Effects of phase selection and microsegregation on corrosion behaviors of Ti-Al-Mo alloys

The effects of phase constitution and microsegregation on corrosion behaviors and passivation film of Ti50Al50−xMox alloys (x = 0–12 at%) in substitute sea water solution were investigated. As Mo content increased, alloys displayed different phase constitution and microstructure. Corrosion resistance of alloys was significantly improved by adding 2 or 6 at% Mo, with increasing Mo content to more than 6 at%, Mo is more difficult to diffuse in the grains, appearance of Mo microsegregation affected the passivation process, increased defects concentrations and decreased TiO2 conversion in passivation films, consequently reduced corrosion resistance. The micro-galvanic effect aggravated the corrosion of low potential phase and caused different corrosion behaviors in Ti-Al-Mo alloys.