Microstructures of Copper Alloys

Coppers

Overview

The major uses of pure, unalloyed copper are based on its high electrical and thermal conductivity as well its goodcorrosion resistance. Almost all alloying elements are detrimental to the electrical conductivity of copper, making thepurity of the mental an important issue. Commercially pure copper is represented by UNS numbers C10100 toC13000. The various grades of unalloyed copper differ in the amount of impurities and therefore do behavedifferently. Oxygen free coppers are used in applications requiring high conductivity and exceptional ductility.

The pure copper or high copper alloys are made from copper ores that are obtained from the mines as sulfides,which contain zinc, lead and other sulfur. The ores are crushed and milled until they becomes a powder. A technique known as flotation separates the metal from the non-metal components of the powder. The next step is aconcentrating stage where minerals are concentrated into a slurry that is about 15% copper. The copper is thenmelted and purified in several stages until it is 99% pure copper. At this point it is cast into anodes. Oxygen remainsin the structure as cuprous oxide, Cu2O. The majority of the structure is pure copper. The copper metal solidifiesfrom the liquid state by the growth of crystals. The crystals grow in preferred directions and form open, tree likestructures called dendrites. The dendritic structure is very typical of cast metals. A lower melting point mixture ofpure copper and cupprous oxide, called a eutectic, forms in the open spaces between the dendrites. The eutecticparticles are usually dark, globular bodies dispersed in a copper background. The cuprous oxide particles form anetwork, outlining the dendritic cells. Pores, seen as dark spots in the microstructure, are also present in the as-cast material.

The copper anodes are then refined electrolytically to 99.9% purity. Copper melted under non oxidizing conditions iscalled oxygen free copper. The most popular form of pure copper is the standard electrical wire grade of copper(C11000) contains 99.95% Cu, 0.03% O2, and less than 50 ppm metallic impurities. It has a high electricalconductivity, in excess of 100% IACS. In the as cast form it is called electrolytic tough pitch (ETP) copper. Thestructure of the as-cast material is similar to that described above. When the as-cast ETP copper is hot rolled the eutectic structure is completely destroyed. The microstructure of the hot rolled copper contains many small grains.Parallel straight lines extending across many of the grains are called annealing twins. They appear after a metal hasbeen mechanically worked at a high temperature, called annealing, and deformed. The interdendritic network ofcupprous oxide particles was destroyed by hot rolling. After hot rolling, cupprous oxide particles changed form, andare present as stringers or aligned rows of dark particles. The oxide particles are much larger and fewer in numberthan in the as cast microstructure.

Alloy Family: Coppers Product Form:

Processing: Hot extruded Etchant: Urquhart's Reagent Scale Line Length:

~ 250Microns

Alloy: Temper: Material: Copper

Source: University of Florida


Wire

Processing: Continuous cast 5/16" dia rod, annealed 30 min at 700C drawn to .081" dia, annealed 2 hr at 200C,

Etchant: Scale Line Length:

~ 25Microns


Description: Longitudinal section



Wire

Processing: Continuous cast, 5/16" dia, hot rolled rod, drawn to .081 dia, hard wire, not annealed


~ 25Microns


Description: Transverse section



Wire

Processing: Continuous cast hot rolled 5/16" diameter, hot rolled rod drawn to .081 d hard wire, not annealed


~ 25Microns


Description: Longitudinal section



Wire

Processing: Continuous cast hot rolled rod, annealed 30 min at 700 C, drawn to .081 dia, annealed 2 hr at 200 c


~ 25Microns


Description: Transverse section



Rod

Processing: Etchant: Scale Line Length:

~ 125Microns

Alloy: C10100 Temper: Material: Copper OFHC

Nominal Composition: Cu 99.99



Cast

Processing: As cast Etchant: Scale Line Length:

~ 125Microns

Alloy: C11000 Temper: Material: ETP




Processing: Embrittled Etchant: Scale Line Length:

~ 125Microns





Wire

Processing: Hot rolled Etchant: Scale Line Length:

~ 50Microns





Wire

Processing: Soft annealed Etchant: Scale Line Length:

~ 50Microns





Rod

Processing: Continuous cast, 5/16" dia, hot rolled rod


~ 250Microns


Nominal Composition: Cu 99.90, .026% O2

Description: Transverse section at edge



Rod

Processing: Continuous cast, 5/16" dia, hot rolled rod


~ 250Microns



Description: Longitudinal section at edge



Rod

Processing: Continuous cast, 5/16" dia. hot rolled rod


~ 50Microns



Description: Longitudinal section at edge



Cast


~ 500Microns

Alloy: C12200 Temper: Material: DHP



Cadmium Copper

Overview

Pure unalloyed copper is soft and ductile, and usually contains approximately 0.7% impurities. Cadmium copperalloys are considered high copper alloys, they contain approximately 98 - 99 % copper, 0.1 - 1.5% cadmium and sometimes minor amounts of other materials. When cadmium is added to copper the material becomes moreresistant to softening at elevated temperatures. The more cadmium that is added the more heat resistant thematerial becomes. Small additions of cadmium do not affect the thermal and electrical conductivities, and room temperature mechanical properties of cadmium copper. Cadmium copper is used in applications such as trolley wire,heating pads, electric blanket elements, spring contacts, connectors, and high strength transmission lines. Cadmium copper is used for trolley wire because it is extremely resistant to arc erosion. An extremely heat resistant cadmiumoxide forms on the surface of the wire during arcing and protects it from eroding. This enables the cadmium copperwire to retain its strength under the high temperature conditions of the electric trains. It is also used for solderingapplications, particularly to join components in automobile and truck radiators and semi conductor packagingoperations. The UNS alloy designations for cadmium copper alloys containing approximately 1% cadmium areC16200 and C16500. An alloy containing 0.1 to 0.2% cadmium is designated as C14300. There are no castcadmium copper alloys.

