS
BACKSCATTERING
DEFORMATION
ELECTRON DIFFRACTION
GRAIN SIZE
NIOBIUM ALLOYS
NUCLEATION
OPTICAL MICROSCOPES
POWDER METALLURGY
RECRYSTALLIZATION
REGRESSION ANALYSIS
ROTATION
STRAIN RATE
STRAINS
STRESSES
TEMPERATURE RANGE 1000-4000 K
TITANIUM BASE ALLOYS
TRANSMISSION ELECTRON MICROSCOPY