Li Deren

Fabrication and Magnetic Properties of A New Fe-based Amorphous Compound Powder Cores

A new Fe-based amorphous compound powder was prepared from Fe-Si-B amorphous powder by crushing amorphous ribbons as the first magnetic component and Fe-Cr-Mo metallic glassy powder by water atomization as the second magnetic component. Subsequently by adding organic and inorganic binders to the compound powder and cold pressing, the new Fe-based amorphous compound powder cores were fabricated. This new Fe-based amorphous compound powder cores combine the superior DC-Bias properties and the excellent core loss. The core loss of 500 ㎾/㎥ at B m = 0.1T and f = 100 ㎑ was obtained When the mass ratio of FeSiB/FeCrMo equals 3:2, and meanwhile the DC-bias properties of the new Fe-based amorphous compound powder cores just decreased by 10% compared with that of the FeSiB powder cores. In addition, with the increasing of the content of the FeCrMo metallic glassy powder, the core loss tends to decrease.

Giant Stress-Impedance Effect in Amorphous and High-Current-Density Electropulsing Annealed Fe73.5Cu1Nb3Si13.5B9 Ribbons

The stress-impedance (SI) effect has been observed in as-cast and high-current-density electropulsing annealed Fe73.5Cu1- Nb3Si13.5B9 ribbons. Large SI ratios of -35% and 25% have been obtained in high-current-density electropulsing annealed samples but not in as-cast samples. The SI effect changes drastically with the density of the annealing current and the longitudinally applied stress during the annealing process. The effective permeability has been shown to be responsible for the SI effect.

Effect of Copper and Niobium Addition on Crystallization Kinetics in Fe-Cu-Nb-Si-B Alloys

Abstract The activation energies of amorphous Fe78Si11B9 and nanocrystalline Fe73.5Cu1B7Si15.5Nb3 alloys were tested by a high-sensitivity differential scanning calorimeter with different heating rates. Kissinger equation was adopted to calculate the activation energies of the primary phase of Fe73.5Cu1B7Si15.5Nb3 alloy (295±5) kJ and the crystal phase of Fe78Si11B9 alloy (370±3) kJ. The low activation energy of the primary phase for Fe73.5Cu1B7Si15.5Nb3 alloy is related to the precipitation of Cu clusters. The precipitation kinetics of Cu clusters was analyzed. The calculated result of the mean radius Rm of Cu cluster is 3 nm after aging for 3600 s at 773 K in Fe73.5Cu1B7Si15.5Nb3 glass alloy and the maximum value of number density is 3.7 ×1024 /m3 after aging for 2.5 h at 773 K, which accords with K. Honos observation (approximately 3 nm after annealing at 673 K or 3600 s). The density of Cu is in the order of 1024 m−3).

Magnetoelastic Anisotropy of FeSiB Glass-Coated Amorphous Microwires

The magnetoelastic anisotropy of Fe77.5Si7.5B15 glass-coated amorphous microwires is investigated by the law of approach to saturation magnetization in comparison with the ferromagnetic resonance technique. The anisotropy field of the inner core determined by the former method is 7.6 × 104 A/m, which is larger than the value 2.5 × 104 A/m measured by the ferromagnetic resonance method. This difference is ascribed to the skin effect and the uneven distribution of the internal stresses. However, the anisotropy field of the outer shell has a negative value indicating that it has an easy basal plane.

Noise Suppression Effect of Composites Containing Glass-Covered Amorphous CoFeSiBCr Wires

The noise suppression effect and its mechanism are investigated for a composite sheet and a composite film made of glass-covered amorphous CoFeSiBCr wires. Both samples show a significant noise suppression effect. The power loss ratio of the composite sheet is above 80% from 1.6 GHz to 8.5 GHz, and that of the composite film is above 70% from 3.2 GHz to 8.5 GHz even if its thickness is only 0.20 mm. The composite sheet demonstrates high real and imaginary permittivity above 30.7 and low real and imaginary permeability below 1.2. The surface resistivities of the two composite samples are as high as about 3×1012Ω/square. The power loss of the composite containing glass-covered wires should be mainly contributed by dielectric loss derived from electronic polarization and relaxation.

Domain Structure and Magnetization Process in Short Glass-Coated Amorphous Microwires with Positive Magnetostriction

The domain structure and magnetisation process in short glass-coated amorphous Fe45Co20Ni10Si9B16 microwires are investigated by analyzing the hysteresis loops measured by a vibrating sample magnetometer. Methods of calculating the thickness of the outer shell and the critical length to observe magnetic bistability have been established. The thickness of the outer shell is 2.3 μm and the critical length is 8.11 mm for a microwire with a metallic core diameter of 31.1 μm and a glass coat thickness of 10.6 μm. The experimental results demonstrate the reliability of this method to calculate the critical length.

Effects of Sulphurization Temperature on Cuins2 Film Properties

CuInS2 films were synthesized by sulphurization of electrodepositing Cu-In precusor films and investigated the effect of sulphurization temperature on the properties of CIS films. Scanning electron microscopy and energy dispersive spectrometer were used to observe the surface morphologies and to determine the compositions of the CIS films.The structural analysis is performed using X-ray diffraction.The result shows that all the films are strongly oriented to the (112) plane and some peaks which can be assigned to CuS are observed. Regarding the Cu-In-S ternary phase diagram and Rudiger’s work, the CuInS2 growth is diffusion-limited.