Example of a copper alloy object: a Neo-Sumerian "Foundation Nail" of Gudea, circa 2100 BC, made in the lost-wax cast method, overall: 17.5 x 4.5 x 7.3 cm, probably from modern-day Iraq, now in the Cleveland Museum of Art (Cleveland, Ohio, USA)

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 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.[1]

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, bronzes, 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.

Classification of copper and its alloys
FamilyPrincipal alloying elementUNS numbers
Copper alloys, brassZinc (Zn)C1xxxx–C4xxxx,C66400–C69800
Phosphor bronzeTin (Sn)C5xxxx
Aluminium bronzesAluminium (Al)C60600–C64200
Silicon bronzesSilicon (Si)C64700–C66100
Cupronickel, nickel silversNickel (Ni)C7xxxx
Binary Cu Si phase diagram, the base phase diagram for silicon bronzes generated using NIMS Open databases https://cpddb.nims.go.jp/cpddb/cu-ehttps://cpddb.nims.go.jp/cpddb/cu-elem/cusi/cusi.htm - DOI https://doi.org/10.48505/nims.3060 and Computherm Pandat https://computherm.com/
Binary Cu Si phase diagram, the base phase diagram for silicon bronzes
Binary Cu Al phase diagram, the base phase diagram for aluminium bronzes
Binary Cu Al phase diagram, the base phase diagram for aluminium bronzes, generated using NIMS Open databases https://cpddb.nims.go.jp/cpddb/al-elem/alcu/alcu.htm - DOI https://doi.org/10.48505/nims.3060 and Computherm Pandat https://computherm.com/
Binary Cu Sn phase diagram
Binary Cu Sn phase diagram, the base phase diagram for bronzes, generated using NIMS Open databases https://cpddb.nims.go.jp/cpddb/cu-elem/cusn/cusn.htm - DOI https://doi.org/10.48505/nims.3060 and Computherm Pandat https://computherm.com/
Cu Zn binary phase diagram. Base phase diagram for brasses
Binary Cu Zn phase diagram, the base phase diagram for brasses, generated using NIMS Open database https://cpddb.nims.go.jp/cpddb/cu-elem/cu_index.htm  Cu-Zn - DOI https://doi.org/10.48505/nims.3060 and Computherm Pandat https://computherm.com/
Mechanical properties of common copper alloys[2]
Name Nominal composition (percentages) Form and condition Yield strength (0.2% offset, ksi) Tensile strength (ksi) Elongation in 2 inches (percent) Hardness (Brinell scale) Comments
Copper (ASTM B1, B2, B3, B152, B124, R133) Cu 99.9 Annealed 10 32 45 42 Electrical equipment, roofing, screens
Cold-drawn 40 45 15 90
Cold-rolled 40 46 5 100
Gilding metal (ASTM B36) Cu 95.0, Zn 5.0 Cold-rolled 50 56 5 114 Coins, bullet jackets
Cartridge brass (ASTM B14, B19, B36, B134, B135) Cu 70.0, Zn 30.0 Cold-rolled 63 76 8 155 Good for cold-working; radiators, hardware, electrical, drawn cartridge cases.
Phosphor bronze (ASTM B103, B139, B159) Cu 89.75, Sn 10.0, P 0.25 Spring temper — 122 4 241 High fatigue-strength and spring qualities
Yellow or High brass (ASTM B36, B134, B135) Cu 65.0, Zn 35.0 Annealed 18 48 60 55 Good corrosion resistance
Cold-drawn 55 70 15 115
Cold-rolled (HT) 60 74 10 180
Manganese bronze (ASTM 138) Cu 58.5, Zn 39.2, Fe 1.0, Sn 1.0, Mn 0.3 Annealed 30 60 30 95 Forgings
Cold-drawn 50 80 20 180
Naval brass (ASTM B21) Cu 60.0, Zn 39.25, Sn 0.75 Annealed 22 56 40 90 Resistance to salt corrosion
