β phase transformation and dynamic recrystallization of a metastable β -Ti6554 alloy during electrically assisted tension

Phase transformation of orthogonal cube α'' and close-packed ω and dynamic recrystallization of β (β-DRX) are observed in a metastable β titanium alloy during electrically-assisted tension (EAT). Their volume fractions, sizes, shapes, and spatial distribution directly determine the formabi...

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Main Authors: Wu Chuan, Liu Bao Xi
Format: Article
Language:English
Published: Elsevier 2025-07-01
Series:Journal of Materials Research and Technology
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Online Access:http://www.sciencedirect.com/science/article/pii/S2238785425016801
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author Wu Chuan
Liu Bao Xi
author_facet Wu Chuan
Liu Bao Xi
author_sort Wu Chuan
collection DOAJ
description Phase transformation of orthogonal cube α'' and close-packed ω and dynamic recrystallization of β (β-DRX) are observed in a metastable β titanium alloy during electrically-assisted tension (EAT). Their volume fractions, sizes, shapes, and spatial distribution directly determine the formability and mechanical properties. Elucidating the mechanisms of the phase transformation and β-DRX is a necessary step to understand the relationship between microstructure and properties during EAT. Uniaxial EAT tests were carried out on a metastable β alloy Ti–6Cr–5Mo–5V–4Al (Ti6554) at electric current ranging from 9 to 60 A. The true stress strain curves, work hardening and flow softening, stress-induced α'' and ω phase transformation, and β-dynamic recrystallization were analyzed via various characterization methods. Results demonstrated that the macroscopic stress-strain curves can be divided into four stages according to work hardening rate and index. X-ray diffraction (XRD) combined with electron backscatter diffraction (EBSD) indicates that the α'' phase can be transformed from the β matrix phase at ∼20 A lower current range, while begins to be decomposed with the increase of current. In addition, pole figures manifest that classical orientation relationship (OR) can be identified between the β and α'', while OR is gradually blurred with the disappearance of α'' variants until to 40 A. As the current exceeds over 50 A, homogeneous β-DRX occurs in the center of deformation zone. High-resolution scanning transmission electron microscopy (HRS-TEM) analysis discloses the β → ω→α''→β and α activation sequence in the Ti6554 alloy during EAT. To further explain the transformation, decomposition, and DRX mechanisms, the Cr, Mo, V, and Al element diffusion maps are analyzed via EDS (energy-dispersive X-ray spectroscopy). Matched hot tension was performed and compared with EAT to disclose the Joule heating and athermal effects on the microstructural evolution of Ti6554 alloy during EAT. This work can provide valuable guidance in tailoring microstructure and properties of metastable β-titanium alloys during electrically assisted processing.
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spelling doaj-art-d821f131fce9444abb799e559ca0de1a2025-08-20T02:36:04ZengElsevierJournal of Materials Research and Technology2238-78542025-07-01373661367710.1016/j.jmrt.2025.07.022β phase transformation and dynamic recrystallization of a metastable β -Ti6554 alloy during electrically assisted tensionWu Chuan0Liu Bao Xi1National Local Joint Engineering Laboratory of Intelligent Manufacturing Oriented Automobile Die & Mold, Tianjin University of Technology and Education, Tianjin, 300222, China; Corresponding author.Research Institute for Energy Equipment Materials, Tian Jin Key Laboratory of Materials Laminating Fabrication and Interfacial Controlling Technology, School of Materials Science and Engineering, Hebei University of Technology, Tian Jin, 300132, ChinaPhase transformation of orthogonal cube α'' and close-packed ω and dynamic recrystallization of β (β-DRX) are observed in a metastable β titanium alloy during electrically-assisted tension (EAT). Their volume fractions, sizes, shapes, and spatial distribution directly determine the formability and mechanical properties. Elucidating the mechanisms of the phase transformation and β-DRX is a necessary step to understand the relationship between microstructure and properties during EAT. Uniaxial EAT tests were carried out on a metastable β alloy Ti–6Cr–5Mo–5V–4Al (Ti6554) at electric current ranging from 9 to 60 A. The true stress strain curves, work hardening and flow softening, stress-induced α'' and ω phase transformation, and β-dynamic recrystallization were analyzed via various characterization methods. Results demonstrated that the macroscopic stress-strain curves can be divided into four stages according to work hardening rate and index. X-ray diffraction (XRD) combined with electron backscatter diffraction (EBSD) indicates that the α'' phase can be transformed from the β matrix phase at ∼20 A lower current range, while begins to be decomposed with the increase of current. In addition, pole figures manifest that classical orientation relationship (OR) can be identified between the β and α'', while OR is gradually blurred with the disappearance of α'' variants until to 40 A. As the current exceeds over 50 A, homogeneous β-DRX occurs in the center of deformation zone. High-resolution scanning transmission electron microscopy (HRS-TEM) analysis discloses the β → ω→α''→β and α activation sequence in the Ti6554 alloy during EAT. To further explain the transformation, decomposition, and DRX mechanisms, the Cr, Mo, V, and Al element diffusion maps are analyzed via EDS (energy-dispersive X-ray spectroscopy). Matched hot tension was performed and compared with EAT to disclose the Joule heating and athermal effects on the microstructural evolution of Ti6554 alloy during EAT. This work can provide valuable guidance in tailoring microstructure and properties of metastable β-titanium alloys during electrically assisted processing.http://www.sciencedirect.com/science/article/pii/S2238785425016801Titanium alloyElectrically assisted tensionα'' transformationDynamic recrystallizationJoule heatingAthermal effect
spellingShingle Wu Chuan
Liu Bao Xi
β phase transformation and dynamic recrystallization of a metastable β -Ti6554 alloy during electrically assisted tension
Journal of Materials Research and Technology
Titanium alloy
Electrically assisted tension
α'' transformation
Dynamic recrystallization
Joule heating
Athermal effect
title β phase transformation and dynamic recrystallization of a metastable β -Ti6554 alloy during electrically assisted tension
title_full β phase transformation and dynamic recrystallization of a metastable β -Ti6554 alloy during electrically assisted tension
title_fullStr β phase transformation and dynamic recrystallization of a metastable β -Ti6554 alloy during electrically assisted tension
title_full_unstemmed β phase transformation and dynamic recrystallization of a metastable β -Ti6554 alloy during electrically assisted tension
title_short β phase transformation and dynamic recrystallization of a metastable β -Ti6554 alloy during electrically assisted tension
title_sort β phase transformation and dynamic recrystallization of a metastable β ti6554 alloy during electrically assisted tension
topic Titanium alloy
Electrically assisted tension
α'' transformation
Dynamic recrystallization
Joule heating
Athermal effect
url http://www.sciencedirect.com/science/article/pii/S2238785425016801
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