Role of rapidly solidified microstructure in corrosion and passivation of Al–Ni alloys

Abstract

The rapidly solidified Al_100-xNi_x ribbons with x = 0, 3.1, 10 and 25 (labeled as Ni0, Ni3.1, Ni10 and Ni25) were melt spun with the microstructures of monophasic α-Al, α-Al + Al₃Ni eutectic mixture, α-Al + Al₃Ni hypereutectic mixture, and sole peritectic Al₃Ni phase, respectively. As shown in the electrochemical and XPS tests, these ribbons have a monotonic increase in the passive current density, wetting angle, the charge density and Al 2p binding energy of outer layer with increasing Ni content, indicating the electrical properties of their passive films changed continually. In addition, their pitting potential, later corrosion resistance, oxygen diffusion parameter decrease first and then increase with the addition of Ni, showing a minimum in Ni3.1 ribbon with the eutectic microstructure, which is ascribed to the numerous α-Al/Al₃Ni interfaces. These results can help us to deeply understand the passivation of Al–Ni alloys and explore their application in the anti-corrosion environment.