Correlation between metastable pitting and structural heterogeneity in Co-based metallic glasses

Abstract

By employing micrometer-diameter microelectrodes, the metastable pitting corrosion behavior of Co_68.15Fe_4.35Si_12.5B₁₂Cr₃ metallic glasses (MGs) exposed to 0.6 mol/L NaCl solution was investigated to clarify the correlation between metastable pitting and structural heterogeneity in MGs. Thermally induced degeneration of structural heterogeneity inhibits the initiation, decelerates the growth kinetics, and accelerates the repassivation kinetics of metastable pits while also decreasing the probability of transition from metastability to stability. This enhanced resistance to pitting corrosion is attributed to a reduction in active pitting precursor sites and a decrease in electrochemical activity caused by the structural homogenization of MGs.