The corrosion behavior of Ti-(0 to 40)mass%Mo alloys prepared through powder metallurgy (PM) technology was studied by immersion test and electrochemical measurement. The corrosion rate of sintered Ti-Mo alloys in a 35%HCl solution decreased remarkably as molybdenum content increased. The corrosion rate of Ti-40mass%Mo alloy, for example, was found to be 5�~10^-3 mm/year , which was 104 times lower than that of pure titanium. In a 3%NaCl solution, on the other hand, the corrosion rate was not affected by the molybdenum content of the alloy, and was less than 10^-3 mm/year.
Potentiodynamic polarization curves in a 35%HCl solution showed that with increasing molybdenum content the open circuit potential (corrosion potential) shifted toward noble potential, while the anodic current density decreased. It is thought that the presence of spontaneously-passivated film in which molybdenum is enriched by preferential dissolution of titanium suppresses the anodic reaction and improves corrosion resistance. On the other hand, increased molybdenum content in a 3%NaCl solution shifts the corrosion potential toward increased base potential, and increased anodic current density, because of the active molybdenum dissolution.