{332} Deformation twins in a Ti-15.5 pct V alloy

Oka, Mariko; Taniguchi, Yuta

doi:10.1007/bf02658330

Cited by 46 publications

(22 citation statements)

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“…have been observed, depending on the alloy composition [6] and [7]. Each twinning system can be activated in 12 different ways, termed variants in this paper.…”

mentioning

confidence: 97%

“…In bcc structures {1 1 2} 1 1 1 is a well-known twinning system, but other twinning systems such as {3 3 2} 1 1 3 have been observed in some metastable alloys subject to a martensitic transformation, like Fe-Ni-C or Fe-Be [5]. In metastable β-titanium alloys both twinning systems {1 1 2} 1 1 1 and {3 3 2} 1 1 3 have been observed, depending on the alloy composition [6] and [7]. Each twinning system can be activated in 12 different ways, termed variants in this paper.…”

mentioning

confidence: 99%

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Twinning system selection in a metastable β-titanium alloy by Schmid factor analysis

Bertrand

Castany²,

Péron³

et al. 2011

Scripta Materialia

220

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. Twinning system selection in a metastable β-titanium alloy by Schmid factor analysis. Scripta Materialia, Elsevier, 2011, 64 (12) AbstractElectron backscattering diffraction and Schmid factor analysis were used to study the twinning variant selection in a Ti-25Ta-24Nb (mass%) metastable β-titanium alloy. The two twinning systems {1 1 2} 1 1 1 and {3 3 2} 1 1 3 were observed. For each system the Schmid factor was shown to be a relevant parameter to determine the activated variant.Moreover, selection between the two twinning systems depends on the crystallographic orientation of the grain with respect to the tensile direction.Keywords: Titanium alloy; Electron backscattering diffraction; Twinning; Schmid factor Metastable β-titanium alloys can be elaborated with fully biocompatible β-stabilizer elements such as Ta, Nb, Mo, etc. Their interesting mechanical properties make them good candidates for biomedical applications [1] and [2]. Theses alloys possess a non-ordered bcc structure and are subject to numerous deformation mechanisms: a stress induced martensitic transformation which can lead to a superelastic effect, slip and twinning [3] and [4].Twinning is a common deformation mechanism in materials exhibiting a low stacking fault energy in hcp, fcc or bcc structures. In bcc structures {1 1 2} 1 1 1 is a well-known twinning system, but other twinning systems such as {3 3 2} 1 1 3 have been observed in some metastable alloys subject to a martensitic transformation, like Fe-Ni-C or Fe-Be [5]. In metastable β-titanium alloys both twinning systems {1 1 2} 1 1 1 and {3 3 2} 1 1 3 have been observed, depending on the alloy composition [6] and [7]. Each twinning system can be activated in 12 different ways, termed variants in this paper.The Schmid law is commonly used to predict the activated slip system depending on the tensile direction compared with the crystallographic orientation of the crystal. Selection of the twinning variant can also be predicted by the Schmid law for materials exhibiting hcp or fcc structures, as reported in the literature [8] and [9]. Although it is well known that both slip and twinning occur in bcc titanium alloys, the objective of this paper was to confirm that twinning variant selection in each observed system obeys the Schmid law for a metastable β-titanium alloy (bcc). As several twinning systems can be observed in this kind of alloy a selection parameter between these twinning systems will also be established.The metastable β-alloy composition chosen for this study is Ti-25Ta-24Nb (mass%). The ingot was elaborated by cold crucible levitation melting (CCLM). It underwent homogenization annealing at 950 °C for 20 h, followed by a water quench. Each ingot was then cold rolled (CR = 90%), after which a recrystallization annealing was applied at 850 °C for 0.5 h, followed by a water quench in order to retain the β-phase microstructure at room temperature in its metastable state.Before the recrystallization annealing flat tensile test specimens with a section of 3 × 0.7 mm and a gage len...

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“…have been observed, depending on the alloy composition [6] and [7]. Each twinning system can be activated in 12 different ways, termed variants in this paper.…”

mentioning

confidence: 97%

mentioning

confidence: 99%

Twinning system selection in a metastable β-titanium alloy by Schmid factor analysis

Bertrand

Castany²,

Péron³

et al. 2011

Scripta Materialia

220

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“…Hanada et al reported that the ω-phase forms during the cold working of asquenched Ti-Cr alloys within the composition range of 8-11.5 mass% Cr [20]. Moreover, the ω-phase can be introduced by deformation at room temperature in Ti-V, Ti-Fe, and Ti-Mo metastable β-type alloys [10,11,[21][22][23]. Furthermore, Cr is known to control the anodic activity of the alloy and increase the tendency of Ti to passivate [24], and the passive films of Ti alloys, in turn, allow them to maintain corrosion resistance [25][26][27].…”

