Preparation Of Fe-based Amorphous Nanocrystalline Alloy Soft Magnetic Materials By MA And SPS Technologies

With the rapid development of power electronics industry, Fe-based amorphousnanocrystalline alloy materials which have excellent soft magnetic properties is playing anincreasingly important role. Aimed at the defects and insufficiency existing in thetraditional preparation of Fe-based nanocrystalline materials, such as the preparation ofamorphous precursor is difficult, the best annealing heat treatment process is difficult todetermine, the three dimensional size of the material prepared limited and so on. In thisthesis, amorphous nanocrystalline soft magnetic powder prepared by mechanical alloying,bulk nanocrystalline soft magnetic materials prepared by spark plasma sintering.Two systems of soft magnetic powders Fe₇₄Cu₁M（M=Nb、Zr、Mo）₃Si₁₃B₉andFe₇₈Cu₁M（M=Nb、Mo）₃Si₉B₉prepared by mechanical alloying, To have SEM observationand XRD analysis for powders milled different times, researched the mechanical alloyingmechanism. The results showed that, alloying process consists of three stages; in theprocess of the ball milling, accompany with the decrease of grain size and increase ofinterplanar spacing; By adding different elements Nb, Zr, Mo and Ni, combining withDSC, VSM and relevant analysis methods, detailed study the influence of elementsubstitution for alloying mechanism and soft magnetic properties. The results showed that,the addition of Zr improved the formating ability of amorphous and alloying process, theaddition of Mo may delay the process; Ni partly replace the Fe of Fe₇₈Cu₁Mo₃Si₉B₉,athough increased its formating ability of amorphous, but its soft magnetic propertiesdeteriorated.Spark plasma sintered the Fe₇₄Cu₁Zr₃Si₁₃B₉amorphous and Fe₇₈Cu₁Mo₃Si₉B₉nanocrystalline alloy powders prepared by mechanical alloying, by adjusting differentsintering process, combining with correlation analysis and testing method, research theinfluence of different sintering process for organization of sintered body, microstructure,mechanical properties and magnetism properties, developed the best sintering process. Theresults showed that, the mechanical properties of sintered body determined by its densityand grain size, the main factors that influence the soft magnetic properties, consists theexchange coupling interaction among magnetic atoms, the grain size of sintered body, internal defects and so on; the soft magnetic properties of sintered body better than thepowder before sintered; bulk nanocrystalline material prepared by Fe₇₄Cu₁Zr₃Si₁₃B₉amorphous powders sintered under the sintering condition of500MPa pressure,590℃sintering temperature,60K/min heating rate and10min soaking time, with Vickershardness high to1252.15HV, compressive strength high to1800MPa, σshigh to158emu/g,Hc low to₃8.32Oe; Succeed in obtaining Fe₇₈Cu₁Mo₃Si₉B₉bulk nanocrystalline materialswhich have excellent mechanical and magnetic properties under high heating rate of100K/min, significantly improved sintering efficiency.