Electrochemical Behavior of SLM Ti–6Al–4V Alloy After Long Time of Immersion in Lactic Acid Environment

The corrosion behavior of selective laser melted Ti–6Al–4V alloy (SLM Ti–6Al–4V) was assessed in 0.1 M lactic acid + 0.1 M NaCl environment (pH 2.5) after 1150 hours of immersion at 37 °C and was compared with that of wrought Ti–6Al–4V alloy. Corrosion potential E cor ( E cor = 0.083 ± 0.02 V) and corrosion current i cor ( i cor = 0.145 ± 0.05 μA cm −2 ) of SLM Ti–6Al–4V alloy, estimated from anodic polarization tests, are under minimum recommended values for biomaterial surgical applications. Based on open-circuit potential (OCP) investigations, one may infer that this good corrosion resistance is due to the formation of a fast and stable protective oxide layer. According to X-ray photoelectron spectroscopy (XPS) results, this protective oxide layer is mainly formed from TiO 2 . From electrochemical impedance spectroscopy (EIS) investigations, a slightly lower corrosion resistance was observed at SLM Ti–6Al–4V alloy compared to the wrought one. Thus, the R 1 associated with barrier film resistance of SLM Ti–6Al–4V is 339.1 kΩ cm 2 whereas that one of wrought Ti–6Al–4V is 780.1 kΩ cm 2 . These results are conspicuous ones because they point out that SLM technique, which allows obtaining easily customized implants without expensive costs, is a valid alternative for obtaining new alloys for medical applications.