The microstructure of the cadmium copper is similar to the pure copper materials. The alloying elements are in verylow concentrations and they remain in solid solution with the alpha copper. The cadmium coppers are single phasealloys with the alpha copper structure. Cadmium copper is easily cold work and hot formed. Microstructures of the worked materials would contain equiaxed, twinned grains. The structures may contain oxide inclusions throughoutthe grains.

Alloy Family: High copper alloys Product Form:


~ 125Microns

Alloy: C16200 Temper: Material: Cadmium copper

Nominal Composition: Cu 99.8, Cd 0.7-1.2, Fe 0.02



Processing: Cold worked Etchant: Scale Line Length:

~ 50Microns





Wire


~ 125Microns



Description: Wire #10B&S



Sheet

Processing: Temper 1/2 HT Etchant: Scale Line Length:

~ 125Microns


Nominal Composition: Cu 99.8, Cd 0.6-1.0, Sn 0.5-0.7, Fe 0.02



Sheet

Processing: Temper AT Etchant: Scale Line Length:

~ 25Microns





Sheet

Processing: Temper 1/2HM Etchant: Scale Line Length:

~ 250Microns




Beryllium Copper

Overview

Copper beryllium alloys are used for their high strength and good electrical and thermal conductivities. There are twogroups of copper beryllium alloys, high strength alloys and high conductivity alloys.

The wrought high strength alloys contain 1.6 to 2.0% beryllium and approximately 0.3% cobalt. The cast, high-strength alloys have beryllium concentrations up to 2.7%. The high conductivity alloys contain 0.2-0.7% beryllium and higher amounts of nickel and cobalt. These alloys are used in applications such as electronic connectorcontacts, electrical equipment such as switch and relay blades, control bearings, housings for magnetic sensingdevices, non sparking applications, small springs, high speed plastic molds and resistance welding systems. Castberyllium coppers are frequently used for plastic injection molds. The cast materials have high fluidity and canreproduce fine details in master patterns. Their high conductivity enables high production speed, while their good corrosion and oxidation resistance promotes long die life. The UNS designations for the wrought alloys are C17200through C17400 and the cast alloys are C82000 through C82800.

The high strength of the copper beryllium alloys is attained by age hardening or precipitation hardening. The age orprecipitation hardening results from the precipitation of a beryllium containing phase from a supersaturated solidsolution of mostly pure copper. The precipitation occurs during the slow cooling of the alloys because the solubility of beryllium in alpha copper decreases with decreasing temperature. Typically the alloys are rapidly cooled from theannealing treatment, so the beryllium remains in solid solution with the copper. Then the alloy is given a precipitationor age hardening treatment for an hour or more at a temperature between 200 and 460 C. Upon tempering, theberyllium containing phases, called beryllides, precipitate out of solution.

During the first stage of precipitation, there is the homogeneous nucleation of Guinier-Preston (G-P) zones. The G-P zones are small precipitation domains in a supersaturated alpha copper solid solution. The G-P zones have no well defined crystal structure of their own and they contain a high concentration of, in this case, beryllium atoms. The formation of G-P zones usually coincides with a change in properties. In the case of beryllium copper alloys, theproperty change is an increase in strength. As age hardening progresses, coherent metastable gamma double prime precipitates form from the G-P zones. Followed by the precipitation of gamma prime precipitates. The strength ofthese alloys increases as a result of the coherency strains that develop at the interface between the matrix and thegrowing precipitates. Over aging of the copper beryllium alloys is avoided because the equilibrium gamma phaseforms and causes a decreases in strength. The precipitation of the equilibrium gamma phase depletes themetastable gamma prime precipitates, and softens the alloys.

The cast copper beryllium alloys have the typical dendritic structure of alpha (pure) copper, with the addition of theberyllide phases. The general microstructural features of the beryllide phases are similar in the cast and wroughtmaterials. The beryllides can be seen in the as polished condition, it is not necessary to etch the specimens toreveal their structure. Primary beryllides form blue gray intermetallic particles that can be up to 10 microns long.These beryllides form during solidification and have a Chinese script morphology. The secondary beryllides formafter solidification and have a rod like morphology. In the high-strength alloy castings the inter dendritic network iscomposed of alpha and gamma. The gamma double prime and gamma prime precipitates, in both the high conductivity and high strength copper beryllium alloys, are too small to be resolved with an optical microscope, andtherefore do not appear in the optical micrographs. The presence of the age hardening precipitates in the high strength alloys can be detected indirectly by the striations that appear through the grains. The striations result fromthe overlap of coherency strains at the interfaces between the precipitates and the matrix. There are striations on thepolished surface of these alloys when the age hardening precipitates are present and the striations etch very dark.This dark etching is not seen in the high conductivity alloys, the aged and unaged microstructure appear verysimilar. The equilibrium gamma phase appears as dark nodules on a bright matrix in over aged copper berylliumalloys. These gamma precipitates are typically found at the grain boundaries and have a plate like morphology.

The microstructure of the wrought material, after precipitation hardening, contains roughly equiaxed, twinned grains of alpha copper and a dispersion of nickel, cobalt or nickel and cobalt beryllide particles. The grain sizes arerelatively fine due the dispersion of the beryllides. The beryllide particles are roughly spherical and blue gray in color.The beryllides are finer in the wrought material than the cast material because they are broken up during thethermomechanical processing. There is no transformed beta in microstructure of the wrought materials because it isdissolved during thermomechanical processing. The gamma double prime and gamma prime precipitatesresponsible for the age hardening are too small to be resolved directly with an optical microscope. Etching thesample reveals the dark striations associated with the age hardened precipitates.



