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-deposited TbFeCo alloy films was investigated by means of an immersion corrosion test, electrochemical measurement, X-ray photoelectron spectroscopy, and transmission electron microscopy. The corrosion resistance of the alloy films in chloride solutions increased with increasing Co content. This is due to the decrease in the growth rate of pits. The stability of passive films on the surface of the alloys increased with increasing Co content. The number of pits, however, increased with increasing Co content. Colonies of microcrystals were locally formed in an amorphous alloy matrix with increasing Co content. Such colonies are presumed to be responsible for the increase in the number of pits.