Alloy design by tailoring phase stability in commercial Ti alloys
Alloy design by tailoring phase stability in commercial Ti alloys
The mechanical characteristics and the operative deformation mechanisms of a metallic alloy can be optimised by explicitly controlling phase stability. Here an integrated thermoelastic and pseudoelastic model is presented to evaluate the β stability in Ti alloys. The energy landscape of β→α′/α″ martensitic transformation was expressed in terms of the dilatational and transformational strain energy, the Gibbs free energy change, the external mechanical work as well as the internal frictional resistance. To test the model, new alloys were developed by tailoring two base alloys, Ti–6Al–4V and Ti–6Al–7Nb, with the addition of β-stabilising element Mo. The alloys exhibited versatile mechanical behaviours with enhanced plasticity. Martensitic nucleation and growth was fundamentally dominated by the competition between elastic strain energy and chemical driving force, where the latter term tends to lower the transformational energy barrier. The model incorporates thermodynamics and micromechanics to quantitatively investigate the threshold energy for operating transformation-induced plasticity and further guides alloy design.
Alloy design, Phase transformation, Physical modelling, Plasticity, Ti alloys
Zhao, G.-H.
7f8c3487-2fb2-4761-bafd-81a60533a55d
Liang, X.Z.
a3a45c11-e85d-43e7-82a7-15192ec48bd2
Xu, X.
13d1b329-eeb5-4f48-bb6a-efe38a752143
Gamża, M.B.
3479e8a2-e00b-49a9-97fe-4e4725d9ea37
Mao, H.
54b1d3cc-b084-4969-9e14-3477a6442453
Louzguine-Luzgin, D.V.
971998b3-b04e-4a49-a9c2-696a3efe16d7
Rivera-Díaz-del-Castillo, P.E.J.
6e0abc1c-2aee-4a18-badc-bac28e7831e2
23 April 2021
Zhao, G.-H.
7f8c3487-2fb2-4761-bafd-81a60533a55d
Liang, X.Z.
a3a45c11-e85d-43e7-82a7-15192ec48bd2
Xu, X.
13d1b329-eeb5-4f48-bb6a-efe38a752143
Gamża, M.B.
3479e8a2-e00b-49a9-97fe-4e4725d9ea37
Mao, H.
54b1d3cc-b084-4969-9e14-3477a6442453
Louzguine-Luzgin, D.V.
971998b3-b04e-4a49-a9c2-696a3efe16d7
Rivera-Díaz-del-Castillo, P.E.J.
6e0abc1c-2aee-4a18-badc-bac28e7831e2
Zhao, G.-H., Liang, X.Z., Xu, X., Gamża, M.B., Mao, H., Louzguine-Luzgin, D.V. and Rivera-Díaz-del-Castillo, P.E.J.
(2021)
Alloy design by tailoring phase stability in commercial Ti alloys.
Materials Science and Engineering: A, 815, [141229].
(doi:10.1016/j.msea.2021.141229).
Abstract
The mechanical characteristics and the operative deformation mechanisms of a metallic alloy can be optimised by explicitly controlling phase stability. Here an integrated thermoelastic and pseudoelastic model is presented to evaluate the β stability in Ti alloys. The energy landscape of β→α′/α″ martensitic transformation was expressed in terms of the dilatational and transformational strain energy, the Gibbs free energy change, the external mechanical work as well as the internal frictional resistance. To test the model, new alloys were developed by tailoring two base alloys, Ti–6Al–4V and Ti–6Al–7Nb, with the addition of β-stabilising element Mo. The alloys exhibited versatile mechanical behaviours with enhanced plasticity. Martensitic nucleation and growth was fundamentally dominated by the competition between elastic strain energy and chemical driving force, where the latter term tends to lower the transformational energy barrier. The model incorporates thermodynamics and micromechanics to quantitatively investigate the threshold energy for operating transformation-induced plasticity and further guides alloy design.
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Accepted/In Press date: 30 March 2021
e-pub ahead of print date: 20 April 2021
Published date: 23 April 2021
Keywords:
Alloy design, Phase transformation, Physical modelling, Plasticity, Ti alloys
Identifiers
Local EPrints ID: 492233
URI: http://eprints.soton.ac.uk/id/eprint/492233
ISSN: 0921-5093
PURE UUID: 05f7f4be-2fe3-495b-9632-bdea4b12fe94
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Date deposited: 22 Jul 2024 17:00
Last modified: 23 Jul 2024 02:08
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Contributors
Author:
G.-H. Zhao
Author:
X.Z. Liang
Author:
X. Xu
Author:
M.B. Gamża
Author:
H. Mao
Author:
D.V. Louzguine-Luzgin
Author:
P.E.J. Rivera-Díaz-del-Castillo
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