Study of the corrosion properties of powder rolled Ti–6Al–4V alloy applied in the biomedical implants

Great efforts have been made in fabricating Ti–6Al–4V alloys that can be used in the biomedical implants industry. The increasing interest in using fabricated Ti–6Al–4V alloys in industrial applications is mainly due to the properties of alloys which include good combination of mechanical and corrosion resistance. This study was aimed at evaluating the corrosion properties of the Ti–6Al–4V alloy fabricated via powder rolling technique under various simulated human body solutions. A three-electrode electrochemical cell was used to carry out corrosion studies at 37 °C where the fabricated Ti–6Al–4V was immersed in 3.5% NaCl (pH = 6.5) and two simulated human body fluids, namely; Hank's balanced salt solution (HBSS) and Ringers solution with the measured pH of 6.9 and 6.4 respectively. The electrochemical techniques used to investigate the corrosion studies included open circuit potential (OCP), potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The fabricated Ti–6Al–4V alloy was characterized before and after the corrosion experiments via X-ray diffraction (XRD) and scanning electron microscope (SEM). The potentiodynamic polarization curves revealed a passivation phenomenon on the anodic domain indicating high corrosion resistance of Ti–6Al–4V alloy in all three electrolytes. The Ti–6Al–4V alloy exhibited the highest corrosion resistance when immersed in 3.5% NaCl with the estimated corrosion rate of 0.480 μm/yr. The excellent corrosion resistance of Ti–6Al–4V alloy was mainly due to the formation of an oxide film formed on the alloy surface as deduced from the EIS analysis. No corrosion products were detected by XRD analysis on the Ti–6Al–4V alloy surface immersed in all electrolytes which confirmed an excellent corrosion resistance property.