Corrosion behavior of Cr-based bulk metallic glasses in hydrochloric acid solutions

The corrosion behavior of Cr40Co39Nb7B14 and Cr50Co29Nb7B14 bulk metallic glasses in HCl solutions were investigated by immersion, electrochemical tests and microstructural observation. XPS analyses were performed to clarify chemical states of elements in the passive films. The results show that these alloys can be passive against corrosion in 1 and 3 M HCl, and high Cr content in the alloys has advantages on passivation properties. Increasing the exposure time in air and immersion time in 3 M HCl can accelerate the passivation. The high corrosion resistance is attributed to the highly-enriched trivalent Cr-oxide films formed in corrosive environments.