Soft Magnetic Materials Have Low Coercivity And High Permeability

Soft magnetic materials refer to when the magnetization occurs at Hc not greater than 1000A/m, such materials are called soft magnets. Typical soft magnetic materials can achieve maximum magnetization with minimal external magnetic field. Soft magnetic material A magnetic material with low coercivity and high permeability.
Soft magnetic materials are easy to magnetize and easy to demagnetize, and are widely used in electrical equipment and electronic equipment. The most widely used soft magnetic materials are iron-silicon alloy (silicon steel sheet) and various soft magnetic ferrites.
① Pure iron and mild steel
Carbon content less than 0.04%, including electromagnetic pure iron, electrolytic iron and carbonyl iron. It is characterized by high saturation magnetization, low price and good processing performance; However, its low resistivity and eddy current loss in alternating magnetic fields are only suitable for static use, such as the manufacture of electromagnetic cores, pole boots, relays and loudspeaker magnetic conductors, magnetic shielding covers, etc.
② Iron-silicon alloy
Silicon content 0.5% ~ 4.8%, generally made of thin sheet used, commonly known as silicon steel sheet. After the addition of silicon to pure iron, the phenomenon that the magnetic properties of magnetic materials change with time of use can be eliminated. With the increase of silicon content, the thermal conductivity decreases, the brittleness increases, and the saturation magnetization decreases, but its resistivity and permeability are high, and the coercivity and eddy current loss are reduced, so that it can be applied to the field of AC to manufacture the iron core of motors, transformers, relays, transformers, etc.
③ Iron aluminum alloy
Containing 6% to 16% aluminum, with good soft magnetic properties, high permeability and resistivity, high hardness, good wear resistance, but brittle, mainly used in the manufacture of small transformers, magnetic amplifiers, relays and other iron cores and heads, ultrasonic transducers.
④ iron silicon aluminum alloy
It is obtained by adding silicon to binary ferroaluminum alloy. Its hardness, saturation magnetic induction strength, permeability and resistivity are high. The disadvantage is that the magnetic property is sensitive to the fluctuation of the composition, the brittleness is large, and the processing performance is poor. Mainly used for audio and video heads.
⑤ nickel-iron alloy
Nickel content of 30%~90%, also known as Permalloy, through alloying element ratio and appropriate process, can control the magnetic properties, obtain high permeability, constant permeability, moment magnetic and other soft magnetic materials. It has high plasticity and is more sensitive to stress, and can be used as pulse transformer material, inductance core and functional magnetic material.
⑥ Fe-Cobalt alloy
Cobalt content 27%~50%. It has high saturation magnetization and low resistivity. Suitable for the manufacture of pole boots, motor rotor and stator, small transformer core, etc.
⑦ Soft magnetic ferrite
Non-metallic ferromagnetic soft magnetic material. High resistivity (10-2~1010Ω·m), lower saturation magnetization than metal, low price, widely used as inductors and transformer components (see ferrite).
⑧ amorphous soft magnetic alloy
A non-long-range ordered, non-crystalline alloy, also known as metal glass, or amorphous metal. It has high permeability and resistivity, low coercivity, no sensitivity to stress, no magnetic crystal anisotropy caused by crystal structure, corrosion resistance and high strength. In addition, its Curie point is much lower than the crystalline soft magnetic material, the power loss is greatly reduced, is a new soft magnetic material under development and utilization.
⑨ ultramicrocrystalline soft magnetic alloy
A soft magnetic material discovered in the 1980s. It is composed of crystalline phase and amorphous grain boundary phase less than 50 nm. It has better comprehensive properties than crystalline and amorphous alloys. It not only has high permeability, low coercivity, low iron loss, but also has high saturation magnetic induction strength and good stability. Now the main research is iron base ultramicrystalline alloy.