The corrosion mechanism of sputter-deposited TbFe thin films for magneto-optical recording material was investigated using electrochemical methods in aqueous environment with and without Cl- ions. TbFe thin films with varying composition prepared by an ion beam sputtering method were used as specimens. TbFe tape alloys made by the rapid quench method of melting alloys were also used for comparison. In an acid buffer solution without Cl- ions, the corrosion rate of the TbFe thin films and tape alloys decreased with increasing Tb content. In this solution, passive films composed of Tb oxide or hydroxide were formed on both the TbFe thin films and tapes and the selective dissolution of Fe through the passive films occurred. In neutral solutions with Cl- ions, pitting corrosion occurred on both the TbFe thin films and tapes. The stoichiometric dissolution of the substrate at pitted sites and the selective dissolution through the passive films at nonpitted sites take place in these solutions.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Renewable Energy, Sustainability and the Environment
- Surfaces, Coatings and Films
- Materials Chemistry