Corrosion behavior and glass-forming ability of Cu–Zr–Al–Nb alloys

Amorphous Cu50−xZr45Al5Nbx (x = 0, 1, 3 and 5 at.%) samples with critical diameters of 1.54–2.05 mm were formed by copper-mold suction casting. The effects of Nb on the glass formation ability were evaluated with differential scanning calorimetry and the corrosion resistances of the alloys with the addition of Nb were evaluated in 1 N HCl, 3% NaCl and 0.5 N H2SO4 solutions, respectively, by weight loss and polarization curve measurements. The samples surfaces were examined after the corrosion test with SEM. It was found that the addition of Nb causes a decrease of ΔTx of Cu50−xZr45Al5Nbx alloy from 54 K to 45 K. On the other hand, the corrosion resistances in various solutions were improved with the addition of Nb.