Magnetic materials, commonly referred to as magnetic materials, are ancient and widely used functional materials. It is generally believed that magnetic materials are materials that can be directly or indirectly produced by the transition elements iron, cobalt, nickel and their alloys. Magnetic materials are divided into soft magnetic materials and hard magnetic materials. After magnetization, the material whose magnetism is easy to remove is called soft magnetic material, and the material whose magnetism is hard to remove is called hard magnetic material.
The remanence and coercive magnetic force of the soft magnetic material are very small, that is, the hysteresis loop is very narrow, and it almost coincides with the basic magnetization curve. The magnetic material is suitable for the core of inductance coil, transformer, relay and motor. The commonly used soft magnetic materials include silicon steel, permalloy and ferrite.
Hard magnetic material is also called permanent magnetic material. It means the magnetism can stay for a long time after being magnetized. The hard magnetic material mainly includes high carbon steel, aluminum nickel cobalt alloy and titanium cobalt alloy. The magnetic powder used to make magnetic tape belongs to this kind of material.