Corrosion Behavior Of Quaternary Amorphous Al-RE Alloys

We all know that amorphous materials will show better corrosion resistance than itscrystalline materials. Now there are only many researches on the formation mechanism andthe mechanical property of Al based amorphous materials, but less study on its corrosionresistance and the relations between the corrosion resistance and component. For thealuminum alloys, it was widely used in marine construction and aerospace for itsadvantages of low density and easy machining and so on, so it will usually run into theproblem of corrosion resistance. The studying on corrosion resistance of Al basedamorphous alloys plays an important role in expanding its range of application and furthercomprehending the corrosion mechanism. So it is essential for conducting study on Albased amorphous materials.This paper based on the study of the amorphous Al-RE-TM alloy. Adding Ce or Y andtransition elements (Ni, Ti, Cr, Co) to the amorphous Al-RE-TM alloy composedquaternary alloys and quinary alloys. Then quaternary alloys and quinary alloys wereprepared by single roller rotation quenched method in a vacuum. The amorphous structurewas proved by X-ray diffraction. The corrosion resistance of the amorphous Al86Ce7Ni3Co4,Al86Ce5Ni6Cr3, Al88Ce6Ni4Ti2, Al87Y7Ni4Ti2andAl86Y4Ce3Ni4Co3alloys in NaCl (3.5wt.%)solution of different pH(pH=2,7,12) were tested by polarization curve and AC impedance.The morphology of corrosion was tested by scanning electron microscopes. The factoreffecting the corrosion resistance behaviors of amorphous Al-based and the corrosionmechanism were analyzed.The results indicated that:(1) The corrosion resistance of Al86Ce5Ni6Cr3was the bestand the corrosion resistance of Al88Ce6Ni4Ti2was the worst in the NaCl solution (3.5wt.%)with0.01M HCl. The corrosion resistance of the five kinds of alloys were worse than theamorphous pour Al.(2) The corrosion resistance of Al88Ce6Ni4Ti2and Al86Ce7Ni3Co4weresimilar and the best, however the corrosion resistance of Al87Y7Ni4Ti2was the worst in theNaCl solution (3.5wt.%). The corrosion resistance of Al86Ce7Ni3Co4and Al88Ce6Ni4Ti2 were about1~3times of the amorphous pour Al.(3) The corrosion resistance ofAl86Ce7Ni3Co4and Al87Y7Ni4Ti2were similar and the best, were about1~2times of theamorphous pour Al in the NaCl solution (3.5wt.%) with0.01M NaOH. The pittingdeveloping trend of Al86Ce5Ni6Cr3,Al87Y7Ni4Ti2,Al86Y4Ce3Ni4Co3,Al86Ce7Ni3Co4andAl88Ce6Ni4Ti2were increased gradually, and the ability of repair of passivation membranewere reduced gradually.(4) Ti, Cr and Y were rich in the solution whose pH were2,7and12. However Co and Ni were rich in the solution whose pH were7and12. So theelements-rich help to the formation of passivation membrane.