Pitting corrosion studies of mg-bearing hypereutectic al-17% si alloy

Abstract EN

In this study pitting corrosion is investigated in hypereutectic Al- 17wt% Si alloy bearing magnesium .

Many alloys were prepared by die casting with adding different percentages of magnesium : 1 wt%, 4wt% & 9 wt% to the Al-17%Si alloy in order to study the influence of magnesium addition on the corrosion behavior and pitting properties in 3.5% NaCl solution.

Results of microstructure examination show that primary silicon (Si) and eutectic silicon in base alloy was more susceptible to pitting corrosion compared to the other alloys containing magnesium .

It was found that the corrosion rate of alloy Al-17%Si bearing Mg (in all percentages) was lower than that of base alloy.

The corrosion potential shifts to less negative value ( to more noble direction) and Epit to more positive value with increasing Mg content to 9 %wt.

It means that the addition of Mg to Al-17% Si alloy improves resistance to pitting corrosion and that no pitting appears in passive region during the cyclic polarization test.