Optimisation of the Magnetic Properties of Amorphous Powder Cores by Consolidating at High Pressures

Amorphous soft magnetic composites (SMCs) are characterised by low-volume fraction of magnetic material and therefore, poor magnetic permeability and saturation magnetisation. In this work, amorphous powder (Fe0.425 Co0.30 Si0.125 B0.15)96.5Nb3Cu0.5) is coated with 10 and 15 vol.% of resin and consolidated at high pressures (up to 2 GPa). Maximisation of particles packaging is obtained by mixing fractions of 0-10 µm and 20-45 µm in a volume ratio of 27:73 vol.%, respectively. Magnetic properties and power losses of SMCs made from 0-10 µm fraction and from the mixed fractions are compared. SMCs made from mixed fractions result in higher permeability but increased power losses. Low power losses (Pcv = 5850 mW/cm3 at f = 1 MHz, B = 50 mT), highest permeability (µ’ = 43.4) and highest saturation magnetisation (Ms = 0.82 T) are obtained with the SMC made from the mixed fractions after annealing and subsequent resin infiltration.