Development trend of nanocrystalline soft magnetic materials

Nanocrystalline soft magnetic alloy refers to a soft magnetic alloy with nanocrystalline structure obtained by heat treatment on the basis of amorphous alloy, which has more excellent soft magnetic properties.



Compared with traditional silicon steel, ferrite, permalloy and other magnetic materials, the comprehensive performance of nanocrystalline soft magnetic materials has very obvious advantages. Due to the high magnetic permeability, high saturation magnetic induction and flexibility of nanocrystalline soft magnetic alloys It has gradually replaced traditional soft magnetic materials as a new generation of soft magnetic materials, and is widely used in the fields of electricity, electronics and information, and is a hot spot in the research and development of soft magnetic materials.


Nanocrystalline Soft Magnetic Alloy

In fact, reducing the magnetocrystalline anisotropy constant (K) is very important for obtaining excellent soft magnetic materials. The K of a polycrystal is basically determined by the composition of the soft magnetic material. For ordinary Fe-based polycrystalline materials with large grain size, it is very difficult to greatly improve the soft magnetic properties. However, refining the crystal grains to the nanometer scale can effectively reduce the magnetic anisotropy of the material and reduce Hc.


At present, the requirements for nanocrystalline soft magnetic materials used in electronic components such as choke coils and sensors are low Hc, flattened magnetization curves, difficulty in magnetic saturation, and low magnetic permeability. For this reason, the (Fe, Co, Ni)-Si-B-Nb-Cu alloy is developed, and the magnetic anisotropy is controlled by the magnetic field heat treatment method of the alloy, so that the initial specific magnetic permeability of the alloy is 300-5000. In addition, the Fe-Si-B-Nb-Cu alloy amorphous alloy ribbon is subjected to crystallization heat treatment while applying tension to induce magnetic anisotropy, so that the length direction of the ribbon becomes the hard axis of magnetization. The magnetic permeability is controlled in a large range to form nanocrystalline soft magnetic materials with different magnetic permeability. These low-permeability nanocrystalline soft magnetic materials are characterized by small hysteresis, which can suppress the decrease in magnetic permeability under the condition of higher frequency and magnetic field overlap, so they can be applied to DC superposition in high-frequency regions.


With the continuous expansion of the application field of nanocrystalline soft magnetic materials, the application requirements of small and light weight, miniaturization, high performance, high reliability and high environmental adaptability promote the miniaturization, miniaturization, chip and integration of electronic components. The direction of development, while the requirements for complex shape components are becoming increasingly urgent, the integration technology of magnetic functional devices has become a prominent highlight in the development of new electronic technologies in the contemporary era. In order to make good use of the excellent comprehensive magnetic properties of nanocrystalline soft magnetic materials, vigorously develop light Nanocrystalline soft magnetic materials with quantization, miniaturization, high performance, high reliability and complex shapes are imminent.


However, the technology for preparing nanocrystalline soft magnetic materials still needs to be improved, and the process still needs to be optimized. The problem with the original fine-grained nanocrystalline materials is that the suitable cooling conditions for making thin alloy ribbons are narrow. Rapid heating nanocrystalline materials cannot be heated rapidly during heat treatment of a large number of materials, and rapid crystallization causes heat to cause excessive temperature rise inside the material, resulting in the failure of the overall material to form fine nanocrystalline grain structures. The practical threshold for rapid heating nanocrystalline materials is very high. Due to the simple process, economy and good controllability of the mechanical alloying method, the preparation of high-quality nanocrystalline soft magnetic materials by the mechanical alloying method has great application prospects. However, the imperfection and instability of the preparation technology and the selection of preparation process parameters still lack a manipulable theoretical basis, and further research is needed to make it more mature.



The ultimate goal of the basic research and applied research of nanocrystalline soft magnetic materials is to develop nanocrystalline alloy materials into various magnetic devices required in the fields of electric power, electronics and information industries, so that material research can truly become the key to promoting social development. and play an important role in supporting economic development.