Fe-Co-B-Si-Nb-C glassy alloy with the addition of C was prepared by arc melting and copper suck-casting. The thermodynamics and soft magnetic properties were investigated. The casted amorphous alloys were heat-treated at different temperatures. The differential scanning calorimeter （DSC） results and thermal expansion show complete thermodynamics of crystallization. Its magnetostriction properties were studied by capacitance method. Saturation magnetostriction increases to 38×10^-6. The amorphous alloy exhibits good soft magnetic properties with low coercivity and high saturation magnetic induction. The results show that minor addition of C is beneficial to enhance the saturation magnetostriction λs, and do not deteriorate the ability of forming amorphous.
Amorphous Fe62-x Ni19CoxCu0.1 Si3.8B14Cr1. 1 （x=0, 1, 5, 10） ribbons were annealed under magnetic field and tensile stress, respectively, and their magnetic properties were investigated. Fe73.5 Cu1 Nb3 Si15.5 B7 and Fe66 Ni10- Cu1 Nb3Si11 B9 nanocrystalline alloy ribbons were also fabricated for comparison. Excellent DC tolerant property was obtained in the amorphous FeNiCoCuSiBCr ribbons after thermomagnetic treatment and the constant permeable property was improved with increasing Co content. The relative permeability was constant up to the DC bias field of approximately 6 ×10 ^-4 , 9 ×10 ^-4, and 10 × 10^-4 T and the values of relative permeability μ were 1 650, 1 200, and 1 000 with the Co content being 0, 5 at. %, and 10 at.%, respectively. Besides, stress-annealed FeNiCoCuSiBCr al- loy ribbons were proved to exhibit positive saturation magnetostriction constant λs.
The FeSiBC amorphous powder cores were fabricated using powders of the FeSiBC amorphous ribbons which were mechanically crushed for a short time, and the relationship between magnetic properties and powder particle sizes was evaluated. The saturation magnetization Bs of the amorphous Fe82Si2B15C1 alloy was 1.62 T, which provided a superior dc-bias property for the powder cores. Meanwhile, a stable permeability up to high frequency range over 10 MHz and the low core loss of 400 kW/ma at f=50 kHz and Bm =0.1 T were obtained. These excellent high-frequency magnetic properties of the FeSiBC amorphous powder cores could be attributed to the effective electrical insulation between the FeSiBC amorphous powders made by mechanical crushing.
Chun-bo HUANGTian-cheng LIUXiang-yue WANGCao-wei LUDe-ren LIZhi-chao LU
