Internally oxidized cobalt-rich amorphous alloys for potential magnetic recording media application

Abstract

A new class of nanostructured magnetic materials which hold potential for novel recording media is described. Methods for minimizing intercrystalline interactions and reducing wear and corrosion by suitable coatings are obtained using the process of internal oxidation and crystallization of amorphous Co 95.26− x Fe 4.74(BSi) x alloys. Such a process leads to solid state dispersions of single-domain isotropic cobalt particles coated with a borosilicate layer which provides compositional separation between the cobalt grains. Dramatic microstructural differences were observed between samples of different metalloid compositions. The ribbons produced from compositions Co 75.26Fe 4.74Si 2B 18 and Co 74.26Fe 4.74Si 13B 8 proved to be the most promising for recording media application in terms of magnetic properties (coercivity 1200–1400 Oe) as well as morphological properties (size less than 300 Å). High coercivities obtained from these alloys are attributable to the increased surface anisotropy due to interactions between the Co particles and the borosilicate layer.