The continuing interest in development of new soft magnetic alloys is driven by industrial need to enhance the performance of electrical power generation/distribution devices and various energy conversion and sensor systems. In this work we report on development of Fe-Co-B-(P)-Cu melt-spun alloys with high magnetic flux density, where the beneficial effects of a heat treatment under magnetic field are discussed in terms of the improved magnetic softness and the possibility to tune the application-oriented properties. Soft magnetic FeNi-and FeCo-based amorphous and nanocrystalline alloys attract a considerable attention for various magnetic sensors. Examples of our recent work on the utilization of both longitudinal and transverse magnetic field annealing for tuning of giant magnetoimpedance (GMI) response in these alloys are briefly presented. The last part of this paper is devoted to search for magnetic materials with suitable magnetocaloric properties for magnetic refrigeration technology. We report on the beneficial effect of a partial cobalt substitution for iron on the magnetic entropy characteristics and the enhancement of refrigerant capacity in GdFe(Co)Al-based alloys.

The inuence of the magnetic eld annealing on the magnetoimpedance eect has been investigated in rapidly quenched (Fe0.5Ni0.5)78Nb7B15 monolayer and bilayer thin ribbons. The highest impedance ratio value (∆Z/Z)max = 72% and the maximum eld sensitivity ηmax = 12 %/Oe was obtained in the bilayer ribbon, annealed under longitudinal magnetic eld at 773 K that exhibited nanocrystalline structure. The higher values of (∆Z/Z)max in bilayer ribbons, as compared to their monolayer counterparts, are attributed to the increased ratio of their thickness to the penetration depth.

ABSTRACT

Amorphous bilayers consisting of Fe-Si-B and Co-Si-B layers have been prepared by planar ow casting from a single crucible using a double-nozzle technique. Temperature dependencies of magnetization and hysteresis loops have been investigated in a wide temperature range. At room temperature, the eects of interlayer stresses, induced in material due to dierent thermal expansion coecients of two mechanically interconnected soft magnetic layers, resulted in rounded hysteresis loops with attened central part, indicating a dominant role of magnetization rotational processes. With an increase of measurement temperature, the interlayer stresses are relieved and the hysteresis loops became more squared.