Alnicomagneetit

Alnicomagneetit, or Alnico magnets, are permanent magnets made from a family of aluminum-nickel-cobalt-iron alloys, often with small additions of elements such as copper, titanium, or niobium. The combination of these elements gives alloys with high magnetic strength, good temperature stability, and the ability to retain magnetization over a wide temperature range. The name reflects the main elements present: aluminum (Al), nickel (Ni), cobalt (Co), and iron (Fe).

History and development: Alnico magnets were developed in the 1930s and became widespread before rare-earth magnets. They were among the first high-strength permanent magnets and found extensive use in early audio equipment, electronics, and industrial applications. The technology includes both cast magnets and processed forms that can be shaped and magnetized in strong fields.

Composition and grades: There are several grades of Alnico magnets, commonly referred to by numbers such as Alnico 2, 5, and 8. Variations in aluminum, nickel, and cobalt content, as well as processing methods, tailor properties like coercivity, remanence, and maximum energy product. Some magnets are isotropic (properties the same in all directions) while others are anisotropic (directionally oriented to boost performance).

Properties and applications: Alnico magnets offer excellent temperature stability, resistance to demagnetization, and ease of magnetization. They also exhibit good machinability and toughness compared with some other permanent magnets. They are widely used in guitar pickups, loudspeakers, microphones, compass needles, sensors, and high-temperature applications where stability is important.

Manufacturing and limitations: Alnico magnets are often cast and sometimes heat-treated to achieve desired anisotropy. While they provide reliable performance, their magnetic energy density is lower than that of modern rare-earth magnets, which limits their use in some compact or high-strength applications.