Effect of Porosity on Mechanical and Electrochemical Properties of Ti–6al–4v Alloy

In this work, the effect of porosity on Ti–6Al–4V alloy was studied by using the Archimedes method, BET analysis, ultrasound method, micro-hardness, surface analysis, such as scanning electron microscopy, X-ray powder diffraction and X-ray photoelectron spectroscopy, and electrochemical measurements, such as open circuit potential curves, electrochemical impedance spectroscopy and linear swept voltammetry. Apparent porosity of porous electrodes was close to 31% and 42%, which decreased significantly the elastic modulus. BET analysis revealed that the primary porosity for the porous electrodes was macro-porosity and that the micro- and meso-porosity was increased slightly by exposure. Surface analysis revealed the presence of α-phase and β-phase prior to exposure for bulk and porous electrodes. The impedance response for bulk and porous electrodes were completely different. For bulk electrodes, two time-constants were observed in high and low frequencies ranges, being associated with the formation of an oxide layer and the oxygen reduction reaction taking place at the electrolyte/oxide interface. Whereas the porous electrodes showed a De Levie behavior that was not influenced by porosity and exposure time. Anodic current was not modified by exposure. © 2020 Elsevier Ltd