Copper alloys
Encyclopedia
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 these are imprecise terms, and today the term copper alloy tends to be substituted, especially by museums.
s, copper–nickel–zinc (nickel silver), lead
ed 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 .
The following table outlines the chemical composition of various grades of copper alloys.
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.
s like silver
and gold
, to create, for example, Corinthian bronze
, hepatizon
, tumbaga
and shakudo
.
Copper
Copper is a chemical element with the symbol Cu and atomic number 29. It is a ductile metal with very high thermal and electrical conductivity. Pure copper is soft and malleable; an exposed surface has a reddish-orange tarnish...
as their principal component. They have high resistance against corrosion
Corrosion
Corrosion is the disintegration of an engineered material into its constituent atoms due to chemical reactions with its surroundings. In the most common use of the word, this means electrochemical oxidation of metals in reaction with an oxidant such as oxygen...
. The best known traditional types are bronze
Bronze
Bronze is a metal alloy consisting primarily of copper, usually with tin as the main additive. It is hard and brittle, and it was particularly significant in antiquity, so much so that the Bronze Age was named after the metal...
, where tin
Tin
Tin is a chemical element with the symbol Sn and atomic number 50. It is a main group metal in group 14 of the periodic table. Tin shows chemical similarity to both neighboring group 14 elements, germanium and lead and has two possible oxidation states, +2 and the slightly more stable +4...
is a significant addition, and brass
Brass
Brass is an alloy of copper and zinc; the proportions of zinc and copper can be varied to create a range of brasses with varying properties.In comparison, bronze is principally an alloy of copper and tin...
, using zinc
Zinc
Zinc , or spelter , is a metallic chemical element; it has the symbol Zn and atomic number 30. It is the first element in group 12 of the periodic table. Zinc is, in some respects, chemically similar to magnesium, because its ion is of similar size and its only common oxidation state is +2...
instead. Both these are imprecise terms, and today the term copper alloy tends to be substituted, especially by museums.
Compositions
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 nickelNickel
Nickel is a chemical element with the chemical symbol Ni and atomic number 28. It is a silvery-white lustrous metal with a slight golden tinge. Nickel belongs to the transition metals and is hard and ductile...
s, copper–nickel–zinc (nickel silver), lead
Lead
Lead is a main-group element in the carbon group with the symbol Pb and atomic number 82. Lead is a soft, malleable poor metal. It is also counted as one of the heavy metals. Metallic lead has a bluish-white color after being freshly cut, but it soon tarnishes to a dull grayish color when exposed...
ed 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
Bronze Age
The Bronze Age is a period characterized by the use of copper and its alloy bronze as the chief hard materials in the manufacture of some implements and weapons. Chronologically, it stands between the Stone Age and Iron Age...
, are vaguer as the mixtures were generally .
| Family | Principal alloying element | UNS Unified numbering system The unified numbering system is an alloy designation system widely accepted in North America. It consists of a prefix letter and five digits designating a material composition. A prefix of S indicates stainless steel alloys, C for copper, brass, or bronze alloys, T for tool steels, etc... numbers |
|---|---|---|
| Copper alloys, brass | Zinc (Zn) | C1xxxx–C4xxxx,C66400–C69800 |
