Advances in Nanocrystalline Soft Magnetic Materials for Smart Applications

Dear Colleagues,

Nanocrystalline Soft Magnetic Materials (NSMMs) are a class of materials characterized by their small grain sizes and excellent magnetic properties, making them ideal for various applications in electronics and power systems.

NSMMs often consist of alloys like Fe-Si-B, Fe-Ni, Fe-Co, and other transition metals combined with elements like Nb or Cu to stabilize the nanocrystalline structure. Typically, the grain size in nanocrystalline materials is below 100 nm. This fine grain structure significantly affects their magnetic properties. These materials are usually produced by rapidly cooling a molten alloy to form an amorphous structure, which is then partially crystallized through controlled annealing to form the nanocrystalline phase.

NSMMs exhibit the following:

- Special magnetic properties like low coercivity and high saturation magnetization and permeability aid in their easy magnetization and demagnetization, making them suitable for transformer cores and inductors. Research has focused on optimizing the alloy composition and heat treatment processes to further enhance the magnetic permeability and saturation magnetization of nanocrystalline materials. For example, the addition of small amounts of elements like Cu, Nb, and Mo has been shown to refine grain size and improve magnetic properties. Fe-based amorphous and nanocrystalline alloys: new compositions like Fe-Si-B-P-Cu and Fe-Co-Zr-B have been investigated in recent years for their superior magnetic properties and thermal stability. These new alloys aim to combine high permeability and low coercivity with good thermal stability.

- Low core losses due to their small grain size make them energy efficient at high frequencies. Advanced annealing techniques, such as step annealing and magnetic field-assisted annealing, have been developed to control the microstructure more precisely. This results in lower hysteresis and eddy current losses, which are crucial for high-frequency applications. Incorporating non-metallic elements such as nitrogen and carbon has been explored to improve the grain boundary characteristics and further reduce magnetic losses.

The ongoing advancements in nanocrystalline soft magnetic materials continue to push the boundaries of their applications, offering new opportunities for innovation in various industries.

Dr. Gabriel Ababei
Guest Editor

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• nanostructure
• low coercivity
• high-saturation magnetization
• shielding application
• rapid cooling