The corrosion behavior of sputter-deposited Mo-Ta alloys in 12M HCl solution

The corrosion behavior of sputter-deposited Mo-Ta alloys in 12 M HCl at 30 degrees C was investigated by electrochemical measurements and XPS analysis. The Mo-Ta alloys are composed of a single bcc solid solution. These alloys are spontaneously passive in 12 M HCl. The corrosion rate of low tantalum alloys is lower than that of molybdenum and comparable to that of tantalum. Their spontaneously passive film is rich in molybdenum. High tantalum alloys with 43 at% or more tantalum show a lower corrosion rate than tantalum and form spontaneously the tantalum-enriched passive film. Regardless of the concentrating cations in the spontaneously passivated film the concentration of tantalum decreases from the exterior to the interior of the film.