Electrochemical Corrosion Behavior of Ti37Al Alloy in Simulated Artificial Seawater Environment and the Impact of Fluoride Ions and pH Values

Titanium and its alloys exhibit exceptional potential for utilization in numerous manufacturing domains owing to their specific strength, robustness against corrosion, ability to withstand high temperatures, and other attributes. However, the corrosion failure of Ti alloys is garnering significant attention these days due to their steadily growing applications. The tested Ti37Al alloy is composed of α-Ti 3 Al and γ-TiAl phases. We compared TiAl alloy’s and Ti’s corrosion behavior in simulated artificial seawater (SAS). The TiAl alloy submerged in SAS has a higher corrosion resistance than Ti (the lower I corr and i pass ); however, it suffers localized corrosion at higher positive potential. Additionally, the influences of varying F − ion concentrations and pH upon the corrosion behavior of TiAl alloy were systematically examined. The OCP values for the TiAl alloy sample gradually became more positive (− 0.30 V) compared to the Ti sample (− 0.44 V), indicating that the TiAl alloy possesses great corrosion resistance. The corrosion performance of TiAl alloy can be negatively impacted by raising the F − ion concentration or decreasing pH caused by the dissolution of the compact passive film. The TiAl alloy sample submerged in SAS at a pH of 4.0 and 0.01 M F − ions possesses 17 times corrosion rates higher than those in the absence of F − ions. The corrosion rate of the TiAl alloy in SAS is minimal at pH 7.0. Meanwhile, the corrosion behavior of TiAl alloy shifts to more active domains in solutions with an acidic pH. The corrosion rate increases 20 times with a decrease in the pH from 7.0 to 3.0. According to the EIS results, the alloy’s corrosion resistance in F-containing solutions has substantially decreased. With a more capacitive, compact, and stable inner layer and a porous, less compact outer layer, the passive film on the TiAl surface is composed primarily of TiO 2 , Ti 2 O 3 , and a trace quantity of Al 2 O 3 .