Location corrosion of alumina borate whisker reinforced AA2024 T6 composite in aqueous 3.5% NaCl solution

The corrosion behavior of alumina borate whisker reinforced AA2024 composite was studied after T6 treatment. The pitting susceptibility of the composite was analyzed by the measurement of polarization curves. The stress corrosion cracking behavior of the composite was investigated by double cantilever beam specimen. Pitting and stress corrosion cracking were found to be dependent on each other. The stress corrosion crack tip was found to be nucleation sites for pits, as the crack tip was the stress gating region. The crack tip blunting is attributed to the formation of pits in the zone ahead of the crack tip. The tests were carried out in an aqueous solution of 3.5% NaCl solution. Transmission electronic microscopy observation was carried out on the sample to examine the microstructures of the composite. Scanning electron microscopy metallographic studies were carried out on the sample after the corrosion tests to determine the influence of the microstructure changes during aging treatment on the corrosion behavior of the composite. The crack propagation characteristics of stress corrosion were also examined by scanning electron microscopy.