| Great attention of the scientific circle and industries to the amorphous and nanocrystalline metallic materials has been attracted all along becuase of their unique structure, effective preparation technics, excellent properties and wide outlook for application. In the past forty years, with the advancement of the essential research, preparation technics and product application, various amorphous metallic materials has been developing practically, and especially the application of the amorphous and nanocrystalline soft magnetic alloy ribbons in the electrical industry. Later, the giant magneto-impedance effect (GMI) was found in these materials. It supplies a new approach of exploiting magnetic sensors with high sensitivity, and has become a new research field. Hence, there is a great theoretical meaning and practical value to study the influence of microstructure and magneto-structure on the GMI effect in amorphous and nanocrystalline soft magnetic ribbons.In this paper, we have investigated the GMI effect in Fe73.5Cu1Nb3Si13.5B9 amorphous and nanocrystalline ribbons, the influence of annealing temperature on the materials' microstructure, the shape anisotropy of Fe-based alloy ribbons and its influence on the GMI effect. The main results are as follows:1. For FeCuNbSiB nanocrystalline ribbons, the characteristic of longitudinal driven giant magneto-impedance is investigated. It is found that, there are two characteristic frequencies fr0 and frmax, and according to the relation between them and driven ac current frequency, the formation of the curves of magneto-impedance ratio can be deduced. In the condition of ffrmax, the main factor influencing GMI effect is the soft magnetic properties of materials; while in the condition of fr0 |
