Abstract
Al-Cu single crystals with different typical orientations (i.e., (001), (101), and (111)) were prepared to investigate the corrosion behavior of the Al-Cu alloy with and without precipitates by scanning electron microscopy (SEM), transmission electron microscopy (TEM), immersion testing in EXCO solution, and electrochemical impedance spectroscopy (EIS). The results showed that the corrosion rates of the alloy with different orientations increased in the order of (111)< (001)< (101) in the solid solution state (without precipitates), while those of the alloy increased in the order of (101)< (001)< (111) in the aged state (with precipitates). The corrosion resistance of the alloy without precipitates was mainly determined by the atomic density of the crystal plane, and that of the alloy with precipitates was mainly provided by the corrosion product film. After aging, the precipitation of the θ' phase led to anodic dissolution of the nearby matrix and further accelerated the corrosion rates of the alloy. Furthermore, the corrosion pits of the alloy without precipitates showed geometric shapes corresponding to the crystal orientations. The corrosion of the alloy with precipitates propagated in the form of corroded bands, which were parallel to the {001}Al plane.
NSTL
Elsevier