Different corrosion behaviors between α and β phases of Ti6Al4V in fluoride-containing solutions: Influence of alloying element Al

In this study, the different corrosion behaviors between alpha and beta phases of Ti6Al4V in solutions with different NaF concentrations are investigated. When the NaF concentration changes from 0.15 to 0.20 M, alpha phases are more likely to suffer from corrosion than beta phases. However, the formation of a repassive film makes alpha phases exhibit superior corrosion resistance than beta phases as the NaF concentration reaches 0.50 M. The mechanism analysis reveals that the formation of a repassive film on the a phases depends on not only the Al content but also on the active dissolution rate of Ti.