THE CORROSION BEHAVIOR OF SPUTTER-DEPOSITED MO-NB ALLOYS IN 12 M HCL SOLUTION

Single bcc phase Mo-Nb alloys are successfully prepared by sputter dep osition. These alloys are spontaneously passivated and show significan tly high corrosion resistance in 12 M HCl. Their corrosion rates are l ower than those of molybdenum and niobium. XPS analysis revealed that the passive films formed on Mo-Nb alloys by open circuit immersion in 12 M HCl are composed of outer niobium-enriched oxyhydroxide and inner molybdenum-enriched oxyhyroxide with a concentration gradient. The co ncentration gradient in the passive film on Mo-Nb stems from the fact that the corrosion potential of these alloys is close to or rather exc eeds the potential for the transpassive dissolution of molybdenum. Cop yright (C) 1996 EIsevier Science Ltd