Influence of fabrication process on electrochemical and surface properties of Ti–6Al–4V alloy for medical applications

The electrochemical behavior of rolled and sintered Ti–6Al–4V alloy has been investigated by different electrochemical techniques in order to study the influence of the fabrication process on the corrosion mechanisms of those titanium alloys. Before performing the electrochemical tests, an activation of the electrode surface is carried out to minimize the effect of the spontaneous formation of titanium oxides and to quantify the electrochemical active area of the alloys. The results show that the rolled and the sintered alloy have similar electrochemical behavior, but the sintered alloy presents higher corrosion resistance than the rolled one. Roughness factor associated to the powder metallurgy fabrication process is determined by Electrochemical Impedance Spectroscopy (EIS) and an active area 1.54 times higher than the rolled Ti–6Al–4V is obtained. The higher active area of the sintered alloys generate higher amount of metallic cations but also lower passive dissolution through the oxide film, then enhancing the passive film formation. Powder metallurgy is a promising fabrication technique to obtaining titanium biomedical alloys according to the optimal corrosion resistance.