Among the magnetic materials, permanent magnetic materials are also called "hard magnetic materials", which are materials that can maintain constant magnetic properties once they are magnetized. Commonly used permanent magnet materials include AlNiCo permanent magnet alloys, FeCrCo permanent magnet alloys, permanent magnet ferrites, rare earth permanent magnet materials and composite permanent magnet materials.
Soft magnetic materials are magnetic materials with low coercivity and high permeability. They are easy to magnetize and demagnetize. Their main function is to conduct magnetic and electromagnetic energy conversion and transmission. They are widely used in various electric energy conversion equipment. Soft magnetic materials mainly include metal soft magnetic materials, ferrite soft magnetic materials and other soft magnetic materials. The most widely used soft magnetic materials are iron-silicon alloys (silicon steel sheets) and various soft ferrites.
The main difference between hard magnetic materials and soft magnetic materials is that hard magnetic materials have high anisotropy field, high coercivity, large hysteresis loop area, and large magnetic field required for technical magnetization to saturation. Due to the low coercivity of the soft magnetic material, it is easy to demagnetize after the technical magnetization reaches saturation and the external magnetic field is removed, while the hard magnetic material due to the high coercivity, after the technical magnetization to saturation and the magnetic field is removed, it will remain long-term very strong magnetism, so hard magnetic materials are also called constant magnetic materials.