Due to excellent biocompatibility and corrosion resistance, the application of titanium alloys in orthopedic and dental implants has been increasing since the 1970s. However, the elasticity of these alloys as measured by their Young’s modulus is still about two to four times higher than that of human cortical bone. The most widely used titanium alloy for biomedical applications is Ti-6Al-4V, however, previous studies have shown that the vanadium used in this alloy causes allergic reactions in human tissue and aluminum, also used in the alloy, has been associated with neurological disorders. To solve this problem, new titanium alloys without the presence of these elements and with the addition of different elements, usually beta-stabilizers, are being developed. Manganese is a strong candidate as an alloying element for the development of new beta-type titanium alloys, due to its abundance and low cytotoxicity. In this study, Ti-10Mo-5Mn, Ti-15Mo-2.5Mn and Ti-15Mo-5Mn alloys were prepared in an arc furnace, which resulted in an alloy structure clearly showing the predominance of the beta phase with a body-centered cubic crystalline structure. The observed microstructure confirmed the results on the structural characterization of alloys. Measurement of the indirect cytotoxicity of the alloys showed that the extracts of the studied alloys are not cytotoxic for fibroblastic cells.

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Ti and its alloys are the most used metallic biomaterials devices due to their excellent combination of chemical and mechanical properties, biocompatibility, and non-toxicity to the human body. However, the current alloys available still have several issues, such as cytotoxicity of Al and V and high elastic modulus values, compared to human bone. β-type alloys, compared to α-type and (α + β)-type Ti alloys, have lower elastic modulus and higher mechanical strength. Then, new biomedical β-type alloys are being developed with non-cytotoxic alloying elements, such as Mo and Nb. Therefore, Ti-5Mo-xNb system alloys were prepared by argon arc melting. Chemical composition was evaluated by EDS analysis, and the density measurements were performed by Archimedes' method. The structure and microstructure of the alloys were obtained by X-ray diffraction and optical and scanning electron microscopy. Microhardness values were analyzed, and MTT and crystal violet tests were performed to assess their cytotoxicity. As the Nb concentration increases, the presence of the β-Ti phase also grows, with the Ti-5Mo-30Nb alloy presenting a single β-Ti phase. In contrast, the microhardness of the alloys decreases with the addition of Nb, except the Ti-5Mo-10Nb alloy, which has its microhardness increased probably due to the ω phase precipitation. Biological in-vitro tests showed that the alloys are not cytotoxic.

The development of new β-Ti alloys has been extensively studied in the medical field in recent times due to their more suitable mechanical properties, such as a relatively low Young’s modulus. This paper analyzes the influence of heat treatments (homogenization and annealing) and hot rolling on the microstructure, phase composition, and some mechanical properties of ternary alloys of the Ti-xNb-5Mo system, with an amount of Nb varying between 0 and 30 wt%. The samples are produced by argon arc melting. After melting, the samples are homogenized at 1000 °C for 24 h and are hot rolled and annealed at 1000 °C for 6 h with slow cooling. Structural and microstructural analyses are made using X-ray diffraction and optical and scanning electron microscopy. Mechanical properties are evaluated by Vickers microhardness and Young’s modulus. The amount of β phase increases after heat treatment and reduces after hot rolling. The microhardness and Young’s modulus of all heat-treated samples decrease when compared with the hot rolled ones. Some samples exhibit atypical Young’s modulus and microhardness values, such as 515 HV for the as-cast Ti-10Nb-5Mo sample, indicating the possible presence of ω phase in the microstructure. The Ti-30Nb-5Mo sample suffers less variation in its phase composition with thermomechanical treatments due to the β-stabilizing effect of the alloying elements. The studied mechanical properties indicate that the annealed Ti-30Nb-5Mo sample has potential for biomedical applications, exhibiting a Young’s modulus value of 69 GPa and a microhardness of 236 HV.