Sample of the element nickel Ni rotating. Nickel has the atomic number 28, and is a hard, ductile transition metal. It is most often used in alloys with other metals, notably in stainless steel. It is also used in rechargeable batteries, catalysts and plating. It is one of the major components of the Earth磗 core, although it is significantly scarcer in the crust. Nickel is one of the few metals that exhibits ferromagnetism, the ability to form a permanent magnet.