It is a group of nickel alloys consisting mainly of 52% to 67% nickel and copper, containing a small amount of iron, manganese, carbon and silicon. Stronger than pure nickel, these alloys are resistant to many corrosive effects, including fast-flowing seawater.

The Monel Alloy was created in 1901 by Robert Crooks Stanley, who works for the International Nickel Company (INCO). Monel 400 is a dual alloy of nickel and copper, naturally occurring in meteoritic nickel ore from the Sudbury mines and therefore considered a puritan alloy. The name Monel comes from the company's owner, Ambrose Monell, and was patented in 1906. At the end of the name, a single L was left because family names at that time could not be given to trademarks. This name is now a trademark of Special Metals Corporation.

It is a single phase alloy. Therefore, the corrosion resistance and high temperature resistance in salt water are very good. However, it is an expensive material because it contains high amounts of nickel. Although this reduces the high cost usage rate, it is used in offshore applications for marine and oil production due to its high corrosion resistance. It is also involved in aviation applications such as the protection of safety cables in aircraft, experimental rocket aircraft, and stainless wire economy, thanks to its good shaping and high temperature resistance.