Effect of friction stirred Al-Fe-Si particles in 6061 aluminum alloy on structure and corrosion performance of MAO coating

SEM and EDS analysis, immersion and electrochemical tests were performed to evaluate the effect of friction stirring process induced Al-Fe-Si particles in 6061 aluminum alloy on structure and corrosion performance of micro-arc oxidation (MAO) coatings on different regions of the friction stirred plate. The results show that coarse and congregated Al-Fe-Si particles in the base material (BM) and in the thermomechanical affected and heat affected zone (TM-HAZ) lead to formation of large and connected micro voids at interface of MAO coating/substrate and discontinuous inner oxide film. The structure and the corrosion protection performance of the MAO coating can be improved by inducing these coarse and congregated Al-Fe-Si particles into fine and disperse distributed particles as that in the stirred nugget zone (NZ) through the friction stirring process.