Low-temperature superplasticity of forged Ti–43Al–4Nb–2Mo–0.5B alloy

Niu, H.Z.; Kong, Fantao; Chen, Y.Y.; Zhang, C.J.

doi:10.1016/j.jallcom.2012.07.127

Cited by 39 publications

(9 citation statements)

References 17 publications

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“…Their peak stress (σ) is about 500-580 MPa, which is nearly two times as that of CD being perpendicular to columnar grains (pointed by the arrow), and is also much higher than others' results, e.g. Chen [20] finds that the peak stress of as-cast Ti45Al2Nb1.5V1Mo0.3Y alloy is only 250 MPa and Niu [41] finds that the peak stress of as-cast Ti43Al4Nb2Mo0.5B alloys is 295 MPa under the same condition. After DS, the columnar grains and the unsubstantial grain (or colony) boundaries are parallel with CD, and there are a higher percentage of small angle lamellas [13], which means a higher percentage of hard orientation lamellas in CD, thus a very high compressing peak stress is presented in our research.…”

Section: Hot Deformation Behaviorsmentioning

confidence: 69%

“…There are always controversies about the ordering temperature of B2 phase: Yamaguchi [39] and Lin [40] deem that the ordering temperature of B2 phase is only around 600-700°C, certainly, that is for Ti2AlNb-based alloys and the different categories of alloys may have some differences. Niu [41] reported that the ordering temperature of B2 phase in Ti43Al4Nb2Mo0.5B alloy is around 900-950°C, just because it exhibits the superplastic at this temperature range. However, this viewpoint should be thought over: the alloy in Niu's research has been forged and the grains are obviously refined, and then, during the high-temperature tensile testing, the refined microstructure can also contribute to the superplastic, i.e.…”

Section: Microstructure Evolutionmentioning

confidence: 99%

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Deformation behavior and microstructural evolution of directionally solidified TiAlNb-based alloy during thermo-compression at 1373–1573K

et al. 2015

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Section: Hot Deformation Behaviorsmentioning

confidence: 69%

Section: Microstructure Evolutionmentioning

confidence: 99%

Deformation behavior and microstructural evolution of directionally solidified TiAlNb-based alloy during thermo-compression at 1373–1573K

et al. 2015

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“…As a result of brittleness for TiAl-based alloys, the fracturing occurs on their surfaces. In order to avoid or decrease tangential tensile tress during deformation, the canned forging has been applied by Niu et al [23,24], which is also helpful for homogeneous DRX.…”

Section: D Processing Mapmentioning

confidence: 99%

Hot deformation characterization of lamellar Ti-43Al-2Si alloy fabricated by cold crucible continuous casting

Zhang

Wang

Liu

et al. 2016

Journal of Alloys and Compounds

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In order to investigate the hot deformation behavior of lamellar Ti-43Al-2Si (at%, similarly hereinafter) alloy with equiaxed colonies prepared by cold crucible continuous casting, the isothermal compression tests were carried out at different temperatures in the range of 1100-1250oC using the strain rates between 0.001s-1 and 1s-1 with true strain of 0.8. A constitutive equation at elevated temperature and threedimensional processing map of this alloy were established based on flow stress data at different temperatures and strain rates. The microstructures depended on deformation condition were observed by optical microscope (OM), backscattered electron (BSE) and electron backscattered diffraction (EBSD). It was found that the deformation activation energy (Q) varied with the deformation temperature and strain rate, and average value was 451.15kJ/mol which was much larger than that of the powder metallurgy TiAl-based alloy but smaller than that of the well directionally solidified (DS) microstructure TiAl-based alloy. Based on the processing map, the appropriate hot working domain of this alloy without deformed cracks was determined to be within the temperature window from 1150oC to 1250oC and in the strain rate range of 0.001-0.01s-1. The flow softening feature of the present alloy during deformation was noted and caused by synergetic effect of dynamic recrystallization (DRX), globularization and reorientation of lamellae. In addition, the Zener-Hollomom parameter played a key role on the DRX process.

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“…As we know, in the practical isothermal forging process, the deformation of the billet is mainly conducted under compressive stress state, and the deformation at different stages of the process and in different parts of the billet could be controlled by different mechanisms (i.e., dislocation creep versus grain boundary sliding (GBS)) corresponding to different deformation conditions (i.e., non-superplastic condition versus superplastic condition). However, the pioneering research works regarding isothermal compression deformation of γ-TiAl alloys [13][14][15][16][17] and superplasticity of γ-TiAl alloys via tension deformation [18][19][20][21][22] rarely involve the above issues. Therefore, in previous works [23,24] a deformation mechanism transition from dislocation creep to GBS with increasing deformation temperature and decreasing strain rate was revealed via the investigation of the isothermal compression of a fine-grained high Nb containing TiAl alloy with a (α 2 + γ) microstructure.…”

Section: Introductionmentioning

confidence: 99%

Microstructure Evolution of a High Nb Containing TiAl Alloy with (α2 + γ) Microstructure during Elevated Temperature Deformation

Chu

Zhu

et al. 2018

Metals

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In order to verify the correctness of the transition of deformation mechanism with the change in deformation parameters and to reveal the types and mechanism of dynamic recrystallization of γ grains during compression deformation, microstructure characterization of Ti-43.5Al-8Nb-0.2W-0.2B (at. %) alloy after isothermal compression deformation were performed. When the alloy was deformed at 1000 • C/10 −2 s −1 , the initial γ grains are elongated and significantly refined and the fraction of low angle grain boundaries (LAGB) of γ grains is obviously increased and the texture intensity remains unchanged, which indicates that the compression deformation in dislocation creep region is dominated by intragranular deformation and dynamic recrystallization (DRX) of γ grains. Besides, the lattice rotation at grain boundary serrations may be responsible for the nucleation of new recrystallized γ grains, and the following growth process may be achieved by the migration of γ grain boundaries. However, when the alloy deformed at 1050 • C/10 −4 s −1 and 1000 • C/10 −4 s −1 , the γ grains maintain equiaxed shapes and distribute more uniformly and the fraction of LAGB of γ grains is slightly raised and the texture sharpness decreases, which indicates that the compression deformation in grain boundary sliding (GBS) region is mainly controlled by GBS of γ grains and DRX occurs simultaneously within some coarse γ grains.

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Low-temperature superplasticity of forged Ti–43Al–4Nb–2Mo–0.5B alloy

Cited by 39 publications

References 17 publications

Deformation behavior and microstructural evolution of directionally solidified TiAlNb-based alloy during thermo-compression at 1373–1573K

Deformation behavior and microstructural evolution of directionally solidified TiAlNb-based alloy during thermo-compression at 1373–1573K

Hot deformation characterization of lamellar Ti-43Al-2Si alloy fabricated by cold crucible continuous casting

Microstructure Evolution of a High Nb Containing TiAl Alloy with (α2 + γ) Microstructure during Elevated Temperature Deformation

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