Electrochemical Corrosion Behavior in Simulated Body Fluid of a Metastable β-Type Ti29Nb13Ta4.6Zr Biomedical Alloy with Improved Mechanical Properties

Herein, the mechanical properties and corrosion behavior in simulated body fluid of the beta-type Ti29Nb13Ta4.6Zr alloy (TNTZ) are investigated and compared to Ti6Al4V alloy. The samples are obtained from the solution-treated (ST) and water-quenched TNTZ bars. Following quenching, the bars are cold rolled aged (CRA) at 673 K for 20 min in order to reach a desired combination of high yield strength and low elastic modulus. The corrosion tests are conducted using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) during a long period of immersion in physiological Ringer's solution (up to 144 h), and the mechanical behaviors are assessed through uniaxial tensile tests. The results show that both TNTZ ST and CRA conditions have lower Young's moduli than Ti6Al4V. However, with CRA treatment, the alloy is significantly strengthened due to a homogeneous precipitation of nanometer-sized alpha-phase with lenticular morphology in the beta-matrix. Potentiodynamic polarization and EIS results reveal that both TNTZ CRA and Ti6Al4V passivate under testing conditions, and the passive current density is very low, providing corrosion resistance in the potential range studied. The EIS results also reveal that the passive film formed on the surface of both materials is highly corrosion resistant. This study compares mechanical properties and corrosion behavior of beta-type Ti29Nb13Ta4.6Zr (TNTZ) and Ti6Al4V alloys in Ringer's solution. TNTZ, when subjected to cold rolling aging (CRA), shows strength enhancement due to homogeneous precipitation of nanometer-sized alpha-phase in the beta-matrix, resulting in a lower Young's modulus than Ti6Al4V. Both TNTZ CRA and Ti6Al4V alloys exhibit a highly corrosion-resistant passive layer.image (c) 2023 WILEY-VCH GmbH