An Investigation of Microstructural Background for Improved Corrosion Resistance of We43 Magnesium-Based Composites with Zno and Cu/Zno Additions

In this research, WE43-based nanocomposites were fabricated by addition of nano- and micro-sized particles of ZnO and Cu/ZnO, followed by friction stir processing (FSP). In addition to the effect of the size of additives, the effect of geometry of the particle insertions, groove and holes, on the evolution of microstructure and corrosion properties of Mg-based composites were studied. The grain size of the matrix of the fabricated composite was reduced after FSP processing. In addition, significant fragmentation and re-distribution of secondary phase particles occurred which resulted in size reduction, increased density and improved uniformity of the particles. Corrosion behavior of the composite was assessed by scrutinizing potentiodynamic polarization, electrochemical impedance spectroscopy, cyclic polarization and immersion tests. It was found that the corrosion mechanism of Mg-based nanocomposite samples was a combination of pitting and uniform corrosion. Furthermore, the rate of electrochemical corrosive reactions reduces by performing FSP and addition of particles. The composite fabricated using hole insertion and nano-sized particles showed a more uniform distribution of additives resulting in higher corrosion resistance in comparison with groove insertion. In addition, fabricated composite sample with Cu/ZnO particles presents the highest anti-corrosion properties