Microstructure, wear resistance, and corrosion performance of Ti35Zr28Nb alloy fabricated by powder metallurgy for orthopedic applications

A ternary Ti35Zr28Nb alloy was fabricated by powder metallurgy (PM) from pre-alloyed powder. The microstructure, hardness, corrosion behavior, and wear response of the produced alloy were investigated systematically. The results show that nearly full dense Ti35Zr28Nb alloy (relative density is 98.1 ± 1.2 %) can be fabricated by PM. The microstructure was dominated with uniform β phase. The Ti35Zr28Nb alloy displayed spontaneous passivity in a naturally aerated simulated body fluid (SBF) solution at 37 ± 0.5 °C. The Ti35Zr28Nb alloy exhibited the highest corrosion resistance as compared to as-cast Ti6Al4V and pure Ti because of the formation of a protective passive film containing TiO2, Nb2O5, and ZrO2, including the highest corrosion potential (−0.22 ± 0.01 V), the lowest corrosion current density (57.45 ± 1.88 nA), the lowest passive potential (0.05 ± 0.01 V) and the widest passivation range (1.29 ± 0.09 V). Under the same wear condition, the wear rate of the Ti35Zr28Nb alloy (0.0021 ± 0.0002 mm3/m·N) was lower than that of the CP Ti (0.0029 ± 0.0004 mm3/m·N) and close to that of the Ti6Al4V (0.0020 ± 0.0003 mm3/m·N). The wear mechanism of the Ti35Zr28Nb alloy was mainly dominated by abrasive wear, accompanied by adhesive wear. The highest corrosion resistance together with the adequate wear resistance makes the PM-fabricated Ti35Zr28Nb alloy an attractive candidate for orthopedic implant materials.