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

DOI: 10.1002/9781119296126.ch154 DOI Help

Authors: Nicholas Jones (University of Cambridge) , Vassili Vorontsov (Imperial College London) , David Dye (Imperial College London)
Co-authored by industrial partner: No

Type: Conference Paper
Conference: Proceedings of the 13th World Conference on Titanium
Peer Reviewed: Yes

State: Published (Approved)
Published: May 2016
Diamond Proposal Number(s): 6701

Abstract: 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 skepticism, 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 trans formation gives rise to super elasticity, which is of significant interest for engineering applications outside of the biomedical industry. However, little is known as to the stability of the super elastic behaviour with respect to repeated load cycling. Here the response of Gum Metal during super elastic 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-Scherrerring. These orientations formed at different applied stress es 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.

Journal Keywords: Gum Metal; Synchrotron radiation; Martensite transformations; Mechanical behaviour

Subject Areas: Materials, Engineering, Biology and Bio-materials


Instruments: I12-JEEP: Joint Engineering, Environmental and Processing

Added On: 12/10/2016 12:17

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