Fatigue-corrosion behaviour of Ti6Al4V alloys in H2O2-containing physiological solution

Titanium and its alloys stand out as widely employed non-biodegradable materials for medical implants. Among these alloys, Ti6Al4V is the prevalent biomedical implant material. However this materials suffers from degradation when exposed to reactive oxygen species, including oxygen peroxide (H2O2), especially during acute or chronic inflammation phases. This degradation process can lead to the deterioration of the implant device and the subsequent release of its constituents into the surrounding tissues, potentially giving rise to health issues. Moreover, for duplex α/β microstructures, selective dissolution of the β phase has been observed under such conditions, leading to sharp corrosion damage at the grain boundaries of α grains. These damages stand as initiation sites for fatigue mechanism. This study, conducted within the context of the French-Swiss project LoCoMecha, investigates the fatigue-corrosion properties of Ti6Al4V with different microstructures when exposed to an H2O2-containing solution. To gain deeper insights into the underlying damaging mechanisms, the research involves not only comprehensive in situ electrochemical measurements but also ex-situ characterization of the crack path (e.g. 2D BIB-SEM and 3D FIB-SEM). The results are discussed, focusing on the initiation of corrosion defects at the surface, particularly in the β phase, and the subsequent fatigue propagation within the microstructure.