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

Abstract

( Fe 50 Co 50)73.5 Cu 1 Nb 3 Si 13.5 B 9 amorphous ribbons, a type of Co doped Finemet alloy, were prepared by melt-spinning and annealed at 440–560°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 ( Fe 50 Co 50)73.5 Cu 1 Nb 3 Si 13.5 B 9 and Finemet ribbons were tested by an alternating current soft magnetic properties measurement system. A comparative study of frequency dispersion properties between ( Fe 50 Co 50)73.5 Cu 1 Nb 3 Si 13.5 B 9 and Finemet was conducted. Results indicate that the optimal magnetic property has been achieved when ( Fe 50 Co 50)73.5 Cu 1 Nb 3 Si 13.5 B 9 ribbons were annealed at the temperature range of 480°C–520°C, after which the grain size became between 10 nm and 20 nm. Although the permeability of ( Fe 50 Co 50)73.5 Cu 1 Nb 3 Si 13.5 B 9 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.