THE INFLUENCE OF CO CONTENT ON THE CORROSION-RESISTANCE OF SPUTTER-DEPOSITED TBFECO THIN-FILMS IN AQUEOUS ENVIRONMENTS

The influence of Co content on the corrosion resistance of sputter-dep osited TbFeCo alloy films for magneto-optical recording media was inve stigated by means of an immersion corrosion test, electrochemical meas urement, x-ray photoelectron spectroscopy, and transmission electron m icroscopy. The corrosion resistance of the alloy films in chloride sol utions increased with increasing Co content. This is due to the decrea se in the growth rate of pits. The stability of passive films on the s urface of the alloys increased with increasing Co content. The number of pits, however, increased with increasing Co content. Colonies of mi crocrystals were locally formed in an amorphous alloy matrix with incr easing Co content. Such colonies are presumed to be responsible for th e increase in the number of pits.