Corrosion Behavior of Extruded near Eutectic Al—Si—Mg and 6063 Alloys

Yuna Wu，Hengcheng Liao

School of Materials Science and Engineering,Southeast University,Jiangsu Key Laboratory for Advanced Metallic Materials,Campus of Southeast University

摘 要：<正>In this work,a comparison study on corrosion behavior of extruded near eutectic Al—12.3%Si—0.26%Mg and 6063 alloys has been carried out by mass loss test in 4%H₂SO₄ aqueous solution in the open air and potentiodynamic polarization test in 3.5 wt.%NaCI aqueous solution.Results indicate that the corrosion resistance of the near eutectic Al—Si—Mg alloy is less than that of 6063 alloy.Macro/microscopy and scanning electron microscopy results clearly show the difference of the corrosion progress of these two alloys in 4%H₂SO₄ aqueous solution.The corrosion type of 6063 alloy is pitting corrosion.The Mg₂Si and AlFeSi particles and surface defects act as nucleation sites for pitting,and the amount and distribution of them have a significant effect on the pitting behavior.For the near eutectic alloy,there are two types of corrosion cells. One is between the extruded primaryα-AI and the eutectic,the other is between the eutectic Al and eutectic Si particles.Combination of these two types of corrosion cells leads to a lower corrosion resistance,a higher mass loss of the near eutectic alloy compared with 6063 alloy,and the formation of the paralleling corroded grooves.

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