~ 500Microns

Alloy: C17000 Temper: Material: Beryllium copper

Nominal Composition: Cu 99.5, Be 1.6-1.79




~ 50Microns






~ 125Microns




Alloy Family: High Copper Alloys Product Form:

Strip

Processing: Cast, hot rolled, intermediate annealed, cold rolled, solution annealed and cold rolled 37% to Hard temper

Etchant: Ammonium persulfate/ammonium hydroxide; 1 part NH40H (ammonium hydroxide) (conc) and 2 parts (NH4)2S208(arnmonium persulfate), 2.5% in distilled water

Alloy: C17200 Temper: TD04 Material: Beryllium Copper

Nominal Composition: Be 1.80-2.00, Co + Ni 0.20 min, Co + Ni + Fe 0.6 max, Pb 0.02 max, Cu + Sum of Named Elements 99.5 min

Description: Solution annealed at 790 C (1450 F) and cold rolled 37% to full hard temper. Longitudinal section shows elongated grains of alpha phase and cobalt beryllides.

Source: Brush Wellman


Plate

Processing: Cast, homogenized and hot workedEtchant: Ammonium persulfate/ammonium

hydroxide; 1 part NH40H (ammonium hydroxide) (conc) and 2 parts (NH4)2S208 (ammonium persulfate), 2.5% in distilled water

Alloy: C17200 Temper: M20 (Hot worked) Material: Beryllium Copper


Description: Cast, homogenized and hot worked. The microstructure shows nonuniform distribution of grain sizes, typical of hot worked product. Greater uniformity in grain size distribution may be achieved in the finished product by successive cold working and annealing operations.



Strip

Processing: Cast, hot rolled, intermediate annealed, cold rolled, and solution annealed

Etchant: Ammonium persulfate/ammonium hydroxide; 1 part NH40H (ammonium hydroxide) (conc) and 2 parts (NH4)2S208(anmonium persulfate), 2.5% in distilled water.

Alloy: C17200 Temper: TB00 Material: Beryllium Copper


Description: Solution annealed at 790 C (1450 F), quenched to room temperature. Longitudinal section shows equiaxed grains of supersaturated alpha phase, solid solution of beryllium in copper. Cobalt beryllide particles which do not dissolve during solution annealing are observed.



Strip

Processing: Cast, hot rolled, intermediate annealed, cold rolled, solution annealed and age hardened to maximum hardness

Etchant: Ammonium persulfate/ammonium hydroxide; 1 part NH40H (ammonium hydroxide) (conc) and 2 parts (NH4)2S208 (ammonium persulfate), 2.5% in distilled water

Alloy: C17200 Temper: TF00 Material: Beryllium Copper


Description: Solution annealed at 790 C (1450 F), subsequently precipitation hardened at 315 C (600 F) for 3 h to achieve maximum attainable hardness. Longitudinal section shows equiaxed alpha grains and the cobalt beryllide phase uniformly dispersed throughout the matrix. The strengthening precipitates which result from precipitation heat treatment are not resolved by optical microscopy. Small amounts of equilibrium gamma phase are present in the grain boundaries.



Strip

Processing: Cast, hot rolled, intermediate annealed, cold rolled, solution annealed and mill hardened to specific property ranges

Etchant: Ammonium persulfate/anmonium hydroxide, 1 part NH40H (ammonium hydroxide) (conc) and 2 parts (NH4)2S208 (ammonium persulfate), 2.5% in distilled water

Alloy: C17200 Temper: TM00 Material: Beryllium Copper


Description: Mill hardened to TMOO temper to achieve maximum formability at moderate strength. Longitudinal section shows roughly equiaxed grains of alpha copper-rich solid solution matrix phase. Small cobalt beryllide particles are uniformly dispersed throughout the matrix. Strengthening precipitates which form during precipitation heat treatment are not resolved by optical microscopy.



Strip

Processing: Cast, hot rolled, intermediate annealed, cold rolled, solution annealed, age hardened beyond the maximum hardness condition


Alloy: C17200 Temper: Overaged Material: Beryllium Copper


Description: Solution annealed at 790 C (1450 F), precipitation heat treated at 370 C (700 F) for 6 h to attain the soft overaged condition. The structure shows equiaxed grains of alpha phase and equilibrium gamma precipitates in the grain boundaries, which appear as dark nodules in a light matrix. Striations in alpha matrix are the result of concurrent metastable precipitate formation, not optically resolvable.



Strip

Processing: Cast, hot rolled, intermediate annealed, cold rolled, solution annealed, cold rolled 37% to Hard temper, age hardened to maximum hardness


Alloy: C17200 Temper: TH04 Material: Beryllium Copper Nominal Composition:

Be 1.80-2.00, Co + Ni 0.20 min, Co + Ni + Fe 0.6 max, Pb 0.02 max, Cu + Sum of Named Elements 99.5 min

Description: Solution annealed, cold rolled 37% to Hard temper and precipitation hardened at 315 C (600 F) for 2 h to achieve maximum hardness. Longitudinal section shows elongated grains of alpha phase and cobalt beryllides. Striations are caused by metastable precipitates, not resolved by optical microscopy.



Strip

Processing: Cast, hot rolled, intermediate annealed, cold rolled, solution annealed, rolled and mill hardened to specific property ranges


Alloy: C17200 Temper: TM08 Material: Beryllium Copper

Nominal Composition: Be 1.80-2.00, Co + Ni 0.20 min, Co + Ni + Fe 0.6 max, Ph 0.02 max, Cu + Sum of Named Elements 99.5 min

Description: Mill hardened to TM08 temper for high strength and limited formability. Longitudinal section shows the alpha copper-rich solid solution phase with elongated grains as a result of cold working before precipitation hardening. Cobalt beryllide particles are observed uniformly dispersed throughout the matrix. Striations are caused by metastable precipitation within the alloy. The strengthening precipitates which form during precipitation heat treatment are not resolved by optical microscopy.



