Metallic materials of the alnico type
Materials with hard magnetic properties: industrial materials

Initially, the alni alloy of the AlNiFe₂ type, discovered in Japan in 1932 by Mishima, had the following composition by weight: 58Fe-30Ni-12Al. Its coercive field of around 3.45 × 10⁴ A · m^{– 1} (430 Oe) was twice as high as that of the best tungsten steels then in use. In 1938, additions of cobalt, carried out to increase M_s and T_C, as well as additions of copper and titanium, led to the discovery of the beneficial effect of heat treatment under a magnetic field on the anisotropic magnetic properties of this family of materials. Known as alnico, these alloys took precedence over all other permanent magnet materials of the time. Extensive research in the 1940s and 1950s led to a gradual improvement in magnetic properties and...