The Crystallization Kinetics And Magnetic Properties Of Co-finemet Type Alloy

In1988, Yoshizawa invented the Finemet alloy and wide spreaded for its high saturationmagnetic density and low coercivity. With the continuous development of technology, newrequirements are proposed. On the basis of previous studies, the fabrication and magneticproperties of Finemet alloy are studied.The nano-crystallization kinetics of Fe_73.5-xCo_xSi_13.5B₉Cu₁Nb₃（x=10，30，50） amorphousribbons were investigated. It was found that the activation energies of the first crystallizationreduce and the second crystallization rise with increasing Co content calculated by usingKissinger and Ozawa methods.The soft magnetic cores of Co10-Finemet are prepared by insulation coating and coldmolding. Investigations indicate that the optimum process parameters of nanocrystallinemagnetic powder core are listed as follows:355⁸00μm,3%insulation,174kN pressure, andannealing under100℃for11h. The effective permeability μeis56Gs/Oe in frequency of1kHz and it’s39Gs/Oe in frequency of5MHz, the quality factor Q first increases to35at250kHz and then decreases with increasing frequency.In order to increase the high-frenquency magnetic properties, the content of alloy andannealing are studied. By compared, we can know that the increase of Co content and induce ofB content are good for the magnetic properties. After annealed in transverse magnetic field, thehysteresis loop becomes narrow and Br is significantly lower, the stability of permeability withfrequency is increased.