Strip

Processing: Cast, hot rolled, intermediate annealed, cold rolled, solution annealed, and age hardened to maximum hardness

Etchant: Cyanide; 1 g KCN (potassium cyanide) and 100 ml. distilled water


Nominal Composition: Be 0.4-0.7, Co 2.4-2.7, Cu + Sum of Named Elements 99.5 min

Description: Solution annealed at 900 C (1650 F), and precipitation hardened at 480 C (900 F) for 3 h to achieve maximum hardness. Equiaxed fine grains of alpha phase are observed with small cobalt beryllide particles uniformly distributed throughout the matrix. The strengthening metastable precipitates are not resolved.



Strip

Processing: Cast, hot rolled, intermediate annealed, cold rolled, solution annealed, cold rolled and age hardened to maximum hardness


Alloy: C17500 Temper: TH04 Material: Beryllium Copper

Nominal Composition: Be 0.4-0.7, Co 2.4-2.7, Cu + Sum of Named Elements 99.5 min

Description: Solution annealed at 900 C (1650 F), cold rolled to Hard temper and precipitation hardened at 480 C (900 F) for 2 h to achieve maximum hardness. Structure consists of elongated fine grains of alpha phase and cobalt beryllide phase uniformly distributed throughout the matrix.



Strip

Processing: Cast, hot rolled, intermediate annealed, cold rolled, solution annealed and age hardened to maximum attainable hardness



Nominal Composition: Be 0.2-0.6, Ni 1.4-2.2, Cu + Sum of Named Elements 99.5 min

Description: Solution annealed at 900 C (1650 F), and precipitation hardened at 480 C (900 F) for 3 h to achieve maximum hardness. Equiaxed grains of alpha phase are observed with small nickel beryllide particles uniformly distributed throughout the matrix.



Strip

Processing: Cast, hot rolled, intermediate annealed, cold rolled, solution annealed, cold rolled and age hardened to maximum hardness

Etchant: Cyanide / peroxide / hydroxide - 20 ml. KCN (potassium cyanide), 5 ml. H202 (hydrogen peroxide), and 1 to 2 ml. NH40H (ammonium hydroxide)

Alloy: C17510 Temper: TH01 Material: Beryllium Copper

Nominal Composition: Be 0.2-0.6, Ni 1.4-2.2, Cu + Sum of Named Elements 99.5 min

Description: Solution annealed at 900 C (I 650 F), cold rolled 11%, and precipitation hardened at 480 C (900 F) for 2 h to achieve maximum hardness. Structure consists of slightly elongated grains of alpha phase, and small nickel beryllide particles. The strengthening metastable precipitates are not resolved.



Casting

Processing: As-cast Etchant: Cyanide - 1 g KCN (potassium

cyanide) and 100 ml. distilled water Alloy: C82200 Temper: Material: Beryllium Copper

Nominal Composition: Be 0.60, Ni 1.5, Cu + Sum of Named Elements 99.5 min

Description: As-cast microstructure showing interdendritic networks of large primary beryllide phase that form during solidification in an alpha copper-rich solid solution matrix. Small needle-like secondary beryllides with preferred crystallographic orientation, which precipitate from solid solution during slow cooling after casting, are observed throughout.



Casting

Processing: Cast, solution annealed and aged Etchant: Ammonium persulfate/ammonium

hydroxide; 1 part NH40H (ammonium hydroxide) (conc) and 2 parts (NH4)2S208 (ammonium persulfate), 2.5% in distilled water


Nominal Composition: Be 2.06, Co 0.50, Si 0.25, Cu + Sum of Named Elements 99.5 min.

Description: Cast, solution annealed at 790 C (1450 F) and aged to peak hardness (Rockwell C38-43), at 315 C (600 F) for 3 h. Microstructure shows script beryllides, and angular beta phase, transformed to a lamellar aggregate of alpha and gamma phases, in an alpha copper-rich solid solution matrix. Striations are the result of metastable precipitation in the alloy.


Chromium Copper

Overview

Chromium copper alloys are high copper alloys, containing 0.6 to 1.2% Cr. The chromium copper alloys are used for their high strength, corrosion resistance and electrical conductivity. The chromium copper alloys are age hardenable,which, in this case, means that a change in properties occurs at elevated temperature due to the precipitation of chromium out of the solid solution. The strength of fully aged chromium copper is nearly twice that of pure copperand it’s conductivity remains high at 85% IACS, or 85% that of pure copper. These high strength alloys retain theirstrength at elevated temperatures. The corrosion resistance of chromium copper alloys is better than that of purecopper because chromium improves the chemical properties of the protective oxide film. Chromium copper hasexcellent cold formability and good hot workability. It is used in applications such as resistance welding electrodes,seam welding wheels, switch gears, cable connectors, circuit breaker parts, molds, spot welding tips, and electricaland thermal conductors that require strength. Chromium copper alloys are designated as UNS C18050 throughC18600, the cast alloys are C81400 through C81540.

The age hardening reaction occurs because the solid solubility of chromium in copper decreases as the temperaturedecreases. The structure of slow cooled chromium copper is a two phase mixture of chromium and alpha copper.Superior mechanical properties are achieved by fast-cooling the chromium copper alloys from the annealingtemperature, so the chromium remains in a supersaturated solid solution with the copper. Followed by an agingtreatment where the chromium precipitates from the solid solution forming a very fine dispersion of precipitates in thematrix. The microstructure of a quenched or quickly cooled chromium copper alloy appears similar to that of the unalloyed copper. A fast cool prevents the chromium from precipitating out of the solid solution, so the resulting caststructure consists of a single phase alpha copper structure. The first material to solidify is pure copper, followed by aeutectic mixture of alpha and chromium. The alpha and chromium eutectic material forms a lamellar structure in theinterdendritic regions. The microstructure of the wrought alloy consists of equiaxed, twinned grains of alpha coppersolid solution. Typically the allow are cooled rapidly so the chromium remains in alpha copper solid solution. Thetempering treatment allows the chromium to precipitate out of solution forming a dispersion of chromium precipitatesthroughout the matrix. The chromium precipitates, or hardening precipitates, can be very fine and may not be visibleat low magnifications.


