Aqueous corrosion behaviour of Fe-Ni-B metal glasses

摘要

The corrosion performance of Fe-40Ni-20B (at%) amorphous ribbons in 7N NaOH and 3.5% NaCl, at 25 ℃, is investigated by potentiodynamic polarization, chronoamperometry and Raman spectroscopy. Immersion in 7N NaOH induces a multiple stage passivation/pseudopassivation, which is associated with the successive formation of (Ni,Fe) compounds based on Fe_3O_4, Ni(OH)_2/NiO, FeOOH/Fe_2O_3, Ni(OH)_2.2NiOOH and βNiOOH. Fe_3O_4, NiO, Fe_2O_3 and βNiOOH are responsible for true passivity. Although carbonate ions from the environment have penetrated the passive film, the glass is not susceptible to pitting in 7N NaOH. Despite amorphicity, the glass behaviour in 7N NaOH is governed by the behaviour of its crystalline metallic constituents. The alloy exhibits a slight susceptibility to localized corrosion, in 3.5% NaCl.