A "horseshoe magnet" made of Alnico 5, about 1 in. high. The metal bar (bottom) is a keeper. Placed across the poles when the magnet was not in use, it helped preserve the magnetization.

Alnico is an alloy made up of iron with aluminium (Al), nickel (Ni) and cobalt (Co). The name "Alnico" is an acronym from Al-Ni-Co. Alnico may also contain copper and sometimes titanium.

Alnico alloys are ferromagnetic (a mechanism by which some materials form permanent magnets). Alnico alloys also have a high coercivity (they do not easily lose their magnetism) and are used to make permanent magnets. Before rare-earth magnets were developed in the 1970s, lnico magnets were the strongest type of magnet. The development of Alnico began in 1931 when T. Mishima in Japan found that an alloy of iron, nickel, and aluminium had double the coercivity of the best magnets of that time. (the coercivity of Alnico is 400 oersted). view more...