Effects of severe plastic deformation on the corrosion behaviors of aluminum-based binary alloys containing precipitates were investigated. The aluminum alloys were severely deformed by equal-channel angular pressing (ECAP) processes and the corrosion resistance of the aluminum alloys was evaluated by means of potentiodynamic polarization measurements in a neutral buffer solution containing chloride ions at a concentration of 0.002 M. The pitting potential of Al-5.4wt％Ni alloy whose microstructure has a-Al phase and Al/Al₃Ni eutectic region was increased by the introduction of strain by ECAP. ECAP treatment of Al-5wt%Cu alloy also resulted in increase in pitting potential. The pit initiation sites of the Al-Ni alloy without ECAP were in the relatively large a-Al phase and the pit growth was suppressed in the Al/Al₃Ni eutectic region. By applying ECAP, the microstructure of the Al-Ni alloy became more homogeneous and relatively large a-Al phase disappeared. Presumably, the more homogeneous microstructure is attributable to the higher pitting resistance of ECAPed Al-Ni alloys. In the case of the Al-Cu alloy, pit formed selectively in Cu-depleted zones around Al₂Cu particles which seemed to be acting as cathodic sites. The improvement of the pitting resistance seems to be due to diminution of Cu-depleted zone and the refinement of Al₂Cu particles caused by huge plastic strain during ECAP.

In contrast, ECAP treatment of Al with 4N purity resulted in a decrease in open circuit potential, slight increase of passive current and shift of pitting potential to the negative direction. Consequently, the improvement of pitting resistance of Al binary alloys is not because of introduction of dislocations and defects by severe plastic deformation but because of the change in microstructure such as homogenization and refinement of precipitates.

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