| Phosphor bronze Phosphor bronze Phosphor bronze is an alloy of copper with 3.5 to 10% of tin and a significant phosphorus content of up to 1%. The phosphorus is added as deoxidizing agent during melting.... |
Tin (Sn) | C5xxxx |
| Aluminium Aluminium Aluminium or aluminum is a silvery white member of the boron group of chemical elements. It has the symbol Al, and its atomic number is 13. It is not soluble in water under normal circumstances.... bronzes |
Aluminium (Al) | C60600–C64200 |
| Silicon Silicon Silicon is a chemical element with the symbol Si and atomic number 14. A tetravalent metalloid, it is less reactive than its chemical analog carbon, the nonmetal directly above it in the periodic table, but more reactive than germanium, the metalloid directly below it in the table... bronzes |
Silicon (Si) | C64700–C66100 |
| Copper nickel, nickel silvers | Nickel (Ni) | C7xxxx |
| Name | Nominal composition (percentages) | Form and condition | Yield strength (0.2% offset, ksi) | Tensile strength (ksi) | Elongation in 2 inches (percent) | Hardness (Brinell scale Brinell scale The Brinell scale characterizes the indentation hardness of materials through the scale of penetration of an indenter, loaded on a material test-piece. It is one of several definitions of hardness in materials science.... ) |
Comments |
|---|---|---|---|---|---|---|---|
| Copper (ASTM ASTM International ASTM International, known until 2001 as the American Society for Testing and Materials , is an international standards organization that develops and publishes voluntary consensus technical standards for a wide range of materials, products, systems, and services... 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 Gilding metal Gilding metal is a copper alloy, comprising 95% copper and 5% zinc. Technically, it is a brass.Gilding metal is used for various purposes, including the jackets of bullets, driving bands on some artillery shells, as well as enameled badges and other jewellery.... (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; radiator Radiator Radiators are heat exchangers used to transfer thermal energy from one medium to another for the purpose of cooling and heating. The majority of radiators are constructed to function in automobiles, buildings, and electronics... s, hardware, electrical, drawn cartridge cases Cartridge (firearms) A cartridge, also called a round, packages the bullet, gunpowder and primer into a single metallic case precisely made to fit the firing chamber of a firearm. The primer is a small charge of impact-sensitive chemical that may be located at the center of the case head or at its rim . Electrically... . |
| Phosphor bronze Phosphor bronze Phosphor bronze is an alloy of copper with 3.5 to 10% of tin and a significant phosphorus content of up to 1%. The phosphorus is added as deoxidizing agent during melting.... (ASTM B103, B139, B159) |
Cu 70.0, 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 | Forging Forging Forging is a manufacturing process involving the shaping of metal using localized compressive forces. Forging is often classified according to the temperature at which it is performed: '"cold," "warm," or "hot" forging. Forged parts can range in weight from less than a kilogram to 580 metric tons... s |
| |
|
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 Muntz metal Muntz metal is a form of alpha-beta brass with about 60% copper, 40% zinc and a trace of iron. It is named after George Fredrick Muntz, a metal-roller of Birmingham, England who commercialised the alloy following his patent of 1832.... (ASTM B111) |
Cu 60.0, Zn 40.0 | Annealed | 20 | 54 | 45 | 80 | Condensor Condenser (heat transfer) In systems involving heat transfer, a condenser is a device or unit used to condense a substance from its gaseous to its liquid state, typically by cooling it. In so doing, the latent heat is given up by the substance, and will transfer to the condenser coolant... tubes |
