The ferromagnetic materials are the most important magnetic materials used in electricity and electronics. They are easily and strongly magnetized in the same direction as the field. They have high value of relative permeability from 50 to 5000 i.e., they conduct magnetic flux 50 to 5000 times more easily than air. Most commonly used ferromagnetic material is iron, steel, nickel, cobalt and commercial alloys such as alnico, Permalloy and supermalloy.
Alnico is a trade name for an alloy of aluminium, nickel, iron and cobalt. Permanent magnets made of alnico are commonly used in motors, generators, loudspeakers, microphones and meters etc. permalloy has a relative permeability of the order of 100,000. Similarly supermalloy is an alloy of nickel, iron, molybdenum and manganese.