Microstructural, morphological characterization and corrosion behavior of sand cast AlSi10Cu(Fe) alloy in chloride solution

In order to examine the relationship between the microstructure and the corrosion behavior in chloride solution, the microstructure of AlSi10Cu (Fe) sand cast aluminum alloy has been investigated by using different techniques including scanning electron microscopy, energy-dispersive spectroscopy, X-ray diffraction analysis and electrochemical measurements. The microscopic analysis and X-ray diffraction analysis show several phases in addition to matrix phase, including pores and phases at nano- and microscales. The average rate of micropores and nanopores is 4% and 5%, respectively. The nanoparticle size varies between 20 and 150 nm. Plates and corals-like silicon eutectic, rich-Cu phase and Chinese script phase (Al 15 (Mn,Fe) 3 Si 2 ) have been observed. Energy-dispersive spectroscopy analyses show the presence of a new phase (Cu 61.22 Zn 25.39 Ni 11.85 Al 1.54 ), and the pitting corrosion has been demonstrated to be initiated at the nanopores. The electrochemical measurements exhibited the effect of several elements and porosities on the corrosion kinetics that is controlled by charge transfer and diffusion phenomenon. Wide passive windows, followed by the breakdown of passive film and excessive dissolution, have been observed in 0.3 and 3 wt% NaCl solutions. The electrochemical measurements show a high corrosion rate which does not recommend the use of this alloy in seawater.