Soft Magnetic Composites Based on Nanocrystalline Mechanically Alloyed Fe-Ni Powders

摘要

Nanocrystalline soft magnetic composite (SMC) materials based on nanocrystalline Ni-Fe powders and dielectric were produced. Nanocrystalline Ni3Fe powder and a (Ni3Fe + Fe) mixture were used as ferromagnetic powders. Nanocrystalline Ni3Fe powder (17 nm nanocrystallites) has been obtained by mechanical alloying and subsequent annealing. As dielectric binder an epoxy resin was used. SMC materials have been produced by covering the nanocrystalline particles with the dielectric polymer binder, then compacted into toroidal shape and finally polymerized. The magnetic properties (initial and complex permeability, flux density, the frequency dependence of the permeability and losses in the range 1 to 100 kHz) and electrical resistivity were studied in correlation with the dielectric content, tores density and ferromagnetic powder type. A long annealing (120 hours) at 170 °C in Ar atmosphere shows an improvement of the magnetic properties. The magnetic and electrical properties for different soft magnetic composites are discussed.