Cold-drawn 40 65 35 150
Muntz metal (ASTM B111) Cu 60.0, Zn 40.0 Annealed 20 54 45 80 Condensor tubes
Aluminium bronze (ASTM B169 alloy A, B124, B150) Cu 92.0, Al 8.0 Annealed 25 70 60 80 —
Hard 65 105 7 210
Beryllium copper (ASTM B194, B196, B197) Cu 97.75, Be 2.0, Co or Ni 0.25 Annealed, solution-treated 32 70 45 B60 (Rockwell) Electrical, valves, pumps, oilfield tools, aerospace landing gears, robotic welding, mold making [3]
Cold-rolled 104 110 5 B81 (Rockwell)
Free-cutting brass Cu 62.0, Zn 35.5, Pb 2.5 Cold-drawn 44 70 18 B80 (Rockwell) Screws, nuts, gears, keys
Nickel silver (ASTM B122) Cu 65.0, Zn 17.0, Ni 18.0 Annealed 25 58 40 70 Hardware
Cold-rolled 70 85 4 170
Nickel silver (ASTM B149) Cu 76.5, Ni 12.5, Pb 9.0, Sn 2.0 Cast 18 35 15 55 Easy to machine; ornaments, plumbing [4]
Cupronickel (ASTM B111, B171) Cu 88.35, Ni 10.0, Fe 1.25, Mn 0.4 Annealed 22 44 45 – Condensor, salt-water pipes
Cold-drawn tube 57 60 15 –
Cupronickel Cu 70.0, Ni 30.0 Wrought – – – – Heat-exchange equipment, valves
Ounce metal[5] Copper alloy C83600 (also known as "Red brass" or "composition metal") (ASTM B62) Cu 85.0, Zn 5.0, Pb 5.0, Sn 5.0 Cast 17 37 25 60 —
Gunmetal (known as "red brass" in US) Varies Cu 80-90%, Zn <5%, Sn ~10%, +other elements@ <1%
Mechanical properties of Copper Development Association (CDA) copper alloys[6]
FamilyCDATensile strength [ksi]Yield strength [ksi]Elongation (typ.) [%]Hardness
[Brinell 10 mm-500 kg]		Machinability [YB = 100]
Min.Typ.Min.Typ.
Red brass8333210353535
836303714173050–6584
838293512162550–6090
Semi-red brass844293413152650–6090
848253612143050–6090
Manganese bronze8629095454820170–195†30
863110119608318225†8
8656571252830130†26
Tin bronze903404518213060–7530
90540451822257530
90735441822208020
Leaded tin bronze922344016203060–7242
923364016202560–7542
926404418203065–8040
927354221207745
High-leaded tin bronze932303514182060–7070
9342532162055–6570
935253212163055–6570
936333016211579-8380
937253512182055–7080
938253014161850–6080
9432127131042–5580
Aluminium bronze9526580252735110–140†50
9536575252725140†55
9547585303518140–170†60
95590100404412180–200†50
9588595353825150-170†50
Silicon bronze878808330372911540
† Brinell scale with 3000 kg load
Comparison of copper alloy standards[6]
FamilyCDAASTMSAESAE supersededFederalMilitary
Red brass833
836B145-83683640QQ-C-390 (B5)C-2229 Gr2
838B145-838838QQ-C-390 (B4)
Semi-red brass844B145-844QQ-C-390 (B2)
848B145-848QQ-C-390 (B1)
Manganese bronze862B147-862862430AQQ-C-390 (C4)C-2229 Gr9
863B147-863863430BQQ-C-390 (C7)C-2229 Gr8
865B147-86586543QQ-C-390 (C3)C-2229 Gr7
Tin bronze903B143-903903620QQ-C-390 (D5)C-2229 Gr1
905B143-90590562QQ-C-390 (D6)
90790765
Leaded tin bronze922B143-922922622QQ-C-390 (D4)B-16541
923B143-923923621QQ-C-390 (D3)C-15345 Gr10
926926
92792763
High-leaded tin bronze932B144-932932660QQ-C-390 (E7)C-15345 Gr12
934QQ-C-390 (E8)C-22229 Gr3
935B144-93593566QQ-C-390 (E9)
937B144-93793764QQ-C-390 (E10)
938B144-93893867QQ-C-390 (E6)
943B144-943943QQ-C-390 (E1)
Aluminium bronze952B148-95295268AQQ-C-390 (G6)C-22229 Gr5
953B148-95395368BQQ-C-390 (G7)
954B148-954954QQ-C-390 (G5)C-15345 Gr13
955B148-955955QQ-C-390 (G3)C-22229 Gr8
958QQ-C-390 (G8)
Silicon bronze878B30878

