Development of Ti-Al-V alloys for usage as single-axis knee prostheses: evaluation of mechanical, corrosion, and tribocorrosion behaviors.

Single-axis knee prosthesis is an artificial biomechanical device that provides motion to amputees without the need for assistance appliances. Besides it is mainly composed of metallic materials, the current commercial materials did not group adequate properties for long-term usage or accessible cost. This study produced and characterized Ti-(10 -x)Al-xV (x = 0, 2, and 4 wt.%) alloys for potential use as single-axis knee prostheses. The samples exhibited a gradual decrease in the density values, with proper chemical mixing of the alloying elements on the micro-scale. The phase composition exhibited a primary α phase with a minor α' + ß phase for the Ti-8Al-2V and Ti-6Al-4V samples. Due to their different atomic radius compared to Ti, the addition of alloying elements changed the cell parameters. Their selected mechanical properties (Young's modulus, Vickers microhardness, and damping factor) performed better values than the CP-Ti grade 4. The samples also exhibited good corrosion properties against the simulated marine solution. The tribocorrosion resistance of the samples was better than the reference material, with the wear tracks composed of some tribolayers and grooves resulting from adhesive and abrasive wear. The Ti-10Al alloy displayed the best properties and estimated low cost to be used as single-axis knee prostheses.

Microstructure and selected mechanical properties of aged Ti-15Zr-based alloys for biomedical applications.

In this study, Ti-15Zr-xMo (5, 10, 15, and 20 wt%) alloys were submitted to solution and aging treatments and their effects evaluated in terms of phase composition and selected mechanical properties (Vickers microhardness and Young's modulus) for use as biomedical implants. The solution treatment was performed at 1123 K for 2 h, while aging treatments were carried out at 698 K for 4, 8, and 12 h, followed by water quenching. Phase composition and microstructure were dependent of the heat treatments, with Ti-15Zr-5Mo (α +â€¯ß type) and Ti-15Zr-10Mo (metastable ß type) alloys exhibiting intense α phase precipitation. The α-phase precipitates were related to α″ → α and ß → α phase decompositions. The Ti-15Zr-10Mo alloy exhibited an intermediary isothermal ω-phase precipitation after aging for 4 h. Vickers microhardness and Young's modulus values changed gradually with the amount of α phase. Aged Ti-15Zr-15Mo and Ti-15Zr-20Mo alloys presented better combinations of hardness and Young's modulus than CP-Ti and Ti-64 ELI for biomedical applications.

Preparation and characterization of alloys of the Ti-15Mo-Nb system for biomedical applications.

In the development of new metallic biomaterials, the Ti-15Mo alloy has great prominence because of its excellent corrosion resistance and good combination of mechanical properties. In this study, the element niobium was added to the Ti-15Mo alloy, forming the Ti-15Mo-Nb system for the purpose of improving their properties and promoting its application as a biomaterial. These alloys are very promising to use as biomedical implants, because they integrate a new class of titanium alloys without the presence of aluminum and vanadium, which may cause cytotoxic effects. The alloys were produced by arc-melting and characterized by density, X-ray diffraction, scanning electron microscopy, microhardness, elastic modulus, corrosion, and cytotoxicity assays. The developed alloys have ß phase predominance (with bcc crystalline structure). The addition of niobium decreases the microhardness and elastic modulus, with values around 80 GPa, which is well below that of the metallic alloys used commercially for this type of application. Very low passive current densities were found for all alloys studied showing that the passive film on these alloys is highly protective. In vitro cytotoxicity tests revealed that the introduction of niobium did not cause cytotoxic effects in the studied alloys. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 639-648, 2018.

The effect of the solute on the structure, selected mechanical properties, and biocompatibility of Ti-Zr system alloys for dental applications.

New titanium alloys have been developed with the aim of utilizing materials with better properties for application as biomaterials, and Ti-Zr system alloys are among the more promising of these. In this paper, the influence of zirconium concentrations on the structure, microstructure, and selected mechanical properties of Ti-Zr alloys is analyzed. After melting and swaging, the samples were characterized through chemical analysis, density measurements, X-ray diffraction, optical microscopy, Vickers microhardness, and elasticity modulus. In-vitro cytotoxicity tests were performed on cultured osteogenic cells. The results showed the formation essentially of the α' phase (with hcp structure) and microhardness values greater than cp-Ti. The elasticity modulus of the alloys was sensitive to the zirconium concentrations while remaining within the range of values of conventional titanium alloys. The alloys presented no cytotoxic effects on osteoblastic cells in the studied conditions.