Electrochemical characterization of Ti12Mo5Ta alloys in contact with saline medium

The electrochemical behaviours of unrecrystallized and recrystallized Ti12Mo5Ta alloys were compared with those of the unrecrystallized Ti12Mo alloy and commercial pure titanium (cp-Ti). Experiments were carried out using physiological 0.9% NaCl solution (pH 2.3) at 37 degrees C. Very low passive current densities (in order of 10(-6) A/cm(2)) were obtained from the anodic polarization curves, indicating high resistances of all samples in acidified 0.9% NaCl solution. Scanning electron microscopy (SEM) was employed to observe the surface morphology and all sample surfaces were identically corroded, no pitting, cracks, or other defects appeared on the sample surfaces after anodic potentiodynamic polarization tests. Equivalent circuit was used for modeling the electrochemical impedance spectroscopy (EIS) data, in order to characterize the sample surface and better understand the effect of Mo and Ta addition on the cp-Ti and the effect of recrystallization. The EIS results confirm that all titanium samples exhibit passivity in physiological 0.9% NaCl solution (pH 2.3) at open circuit potential (polarization resistance is around 10(5) Omega.cm(2)). The corrosion resistance of these samples in physiological 0.9% NaCl solution (pH 2.3) at 37 degrees C is in the following order of recrystallized Ti12Mo5Ta> unrecrystallized Ti12Mo5Ta > unrecrystallized Ti12Mo > cp-Ti.