Formation of Bulk Glassy Ni-(Co-)Nb-Ti-Zr Alloys with High Corrosion Resistance

Abstract

Ni_60−xCo_xNb₂₀Ti₁₀Zr₁₀ (x=0–40 at%) glassy alloys were formed by melt spinning and a large supercooled region of over 40 K for the 0–20 at%Co alloys was found. The Ni_60−xCo_xNb₂₀Ti₁₀Zr₁₀ (x=0–20 at%) alloys have high glass-forming ability leading to the formation of bulk glassy rods with diameters up to 1.5 mm by copper-mold casting. The bulk glassy alloys with 0–20 at%Co exhibited nearly the same anodic polarization behavior in 1 N HCl solution. They were spontaneously passivated with a low passive current density of the order of 10⁻² A/m² and no pitting corrosion due to anodic polarization with a potential sweeping up to 2.0 V vs. Ag/AgCl occurred, indicating their high corrosion resistance in the aggressive acid.