ANODIC FILM FORMATION ON A SPUTTER-DEPOSITED AMORPHOUS AL-40AT.PERCENT-SM ALLOY

The mechanism of ionic transport in the amorphous anodic film formed o n Al-40 at. % Sm alloy has been examined by transmission electron micr oscopy and Rutherford backscattering spectroscopy. The film consists o f an outer layer, about 6% of the total film thickness, composed of re latively pure Sm2O3 and an inner layer containing units of Al2O3 and S m2O3 distributed homogeneously at the available resolution. The anodic film material is formed by migration of O2-/OH- ions inward and migra tion of cations outward, with a cation transport number about 0.29. Th e two-layered film develops as a consequence of faster migration of Sm 3+ ions than Al3+ ions in the film.