Magnetic Properties and Applications of Soft Magnetic Alloys

Soft magnetic alloys exhibit extremely low coercivity and high permeability, enabling efficient magnetisation reversal with minimal hysteresis and eddy-current losses. Characteristically composed of Fe-based amorphous and nanocrystalline systems, these materials leverage ultrafine microstructures to achieve narrow domain walls, reduced anisotropy and enhanced saturation magnetisation. Nanocrystalline alloys, produced via controlled annealing of amorphous precursors, present grain sizes below the magnetic exchange length, which suppresses anisotropic contributions and further lowers core loss. Applications span power transformers, high-frequency inductors, electrical motors and emerging energy-efficient devices in renewable energy and electric vehicle technologies. Key parameters such as magnetostriction, thermal stability and electrical resistivity are tailored through compositional design—incorporating metalloids like boron, silicon and phosphorus and minor additions of copper or niobium—to balance ductility, magnetic softness and operational frequency response. Advances in modelling of magnetisation dynamics and magnetoelastic coupling underpin the rational design of next-generation soft magnets. These developments collectively aim to reduce global energy consumption by optimising core components in power conversion and electro-mechanical systems.

Research from Nature Portfolio

Recent studies have elucidated the influence of elemental substitution on the formation and growth of nanocrystalline phases in Fe-based soft magnets. By systematically varying silicon and phosphorus contents in melt-spun amorphous precursors, researchers demonstrated control over nucleation site density and grain coarsening, achieving exceptionally low coercivity while retaining thermal stability of the amorphous matrix. Another foundational investigation employed first-principles and molecular-dynamics simulations to reveal how local atomic packing and p–d orbital hybridisation govern saturation magnetisation in Fe–Si–B–P metallic glasses, providing theoretical guidance for designing soft-magnetic metallic glasses with high flux density.

Magnetic Properties and Applications of Soft Magnetic Alloys publication trend

The graph below shows the total number of articles in magnetic properties and applications of soft magnetic alloys across all publications each year (not limited to Nature Index journals).

Technical terms

Coercivity (Hc): The intensity of the reverse magnetic field required to reduce magnetisation to zero.

Saturation magnetisation (Ms): The maximum magnetisation achieved when all magnetic domains are fully aligned.

Permeability (μ): The measure of how easily a material supports the formation of a magnetic field within itself.

Hysteresis loss: Energy dissipated as heat during cyclic magnetisation due to irreversible domain realignment.

Magnetostriction: The dimensional change of a ferromagnetic material under magnetisation, leading to coupling between magnetic and elastic energies.

Nanocrystalline alloy: A material containing nanoscale grains, typically below 20 nm, which reduces magnetocrystalline anisotropy and core loss.

References

1. Formulation of energy loss due to magnetostriction to design ultraefficient soft magnets. NPG Asia Materials (2024).
2. Local structure, nucleation sites and crystallization behavior and their effects on magnetic properties of Fe81SixB10P8−xCu1 (x = 0~8). Scientific Reports (2018).
3. Structural, magnetic, and electronic properties of Fe82Si4B10P4 metallic glass. Scientific Reports (2018).