Influence of microstructure and chemical compositions on the corrosion properties of Zr-based bulk metallic glasses

Corrosion behavior of bulk metallic glass was greatly influenced by microstructure and chemical composition. Effects of microstructure and chemical composition on corrosion property of Zr58Nb3Cu16Ni13Al10 bulk metallic glass were studied. In 1 mol/L H2SO4 solution, all Zr-based bulk metallic glasses with different atomic microstructures displayed good passivation behavior with wide passive region and low corrosion current densities at 333 K. The as-cast Zr-based bulk metallic glass showed the best corrosion resistance owing to its highest atomic mobility, which is beneficial to the formation of passive film. The passive current densities increased as the annealing temperature increased, implying that the corrosion resistance was reduced by structural relaxation and crystallization. The passive films of the Zr-based bulk metallic glasses mainly exhibited n-type semiconductor properties, and the defects concentrations increased with the increase of annealing temperature. In neutral 3.5% NaCl solution, the Zr-based bulk metallic glasses with different yttrium additions showed good corrosion resistance at 293 K. However, chemical activity of copper in the Zr-based bulk metallic glasses was enhanced by yttrium addition, as indicated by enrichment of yttrium in the pitting area after anodic polarization. In general, addition of yttrium was slightly detrimental to the corrosion resistance of the Zr-based BMGs and the pitting potential decreased with increasing yttrium.