Influence of the Corrosion on the Surface Magnetic Properties in Amorphous and Nanocrystalline Materials

Abstract

In this review article recent studies about the corrosion and the influence of corrosion on the surface magnetic properties of amorphous and nanocrystalline magnetic ribbons are presented. The studies have been performed in Febased and Co-based amorphous ribbons, because these ribbons are used in different magnetic sensors. In the first case the investigation has been focused on the corrosion, the influence of corrosion in the surface magnetic properties and the influence of the nickel content on the electrochemical behaviour. The results show that in the amorphous samples, when the oxidized layer increases, the surface saturation magnetization decreases. However, in the nanocrystalline samples the surface saturation magnetization does not change significantly. The values of the surface coercive field for the oxidized and non oxidized samples with the same Ni content are practically the same. In the case of Co-based ribbons the study has been focused in the corrosion process and how the corrosion affects the magnetoimpedance response of the ribbons. The results indicate that FeCoCrSiB ribbons show an excellent corrosion stability and high magnetoimpedance response, meanwhile FeCoSiB ribbons show low corrosion resistance but high magnetoimpedance response. The relevant patents discussed in this article cover the areas connected with the application, magnetic behaviour and corrosion of amorphous and nanocrystalline materials. Keywords: Metallic glasses, nanocrystalline, corrosion, magnetic properties, biocorrosion, biosensors, magnetoimpedance