Backscattering spectrometry of oxide films formed on aluminium in weakly alkaline solutions

The corrosion and passive behavior of high-purity Al in weakly alkaline solution (p H 7-10) has been studied by electrochemical measurements and by Auger electron spectroscopic investigations of oxide films formed. The films were found to be duplex ones, generally having a thin inner barrier layer (whose thickness decreases with increasing p H) and a thicker outer nonbarrier layer (whose thickness increases with increasing p H). Some supplementary studies on such films by backscattering spectrometry using a normally incident beam of 2 MeV helium ions and measuring at a scattering angle of 165 deg and with a channel width of 5 keV, are reported.--AA.