预存晶核型铁基纳米晶球形粉体的制备及软磁性能研究

铁基纳米晶粉芯具有比传统晶态合金磁粉芯、金属软磁合金和铁氧体更为优异的综合磁性能，但当前具有高饱和磁化强度（Ms）的铁基纳米晶球形粉体的结构和磁性能十分不稳定，只有采用高升温速率热处理才可获得优异软磁性能，较差的工艺性严重阻碍了其产业化。本项目拟以具有较低溶剂元素Fe（70-80at.%）和较高形核元素Cu含量（1.0-2.0at.%）的Fe-(Si,B,P,C)-Cu系合金为研究对象，采用气雾化法将其制备成含有α-Fe晶核的急冷态球形粉体，研究合金成分对急冷态粉体微观结构的影响规律，并从类金属元素和Cu及其协同作用影响富Cu团簇形成、α-Fe相异质形核和生长的角度阐明其机理；在此基础上优化合金成分，制备出可在较大粒径范围内含有高数密度α-Fe晶核的非晶态粉体，再采用低升温速率热处理将其制备成具有细微α-Fe晶粒、高Ms和优异软磁性能的纳米晶球形粉体。

Fe-based nanocrystalline powder cores show superior soft magnetic properties than conventional crystalline magnetic powder cores, soft magnetic alloys and ferrites, while the microstructure and soft magnetic properties of developed Fe-based nanocrystalline spherical powders with high saturation magnetization (Ms) are very unstable, and the excellent magnetic softness can only be obtained under a high heating rate, hence the poor manufacturability hinders their industrialization. The present project will select the Fe-(Si,B,P,C)-Cu alloy system with relatively low solvent Fe (70-80at.%) and high nucleation element Cu (1.0-2.0at.%) contents as the research objects, make them into amorphous spherical powders with α-Fe crystals by using gas atomization, and investigate the effects of alloy composition on the microstructure of the as-atomized powders and then illustrate the related mechanisms in terms of the synergistic effects between metalloid elements and Cu affecting the formation of Cu-enriched clusters, heterogeneous nucleation and growth of α-Fe phase; then optimize alloy composition on this basis, produce the amorphous powders containing α-Fe crystals with high number densities in a large size range, and then make them into nanocrystalline powders with fine α-Fe grains, high Ms and excellent soft magnetic properties by low heating rate annealing.