In situ EC-AFM study of the effect of nanocrystals on the passivation and pit initiation in an Al-based metallic glass

The effect of nanocrystals on pit initiation in metallic glasses is an unresolved issue. The passive film formation and pit initiation in the Al-Ni-Ce metallic glass were investigated using in situ electrochemical atomic force microscope (EC-AFM). The α-Al nanophases were identified from the amorphous matrix based upon the phase imaging in the tapping mode AFM. In the early stage of the passive film formation, the corrosion products Al(OH)3 formed on the α-Al nanoparticles due to the galvanic coupling. The corrosion products incorporated into the passive film changed the local structure and component of the passive film, lowering its stability.