Corrosion characteristics of in situ hybrid (AlNi + AlO)/Al composites synthesized by the solid-state combustion

In this study, in situ hybrid (AlNi + AlO)/Al composites were prepared successfully by the solid-state combustion via Al-NiO system. The effects of AlNi + AlO on the corrosion features of composites were analyzed using potentiodynamic polarization, electrochemical impedance spectroscopy, and immersion corrosion in 3.5 wt% NaCl solution. The results show that with the increase of NiO addition, the corrosion resistance of composites is improved, and the corrosion resistance of 15 % NiO-Al composite is almost comparable to the Al matrix. The increased quantity and dispersive distribution of AlNi and AlO particles can effectively prevent the occurrence of corrosion and the movement of free electrons. Besides, more fine AlO particles distributed in grain boundaries can increase the impedance and hinder the electrochemical corrosion preferentially starting at the boundary. Also, in the composite with high NiO addition, a better and compact interface bonding can be formed due to reduction of large size AlNi particles and improvement in the dispersion of particles, thereby inhibiting interface damage. This study has advanced understanding of corrosion.