MAGNETIC-PROPERTIES OF COMPACTED ALLOY FE73.5CU1NB3SI13.5B9 IN AMORPHOUS AND NANOCRYSTALLINE STATE

The uniaxial cold and hot pressing and shock wave compaction were used to produce ring cores from amorphous Fe73.5Cu1Nb3Si13.5B9 powder and ribbon. The microstructure of the cores was checked by X-ray diffraction. No crystallization was found during compaction. The magnetic hysteresis loops of the cores were measured in as-compacted state and after various heat treatment. Coercive force H(c) and permeability mu(r) were determined as a function of annealing temperature between 400 and 650-degrees-C. Annealing to produce nanocrystalline state was found to improve magnetic properties considerably. The lowest H(c), about 10A/m and the highest mu(r), about 10(5) found for ribbon-compacted sample are close to those measured in the wound ribbon. The observed magnetic behaviour of the samples compacted in different ways is explained on the basis of stress and creep-induced anisotropies.