Alnico

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Alnico alloys are composed primarily of aluminium, nickel and cobalt (hence the term al-ni-co) with the addition of iron, copper, and sometimes titanium.

Alnico alloys make strong permanent magnets. They can be magnetized to produce strong magnetic fields. Of the more commonly available magnets, only rare-earth magnets such as neodymium and samarium-cobalt are stronger. Alnico magnets produce magnetic field strength at their poles as high as 1500 gauss (0.15 tesla), or about 3000 times the strength of the earth's magnetic field.

Alnico alloys have some of the highest Curie points of any magnetic material, around 800 °C. This property, as well as its brittleness and high melting point, is the result of the strong tendency toward order due to intermetallic bonding between aluminum and its other constituents.

Alnico magnets are used in electric motors, electric guitar pickups, sensors, loudspeakers, and cow magnets. Alnico is produced by casting or sintering processes.

Some types of Alnico are isotropic, meaning they can be efficiently magnetized in any direction. Other types, such as Alnico 5 and Alnico 8, are anisotropic, meaning that they have a preferred direction of magnetization, or orientation. Anisotropic alloys generally have greater magnetic capacity in their preferred orientation than isotropic types. Anisotropic Alnico magnets are oriented by heating them above a critical temperature, and cooling them in the presence of a magnetic field.