The electrochemical corrosion characterization of bulk nanocrystalline aluminium by X-ray photoelectron spectroscopy and ultra-violet photoelectron spectroscopy

The electrochemical corrosion of bulk nanocrystalline aluminium (BN-Al) produced by severe rolling technique and its conventional polycrystalline aluminium counterpart (CP-Al) was studied by weight loss and scanning electron microscope (SEM). The uniform and localized corrosion resistances of BN-Al were simultaneously enhanced in comparison with CP-Al in 0.25 mol/L HCl solution at room temperature due to the thinner, more compact and stable oxide film on BN-Al. The valence electron configurations of BN-Al and CP-Al were characterized by ultra-violet photoelectron spectroscopy (UPS). The electronic structures of oxide films on BN-Al and CP-Al were studied by X-ray photoelectron spectroscopy (XPS). The larger work function of BN-Al, the larger binding energies of valence electrons of BN-Al, the weaker Cl− adsorption on BN-Al, and the larger binding energies of Al3+2p3/2 and Cl−2p3/2 in the oxide film on BN-Al could explain the enhanced corrosion resistance of BN-Al and the inconsistent corrosion results of nanocrystalline materials at atomic scale.