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Nanocrystallization and Soft Magnetic Properties of Fe-based Amorphous Alloy Annealed under Electric Field and Pressure

Author: ZhongHaiJian
Tutor: TangJianCheng
School: Nanchang University
Course: Materials Physics and Chemistry
Keywords: nucleation rate grain growth rate grain size volume fraction soft ferromagnetic properties
CLC: TG139.8
Type: Master's thesis
Year: 2009
Downloads: 44
Quote: 0
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Abstract


In recent years,extensive research on Fe-Zr-B-Cu nancrystalline soft magnetic materials（Nanoperm） has been carried out because of their excellent soft magnetic properties like a high saturation magnetization and a high permeability.Optimizing microstructures is an important physical metallurgy approach to improve soft ferromagnetic properties.In this paper,the effects of electric field and hot isothermal pressing on the nanocrystallization and soft magnetic properties of nanocrystalline Fe86Zr7B6Cu1 alloy were studied by X-ray diffraction（XRD） and HP4284A impedance analyzer.Electric field has apparent influences on the nanocrystallization and soft magnetism properties of nanocrystalline Fe86Zr7B6Cu1 alloy.With the increase of the amplitude of electric field from 0 to 106V/m,the grain size of crystallineα-Fe phase increases from 13.4 to 18.5nm.The volume fraction of crystallineα-Fe phase increases from 64.6%to 73.8%with increasing the amplitude of electric field from 0 to 104V/m and then decreases with its further increase.Nanocrystalline Fe86Zr7B6Cu1 alloy with an initial permeability of 1.9×104 and a relaxation frequency of 1.8×105 Hz is formed after annealing at 600℃for 0.5h in the presence of an alternating current electric field.However,the initial permeability and relaxation frequency of the sample annealed at 600℃for lh in the absence of electric field are 1.2×104and 2.5×105 Hz,respectively.The nanocrystallization of amorphous Fe86Zr7B6Cu1 alloy is promoted by electric field because the crystal growth rate of crystallineα-Fe phase increases with the increase of the amplitude of electric field and the nucleus rate increases with its increase from 0 to 104V/m and then decreases with its further increase.Hot isothermal pressing results in the improvement of the microstructures of nanocrystalline Fe86Zr7B6Cu1 alloy and the increase of its soft magnetic properties. The grain size of crystallineα-Fe phase decreases from 13.4 to 7.6nm with increasing pressure from 0 to 150MPa.The volume fraction of crystallineα-Fe phase increases from 64.6%to 72.4%with increasing pressure from 0 to 100MPa and then decreases to 70.4%with increasing pressure to 150 MPa.With the increase of pressure from 0 to 150 MPa,the initial permeability increases from 1.2?104 to 6.4?104 and the relaxation frequency decreases from 2.5?105 Hz to 5.0?104 Hz.Hot isothermal pressing results in the improvement of the microstructures of nanocrystalline Fe86Zr7B6Cu1 alloy because the crystal growth rate of crystalline a-Fe phase decreases with the increase of pressure and the nucleus rate increases with its increase from 0 to 100MPa and then decreases with its further increase.

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CLC: > Industrial Technology > Metallurgy and Metal Craft > Metallurgy and Heat Treatment > The alloy learn with a variety of properties of alloys > Other special nature of the alloy > Amorphous alloy
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