Deformation Mechanisms and Biocompatibility of the Superelastic Ti–23Nb–0.7Ta–2Zr–0.5N Alloy

Abstract

In this study, we have synthesized a new Ti-23Nb-0.7Ta-2Zr-0.5N alloy composition with the aim to obtain useful mechanical properties to be used in medicine such as high strength, good superelastic property, low modulus, and large ductility. Thus, mechanical properties including superelasticity and plasticity were investigated in relation with the different deformation mechanisms observed (stress-induced martensitic transformation, twinning and dislocation slip). On the other hand, the corrosion resistance in simulated body fluid (Ringer solution) and the in vitro cell behavior (MG63 human osteoblasts) of such biomedical alloy were also evaluated in order to assess its biocompatibility.

Stress release-induced interfacial twin boundary ω phase formation in a β type Ti-based single crystal displaying stress-induced α” martensitic transformation

“…Fig. 5a according to the crystallographic orientation of the single crystal shows the dislocations slip in a {1 1 0} β plane (more details about the method can be found in reference [42]). This result is consistent with the most common slip planes observed in the β phase of titanium alloys but also in other bcc alloys [43][44][45].…”

Superelastic Behavior of Biomedical Metallic Alloys

“…are now widely studied and appear to be promising candidates to replace NiTi for such biomedical devices. [4][5][6] The reason for this interest is because metastable b titanium-based alloys can be mechanically unstable for certain chemical compositions. Consequently, they can also exhibit a shape memory effect and superelastic behavior.…”

“…Indeed, a reversible martensitic transformation between the parent b phase (body-centered cubic structure, space group Im 3m) and the martensitic a¢¢ phase (C-centered orthorhombic, space group Cmcm) is also observed in such alloys. [4][5][6][7] Superelastic behavior is obtained when the quenched microstructure is composed of the -metastable phase at room temperature. In this case, the stress-induced martensitic transformation (b into a¢¢) can directly occur under mechanical stimulation, and large elastic recovery can be obtained because this transformation is fully reversible once the mechanical stress is released.…”

Microstructure, thermo-mechanical properties and Portevin-Le Chatelier effect in metastable β Ti-xMo alloys

“…Titanium alloys are extensively used in many applications from biomedical devices to aeronautics, owing to their good strength-to-weight ratio, high corrosion resistance, enhanced hardenability and excellent biocompatibility [1][2][3][4]. Focusing on metallic biomaterials, much effort has been devoted to investigating the β titanium alloys made of nontoxic elements [5][6][7][8], especially employing Mo alloying element [9][10][11]. This is mainly attributed to the fact that molybdenum, as an effective β stabilizer, is less toxic than other alloying elements, and it can be used to develop titanium alloys with a high strength and low elastic modulus suitable for implant applications [12].…”