A new titanium alloy with a combination of high strength, high strain hardening and improved ductility

doi:10.1016/j.scriptamat.2014.09.005

Scripta Materialia

Volume 94, 1 January 2015, Pages 17-20

https://doi.org/10.1016/j.scriptamat.2014.09.005 Get rights and content

A ternary β-metastable titanium Ti–9Mo–6W (wt.%) was designed. A very high work hardening rate close to 2100 MPa and a uniform deformation larger than 35% were recorded, thanks to combined transformation-induced plasticity and twinning-induced plasticity effects. In this paper, detailed microstructural analysis was performed to understand the deformation process. Various mechanisms, {3 3 2}〈1 1 3〉 mechanical twinning, stress-induced ω phase and stress-induced α″ martensite were identified after mechanical testing, resulting in a complex network of deformed microstructures with very special synergetic features.

References (25)

D. Banerjee et al.
Acta Mater.
(2013)
T. Grosdidier et al.
Mater. Sci. Eng., A
(2000)
A. Gysler et al.
Acta Metall.
(1974)
H.Y. Kim et al.
Acta Mater.
(2006)
E. Bertrand et al.
Scripta Mater.
(2011)
F. Sun et al.
Scripta Mater.
(2010)
P. Laheurte et al.
J. Mech. Behav. Biomed.
(2010)
Y.L. Hao et al.
Acta Biomater.
(2007)
S. Miyazaki et al.
Mater. Sci. Eng., A
(2006)
F. Sun et al.
J. Mech. Behav. Biomed.
(2011)

Y. Al-Zain et al.

Acta Mater.

(2011)

Y.L. Hao et al.

Scripta Mater.

(2012)

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A new titanium alloy with a combination of high strength, high strain hardening and improved ductility

Acta Mater.

Mater. Sci. Eng., A

Acta Metall.

Acta Mater.

Scripta Mater.

Scripta Mater.

J. Mech. Behav. Biomed.

Acta Biomater.

Mater. Sci. Eng., A

J. Mech. Behav. Biomed.

Acta Mater.

Scripta Mater.