Section: Possible Alloy Systemmentioning

confidence: 99%

Low-Modulus Ti Alloys Suitable for Rods in Spinal Fixation Devices

Niinomi

2016

Interface Oral Health Science 2016

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Low-Young's modulus Ti alloys are expected to be suitable for use in the rods of spinal fixation devices. However, in addition to a low Young's modulus, the rods must also exhibit a high Young's modulus at the deformed region to reduce springback when surgeons bend the rod inside the narrow bodies of patients. Ti-Mo and Ti-Cr alloys are potential candidates to satisfy these two conflicting demands. In these alloys, known as Young's modulus changeable or Young's modulus selfadjustable Ti alloys, the ω-phase with high Young's modulus is induced by deformation. Among these alloys, Ti-12Cr is judged to be the most suitable for use in the rods of spinal fixation devices. This alloy exhibits a high uniaxial fatigue strength, and its compressive fatigue strength is significantly improved by cavitation peening.

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“…{112}〈111〉 twinning mode has also been observed in metastable alloys [42,43]. Table 2.2 shows the 12 variants in each twinning mode [45].…”

Section: Martensitic Transformation and Heat Treatments On  Titaniummentioning

confidence: 89%

“…In metastable β-Ti alloys, {112}〈111〉 and {332}〈113〉 twinning system have been reported [42,43]. In comparison with {112}〈111〉, the {332}〈113〉 twinning mode has been more frequently reported in the β-Ti alloys with lower amounts of β phase stabilising elements.…”

Section: Microstructural Evolution Of β Titanium Alloys In the Procesmentioning

confidence: 99%

Mechanical and microstructural characterisation in the processing of biomedical metallic fine tubes

Yao-wu¹

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Fine tube stents are used for maintaining localised flow in stenotic blood vessels. Elasticity and plasticity for expansion, rigidity for resisting bending under force and strength to prevent unexpected failure, are required properties of the tubes from which these stents are formed. Biomedical metastable β titanium alloys have been developed as implant materials for a large number of biomedical applications due to a combination of favourable characteristics, e.g. good biocompatibility, excellent toughness and corrosion resistance. A metastable β alloy, Ti-25Nb-3Mo-3Zr-2Sn, has been developed without toxic alloying elements, which is a promising candidate material for stent applications. Metallic materials used for stents are commonly not biodegradable and implanted in the vessel permanently, which may provoke in-stent restenosis and stent thrombosis. In order to remove the implanted materials after service, biodegradable materials, absorbed by the body slowly, are also a field of research interest. Magnesium alloys have been used in studies for biomedical stent applications as a new biodegradable material. Magnesium stents can reopen the blocked blood vessels temporarily before degrading in physiological environments. In addition to the biodegradable characteristics, their mechanical properties are reasonable. The Mg-3Al-1Zn (AZ31) alloy is the subject of some research on the processing of biomedical magnesium alloys as it is a commonly available commercial alloy. Consequently, the Ti-25Nb-3Mo-3Zr-2Sn alloy and the AZ31 magnesium alloy have been used in this thesis to investigate the evolution of mechanical properties and microstructure in the processing of fine tubes.The deformation mechanisms during cold deformation of metastable β titanium alloys are mainly associated with martensitic phase transformations and mechanical twinning. It has been reported that stress-induced phase transformations and {112}〈111〉, {332}〈113〉 twinning modes may be activated under different stress states in metastable β titanium alloys. They can exhibit varying elasticity, Young's modulus and strain hardening behaviour. Because the martensitic start temperature is below room temperature for most metastable β titanium alloys, the α″ martensitic transformation can easily occur under a small amount of external stress. Mechanical twins were reported to hinder slip and dislocation motion thereby increasing the strain hardening rate. The development of β and α″ texture during processing is another critical influence on the mechanical properties of fine tubes. Therefore, studies on the martensitic transformation, mechanical twins and texture evolution is of significance in order to understand the processing of β titanium fine tubes.ii Magnesium alloys deform through the formation of a large amount of mechanical twins due to the relatively low critical stress to activate twinning in comparison with 〈 + 〉 slip. There are typically two primary mechanical twinning modes for magnesium alloys, {101 ̅ 2} extension twins and {101 ̅ 1} cont...

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{332} Deformation twins in a Ti-15.5 pct V alloy

Cited by 46 publications

References 9 publications

Twinning system selection in a metastable β-titanium alloy by Schmid factor analysis

Twinning system selection in a metastable β-titanium alloy by Schmid factor analysis

Low-Modulus Ti Alloys Suitable for Rods in Spinal Fixation Devices

Mechanical and microstructural characterisation in the processing of biomedical metallic fine tubes

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