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 Bronze is an alloy consisting primarily of copper, commonly with about 12–12.5% tin and often with the addition of other metals (including aluminium, manganese, nickel, or zinc) and sometimes non-metals, such as phosphorus, or metalloids such ...

, where tin is a significant addition, and brass, using zinc instead. Both of these are imprecise terms, having both been commonly referred to as lattens in the past. Today the term ''copper alloy'' tends to be substituted, especially by museums.British Museum, "Scope Note" for "copper alloy"
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Composition

The similarity in external appearance of the various alloys, along with the different combinations of elements used when making each alloy, can lead to confusion when categorizing the different compositions. There are as many as 400 different copper and copper alloy compositions loosely grouped into the categories: copper, high copper alloy, brasses,

s, copper nickels, copper–nickel–zinc (nickel silver), leaded copper, and special alloys. The following table lists the principal alloying element for four of the more common types used in modern industry, along with the name for each type. Historical types, such as those that characterize the Bronze Age, are vaguer as the mixtures were generally variable. Section 23 2D CU-SI

The following table outlines the chemical composition of various grades of copper alloys.

Brasses

A brass is an alloy of copper with zinc. Brasses are usually yellow in colour. The zinc content can vary between few % to about 40%; as long as it is kept under 15%, it does not markedly decrease corrosion resistance of copper. Brasses can be sensitive to

selective leaching In metallurgy, selective leaching, also called dealloying, demetalification, parting and selective corrosion, is a corrosion type in some solid solution alloys, when in suitable conditions a component of the alloys is preferentially leached from ...

corrosion under certain conditions, when zinc is leached from the alloy (''dezincification''), leaving behind a spongy copper structure. * Nordic Gold

Bronzes

A bronze is an alloy of copper and other metals, most often tin, but also aluminium and silicon. * Aluminium bronzes are alloys of copper and aluminium. The content of aluminium ranges mostly between 5% and 11%. Iron, nickel, manganese and silicon are sometimes added. They have higher strength and corrosion resistance than other bronzes, especially in marine environment, and have low reactivity to sulphur compounds. Aluminium forms a thin passivation layer on the surface of the metal. *

Bell metal Bell metal or bell bronze is an alloy used for making bells and related instruments, such as cymbals. It is a form of bronze with a higher tin content, usually in approximately a 4:1 ratio of copper to tin (typically, 78% copper, 22% tin by mas ...

* Phosphor bronze * Nickel bronzes, e.g. nickel silver and cupronickel * Speculum metal *

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

Precious metal alloys

Copper is often alloyed with

precious metal Precious metals are rare, naturally occurring metallic chemical elements of high economic value. Chemically, the precious metals tend to be less reactive than most elements (see noble metal). They are usually ductile and have a high lustre. ...

s like gold (Au) and silver (Ag). † amount unspecified

References

Bibliography

* {{cite book , first1=Erik , last1=Oberg , first2=Franklin D. , last2=Jones , first3=Holbrook L. , last3=Horton , year=1992 , title=Machinery's Handbook , edition=24 , page=501 , publisher=Industrial Press Inc , location=New York , isbn=0-8311-2492-X

External links

Corrosion tests and standards: application and interpretationCopper Development Association
*Copper Binary Phase Diagrams generation code (batch file - http://www.gotrawama.eu/copperNIMS/ramefabio.txt ) using open thermodynamic databases available at NIMS https://cpddb.nims.go.jp/cpddb/periodic.htm and a commercial software, Computherm Pandat, available for free at https://computherm.com/ ( help for use https://computherm.com/docs/pandat_manual.pdf. Images of the 34 binary phase diagrams are available at http://www.gotrawama.eu/copperNIMS/PNG/ Copper alloys, Sculpture materials