Effect of microstructure on corrosion behaviours of a Ni-based metallic glass

Abstract

Electrochemical corrosion behaviours of as-spun, as-cast, and relaxed Ni 55 Nb 20 Ti 10 Zr 8 Co 7 metallic glasses were investigated in 3 mass% NaCl and 1 N H 2 SO 4 solutions in order to study the effect of different amorphous microstructure. Static immersion tests indicate that the as-spun ribbon possesses the most active state in the NaCl solution at its open circuit potential, followed by the as-cast rod, the relaxed ribbon, and the relaxed rod. While in the H 2 SO 4 solution, the rod samples are more stable than the ribbons, and the relaxed samples exhibit higher stability than the as-quenched samples. The polarization tests revealed slightly higher passive current density (i pass ) for the ribbons than those of the rods in both electrolytes, although no significant differences in i pass were found between the relaxed and the as-quenched specimens. It is concluded that electrochemical corrosion behaviours of metallic glasses are related to the amorphous structure, and a decrease in free volume generally favors corrosion resistance.

Microstructure and corrosion study of Fe-based bulk metallic glass obtained by spark plasma sintering

“…Re is in the range of 50 to 150 Ohm cm² for all the tests, which is expected for a sulfate solution at 10 g/L. The crystallinity state induces a polarization resistance increase confirming the underneath microstructure's role in the passive film grown [51][52][53][54]. For Qdl and n, the results in table 2 show a significant difference between crystalline (i.e., S1) and quasi amorphous structures (i.e., S2, S3, and S4-300).…”