| Aluminium bronze Aluminium bronze Aluminium bronze is a type of bronze in which aluminium is the main alloying metal added to copper, in contrast to standard bronze or brass... (ASTM B169 alloy A, B124, B150) |
Cu 92.0, Al 8.0 | Annealed | 25 | 70 | 60 | 80 | — |
| |
|
Hard | 65 | 105 | 7 | 210 | |
| Beryllium copper Beryllium copper Beryllium copper , also known as copper beryllium, beryllium bronze and spring copper, is a copper alloy with 0.5—3% beryllium and sometimes with other alloying elements. Beryllium copper combines high strength with non-magnetic and non-sparking qualities. It has excellent metalworking, forming... (ASTM B194, B196, B197) |
Cu 97.75, Be 2.0, Co or Ni 0.25 | Annealed, solution-treated | 32 | 70 | 45 | B60 (Rockwell Rockwell scale The Rockwell scale is a hardness scale based on the indentation hardness of a material. The Rockwell test determines the hardness by measuring the depth of penetration of an indenter under a large load compared to the penetration made by a preload. There are different scales, denoted by a single... ) |
Electrical, valves, pumps |
| |
|
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 Nickel silver Nickel silver, also known as German silver, Argentann, new silver, nickel brass, albata,, or alpacca, is a copper alloy with nickel and often zinc. The usual formulation is 60% copper, 20% nickel and 20% zinc. Nickel silver is named for its silvery appearance, but it contains no elemental silver... (ASTM B112) |
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 |
| Cupronickel Cupronickel Cupronickel or copper-nickel or "cupernickel" is an alloy of copper that contains nickel and strengthening elements, such as iron and manganese. Cupronickel is highly resistant to corrosion in seawater, because its electrode potential is adjusted to be neutral with regard to seawater... (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 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 Gunmetal Gunmetal, also known as yellow brass in the United States, is a type of bronze – an alloy of copper, tin, and zinc. Originally used chiefly for making guns, gunmetal was eventually superseded by steel... (known as "red brass" in US) |
Varies Cu 80-90%, Zn <5%, Sn ~10%, +other elements@ <1% |
| Family | | CDA | | Tensile strength [ksi] | | Yield strength [ksi] | | Elongation (typ.) [%] | | Hardness [Brinell 10 mm-500 kg] | | Machinability [YB = 100] | ||||
|---|---|---|---|---|---|---|---|---|---|---|
| Min. | Typ. | Min. | Typ. | |||||||
| Red brass | 833 | 32 | 10 | 35 | 35 | 35 | ||||
| 836 | 30 | 37 | 14 | 17 | 30 | 50–65 | 84 | |||
| 838 | 29 | 35 | 12 | 16 | 25 | 50–60 | 90 | |||
| Semi-red brass | 844 | 29 | 34 | 13 | 15 | 26 | 50–60 | 90 | ||
| 848 | 25 | 36 | 12 | 14 | 30 | 50–60 | 90 | |||
| Manganese bronze Manganese Bronze Manganese Bronze Holdings PLC is an engineering company based in Coventry, England. Since the sale of its components division in 2003 the company has only one operating division—LTI Limited, trading as The London Taxi Company—which manufactures and retails London Black Taxis.The London... |
862 | 90 | 95 | 45 | 48 | 20 | 170–195† | 30 | ||
| 863 | 110 | 119 | 60 | 83 | 18 | 225† | 8 | |||
| 865 | 65 | 71 | 25 | 28 | 30 | 130† | 26 | |||
| Tin bronze | 903 | 40 | 45 | 18 | 21 | 30 | 60–75 | 30 | ||
| 905 | 40 | 45 | 18 | 22 | 25 | 75 | 30 | |||
| 907 | 35 | 44 | 18 | 22 | 20 | 80 | 20 | |||
| Leaded tin bronze | 922 | 34 | 40 | 16 | 20 | 30 | 60–72 | 42 | ||
| 923 | 36 | 40 | 16 | 20 | 25 | 60–75 | 42 | |||
| 926 | 40 | 44 | 18 | 20 | 30 | 65–80 | 40 | |||
| 927 | 35 | 42 | 21 | 20 | 77 | 45 | ||||
| High-leaded tin bronze | 932 | 30 | 35 | 14 | 18 | 20 | 60–70 | 70 | ||
| 934 | 25 | 32 | 16 | 20 | 55–65 | 70 | ||||
| 935 | 25 | 32 | 12 | 16 | 30 | 55–65 | 70 | |||
| 936 | 33 | 30 | 16 | 21 | 15 | 79-83 | 80 | |||
| 937 | 25 | 35 | 12 | 18 | 20 | 55–70 | 80 | |||
| 938 | 25 | 30 | 14 | 16 | 18 | 50–60 | 80 | |||
| 943 | 21 | 27 | 13 | 10 | 42–55 | 80 | ||||
