铁基纳米晶合金的动态微观磁结构调控及对高频损耗特性的影响研究

Fe-based nanocrystalline alloys have a broad range of applications in the field of high-frequency power electronics due to their excellent soft magnetic properties, such as high permeability, high resistivity, low coercivity, low loss and low magnetostriction. However, these alloys exist some problems as annealing embrittlement and stress sensitivity. In addition, the studies on the microscopic mechanism of the magnetic losses in nanocrystalline alloys are usually affected by the stress sensitivity. Therefore, the correlation between magnetic microstructure and magnetic losses in nanocrystalline alloys without influence of stress remain unclear so far. This project aims to modify the magnetic anisotropy of the FeSiBNbCu amorphous alloys by heat treatment. The influence of magnetic anisotropy on magnetic microstructure and magnetic losses will then be investigated. Furthermore, the effect of dynamic magnetic microstructure on magnetic losses will be studied in situ heat treatment processes. The relationship between magnetic domain structure, magnetic relaxation behavior and magnetic losses in the nanocrystalline alloy will be established. Finally, the influence mechanism of the magnetic microstructure on magnetic losses without the influence of stress will be elucidated. In conclusion, our project is expected to provide a new insight into improvement of high-frequency magnetic losses in Fe-based nanocrystalline alloys.

铁基纳米晶合金具有高磁导率、高电阻率、低矫顽力、低损耗和低磁致伸缩系数等优点，在高频电力电子领域有着广阔的应用前景。但是此类合金存在退火脆化和应力敏感等问题。目前有关纳米晶合金的磁损耗的微观机理研究无法消除应力的影响，其无应力影响下与微观磁结构的关联性和调控机制尚不清楚。因此，本项目以新开发的FeSiBNbCu非晶合金作为研究对象，拟通过热处理调控纳米晶合金的磁各向异性，研究磁各向异性对微观磁结构和磁损耗特性的影响规律。原位热处理过程中研究动态微观磁结构对磁损耗特性的影响规律，通过模型建立，分析热处理参数、磁畴结构、磁弛豫行为与磁损耗的关联，阐明无应力影响下铁基非晶合金的微观磁结构对磁损耗特性的影响机制，从而为纳米晶合金的高频磁损耗调控提供新思路。

高磁感Fe基纳米晶软磁合金有利于磁元件的高功率化和小型化，在大功率电力电子器件中具有良好的应用前景。然而高磁感纳米晶合金的磁损耗随频率剧增，且其微观磁结构与高频磁损耗之间的关联机制并不明晰。本项目选用高磁感合金，通过原位表征磁畴结构及演变规律, 发现磁场诱导随机磁晶与单轴双各向异性可细化磁畴，阻碍高频下畴壁运动。通过建立热处理、微观结构、磁各向异性常数、磁畴结构与磁损耗特性的相互关机制，从动态微观磁结构和磁各向异性角度解析了影响磁损耗的关键因素，并提出了磁场热处理诱导随机磁晶与单轴相竞争的双各向异性降低磁损耗的方法。此外还通过原位升温分析了纳米晶粒形核长大规律。上述研究结果为纳米晶合金的高频磁损耗调控提供了新思路。