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.

ABSTRACT

Impact of rapid annealing on the soft magnetic properties of the Fe80Nb3Cu1Si6B10 alloy has been investigated. Parent as-quenched ribbons were prepared by planar flow casting method. Rapid thermal treatments (7-30s) has been conducted at 500°C using the preheated Cu blocks to ensure elevated heating rate of more than 100 K/s. Reference samples were isothermally annealed in the vacuum furnace for 1 h at the same temperature. X-Ray diffraction unveiled formation of nanocrystalline structure of bcc α-Fe(Si) grains, embedded in the residual amorphous matrix in all processed samples, irrespective of the annealing technique. Evolution of coercivity and saturation magnetization values, obtained from the measured hysteresis loops, showed improved magnetic softness of the rapidly annealed samples, compared to the as-quenched and conventionally processed ones. Significant embrittlement of the samples after nanocrystallization has been observed regardless of annealing time and thermal treatment technique used.