Localized corrosion of aluminum (Al) alloys, such as pitting corrosion, intergranular corrosion, and stress corrosion cracking is closely related to the micro-galvanic corrosion between the second phase and the Al matrix. Using high-resolution transmission electron microscopy and first principles calculations, the factors that affect corrosion mechanisms of the second phase in Al alloys at micro-scale and atomic-scale were examined, including the composition and structure of second phase, pH of the environment, stress and adsorption behavior of adsorbates (such as Cl^-, H₂O, OH^- and O^2-).