| Aluminium bronze Aluminium bronze Aluminium bronze is a type of bronze in which aluminium is the main alloying metal added to copper, in contrast to standard bronze or brass... |
952 | 65 | 80 | 25 | 27 | 35 | 110–140† | 50 | ||
| 953 | 65 | 75 | 25 | 27 | 25 | 140† | 55 | |||
| 954 | 75 | 85 | 30 | 35 | 18 | 140–170† | 60 | |||
| 955 | 90 | 100 | 40 | 44 | 12 | 180–200† | 50 | |||
| 958 | 85 | 95 | 35 | 38 | 25 | 150-170† | 50 | |||
| Silicon bronze | 878 | 80 | 83 | 30 | 37 | 29 | 115 | 40 | ||
| † Brinell scale with 3000 kg load | ||||||||||
| Family | CDA | ASTM ASTM International ASTM International, known until 2001 as the American Society for Testing and Materials , is an international standards organization that develops and publishes voluntary consensus technical standards for a wide range of materials, products, systems, and services... | SAE SAE International SAE International is an organization for engineering professionals in the aerospace, automotive, and commercial vehicle industries. The Society is a standards development organization for the engineering of powered vehicles of all kinds, including cars, trucks, boats, aircraft, and others.SAE... | SAE superseded | Federal | Military |
|---|---|---|---|---|---|---|
| Red brass | 833 | |||||
| 836 | B145-836 | 836 | 40 | QQ-C-390 (B5) | C-2229 Gr2 | |
| 838 | B145-838 | 838 | QQ-C-390 (B4) | |||
| Semi-red brass | 844 | B145-844 | QQ-C-390 (B2) | |||
| 848 | B145-848 | QQ-C-390 (B1) | ||||
| Manganese bronze | 862 | B147-862 | 862 | 430A | QQ-C-390 (C4) | C-2229 Gr9 |
| 863 | B147-863 | 863 | 430B | QQ-C-390 (C7) | C-2229 Gr8 | |
| 865 | B147-865 | 865 | 43 | QQ-C-390 (C3) | C-2229 Gr7 | |
| Tin bronze | 903 | B143-903 | 903 | 620 | QQ-C-390 (D5) | C-2229 Gr1 |
| 905 | B143-905 | 905 | 62 | QQ-C-390 (D6) | ||
| 907 | 907 | 65 | ||||
| Leaded tin bronze | 922 | B143-922 | 922 | 622 | QQ-C-390 (D4) | B-16541 |
| 923 | B143-923 | 923 | 621 | QQ-C-390 (D3) | C-15345 Gr10 | |
| 926 | 926 | |||||
| 927 | 927 | 63 | ||||
| High-leaded tin bronze | 932 | B144-932 | 932 | 660 | QQ-C-390 (E7) | C-15345 Gr12 |
| 934 | QQ-C-390 (E8) | C-22229 Gr3 | ||||
| 935 | B144-935 | 935 | 66 | QQ-C-390 (E9) | ||
| 937 | B144-937 | 937 | 64 | QQ-C-390 (E10) | ||
| 938 | B144-938 | 938 | 67 | QQ-C-390 (E6) | ||
| 943 | B144-943 | 943 | QQ-C-390 (E1) | |||
| Aluminium bronze | 952 | B148-952 | 952 | 68A | QQ-C-390 (G6) | C-22229 Gr5 |
| 953 | B148-953 | 953 | 68B | QQ-C-390 (G7) | ||
| 954 | B148-954 | 954 | QQ-C-390 (G5) | C-15345 Gr13 | ||
| 955 | B148-955 | 955 | QQ-C-390 (G3) | C-22229 Gr8 | ||
| 958 | QQ-C-390 (G8) | |||||
| Silicon bronze | 878 | B30 | 878 |
The following table outlines the chemical composition of various grades of copper alloys.
| Family | CDA | AMS | UNS | Cu [%] | Sn [%] | Pb [%] | Zn [%] | Ni [%] | Fe [%] | Al [%] | Other [%] |
|---|---|---|---|---|---|---|---|---|---|---|---|
| Red brass | 833 | C83300 | 93 | 1.5 | 1.5 | 4 | |||||
| C83400 | 90 | 10 | |||||||||
| 836 | 4855B | C83600 | 85 | 5 | 5 | 5 | |||||
| 838 | C83800 | 83 | 4 | 6 | 7 | ||||||
| Semi-red brass | 844 | C84400 | 81 | 3 | 7 | 9 | |||||
| 845 | C84500 | 78 | 3 | 7 | 12 | ||||||
| 848 | C84800 | 76 | 3 | 6 | 15 | ||||||
| Manganese bronze | C86100 | 67 | 0.5 | 21 | 3 | 5 | Mn 4 | ||||
| 862† | C86200 | 64 | 26 | 3 | 4 | Mn 3 | |||||
| 863† | 4862B | C86300 | 63 | 25 | 3 | 6 | Mn 3 | ||||
| 865 | 4860A | C86500 | 58 | 0.5 | 39.5 | 1 | 1 | Mn 0.25 | |||
| Tin bronze | 903 | C90300 | 88 | 8 | 4 | ||||||
| 905 | 4845D | C90500 | 88 | 10 | 0.3 max | 2 | |||||
| 907 | C90700 | 89 | 11 | 0.5 max | 0.5 max | ||||||
| Leaded tin bronze | 922 | C92200 | 88 | 6 | 1.5 | 4.5 | |||||
| 923 | C92300 | 87 | 8 | 1 max | 4 | ||||||
| 926 | 4846A | C92600 | 87 | 10 | 1 | 2 | |||||
| 927 | C92700 | 88 | 10 | 2 | 0.7 max | ||||||
| High-leaded tin bronze | 932 | C93200 | 83 | 7 | 7 | 3 | |||||
| 934 | C93400 | 84 | 8 | 8 | 0.7 max | ||||||