Processing: Age hardened and drawn 20% Etchant: Scale Line Length:

~ 500Microns

Alloy: C18200 Temper: Material: Chromium copper

Nominal Composition: Cu 99.5, Cr 0.6-1.2, Si 0.10, Fe 0.10, Pb 0.05




~ 250Microns


Nominal Composition: Cu 99.5, Cr 0.6-1.2, Si 0.10, Fe 0.10, Pb 0.05




~ 50Microns


Nominal Composition: Cu 99.8, Cr 0.4-1.0, Pb .015, P .04




~ 50Microns






~ 25Microns






~ 125Microns






~ 50Microns






~ 25Microns




Brasses

Overview

Brasses are copper zinc alloys. In general, they have good strength and corrosion resistance, although theirstructure and properties are a function of zinc content. Alloys containing up to approximately 35% zinc are singlephase alloys, consisting of a solid solution of zinc and alpha copper. These brasses have good strength and ductility,and are easily cold worked. The strength and ductility of these alloys increases with increasing zinc content. Thealpha alloys can be differentiated by a gradual change in color, from golden yellow to red, as the zinc content isincreased up to 35%. Gilding 95%, Commercial Bronze, Jewelry Bronze, Red Brass and Cartridge Brass are in thiscategory of brasses. These are known for their ease of fabrication by drawing, high cold worked strength andcorrosion resistance. Increasing the zinc content up to 35 % produces a stronger, more elastic brass alloy with amoderate decrease in corrosion resistance. Brasses containing between 32 and 39% zinc have a two phase structure, composed of alpha and beta phases. Yellow brasses are in this intermediate category of brasses. Brassescontaining more than 39% zinc, such as Muntz metal, have a predominantly beta structure. The beta phase isharder than the alpha phase. These materials have high strengths and lower ductility at room temperature than thealloys containing less zinc. The two phase brasses are easy to hot work and machine, but cold formability is limited.Brasses are used in applications such as blanking, coining, drawing, piercing, springs, fire extinguishers, jewelry,radiator cores, lamp fixtures, ammunition, flexible hose, and the base for gold plate. Brasses have excellentcastability, and a good combination of strength and corrosion resistance. The cast brasses are used in applications such as plumbing fixtures, fittings and low pressure valves, gears, bearings, decorative hardware and architecturaltrim. The UNS designations for wrought brasses includes C20500 through C28580, and C83300 through C85800 for cast brasses.

Certain brasses can corrode in various environments. Dezincification can be a problem in alloys containing morethan 15% zinc in stagnant, acidic aqueous environments. Dezincification begins as the removal of zinc from thesurface of the brass, leaving a relatively porous and weak layer of copper and copper oxide. The dezincification canprogress through the brass and weaken the entire component. Stress corrosion cracking can also be a problem forbrasses containing more than 15% zinc. Stress corrosion cracking of these brasses occurs when the componentsare subject to a tensile stress in environments containing moist ammonia, amines, and mercury compounds. If eitherthe stress or chemical environment is removed the stress corrosion cracking will not occur. Sometimes a stressrelieving treatment is sufficient to prevent stress corrosion cracking from occurring. The microstructure of the singlephase brass alloys, with up to 32% zinc, consists of a solid solution of zinc and alpha copper. The as-cast structure of the low zinc brasses consists of alpha dendrites. The first material to solidify is almost pure copper, as thedendrites continue to solidify they become a mixture of copper and zinc. A composition gradient exists across the dendrite, with zero zinc content at the center and highest zinc content at the outer edge. The composition gradient iscalled coring, and it typically occurs with alloys that freeze over a wide temperature range. Subsequent working andannealing breaks up the dendritic structure. The resulting microstructure consists of twinned, equiaxed grains ofalpha brass. The annealed microstructure is made up of equiaxed, twinned grains of alpha copper, similar to thestructure of unalloyed copper. The grains appear in different shades due to their different orientations. The twins areparallel lines that extend across individual grains. The twins result from a fault in the staking sequence of the copperatoms, making it difficult to distinguish the individual grains.

Alpha copper is the primary phase in cast alloys containing up to approximately 40% zinc. The beta phase,which isthe high zinc phase, is the minor constituent filling in the areas between the alpha dendrites. The microstructure ofbrasses containing up to approximately 40% zinc consists of alpha dendrites with beta surrounding the dendrites.The wrought materials consist of grains of alpha and beta. Cast alloys with greater than 40% zinc contain primarydendrites of beta phase. If the material is fast-cooled, the structure consists entirely of beta phase. During a slowercool, the alpha precipitates out of solution at the crystal boundaries, forming a structure of beta dendrites surroundedby alpha. This structure is called a Widmanstatten structure, because a geometrical pattern of alpha is formed on thecertain crystallographic orientations of the beta lattice. The wrought, two phase material consists of grains of betaand alpha. Hot rolling tends to elongate the grains in the rolling direction.

Brasses frequently contain lead in order to improve machinability. The microstructure of the leaded brasses is similarto that of the unleaded brasses with the addition of almost pure lead particles found in the grain boundaries andinter-dendritic spacings. The lead is observed in the microstructure as discrete, globular particles because it ispractically insoluble in solid copper. The number and size of the lead particles increases with increasing leadcontent.

