A Low-Modulus Ti-19Nb-10Zr-6Sn-2.5Fe (TNZSF) Alloy for Biomedical Applications: Processing via Elemental Powder Metallurgy and Mechanical Evaluation

The high elastic modulus of Ti-6Al-4V implants may promote stress shielding, while Al and V raise toxicological concerns, motivating the development of compliant and chemically stable titanium alloys. A Ti-19Nb-10Zr-6Sn-2.5Fe (TNZSF) alloy was designed to exploit the effects of Nb, Zr, Sn, and Fe on β-phase stability, ω-phase suppression, and strengthening. The alloy was produced from blended elemental powders and evaluated in the as-sintered condition without post-sintering heat treatment. Thermodynamic calculations, XRD, SEM-EDS, EBSD, mechanical testing, potentiodynamic polarization, and ICP-OES were used for characterization. The alloy exhibited an α+β microstructure with fine α laths along prior β-grain boundaries and 2.5 ± 0.2% porosity. Four-point bending yielded an ultimate flexural strength of 1130 ± 9 MPa and a flexural modulus of 60 ± 2 GPa. Tensile testing resulted in an ultimate tensile strength of 583 ± 4 MPa, a yield strength of 536 ± 24 MPa, a Young’s modulus of 65 ± 3 GPa, and 9.8 ± 0.2% elongation. Small-punch testing estimated a yield strength of 532 ± 17 MPa, closely matching the tensile result, while fractography confirmed ductile failure by microvoid coalescence. In Ringer’s solution, the alloy showed a corrosion current density of 0.700 ± 0.070 μA·cm⁻², a passive region extending to approximately 1.5 V, and no stable pitting. After 730 h of static immersion in protein-free artificial saliva, elemental release rates remained between 0.008 and 0.032 μg·cm⁻²·day⁻¹. These results support further biological investigation of TNZSF as a candidate material for structural biomedical applications.