UNS C69100, also known as Tungum alloy, CW700R and CZ127, is a bronze

copper alloy Copper alloys are metal alloys that have copper as their principal component. They have high resistance against corrosion. The best known traditional types are bronze, where tin is a significant addition, and brass, using zinc instead. Both of t ...

. It has a naturally occurring oxide layer, which on exposure to reagents develops into a very thin protective coating. Tungum resists both pitting and

crevice corrosion Crevice corrosion refers to corrosion occurring in occluded spaces such as interstices in which a stagnant solution is trapped and not renewed. These spaces are generally called crevices. Examples of crevices are gaps and contact areas between pa ...

in marine environments/atmospheres. This offers excellent service-life, even at intermittent duty in the corrosive "splash" zone. Tungum is non-magnetic and has non-sparking properties. This allows Tungum to be used in high pressure gas pipework systems (

oxygen Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as ...

and

inert gases An inert gas is a gas that does not readily undergo chemical reactions with other chemical substances and therefore does not readily form chemical compounds. The noble gases often do not react with many substances and were historically referred to ...

). Unusually for a copper alloy, it can be precipitation hardened using heat treatment techniques. This enables its physical properties to be modified as required, to suit various applications. It can be used for low temperature ( cryogenic) applications. In the decade after

World War I World War I (28 July 1914 11 November 1918), often abbreviated as WWI, was one of the deadliest global conflicts in history. Belligerents included much of Europe, the Russian Empire, the United States, and the Ottoman Empire, with fightin ...

, Sidney Tungay, a metallurgist, was experimenting with a new copper-based alloy which he hoped would look like gold when polished and which would be durable in everyday use. In an article in the 1934 ''British Trade Review'', Tungum alloy was introduced thus:

"Tungum is an alloy discovered by a well known metallurgist from whose name the alloy is derived. Experimenting with a view to finding a combination of metals suitable for a special purpose he had in view, he produced a compound which is known as TUNGUM. Recognising that its close likeness to 22 carat
gold Gold is a chemical element with the symbol Au (from la, aurum) and atomic number 79. This makes it one of the higher atomic number elements that occur naturally. It is a bright, slightly orange-yellow, dense, soft, malleable, and ductile me ...
would make it a marketable commodity the inventor carried out a series of tests which satisfied him that he had discovered a wonderful alloy."

The material is now mainly used in

commercial diving Commercial diving may be considered an application of professional diving where the diver engages in underwater work for industrial, construction, engineering, maintenance or other commercial purposes which are similar to work done out of the wate ...

and offshore applications, for the material's resistance to salt water corrosion. Its composition is: 81-84% Cu, 0.70-1.20 Al, 0.8-1.40 Ni, 0.80-1.30 Si, with the remainder Zn

References

*http://tungum.co.uk/technical-zone/chemical-mechanical//

External links

The melting point of UNS C69100
Copper alloys {{alloy-stub