Electrochemical corrosion characteristics of friction stir-reacted aluminum matrix hybrid nanocomposites

This research work involves the advanced microstructural characterization and corrosion resistance of hybrid nanocomposites produced by friction stir-induced reaction in an Al–Mg alloy/TiO2 system tested by potentiodynamic and spectroscopy analyses in the form of polarization and impedance. The impact of TiO2 content and submerged cooling medium were assessed on the subsequent electrochemical behavior of the composites. The electrochemical polarization measurements reveal a substantial variation in the corrosion performance correlated to the chemistry of nanocomposites and aluminum matrix grain structure, depending on friction stirring parameters. The heterogeneity of reinforcing nanoparticles at high fractions can increase the corrosion rate in the stirred region by more than 140 times compared to the primary alloy. This is attributed to secondary phase interfaces and nanoparticle clustering at the grain boundaries, promoting galvanic and pitting corrosion phenomena. In contrast, submerged reactive methods employing a cooling medium led to the formation of ultra-fine/nano-sized cellular structured in-situ hybrid nanocomposites with superior corrosion resistance and an excellent combination of mechanical and chemical properties.