Identifying the role of nanoscale heterogeneities in pitting behaviour of Al-based metallic glass

To clarify the correlation of nanoscale heterogeneity with corrosion in Al-based metallic glasses, three model alloys with a single nanoscale α-Al, Al3Ni or Al11Ce3 phase embedded in amorphous Al-Ni-Ce alloy matrix were obtained directly by melt quenching. The results indicated that the high pitting corrosion resistance of AM alloys was not deteriorated by nanocrystalline α-Al precipitation; whereas the pitting potential was slightly decreased and considerably reduced relative to their amorphous state due to the precipitation of nanocrystalline Al3Ni or Al11Ce3 respectively. Such a pitting sensitivity of different types of heterogeneities attributes to the nano-scale pit initiation events.

► Amorphous-nanocrystalline alloys, with single nanoscale α-Al, Al3Ni or Al11Ce3 embedded in amorphous matrix, was fabricated.
► The susceptibility of nanocrystals to corrosion is in the order α-Al► The high pitting resistance for α-Al precipitated alloy attributes to the covering of homogeneous Al-rich oxides.
► The deterioration of pitting resistance for Al3Ni or Al11Ce3 precipitated alloy is due to locally instable passive film.