New FeNbB based bulk amorphous and nanocomposite soft magnets for applications

The preparation and magnetic characterization over a wide frequency range of (Fe, Co, Ni)₇₀Nb₁₀B₂₀ bulk amorphous and nanocomposite alloys are presented. Master alloys each prepared by induction melting in high vacuum were used to cast toroids, discs and bars by Cu mould casting method. X-ray diffraction and differential scanning calorimetry measurements show that the samples are either fully amorphous or consists of very fine nanoparticles embedded within the amorphous matrix. AC magnetic permeability of the samples were measured by using an AC-fluxmetric method in fields up to 1 kA/m. Curie temperature and thermomagnetic behavior were determined through a vibrating sample magnetometer.