Alloy Family: Brasses Product Form:


~ 500Microns

Alloy: C21000 Temper: Material: Guilding, 95%

Nominal Composition: Cu 97.0-98.0, Zn 1.9-3.0, Fe 0.05, Pb 0.02



Wrought


~ 125Microns





Wrought


~ 25Microns






~ 50Microns

Alloy: C22000 Temper: Material: Commercial bronze, 90%





~ 500Microns





Wrought


~ 125Microns





Wrought


~ 25Microns

Alloy: C23000 Temper: Material: Red brass, 85%




Wrought


~ 250Microns

Alloy: C23000 Temper: Material: Red brass, 85%




Wrought


~ 125Microns

Alloy: C26000 Temper: Material: Cartridge brass, 70%

Nominal Composition: Cu 68.5-71.5, Zn 28.38-31.38, Pb 0.07, Fe 0.05



Wrought


~ 25Microns

Alloy: C26000 Temper: Material: Cartridge brass, 70%

Nominal Composition: Cu 68.5-71.5, Zn 28.38-31.38, Pb 0.07, Fe 0.05


Alloy Family: High strength yellow brasses Product Form:

Cast


~ 25Microns

Alloy: C86300 Temper: Material: Manganese bronze

Nominal Composition: Cu 60-66, Zn 22-28, Al 5.0-7.5, Mn 2.5-5.0, Fe 2.0-4.0, Ni 1.0, Pb 0.20 , Sn 0.20


Alloy Family: High strength yellow brasses Product Form:

Cast ingot


~ 125Microns

Alloy: C86300 Temper: Material: Manganese bronze

Nominal Composition: Cu 60-66, Zn 22-28, Al 5.0-7.5, Mn 2.5-5.0, Fe 2.0-4.0, Ni 1.0, Pb 0.20 , Sn 0.20


Silicon Brasses

Overview

Silicon brasses are part of the subgroup of high strength brasses. These materials contain less than 20% zinc andless than 6% silicon. The silicon brasses are solid solution strengthened. These silicon brasses are typically chosenbecause of their high strength and moderately high corrosion resistance. The conductivity of the silicon brasses ismuch less than that of unalloyed copper. The silicon red brasses are used for valve stems where corrosion and highstrength are critical. The wrought silicon red brasses are designated as UNS C69400 through C69710. Included inthis category are the silicon red bronzes. These alloys are similar to the silicon red brasses except they contain verylow concentrations of zinc. The silicon red bronze alloys are designated UNS C47000 through C66100. The castsilicon red brasses are C87300 to C87900. Silicon brass castings exhibit moderate strength and very good aqueous and atmospheric corrosion resistance. They are used in applications such as bearings, gears, and intricately shapedpump and valve components.

The silicon red brasses are single phase alloys. The zinc and silicon contents of the silicon brasses and bronzes are low enough that the alloying elements remain in solid solution. The microstructure of the cast material containscored dendrites of alpha copper solid solution containing zinc and silicon. The coring occurs because the alloys solidify over a wide temperature range, which allows segregation of the alloying elements. The zinc and siliconcomposition varies form zero at the center of the dendrite to a maximum at the outer edge. The subsequent workingand annealing breaks up the dendrites and results in a structure consisting of equiaxed, twinned grains of alphasolid solution. The microstructure of the wrought materials consists of equiaxed, twinned grains of alpha copper solidsolution.

The microstructure of leaded silicon red brass is similar to the unleaded alloys with exception of lead particlesdistributed in the grain boundaries and inter dendritic areas. The lead solidifies as globules in the grain boundariesbecause it is practically insoluble in solid copper.

Alloy Family: Silicon brasses Product Form:

Wrought


~ 50Microns

Alloy: C69400 Temper: Material: Silicon red brass

Nominal Composition: Cu 80.0-83.0, Si 3.4-5.4, Zn 12.0-13.0, Fe 0.20, Pb 0.30



Cast


~ 25Microns


Nominal Composition: Cu 80.0-83.0, Si 3.4-5.4, Zn 12.0-13.0, Fe 0.20, Pb 0.30, As 0.03-0.06



Cast


~ 50Microns


Nominal Composition: Cu 80.0-83.0, Si 3.4-5.4, Zn 12.0-13.0, Fe 0.20, Pb 0.30, As 0.03-0.06



Cast


~ 50Microns

Alloy: C69710 Temper: Material: Silicon brass

Nominal Composition: Cu 75.0-80.0, Si 2.5-3.5, Zn 14.0-21.4, Fe 0.20, Pb 0.5-1.5, Mn 0.4



Wrought


~ 25Microns





Wrought


~ 50Microns




Alloy Family: Silicon bronzes Product Form:

Cast


~ 500Microns

Alloy: C65500 Temper: Material: High silicon bronze A

Nominal Composition: Cu 94.8, Si 2.8-3.8, Zn 1.5, Mn 0.50-1.3, Fe 0.8, Ni 0.6, Pb 0.05


Alloy Family: Silicon bronzes Product Form:

Cast


~ 25Microns

Alloy: C65500 Temper: Material: High silicon bronze A

Nominal Composition: Cu 94.8, Si 2.8-3.8, Zn 1.5, Mn 0.50-1.3, Fe 0.8, Ni 0.6, Pb 0.05


Tin Brasses

Overview

Tin brass is used for its increased corrosion resistance and somewhat higher strength than straight brass. Thisfamily of alloys is made with zinc contents ranging form 2 to 40% zinc, and 0.2 to 3.0% tin. Tin reduces susceptibilityof the high zinc brass to dezincification. Dezincification is the selective leaching of zinc from the brass leaving aporous copper structure. Arsenic, antimony and phosphorus also reduce the susceptibility of brasses to dezincification. The tin brasses are economical and have slightly better properties than the straight brasses. Theyhave good hot forgeability and reasonably good cold formability. The tin brasses are used in applications such ashigh strength fasteners, electrical connectors, springs, corrosion resistant mechanical products, marine hardware,pump shafts, and corrosion resistant screw machine parts. This category of brasses includes admiralty brasses,naval brasses and free machining tin brasses. The cast tin brasses are called cast red brasses. Alloys that containless than 8% zinc are a red copper like color, and hence the name red brass. Semi red brasses contain up to 15%zinc and are lighter in color than the red brasses. They have reduced corrosion resistance, but retain their good strength. These materials have moderate strength, high atmospheric and aqueous corrosion resistance, andexcellent electrical conductivity. Cast red brasses are also made containing lead which increases their machinability and pressure tightness. The wrought tin brasses are designated by UNS C40400 through C48600. The cast redbrasses are labeled UNS C83300 through C83810 and the cast semi red brasses are UNS C84200 throughC84800.

