Structural and electrochemical performance of sputtered Al-Ce films on AA6061 aluminum alloy substrates

In this work, sputtered Al-Ce films were studied in order to evaluate their possible application as coatings to delay pitting corrosion of aluminum alloy substrates. The morphology and structure of the coatings deposited on both silicon and AA6061 aluminum alloy substrates were studied by varying the magnetron sputtering conditions. The preliminary electrochemical performance was also discussed by means of Tafel plots and electrochemical impedance spectroscopy (EIS). The X-ray diffraction studies indicated that the microstructure varied from crystalline to amorphous, depending on the deposition parameters. The AFM images show that the films consist of equi-axial round domes distributed homogeneously. The mean grain size, roughness and thickness of the coatings were increased by augmenting the power and pressure. The EIS studies showed that there was a significant increase in the resistance to corrosion after depositing Al-Ce films on AA6061 aluminum alloy substrates. The electrochemical behavior of the films was related to the Ce/Al composition ratio as well as process parameters.