Magnetic Study And Application Of Fe-based Amorphous Alloy And Nanocrystal

In this paper, the glass-forming ability, thermal stability, preparation for amorphous alloy, preparation for nanocrystal alloy and nanocrystal formation process were investigated for Fe-Co-B-Si-Nb and Fe-Zr-B alloy systems. With the method of devitrification by making amorphous alloy isothermal annealing, composite material with nanocrystal distributed uniformly in the matrix of bulk amorphous alloy was obtained. The magnetic properties and the work characteristics of the sensor and the mutual inductance device of amorphous alloy and nanocrystal alloy were measured and researched.The main researched work for the dissertation was focused on the following aspects: â‘  Preparation for metallic glass. Amorphous alloy ribbon with width of 2 mm and thickness of 40μm for Fe₈₈Zr₈B₄ was obtained by the method of melt-spinning; Amorphous alloy Fe₃₆Co₃₆B₂₀Si₄Nb₄ with diameter of 2 mm in the shape of rod was obtained by the method of copper mould injection casting; Amorphous alloy Fe₃₆Co₃₆B₂₀Si₄Nb₄ with inside diameter of 3 mm and outside diameter of 4 mm in the shape of pipe was obtained by the method of copper mould sucking casting. The copper mould sucking casting technique appears to eliminate the limitation for the size in axial direction of the glassy tube, which makes it true to produce Fe-based magnetic glassy ring with large thickness. â‘¡ Preparation for nanocrystal alloy. Based on the method of devitrification by annealing metallic glass, Amorphous alloy Fe₃₆Co₃₆B₂₀Si₄Nb₄ was made isothermal annealing for temperature being 580℃ and 660℃ and time at maximum temperature being 60min, 120min, 180min, 240min and 300min, composite materials with nanocrystal distributed uniformly in the matrix of bulk amorphous alloy was obtained. The advantage of devitrification by annealing amorphous alloy method is that cost is low, output is large, interface is clean and dense, crystal grain is easy to control and this method is helpful to research nanocrystal formation mechanism and verifies the applied possibility of formation and growth of classical crystal grain in the condition of quick solidification. (3) structure and property analysis. With Differential Scanning Calorimetry(DSC),X-ray Diffraction (XRD) and Transmission Electron...