Corrosion Behavior of a Zr-Base Bulk Glassy Alloy and Its Crystallized Counterparts

Abstract

A Zr-base bulk glassy alloy with a nominal composition of Zr_52.5Cu_17.9Ni_14.6Al₁₀Ti₅ (at. percents) was evaluated by conducting corrosion experiments in 0.5 kmol·m⁻³ H₂SO₄ and 0.5 kmol·m⁻³ NaCl electrolyte respectively using electrochemical measurements. Potentiodynamic polarization experiments were carried out with a scan rate of 20 mV/min. Passive current density and pitting corrosion potential were evaluated from potentiodynamic polarization curves. The results indicate that the full glass has a higher resistance to general corrosion and good resistance to pitting corrosion than the counterparts of the partially and completely crystallized glassy alloy. The resistance to general corrosion decreases with increase of the volume fraction of nanocrystalline phases. This is mainly due to the inhomogeneity of microstructure, the structural defects such as grain boundaries, as well as the formation of crystalline phases that have lower corrosion resistance in the partially and completely crystallized samples.