Soft magnetic materials are characterized by their low coercivity, high permeability, and low hysteresis loss, making them easily magnetized and demagnetized. They are widely used in electrical and electronic applications where efficient magnetic flux variation is required. The main types of soft magnetic materials include:
1. Pure Iron & Low-Carbon Steel
High permeability and saturation flux density.
Used in electromagnets, relays, and magnetic shields.
Susceptible to eddy currents, so often laminated.
2. Silicon Steel (Electrical Steel)
Contains 1–4.5% silicon to increase resistivity and reduce eddy current losses.
Used in transformers, motors, and generators.
Available in grain-oriented (better in one direction) and non-oriented (isotropic) forms.
3. Nickel-Iron Alloys (Permalloys)
High-permeability alloys (e.g., 78% Ni-Fe, 80% Ni-Fe).
Used in sensitive transformers, inductors, and magnetic shielding.
Supermalloy (79% Ni, 15% Fe, 5% Mo) has extremely high permeability.
4. Cobalt-Iron Alloys (Permendur, Vacoflux)
High saturation flux density (~2.4 T).
Used in high-performance motors, aerospace, and specialized transformers.
5. Amorphous & Nanocrystalline Alloys
Amorphous metals (Metglas): Rapidly cooled alloys with no crystalline structure (low core loss).
Nanocrystalline alloys (e.g., Finemet): Fine-grained structure, excellent high-frequency performance.
Used in high-efficiency transformers, inductors, and EMI suppression.
6. Soft Ferrites
Ceramic materials (e.g., Mn-Zn, Ni-Zn ferrites) with high resistivity, reducing eddy currents.
Used in high-frequency applications (switching power supplies, RF transformers, inductors).
7. Powdered Iron & Soft Magnetic Composites (SMCs)
Insulated iron particles pressed into cores.
Used in high-frequency inductors and motors.
Key Applications:
AC power systems (transformers, motors, generators).
Electronics (inductors, chokes, sensors).
High-frequency devices (RF cores, switching power supplies).