The microstructure of the tin brasses is dependent on the zinc and tin content of the alloy. Tin brasses with low zincand low tin contents are single phase alloys. The structure consists of alpha copper solid solution containing zincand tin. The cast structures contain cored dendrites, the zinc and tin content of the dendrites increasing from thecenter to the edge of the dendrites. The wrought microstructure contains twinned grains of alpha solid solution.Alloys with higher zinc contents have multi phase structures, made up of alpha and beta. The wroughtmicrostructure contains twinned grains of alpha copper solid solution and beta grains. The cast red brasses haveless than 12% zinc and less than 7% tin. While the semi red cast brasses have up to 17% zinc and less than 6% tin.These alloys have a wide freezing range and segregation of the alloying elements occurs during solidification. Theformation of zinc rich and tin rich beta occurs during solidification. The tin rich phase transforms to alpha plus delta,which fills the areas between the alpha dendrite arms. The wrought structure consists of grains of alpha solidsolution and grains of zinc and tin rich alpha and delta phases.

Alloy Family: Tin brasses Product Form:

Processing: Cast and hot rolled Etchant: Scale Line Length:

~ 50Microns

Alloy: C46400 Temper: Material: Naval brass, unihibited

Nominal Composition: Cu 59.0-62.0, Zn 36.7-40.0, Sn 0.5-1.0, Pb 0.20, Fe 0.10




~ 500Microns





Cast

Processing: as cast Etchant: Scale Line Length:

~ 250Microns





Cast


~ 500Microns




Leaded Brasses

Overview

Lead brasses are used for their high machinability and atmospheric corrosion resistance. The machinability of brassis increased by the addition of lead because it acts as a microscopic chip breaker and tool lubricant. The leadedbrasses are used for copper base screw machine material. The alloys have excellent machinability, good strengthand corrosion resistance. Lead can be added to any brass to increase machinability and provide pressure tightness by sealing the shrinkage pores. There are low, medium and high leaded brasses, with lead contents up to 3.5%. Thelead brasses are used for architectural hardware, general purpose screw machine parts, screws, valves, fittings,bearings and specialty fasteners. The wrought lead brasses are designated by UNS C31200 through C38500. Thecast lead brasses are grouped with their unleaded counter parts, and fall in the range of alloys between C83600through C97300.

The microstructure of the leaded brasses is similar to that of the unleaded brasses. The microstructure of the leadedbrasses contain discrete lead particles primarily in the grain boundaries or inter-dendritic regions. Lead is practically insoluble in solid copper and is present in the cast and wrought materials as discrete particles that appear dark inthe structure. The microstructure of the as cast lead brasses is a function of the zinc content. The lower zinccontaining alloys are single phase solid solution alpha dendrites, with lead particles dispersed throughout the interdendritic regions. Those with a higher zinc content have a two phase structure, consisting of alpha and beta.The higher zinc containing alloys have a microstructure of all beta. The lead appears as discrete particles, appearingdark in the microstructure. The microstructure of the wrought low zinc leaded brasses consists of twinned grains ofalpha with lead particles throughout the matrix. The higher zinc containing alloys contain a mixture of alpha and betaphases and lead particles.

Alloy Family: Leaded brass Product Form:

Cast


~ 125Microns

Alloy: C35000 Temper: Material: Medium leaded brass, 62%

Nominal Composition: Cu 59.0-64.0, Zn 34.5-40.0, Pb 0.8-1.4, Fe 0.10



Cast


~ 25Microns





Wrought


~ 250Microns





Wrought


~ 50Microns





Cast


~ 250Microns

Alloy: C35300 Temper: Material: High leaded brass, 62%




Cast


~ 25Microns

Alloy: C35300 Temper: Material: High leaded brass, 62%




Cast


~ 50Microns

Alloy: C36000 Temper: Material: Free machining brass




Wrought


~ 25Microns

Alloy: C36000 Temper: Material: Free machining brass




Wrought


~ 250Microns

Alloy: C36500 Temper: Material: Leaded Muntz metal, inhibited

Nominal Composition: Cu 58.0-61.0, Zn 38.0-41.0, Pb 0.40-0.9, Sn 0.25, Fe 0.15



Wrought


~ 50Microns





Wrought


~ 25Microns




Phosphor Bronze

Overview

Phosphor Bronzes, or tin bronzes, are alloys containing copper, tin and phosphorous. The phosphor bronzes containbetween 0.5 and 11% tin and 0.01 to 0.35 % phosphorous. The addition of tin increases the corrosion resistanceand strength of the alloy. The phosphorous increases the wear resistance and stiffness of the alloy. The phosphorbronzes have superb spring qualities, high fatigue resistance, excellent formability and solderability, and highcorrosion resistance. They are primarily used for electrical products, other uses include corrosion resistant bellows, diaphragms, and spring washers. The phosphor bronzes are designated as UNS C50100 through C54200. Leadedphosphor bronzes combine good strength and fatigue resistance with good machinability, high wear resistance andcorrosion resistance. They are used in applications such as sleeve bearings, thrust washers, and cam followers.They are designated as UNS C53400 through C54400.

