Mechanical properties and corrosion behavior of β-type Ti-Zr-Nb-Mo alloys for biomedical application

A series of novel beta-type Ti-Zr-Nb-Mo alloys was fabricated to develop potential biomedical materials. The effects of the Mo content on microstructure, mechanical properties and electrochemical behavior were investigated in depth. The phase composition of all Ti-Zr-Nb-Mo alloys consists of a single beta phase. The grains are obviously refined due to the addition Mo. The average grain size of the (TiZr)(72)Nb15Mo13 alloy is the smallest. The yield strength and hardness of the alloys are significantly improved as the content of the Mo element increases. Due to the contributions of the fine-grained and solution strengthening, the (TiZr)(70)Nb15Mo15 alloy exhibits the highest yield strength (834 MPa) and hardness (486 HV). The elastic modulus of the Ti-Zr-Nb-Mo alloys ranges from 96 GPa to 105 GPa, which is lower than that of the Ti-6Al-4V alloy. The potentiodynamic polarization curves and electrochemical impedance spectroscopy show that each sample exhibits a great corrosion behavior in the simulated body fluid at 37 degrees C. The corrosion resistance of Ti-Zr-Nb-Mo alloys is markedly altered by adding the Mo element. In particular, the (TiZr)(72)Nb15Mo13 alloy exhibits the best corrosion resistance of all the samples, ant its corrosion potential and corrosion current density are -0.344 +/- 0.005 V and 71.9 +/- 5.3 nA.cm(-2), respectively. This finding is potenially explained by the fact that grain refinement leads to the formation of a compact and stable passive film on the surface of the alloy. (C) 2020 Elsevier B.V. All rights reserved.