H2O2-driven corrosion of Ti6Al4V investigated by electrochemical impedance spectroscopy and quantitative microstructure analysis

Ti6Al4V, as biomedical implant material, degrades in the presence of reactive oxygen species, such as oxygen peroxide (H2O2) during acute or chronic inflammation phases. This leads to the device degradation and the release of its constituents in the surrounding tissues, which may cause health issues (peri-implantitis, osteolysis, neurotoxicity). H2O2 is also used as tissue disinfection agent during surgical operation. In this contribution, within the framework of the French-Swiss project LoCoMecha, the in-vitro corrosion by H2O2 is investigated by in situ electrochemical methods like impedance spectroscopy and ex situ characterisation techniques, notably highresolution imaging and spectroscopy (SEM-SE, SEM-EBSD, SEM-EDX, FIB-SEM and (S)TEM-EDX). The effect of the microstructure of the samples prepared by forging and additive manufacturing on the alloy corrosion will be reported. The extent of phase dissolution, a key-aspect for the mechanical integrity of the implant is assessed by quantitative microstructure analysis. First insights on the mechanisms of the Ti6Al4V degradation (phase dissolution and phase oxidation) will be provided.