Design and preparation of new soft magnetic bulk amorphous alloys for applications

摘要

This work is focussed on our recent results on the preparation and frequency dependence (5 Hz-10 MHz) characterisation of new bulk amorphous alloys with large supercooled liquid region and good soft magnetic properties in (Fe, Co, Ni)_(70)M_(10)B_(20) (M = Zr, Nb, Ti, Ta) multicomponent systems. Melt-spinning, suction casting and Cu-mould casting methods were used to prepare 2-6 mm wide and 20-200 μm thick amorphous ribbons, as well as rods and ring-shaped samples with diameters and heights no larger than 3 mm, respectively. Electrical resistivity ((180-230) x 10~(-8) Ω m) and magnetic properties such as coercive field (H_c < 6 A/m), magnetic permeability (up to 3 x 10~4, depending on composition), saturation magnetisation (μ_0M_s ～ 1-2 T), Curie temperature (T_C about 600 K) and core losses were determined. The influence of the preparation conditions, composition and thermal or thermomagnetic treatments on the magnetic properties and electrical resistivity in the as-cast state is discussed in detail. The results are used to design new applications of bulk amorphous alloys with soft magnetic properties.