Preparation And Magnetic Properties Of Fe-based As-quenched Nanocrystalline Thin Bands

With the rapid development of the worldwide science and technology, metal soft magnetic materials have played a fundamental role in the process of the world's industrialization and informationize. They have been exploited and used more extensively.In the late 1980s, Yoshizawa et al. in Hitachi Metal Laboratory of Japan invented the Fe-based nanocrystalline soft magnetic materials. They found that the nanocrystalline soft magnetic materials (Trade names:FINEMET) could be formed when they doped Cu and Nb into FeSiB alloy and annealed. Such material has been used extensively. Japanese scientist Suzuki et al. found Fe-M-B (M=Zr, Hf, Nb) alloys have excellent soft magnetic properties.With the rapid development of the worldwide science and technology, metal soft magnetic materials have played a fundamental role in the process of the world's industrialization and informationize. At present, Fe-Cu-Nb-Si-B nanocrystalline soft magnetic material has been produced in industry and used extensively in a mass of fields such as zero sequence current transformer of frame leakage protection, primary power inverter of Switching Power Supply, high pressure-insulate-pulse-transformers, special sensors, filtering inductance components, weak magnetism sensors, module in BL sensors, high-speed magnetic core of Hall Current Sensors, iron cores in medium high frequency high power CD-type transformers, inverter welding, inverter plasma cutting machine, power inverter in armored vehicles, direct-current power supply in naval vessels, power supply in ultrasonic disruptors, Uninterrupted Power Supply (UPS), power supply in X-ray apparatus and so on. In the year 2000, the output of soft magnetic materials has reach to 300t in our country and it was 600t in 2002. At present, the production line of nanocrystalline was built in our country and its product could reach to 500t, which is the third of world.Fe-Cu-Nb-Si-B nanocrystalline soft magnetic material was found by Yoshizawa in Hitachi Metal Laboratory of Japan and Fe-(Zr, Nb)-B was found in Tohoku University. Although Fe-Cu-Nb-Si-B nanocrystalline soft magnetic material has been produced on a large scale, our country has been suffering restriction in the intellectual property and patents from Japan. Therefore, it is urgent and necessary for us to investigate new type nanocrystalline soft magnetic materials. This thesis mainly studies the preparation and soft magnetic properties of nanocrystalline soft magnetic materials. We found that the nanocrystalline could be formed without annealing under some special formulas such as Fe-Nb-B serials. Fe-Nb-B non-crystalline material has been produced from now on and the patent was hold by America. We studied the Fe-Si-B-Cu rapid annealing nanocrystalline materials. The nanocrystalline was formed by the nucleation effect of Cu atoms. We found that the intensity of magnetization was increased and the magnetostriction constant was decreased. Such material has utility in some fields. This thesis has strong innovativeness.At present, there are still some defects in the investigation on the Fe-based nanocrystalline soft magnetic materials. Crystallization of the Fe-based nanocrystalline soft magnetic materials was always achieved by annealing, e.g. We found that nanocrystalline soft magnetic materials could be prepared without annealing process only by changing Cu content and adjusting the rate of rapid annealing. It could not only save cost of experiment, but also simplify the preparing process. This thesis mainly investigates on the aspects as following:1. The Fe78-xSi9B13Cux(x=0,1,2,3,3.5,4)nanocrystalline thin band was prepared directly by rapid-annealing spin-band method through modifying the Cu content and controlling the rate of rapid annealing properly. Crystallization process was achieved without any follow-up annealing. The Fe nanocrystalline grains were dissolved out from the thin band and could be found by X-ray diffraction pattern. The average sides of grains were about 20-40nm in the thin band. The saturation magnetization, magnetostriction constant, initial permeability and magneto resistive was measured related to the Cu content and its corresponding diagram was obtained.2. The Fe77.5_xSi13.5B9Cux(x=0,1,2.5) nanocrystalline rapid annealing thin band was prepared and studied, Theα-Fe(Si) nanocrystalline grains were dissolved out from the thin band and could be found by X-ray diffraction pattern.3. The Fe85-xNb6.8B7.7Cux(x=0,1,3)nanocrystalline thin band was prepared directly by rapid-annealing spin-band method without the follow-up annealing. The Fe nanocrystalline grains were dissolved out from the thin band and could be found by X-ray diffraction pattern. The sides of grains were about 13-23nm.The resistance, electrical inductance under different external magnetic field and frequency of drive current was measured. The rate of change of the impedance verses the intensity of the magnetic field was obtained through calculating the rate of change of the impedance. The magneto-resistor and inductance versus the frequency of the alternating current (AC) drives of the rapid-annealing thin band was also studied.4. Through analyzing the structures of the rapid-annealing nanocrystalline thin bands, we found that Cu content had the function of lavigating the grains of the rapid-annealing nanocrystalline thin bands. Cu element could promote nucleus formation of theα-Fe and a-Fe(Si) grains and increase the Volume fraction of them. With the excessive Cu content, Cu atoms could reduce the effective positions ofα-Fe(Si) in the process of nucleus formation. The appearance of FeB phase decreased the soft magnetic properties of the two rapid-annealing nanocrystalline thin bands. We obtained the best Cu content of the two rapid-annealing nanocrystalline thin bands in experimentA...