The Effect of Ti and REE Addition on the Corrosion Resistance of the AlZn12Mg3.5Cu2.5 Alloy in "Acid Rain" Environment

A significant problem associated with the use of high-strength aluminum-zinc alloys is their insufficient resistance to corrosion. A often used method of improving the resistance to corrosion is plating, resulting in a decrease of their strength. Improving the corrosion resistance can be achieved by application of micro - alloying elements. Titanium and rare earth elements are particularly interesting micro - alloying elements. Subject of examination were AlZn12Mg3.5Cu2.5 base alloy (without micro-alloying) and alloy with the addition of titanium alloy and alloy with the addition of rare earth elements. Corrosion examinations were carried out in a solution of "acid rain", pH = 3.5. The scope of the research included potentiodynamic and potentiostatic tests , examination of the surface and structure of the samples after corrosion.The research found that the addition of titanium does not cause a significant improvement in corrosion resistance of the AlZn12Mg3.5Cu2.5 alloy. A significant improvement was achieved with the addition of rare earth elements. It was found that corrosion tested alloys is local and leads to the formation of pits.