Thermodynamics and corrosion properties of nitrogen doped zirconium-based bulk metallic glasses

Abstract

The effect of adding N on the thermodynamics and corrosion resistance of as-cast Zr55Cu30Ni5Al10 bulk metallic glass (BMG) is clarified using electrochemical measurements, microstructure characterization and surface analyses. Compared with Zr55Cu30Ni5Al10 BMG, Nitrogen-doped (Zr55Cu30Ni5Al10)98.5N1.5 BMG is easier to nucleate during heating, but the nucleation growth process becomes more difficult. The corrosion potential (Ecorr) of (Zr55Cu30Ni5Al10)98.5N1.5 BMG and Zr55Cu30Ni5Al10 BMG is −0.32 V and −0.39 V respectively, and the corrosion current density (Icorr) of (Zr55Cu30Ni5Al10)98.5N1.5 BMG and Zr55Cu30Ni5Al10 BMG is 7.90 × 10−8 A/cm2 and 9.13 × 10−5 A/cm2, respectively. I.e., after nitrogen doping the corrosion potential increased slightly, but the corrosion current density decreased by about three orders of magnitude. Meanwhile the oxide film resistance increased significantly, and the surface corrosion diffusion effect weakened. Nitrogen reduces the H+ concentration in the pitting pits, slows down the pitting rate, and improves the corrosion resistance. Proper nitrogen can improve the thermal-stability and surface corrosion resistance of Zr-based BMGs.