Highly corrosion-resistant Ni-based bulk amorphous alloys

Bulk amorphous Ni-Nb-Ta-P alloys were successfully prepared by copper mold casting method. The addition of tantalum is effective in decreasing the corrosion rate. The corrosion rates of the alloys containing certain amounts of tantalum are more than four orders of magnitude lower than that of nickel metal and are almost equivalent to that of tantalum even in aggressive 12 M HCl open to air at 30°C. They are spontaneously passive and are characterized by immune to pitting by anodic polarization. The corrosion behavior of the bulk amorphous alloys is almost the same as corresponding melt-spun amorphous alloy ribbons.