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

Chemical composition of copper alloys[6][7]
FamilyCDAAMSUNSCu [%]Sn [%]Pb [%]Zn [%]Ni [%]Fe [%]Al [%]Other [%]
Red brass833C83300931.51.54
C83400[8]9010
8364855BC8360085555
838C8380083467
Semi-red brass844C8440081379
845C84500783712
848C84800763615
Manganese bronzeC86100[9]670.52135Mn 4
862†C86200642634Mn 3
863†4862BC86300632536Mn 3
8654860AC86500580.539.511Mn 0.25
Tin bronze903C903008884
9054845DC9050088100.3 max2
907C9070089110.5 max0.5 max
Leaded tin bronze922C922008861.54.5
923C923008781 max4
9264846AC92600871012
927C92700881020.7 max
High-leaded tin bronze932C9320083773
934C9340084880.7 max
935C93500855910.5 max
9374842AC937008010100.7 max
938C93800787150.75 max
9434840AC94300705250.7 max
Aluminium bronze952C952008839
953C9520089110
9544870B
4872B		C9540085411
C95410[10]85411Ni 2
955C95500814411
C95600[11]917Si 2
C95700[12]75238Mn 12
958C9580081549Mn 1
Silicon bronzeC87200[13]89Si 4
C87400[14]8314Si 3
C87500[15]8214Si 4
C87600[16]905.5Si 4.5
878C87800[17]8014Si 4
C87900[18]6534Si 1
† Chemical composition may vary to yield mechanical properties

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

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
  • Phosphor bronze
  • Nickel bronzes, e.g. nickel silver and cupronickel
  • Speculum metal
  • UNS C69100

Precious metal alloys

Copper is often alloyed with precious metals like gold (Au) and silver (Ag).

NameCu [%]Au [%]Ag [%]Other [%]
Auricupride††
Ashtadhatu†††Fe†, Hg†, Sn†, Zn†
Billon††Hg†
Chinese silver58217.5 Zn, 11.5 Ni,
Corinthian bronze†††
CuSil2872
Dymalloy2080C (type I diamond)
Electrum, Green gold6-2375-800-150-4 Cd
Grey gold††Mn†
Guanín255618
Hepatizon†tracetrace
Niello††Pb sulfides†
Panchaloha†††Fe†, Sn†, Pb†, Zn†,
Rose, red, and pink gold20-5050-750-5
Spangold18-19765-6 Al
Shakudō90-964-10
Shibuichi40-770-123-60
Tibetan silver††Ni†, Sn†
Tumbaga3-973-97
White gold††Ni†, Zn†

† amount unspecified

See also

References

  1. ↑ British Museum, "Scope Note" for "copper alloy"
  2. ↑ Lyons, William C. and Plisga, Gary J. (eds.) Standard Handbook of Petroleum & Natural Gas Engineering, Elsevier, 2006
  3. ↑ National Bronze & Metals | Beryllium Copper
  4. ↑ Lewis Brass & Company | Copper Alloy Data
  5. ↑ Cast copper alloy C83600 (Ounce Metal) substech.com
  6. 1 2 3 Industrial Investment Castings - Franklin Bronze, retrieved 2009-09-07.
  7. ↑ Brass and Bronze Alloys, archived from the original on 2009-08-25, retrieved 2009-09-08.
  8. ↑ UNS C83400, retrieved 2009-09-08.
  9. ↑ UNS C86100, retrieved 2009-09-08.
  10. ↑ UNS C95410, retrieved 2009-09-08.
  11. ↑ UNS C95600, retrieved 2009-09-08.
  12. ↑ UNS C95700, retrieved 2009-09-08.
  13. ↑ UNS C87200, retrieved 2009-09-08.
  14. ↑ UNS C87400, retrieved 2009-09-08.
  15. ↑ UNS C87500, retrieved 2009-09-08.
  16. ↑ UNS C87600, retrieved 2009-09-08.
  17. ↑ UNS C87800, retrieved 2009-09-08.
  18. ↑ UNS C87900, retrieved 2009-09-08.

Bibliography

  • Oberg, Erik; Jones, Franklin D.; Horton, Holbrook L. (1992). Machinery's Handbook (24 ed.). New York: Industrial Press Inc. p. 501. ISBN 0-8311-2492-X.
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