Corrosion Behavior Of Traditional Aluminum Alloys And Novel Amorphous Aluminium Alloys

Aluminum alloys are widely used in aeronautical, astronautical, national defense andmarine industries because of their light weight, high ratio of strength to weight andexcellent corrosion resistance. In this paper, the corrosion behavior of traditional aluminumalloys AA2024, AA6061, AA7075were investigated.To ensure mechanical capability and corrosion resistance, amorphous aluminumalloys have aroused great interest over the globe because the alloys exhibit mechanicalproperties and corrosion resistance much better than their traditional counterpart whilekeeping low density. As such, aluminum alloys in composition of Al₈₅Y₅Ni₇Ti₃andAl₈₈Ce₈Co₄were prepared by melt-spinning （MS） method. Crystal structures of the alloyswere studied using X-ray diffraction technique. The results show that Al₈₅Y₅Ni₇Ti₃alloy,composed of multipal phases, has a amorphous matrix embedded with crystalline phases.Al₈₈Ce₈Co₄alloy, however, is completely of an amorphous phase. The crystallizationmechanism and the glass forming ability （GFA） were studied using DSC technique. Thecorrosion behavior of Al₈₅Y₅Ni₇Ti₃and Al₈₈Ce₈Co₄alloys were investigated usingpotentiodynamic polarization and electrochemical impedance techniques （EIS）. It has beenfound that Al₈₅Y₅Ni₇Ti₃alloy has higher corrosion current density and lower chargetransfer resistance compared with AA2024and AA6061in NaCl aqueous solutions,indicating less corrosion resistance. Al₈₈Ce₈Co₄amorphous alloy has higher corrosionpotential, lower corrosion current density and higher charge transfer resistance comparedwith AA2024and AA6061in acidic, alkali and salt aqueous solutions, indicatingAl₈₈Ce₈Co₄amorphous alloy have excellent corrosion resistance.Effect of pH value and chloride concentration in NaCl solution and annealing processon corrosion behavior of Al₈₈Ce₈Co₄amorphous alloy was also studied in thia paper. Whenthe concentration of chloride is in the range of0.5-2mol/L, corrosion resistance of thealloy increases with the increase of concentration. However, when the concentration ofchloride reaches the4mol/L, corrosion resistance of the alloy decreases compared that inthe concentration of2mol/L. Al₈₈Ce₈Co₄amorphous alloy show different corrosion mechanism in acidic solution and alkaline solution. In acidic solution, The lower the pHvalue, the lower the corrosion resistance. In the alkaline solution, the higher the pH, thelower the corrosion resistance. Based on DSC experiment,the temperature of annealingtreatment of Al₈₈Ce₈Co₄amorphous alloy was selected at572k and607K, respectively.The results show that the post heat-treated alloys exhibit much less corrosion resistance,the alloy treatmented at572K shows better corrosion resistance than that heat treated at607K. Al₈₈Ce₆X₆（X=Ni、Co、Fe、Mn） have excellent corrosion resistance in NaCl aqueoussolutions, the corrosion resistance of Al₈₈Ce₆X₆change with the alloy composition.