Corrosion-Electrochemical Behavior of Al–Nano–Al₂O₃ Metal Matrix Composites in an Aqueous 0.5 M NaCl Solution

Abstract—The corrosion-electrochemical behavior of aluminum–aluminum nanooxide nanocomposites formed during the direct chemical interaction of molten aluminum with titanium nanooxide in molten alkali metal chlorides is studied at temperatures above 700°C. Aluminum nanooxide crystals in the α-Al₂O₃ modification uniformly distributed over the metal matrix volume are detected by electron microscopy and X-ray diffraction. The corrosion rate in a 0.5 M NaCl solution determined by a gravimetric method decreases by 3–4 times during the transition from the initial aluminum to Al–Al₂O₃ composites, the character of corrosion changes from pitting to uniform, and the corrosion resistance class increases from 3 (resistant) to 2 (very resistant). This behavior is caused by the formation of a denser single-phase hydroxide coating on the surface of the composite as compared to a two-phase loose coating on aluminum. The corrosion potential does not depend on the introduction of aluminum oxide nanoparticles into the aluminum matrix.