STRUCTURE AND MAGNETIC PROPERTIES OF NANOCRYSTALLINE (Fe50Co50)73.5Cu1Nb3Si13.5B9 ALLOYS

(Fe50Co50)(73.5)Cu1Nb3Si13.5B9 amorphous ribbons, a type of Co doped Finemet alloy, were prepared by melt-spinning and annealed at 440-560 degrees C for 30 min. Influences of heat treatment and Co content on the crystallization were analyzed through differential scanning calorimetric (DSC) and X-ray diffractometry (XRD). The microstructure was analyzed by atomic force microscopy (AFM). The magnetic properties of (Fe50Co50)(73.5)Cu1Nb3Si13.5B9 and Finemet ribbons were tested by an alternating current soft magnetic properties measurement system. A comparative study of frequency dispersion properties between (Fe50Co50)(73.5)Cu1Nb3Si13.5B9 and Finemet was conducted. Results indicate that the optimal magnetic property has been achieved when (Fe50Co50)(73.5)Cu1Nb3Si13.5B9 ribbons were annealed at the temperature range of 480 degrees C-520 degrees C, after which the grain size became between 10 nm and 20 nm. Although the permeability of (Fe50Co50)(73.5)Cu1Nb3Si13.5B9 is not as high as that of Finemet, this Co-doped Finemet amorphous alloy presents better high frequency properties, and therefore is a promising candidate for the high frequency field applications.