Thermomechanical processing of In-containing β-type Ti-Nb alloys

Coinciding significance of the crystallographic orientation and nanostructuring on the biocompatibility of TZNT-Ag1 .5 alloy deformed by the cold rolling process

In this study, the simultaneous significance of the crystallographic texture and nanostructuring on the cytocompatibility of as-cast (Ti₅₅ Zr₂₅ Nb₁₀ Ta₁₀ )_98.5 -Ag_1.5 alloy (at. %, TZNT-Ag_1.5 ), subjected to cold rolling up to 90% reduction, along with the changes of Young's modulus and hardness under cold rolling were investigated. For this purpose, the as-cast and cold-rolled TZNT-Ag_1.5 alloy test specimens were analyzed by XRD, TEM, HRTEM, SEM, contact angle, nanoindentation, and OM techniques. Moreover, to evaluate the effect of severe cold deformation on the biocompatibility, MG-63 osteoblastic cell was cultured on the surface of 90% cold-rolled and as-cast test specimens of TZNT-Ag_1.5 alloy. The results showed that severe cold deformation was led to fast grain refinement of β grains of the as-cast TZNT-Ag_1.5 alloy in the range of 50-100 nm. In addition to the nanostructuring, upon severe cold deformation, the <gamma>-fiber (<111>// normal direction) texture was formed and after 90% reduction, the (111)<1 1 ¯ 0 > γ_-fiber component was strengthened. The micro-hardness and reduced Young's modulus are 235 ± 5.29, 246 ± 1.73, 271 ± 4.0, and 283 ± 6.25 (HV); and 73.725 ± 1.70, 83.98 ± 5.10, 81.26 ± 6.55, and 88.66 ± 7.16 (GPa) for TZNT-Ag_1.5 (as-cast), TZNT-Ag_1.5 (20%CR), TZNT-Ag_1.5 (50%CR), and TZNT-Ag_1.5 (90%CR) test specimens, respectively. Further, with increasing the cold deformation degree, the dislocation density of TZNT-Ag_1.5 alloy increased as this parameter is 2.79 × 10¹⁵ (m^-2 ) for the 90%CR test specimen. On the other hand, the values of the contact angle for the 90%CR test specimen (46.2 ± 3.5°) exhibit a higher hydrophilic and wettable surface as compared to the other studied test specimens. After 5 days of incubation, osteoblastic cells on the surface of the 90% cold-rolled TZNT-Ag_1.5 test specimens revealed significant differences in cell proliferation and differentiation as compared to the as-cast alloy test specimens and/or CP-Ti. Finally, because the maximum orientation intensities were generally <3, it was deduced that grain refinement rather than the crystallographic texture plays a significant role in improving the surface biocompatibility of the new TZNT-Ag_1.5 alloy.

A study on the mechanical properties and corrosion behavior of the new as-cast TZNT alloys for biomedical applications

In this study, four different TZNT based alloys, (Ti₅₅Zr₂₅Nb₁₀Ta₁₀, (Ti₅₅Zr₂₅Nb₁₀Ta₁₀)_99.5Fe_0.5, (Ti₅₅Zr₂₅Nb₁₀Ta₁₀)₉₈Sn₂, and (Ti₅₅Zr₂₅Nb₁₀Ta₁₀)_98.5Ag_1.5, (at. %), designated TZNT, TZNT-Fe, TZNT-Sn, TZNT-Ag, respectively) are produced by non-consumable vacuum arc melting and suction casting. These alloys using the d-electron alloy design method and considering the criteria of [Mo]eq and (e/a) _ratio for β-phase Ti alloys are designed. The microstructure, mechanical properties, and corrosion behavior of the alloys are investigated via optical microscopy, scanning electron microscopy, X-ray diffraction, nanoindentation, and electrochemical tests. The designed alloys exhibit dendritic morphology, however, the TZNT-Ag alloy indicates a more homogenous microstructure after suction casting. X-ray diffraction analyses reveal not only the beta phase in the TZNT, TZNT-Fe, and TZNT-Ag alloys, but also beta lean/beta rich separation in the TZNT-Sn alloy. In addition to the microstructural features, the new TZNT alloys show very high ductility upon cold compressive deformation, as well as the lowest Young's modulus (65.54±1.7 GPa, P<0.05) is achieved in TZNT-Ag alloy. Furthermore, the compressive yield stress to Young's modulus (Y_cys/E) ratio of the designed alloys is in the range of 0.92-1.08%. In terms of corrosion behavior, Ag increases the corrosion resistance of the TZNT alloy in Ringer's solution. As a result, owing to the effect of Ag on the optimization of the mechanical properties and corrosion resistance of the TZNT alloy, the as-cast Ag-containing TZNT alloy can be developed to be a promising candidate for biomedical applications.

Review on titanium and titanium based alloys as biomaterials for orthopaedic applications

Variety of implant materials have been employed in various disciplines of medical science depending on the requirement of a particular application. Metals, alloys, ceramics, and polymers are the commonly used biomaterials. The main focus of this study is to review the various structural and microstructural properties of titanium and titanium based alloys used as orthopaedic implants. Orthopaedic implants need to possess certain important qualities to ensure their safe and effective use. These properties like the biocompatibility, relevant mechanical properties, high corrosion and wear resistance and osseointegration are summarized in this review. Various attempts to improve upon these properties like different processing routes, surface modifications have also been inculcated in the paper to provide an insight into the extent of research and effort that has been put into developing a highly superior titanium orthopaedic implant.