Stress-introduced α″ martensite and twinning in a multifunctional titanium alloy

Yang, Yi; Li, G.P.; Cheng, Guangming; Wang, H.; Zhang, M.; Xu, Fen; Yang, Ke

doi:10.1016/j.scriptamat.2007.09.010

Cited by 67 publications

(29 citation statements)

References 22 publications

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“…Most of the work to date relating to strain-induced phase transformation of titanium alloys, have been concerned with the formation of martensite during cold deformation of different Ti alloys, specifically near-β alloys as a means of developing ultra-fine grained microstructures [5,[15][16][17]. However, the most industrially important titanium components are manufactured from duplex α+β alloys, which are usually manufactured by employing a variety of thermomechanical processing techniques above and below the β-transus temperature, T β .…”

Section: Discussionmentioning

confidence: 99%

“…Apart from earlier studies of martensite-based strain-induced transformation following cold deformation [5][6][7], the merit of manipulating the mechanical properties of candidate titanium alloys by strain-induced phase transformations at high temperature, utilizing the β↔α phase transformation, does not seem to have been fully assessed nor exploited, probably due to the complex phase transformations in titanium alloys and the practical difficulties of applying thermo-mechanical processing for the production of components of industrial importance.…”

Section: Introductionmentioning

confidence: 99%

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Strain-induced phase transformation during thermo-mechanical processing of titanium alloys

Dehghan-Manshadi

Dippenaar

2012

Materials Science and Engineering: A

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Strain-induced phase transformation studies have been conducted in a Ti-6Al-2Sn-4Zr-6Mo alloy. This alloy was subjected to b sub-transus deformation upon slow cooling from the b-phase field and the effect of strain on the extent and morphology of the phase transformation during hot-deformation was determined. In addition, the transformation kinetics and the morphology of the newly formed a-phase were studied following deformation under different cooling conditions. By applying strain, the rate of the b-to-a phase transformation increased significantly during deformation as well as during slow cooling following deformation. This increase in the kinetics of the b-to-a transformation can be ascribed to straininduced phase transformation. Also, the extent of deformation of the b-phase had a marked effect on the resulting morphology and size of the newly formed a-phase. Transformation of un-deformed b-phase rendered a-phase of acicular morphology only. However, following deformation of the b-phase, acicular as well as globular a-phase morphologies have been observed upon cooling. alloy. This alloy was subjected to β sub-transus deformation upon slow cooling from the β-phase field and the effect of strain on the extent and morphology of the phase transformation during hot-deformation was determined. In addition, the transformation kinetics and the morphology of the newly formed D-phase were studied following deformation under different cooling conditions. By applying strain, the rate of the β-to-α phase transformation increased significantly during deformation as well as during slow cooling following deformation. This increase in the kinetics of the E-to-D transformation can be ascribed to strain-induced phase transformation. Also, the extent of deformation of the β-phase had a marked effect on the resulting morphology and size of the newly-formed D-phase. Transformation of un-deformed β-phase rendered D-phase of acicular morphology only. However, following deformation of the β-phase, acicular as well as globular D-phase morphologies have been observed upon cooling.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Strain-induced phase transformation during thermo-mechanical processing of titanium alloys

Dehghan-Manshadi

Dippenaar

2012

Materials Science and Engineering: A

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“…It has been reported [45] that ω particles smaller than 10 nm form plate-like structures in the {112} β planes and cause brittleness in solution treated Ti-7.5Mo-1Fe (wt%) alloy. Also, deformation {112}<111> β twinning was reported in β-Ti alloys containing fine ω particles; an ω phase with a single particle size of about 5 nm was observed to form clusters along {112}-type twins in cold deformed gum metal [46,47]. The {112}-type twinning of the β matrix was also found to be associated with the ω phase in Ti-V alloys [48].…”

Section: Discussionmentioning

confidence: 87%

Effect of Pd addition on the microstructure of Ti-30Nb alloy

et al. 2015

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The effect of Pd addition on deformation mechanisms, phase transitions and twinning has been extensively investigated in as-cast β-type Ti-30Nb (wt%) alloy using electron backscattered diffraction and transmission electron microscopy techniques. The addition of Pd resulted in refinement of the metastable ω phase. The {112}<111>-type twinning was found to strongly depend on the size of the ω particles. No β phase twins were observed in the binary alloy with larger ω particles. In the ternary alloy with much finer ω particles, {332}<113> and abundant {112}<111>-type twins were detected. On the contrary, the volume fraction of stress-induced α" martensite in the binary alloy was higher than that in the ternary one. Based on the analysis of phase diagrams and Gibbs free energy calculations, such complex phase transition and twinning phenomena have been explained in terms of relative phase stability between the ω particles and the β matrix.

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“…However, no α phase formation was detected by in-situ XRD measurements in the elastic region for Gum Metal 27) . Yang et al reported in quenched Ti-22.4Nb-0.73Ta-2.0Zr-1.34O (mol%) alloy deformed by compression, stress-induced α phase and {112}〈111〉 twins were formed after aging at 300 C 37) . Those produced α phase and twins are of microscopic scale, and no massive stress-induced phase formation as presented in Fig.…”

Section: Deformation Mechanism Of Single Crystalsmentioning

confidence: 99%

Basic Deformation Mechanism of Bcc Titanium-Based Alloy of Gum Metal

et al. 2016

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Single crystals and cold-swaged polycrystalline specimens of Gum Metal of Ti-36Nb-2Ta-3Zr-0.3O (mass %) have been compressed with the stress-relaxation test in the temperature range from 77 K to 450 K. In both single crystals and cold-swaged specimens, the yield stress decreases with increasing temperature rapidly to the room temperature and then gently above it forming a plateau at high temperature. The activation analysis of plastic deformation showed that the applied shear stress dependence of activation enthalpy and that of activation volume for single crystals and those for cold swaged specimens are almost identical if we shift the stress scale by about 120 MPa, meaning that the basic deformation mechanism is common to both samples. The above results are contradictory with the previously proposed non-dislocation deformation mechanism at the ideal shear strength, but consistent with the established features of usual bcc alloys, i.e., the deformation is governed by the Peierls mechanism at low temperature and by defect hardening at high temperature. τ χ − χ and ψ − χ relations of single crystals showed a typical slip asymmetry seen in bcc metals, where slip in Gum Metal belongs to the {112} slip type as in binary Ti-Nb single crystals reported previously (S. Hanada et al.: Metall. Trans. A 16 (1985) 789). Yielding by massive {332}〈113〉 twin formation in single crystals at low temperatures was observed for the rst time in Gum Metal.

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Stress-introduced α″ martensite and twinning in a multifunctional titanium alloy

Cited by 67 publications

References 22 publications

Strain-induced phase transformation during thermo-mechanical processing of titanium alloys

Strain-induced phase transformation during thermo-mechanical processing of titanium alloys

Effect of Pd addition on the microstructure of Ti-30Nb alloy

Basic Deformation Mechanism of Bcc Titanium-Based Alloy of Gum Metal

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