| 935 | C93500 | 85 | 5 | 9 | 1 | 0.5 max | |||||
| 937 | 4842A | C93700 | 80 | 10 | 10 | 0.7 max | |||||
| 938 | C93800 | 78 | 7 | 15 | 0.75 max | ||||||
| 943 | 4840A | C94300 | 70 | 5 | 25 | 0.7 max | |||||
| Aluminium bronze | 952 | C95200 | 88 | 3 | 9 | ||||||
| 953 | C95200 | 89 | 1 | 10 | |||||||
| 954 | 4870B 4872B |
C95400 | 85 | 4 | 11 | ||||||
| C95410 | 85 | 4 | 11 | Ni 2 | |||||||
| 955 | C95500 | 81 | 4 | 4 | 11 | ||||||
| C95600 | 91 | 7 | Si 2 | ||||||||
| C95700 | 75 | 2 | 3 | 8 | Mn 12 | ||||||
| 958 | C95800 | 81 | 5 | 4 | 9 | Mn 1 | |||||
| Silicon bronze | C87200 | 89 | Si 4 | ||||||||
| C87400 | 83 | 14 | Si 3 | ||||||||
| C87500 | 82 | 14 | Si 4 | ||||||||
| C87600 | 90 | 5.5 | Si 4.5 | ||||||||
| 878 | C87800 | 80 | 14 | Si 4 | |||||||
| C87900 | 65 | 34 | Si 1 | ||||||||
| † Chemical composition may vary to yield mechanical properties | |||||||||||
Brasses
A brass is an alloy of copper with zinc. Brasses are usually yellow in color. 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
Selective leaching
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 the material. The less noble metal is removed from the alloy by...
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 5-11%. 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 sulfur compounds. Aluminium forms a thin passivation layer on the surface of the metal.
- Bell metalBell metalBell metal is a hard alloy used for making bells. It is a form of bronze, usually approximately 4:1 ratio of copper to tin...
- Phosphor bronzePhosphor bronzePhosphor bronze is an alloy of copper with 3.5 to 10% of tin and a significant phosphorus content of up to 1%. The phosphorus is added as deoxidizing agent during melting....
- Nickel bronzes, e.g. nickel silver and cupronickel
- Speculum metalSpeculum metalSpeculum metal is a mixture of around two-thirds copper and one-third tin making a white brittle alloy that can be polished to make a highly reflective surface. It is used primarily to make different kinds of mirrors including early reflecting telescope optical mirrors...
- UNS C69100
Precious metal alloys
Copper is often alloyed with precious metalPrecious metal
A precious metal is a rare, naturally occurring metallic chemical element of high economic value.Chemically, the precious metals are less reactive than most elements, have high lustre, are softer or more ductile, and have higher melting points than other metals...
s like silver
Silver
Silver is a metallic chemical element with the chemical symbol Ag and atomic number 47. A soft, white, lustrous transition metal, it has the highest electrical conductivity of any element and the highest thermal conductivity of any metal...
and gold
Gold
Gold is a chemical element with the symbol Au and an atomic number of 79. Gold is a dense, soft, shiny, malleable and ductile metal. Pure gold has a bright yellow color and luster traditionally considered attractive, which it maintains without oxidizing in air or water. Chemically, gold is a...
, to create, for example, Corinthian bronze
Corinthian bronze
Corinthian bronze, also called Corinthian brass or æs Corinthiacum, was a highly valuable metal alloy in classical antiquity. It is thought to be an alloy of copper with gold or silver , although it has also been contended that it was simply a very high grade of bronze, or a kind of bronze that...
, hepatizon
Hepatizon
Hepatizon , also known as Black Corinthian Bronze, was a highly valuable metal alloy in classical antiquity...
, tumbaga
Tumbaga
Tumbaga was the name given by Spaniards to a non-specific alloy of gold and copper which they found in widespread use in pre-Columbian Mesoamerica and South America.-Composition and properties:...
and shakudo
Shakudo
Shakudō is a billon of gold and copper , mostly designed for its dark blue-purple patina. It was historically used in Japan to decorate katana fittings such as tsuba and kozuka...
.