TiTaMo medium entropy alloys with synergistic biomechanical properties for long term implantation

Ti-based multi-principal element alloys exhibit excellent comprehensive properties and hold great promise as biomaterials for hard tissue implants. In the present study, a novel equiatomic TiTaMo medium entropy alloy (MEA) was designed and fabricated via vacuum arc melting followed by rapid solidification (cooling rate ∼10³ K/s) to address the limitations of conventional Ti-based alloys. The microstructures, mechanical properties, wear behavior and corrosion resistance in Hank's solution were thoroughly investigated. The as-cast TiTaMo MEA, characterized by a body-centered cubic structure with a lattice parameter of 3.229 Å, demonstrated a yield strength of 1230.79 MPa, an elastic modulus suitable for bone compatibility, and a plastic deformation strain exceeding 30 % under compression. Additionally, it exhibited a Vickers microhardness of approximately 471 HV. Although the overall wear resistance of the TiTaMo MEA was slightly inferior to that of Ti6Al4V, its coefficient of friction was notably lower and more stable level (μ ≈ 0.11) during the initial 200 s of testing. Moreover, in comparison with biomedical-grade pure Ti and Ti6Al4V alloy, the TiTaMo MEA displayed superior corrosion resistance with a stable passivation plateau extending beyond 4.5 V_SCE and no detectable pitting corrosion. These preliminary findings indicate that the TiTaMo MEA has significant potential as a candidate for next-generation orthopedic and dental implants.