FIELD-EMISSION MICROSCOPY OF AMORPHOUS COSI ALLOY

Low-temperature ultrahigh field-emission microscopy operating in elect ron and ion regimes was applied to study the inhomogeneities of a meta llic glass structure. Needle-shaped specimens with radius of curvature 10-50 Mn at the top were prepared by electrochemical etching of rapid ly-quenched Co75Si25 wires. From the shift of the constant brightness contour of the field electron current, the cluster alloy structure was revealed and the configurations of its isoenergetic cross-sections we re determined. It is shown that the mean cluster size is about 11 nm; the local field evaporation at the cluster surface energy varies up to 1.6 eV. The energy of structure imperfections at intercluster boundar ies is localized in a layer of 1.0 +/- 0.3 nm thickness. This means th at the topological and/or chemical order change in the vicinity of the intercluster boundary. The data obtained are in qualitative agreement with results of atom-probe investigations of metallic glasses and con firm the main statement of the polycluster model.