The effect of oxygen on α″ martensite and superelasticity in Ti–24Nb–4Zr–8Sn

Obbard, E.G.; Hao, Yu; Talling, R.J.; Li, S.J.; Zhang, Y.W.; Dye, David; Yang, Rui

doi:10.1016/j.actamat.2010.09.015

Cited by 120 publications

(62 citation statements)

References 41 publications

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“…Consequently, the oxygen content in the present alloy is not high enough to suppress the martensitic transformation as this phase was clearly observed by TEM. In a recent work concerning Ti-24Nb-4Zr-8Sn-(0.08-0.40)O (wt%) alloys (Obbard et al, 2011), it was established that oxygen raises the critical stress required to induce martensitic transformation; in other word suppression of the martensitic transformation becomes stronger with increasing oxygen content. The absence of the plateau in Ti-24Nb-0.5O can thus be explained by the fact that the stress required to induce the martensite transformation is close to the yield strength situated at about 665 MPa.…”

Section: Microstructure After Deformationmentioning

confidence: 99%

Microstructure and mechanical behavior of superelastic Ti–24Nb–0.5O and Ti–24Nb–0.5N biomedical alloys

Ramarolahy

Castany

Prima

et al. 2012

Journal of the Mechanical Behavior of Biomedical Materials

131

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To cite this version:A. Ramarolahy, Philippe Castany, F. Prima, P. Laheurte, Isabelle Péron, et al.. Microstructure and mechanical behavior of superelastic Ti-24Nb-0.5O and Ti-24Nb-0.5N biomedical alloys.Journal AbstractIn this study, the microstructure and the mechanical properties of two new biocompatible superelastic alloys, Ti-24Nb-0.5O and Ti-24Nb-0.5N (at.%), were investigated. Special attention was focused on the role of O and N addition on α ″ formation, supereleastic recovery and mechanical strength by comparison with the Ti-24Nb and Ti-26Nb (at.%) alloy compositions taken as references. Microstructures were characterized by optical microscopy, X-ray diffraction and transmission electron microscopy before and after deformation. The mechanical properties and the superelastic behavior were evaluated by conventional and cyclic tensile tests. High tensile strength, low Young's modulus, rather high superelastic recovery and excellent ductility were observed for both superelastic Ti-24Nb-0.5O and Ti24Nb-0.5N alloys. Deformation twinning was shown to accommodate the plastic deformation in these alloys and only the {332} 113 twinning system was observed to be activated by electron backscattered diffraction analyses.

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Section: Microstructure After Deformationmentioning

confidence: 99%

Microstructure and mechanical behavior of superelastic Ti–24Nb–0.5O and Ti–24Nb–0.5N biomedical alloys

Ramarolahy

Castany

Prima

et al. 2012

Journal of the Mechanical Behavior of Biomedical Materials

131

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“…Detailed analysis of synchrotron x-ray diffraction of in situ tensile experiment with Ti2448 sheds light on the stress induced phase transformation process. The thoroughness of shuffle of the (110) β atomic planes is much less in Ti2448 than in binary Ti-Nb alloys: the fraction of those achieving complete shuffle is only 0.26 ∼ 0.43 for Ti2448, but 0.60 ∼ 0.83 for binary Ti-Nb (Obbard et al (2011)). Interstitial oxygen reduces both the degree of (110) β shuffle and the principal strains of the β-α ′′ transformation, to the effect that the critical stress for the α ′′ formation is increased, and stress plateau on the stress-strain curves is shortened.…”

Section: Elastic Deformationmentioning

confidence: 99%

“…These two factors lead to the disappearance of the double yield feature on the stress-strain curves of Ti2448. Figure 12 compares the experimental stress-strain curves of both the 7.6Sn alloy and Ti2448 with theoretical ones obtained by sophisticated modelling based on synchrotron x-ray diffraction data and a model of α ′′ phase transformation (Obbard et al (2011)). With increasing stress the mechanisms of recoverable strain of thermoelastic martensitic materials include martensitic shape change, detwinning of martensitic variants (Gao et al (2000)), and martensite reorientation (Heinen et al (2009)).…”

Section: Elastic Deformationmentioning

confidence: 99%

“…Dark and light symbols show normalised H of {110} β and the absolute H of (021) α ′′ . Radius of symbols is proportional to peak half-width-half-maximum; vertical lines mark nominal yield stress measured from stress-strain curves; inset stress is maximum (in MPa) for given cycle (Obbard et al, 2011). therefore very small, leading to postulation that the β phase is approaching its limit of elastic stability in Ti2448 under applied stress.…”

Section: Elastic Deformationmentioning

confidence: 99%

“…12. Cyclic stress-strain plots (solid lines) and strain (circles) calculated using a phase transformation model applying texture and crystallography observed through synchrotron x-ray diffraction: (a) Ti-24Nb-4Zr-7.6Sn-0.08O; (b) Ti-24Nb-4Zr-8Sn-0.15O (Obbard et al, 2011). Fig.…”

Section: Elastic Deformationmentioning

confidence: 99%

See 2 more Smart Citations

Development and Application of Low-Modulus Biomedical Titanium Alloy Ti2448

Yang¹,

Hao²,

Li³

2011

Biomedical Engineering, Trends in Materials Science

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The Behaviour of Gum Metal (Ti‐36Nb‐2Ta‐3Zr‐0.3O wt.%) During Superelastic Cycling

Jones

Vorontsov

Dye

2016

Proceedings of the 13th World Conference on Titanium

Self Cite

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Metastable beta titanium alloys, such as Gum Metal (Ti-36Nb-2Ta-3Zr-0.3O wt.%), have received significant attention from the biomedical field over the last decade due to their low elastic modulus. Despite initial scepticism, it is now widely accepted that these alloys undergo a stress-induced transformation when subjected to an applied load, forming an orthorhombic martensite phase within the beta matrix. The reversible nature of this transformation gives rise to superelasticity, which is of significant interest for engineering applications outside of the biomedical industry. However, little is known as to the stability of the superelastic behaviour with respect to repeated load cycling. Here the response of Gum Metal during superelastic cycling was studied in situ, using high energy synchrotron diffraction. The material was observed to accumulate permanent damage with every cycle and the critical stress required for transformation decreased. The diffraction data was used to track the evolution of the martensite phase, both as a function of applied stress and cycle number. The martensite that formed was highly textured, with two independent orientations observed on each Debye-Scherrer ring. These orientations formed at different applied stresses and had different volume fractions at the peak stress. The volume fraction at the peak stress of all martensite orientations increased with cycling, which is believed to increase the defect concentration in the material and hence influence the deformation behaviour.

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The effect of oxygen on α″ martensite and superelasticity in Ti–24Nb–4Zr–8Sn

Cited by 120 publications

References 41 publications

Microstructure and mechanical behavior of superelastic Ti–24Nb–0.5O and Ti–24Nb–0.5N biomedical alloys

Microstructure and mechanical behavior of superelastic Ti–24Nb–0.5O and Ti–24Nb–0.5N biomedical alloys

Development and Application of Low-Modulus Biomedical Titanium Alloy Ti2448

The Behaviour of Gum Metal (Ti‐36Nb‐2Ta‐3Zr‐0.3O wt.%) During Superelastic Cycling

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