| In this thesis, a series of FeSiBCuP amorphous and nanocrystalline alloys are prepared by single-roller melt spinning method and subsequent crystallization using industrial raw materials. With Differential Scanning Calorimetry and X-ray Diffraction, the glass-forming ability (GFA), thermal stability, crystallization process and structure are investigated for amorphous and nanocrystalline alloys. In addition, the magnetic properties and brittleness of amorphous alloys and nanocrystalline alloys are studied. The effects of composition and heat treatment on the microstructure and properties of amorphous and nanocrystalline soft magnetic alloys are systematically investigated in order to obtain excellent magnetic materials with high Bs and low coercivity.It is found that the ratio of Si and B in Fe81SixB16-xCu1P2 (x = 2, 4, 8, 12) alloys has an effect on their structure and GFA. A uniform amorphous Fe81SixB16-xCu1P2 ribbons was obtained at x = 4 with higher GFA than others. The addition of Nb element is believed to be benefit to raise the crystallization temperature and to stabilize the amorphous structure. The addition of Nb has a significant effect on retarding the growth of theα-Fe(Si) nanocrystallities. The microstucture and properties of nanocrystalline alloys vary with the annealing process. The two phase structure containing amorphous and nanocrystalline phases can be obstained by crytallizing Fe-based amorphous alloys in the optimum annealing preocss, from which the average grain size ofα-Fe(Si) nanocrystallity was about 10nm. The rearrangement of atoms in thermodynamically metastable amorphous soft magnetic alloys is responsible for the brittleness in annealing process. The combination of ductility and excellent magnetic properties can be achieved by optimizing the annealing process. The optimal properties can be obtained in the Fe81Si4B12Cu1P2 nanocrystalline alloy annealled at 753K for 3min with a heating rate of 0.5K/s.
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