Magnetic properties of compacted alloy Fe/sub 73.5/Cu/sub 7/Nb/sub 3/Si/sub 13.5/B/sub 9/ in amorphous and nanocrystalline state

摘要

Uniaxial cold and hot pressing and shock wave compaction are used to produce ring cores from amorphous Fe/sub 73.5/Cu/sub 1/Nb/sub 3/Si/sub 13.5/B/sub 9/ powder and ribbon. The microstructure of the cores is checked by X-ray diffraction. No crystallization is found during compaction. The magnetic hysteresis loops of the cores are measured in as-compacted state and after various heat treatments. Coercive force H/sub c/ and permeability mu , are determined as a function of annealing temperature between 400 and 650 degrees C. Annealing to produce a nanocrystalline state is found to improve magnetic properties considerably. The lowest H/sub c/ (about 10 A/m) and the highest mu (about 10/sup 5/) found for a ribbon-compacted sample are close to those measured in the wound ribbon. The observed magnetic behavior of the samples compacted in different ways is explained on the basis of stress and creep-induced anisotropies.