Effect of silicon content on microstructure and electrochemical behavior of hypoeutectic Al-Si alloys

The correlation of mechanical properties and corrosion behavior with microstructure parameters can be very useful for planning solidification conditions in order to achieve a desired level of final properties. The present study aims to investigate the influence of silicon content on the microstructural pattern, i.e., dendrite spacings and distribution of interdendritic phases on the corrosion behavior of Al-Si alloys castings. The corrosion resistance was analyzed by both the electrochemical impedance spectroscopy (EIS) technique and Tafel's plots carried out in a 0.5 M NaCl test solution at 25 degrees C. The increase on silicon content has provided a dendritic refinement and a more extensive redistribution of the eutectic mixture which has provoked a decrease on the corrosion resistance. (C) 2007 Elsevier B.V. All rights reserved.