Resistance Alloys

Nichrome (also known as Ni-Cr, nickel-chromium or chromium-nickel) is a family of alloys of nickel, chromium, and often iron (and possibly other elements) commonly used as resistance wire, heating elements in things like toasters, space heaters and in a few other applications. A common nichrome alloy is 80% nickel and 20% chromium, by mass, but there are many other combinations of metals for various applications.

Nichrome is consistently silvery-grey in colour, is corrosion-resistant, and has a high melting point of about 1,400 °C (2,550 °F).

Almost any conductive wire can be used for heating, but most metals conduct electricity with great efficiency, requiring them to be formed into very thin and delicate wires to create enough resistance to generate heat. When heated in air, most metals then oxidize quickly, become brittle and break. Nichrome wire, when heated to red-hot temperatures, develops an outer layer of chromium oxide,^[3] which is thermodynamically stable in air, is mostly impervious to oxygen, and protects the heating element from further oxidation.