alnico, any member of a series of alloys used to make powerful permanent magnets. Primary constituents are aluminum, nickel, and cobalt in various proportions, with small amounts of one or more of the elements copper, iron, and titanium added; the titanium-containing material is sometimes referred to by the trade name Ticonal. These alloys are very hard and difficult to machine; they are usually cast into their final shape and then subjected to a strict regime of heat and magnetic-field treatment.