The microstructure of wrought phosphor bronzes contain the twinned grains typical of copper alloys. The tin remainsin the alpha copper solid solution. The phosphorus forms a copper phosphide phase. The phosphor bronzes have awide freezing range and extensive segregation of the alloying occurs on cooling. The material that cools first aredendrites of the copper rich alpha phase. The dendrites are heavily cored, or contain a range of compositions overtheir thickness. The second phase to form is tin rich, initially transforming to beta, and finally to a mix of alpha anddelta. The alpha and delta phases form in between the dendrites. The phosphor rich phase solidifies last as the eutectic composition of copper phosphide. The dendrites are broken up during working and annealing, the resultingstructure consists of grains of alpha copper and are of the alpha and tin rich delta phases, and copper phosphide.

Alloy Family: Phosphor bronzes Product Form:

Processing: Gate MRL Etchant: Scale Line Length:

~ 125Microns

Alloy: C50500 Temper: Material: Phosphor bronze, 1.25% E

Nominal Composition: Cu 97.5-98.5, Sn 1.0-1.7, P 0.03-0.35, Zn 0.30, Fe 0.10, Pb, 0.05



Processing: Gate MRL Etchant: Scale Line Length:

~ 500Microns





Wrought

Processing: Wrought MRL Etchant: Scale Line Length:

~ 125Microns





Cast

Processing: As Cast Etchant: ASTM E407 Etchant #44 - 50 ML

NH40H, 50ML h2o2 (3%), 50ML water

Scale Line Length:

~ 110Microns

Alloy: C51000 Temper: As Cast Material: Phosphor bronzes

Nominal Composition: Sn 4.2-5.8, P 0.03-0.35, Fe 0.10 max, Pb 0.05 max, Zn 0.30 max, Cu remainder

Description: Horizontally, continuous cast bar. The as cast structure is a coarse grained structure containing alpha solid solution dendrites surrounded by globules of alpha solid solution.

Source: The Miller Company


Strip

Processing: Hard rolled and annealed to 0.035-0.040 mm average Grain Size

Etchant: ASTM E407 Etchant #44 - 50 ML NH40H, 50ML h2o2 (3%), 50ML water

Scale Line Length:

~ 440Microns

Alloy: C51000 Temper: Annealed Material: Phosphor bronzes


Description: Cold rolled and annealed metal. A re-crystallized alpha grain with annealing twins structure.



Strip

Processing: Hard rolled and annealed to 0.005 mm average Grain Size.


Scale Line Length:

~ 440Microns



Description: Cold rolled and annealed metal. Structure consists of small equated grains of alpha solid solution.



Cast

Processing: As Cast Etchant: ASTM E407 Etchant #44 - 50 ML

NH40H, 50ML h2o2 (3%), 50ML water

Scale Line Length:

~ 110Microns

Alloy: C52100 Temper: As Cast Material: Phosphor bronzes


Description: Horizontally, continuous cast bar. The as cast structure is coarse grained structure containing alpha solid solution dendrites surrounded by alpha solid solution.



Strip

Processing: Hard rolled and annealed to 0.035-0.040 mm average Grain Size


Scale Line Length:

~ 440Microns



Description: Cold rolled and annealed metal. A re-crystallized alpha grain with annealing twins structure.



Strip

Processing: Hard rolled and annealed to 0.005 mm average Grain Size.


Scale Line Length:

~ 440Microns



Description: Cold rolled and annealed metal. Structure consists of small equated grains of alpha solid solution.


Aluminum Bronzes

Overview

Aluminum bronzes are used for their combination of high strength, excellent corrosion and wear resistance.Aluminum bronze alloys typically contain 9-12% aluminum and up to 6% iron and nickel. Alloys in these compositionlimits are hardened by a combination of solid solution strengthening, cold work, and precipitation of an iron richphase. High aluminum alloys are quenched and tempered. Aluminum bronzes are used in marine hardware, shaftsand pump and valve components for handling seawater, sour mine waters, nonoxidizing acids, and industrialprocess fluids. They are also used in applications such as heavy duty sleeve bearings, and machine tool ways. Theyare designated by UNS C60800 through C64210. Aluminum bronze castings have exceptional corrosion resistance,high strength, toughness and wear resistance and good casting and welding characteristics. Aluminum bronzecastings are designated as UNS C95200 to C95900.

The microstructure of the aluminum bronzes with less than 11% aluminum consist of alpha solid solution and the iron and nickel rich kappa phase. The kappa phase absorbs aluminum from the alpha solid solution preventing theformation of the beta phase unless the aluminum content is above 11%. The kappa phase increases the mechanicalstrength of the aluminum bronzes, with no decrease in ductility. The decrease in ductility of the aluminum bronzesoccurs when the beta phase forms. The beta phase is harder and more brittle than the alpha phase. Beta is formedif the material is quenched or fast cooled, which then transforms into a hard, acicular martensite structure.Tempering the martensite results in a structure of alpha with kappa precipitates. The tempered structure is verydesirable, it has high strength and hardness. The slow cooled, as cast structures consist of alpha and kappa phases. Kappa is present in the lamellar form and finely divided in all the alpha areas. The addition of iron and nickel alsosuppress the formation of the gamma double prime phase which has deleterious effects on the properties of aluminum copper alloys.

Alloy Family: Aluminum bronzes Product Form:

Plate


~ 125Microns

Alloy: C61300 Temper: Material: Aluminum bronze, 6-7.5 Al

Nominal Composition: Cu 90.83, Al 6.5, Fe 2.4, Sn 0.27



Rod

Processing: Extruded and cold drawn Etchant: Scale Line Length:

~ 125Microns


Nominal Composition: Cu 90.83, Al 6.5, Fe 2.4, Sn 0.27



Rod

Processing: Extruded and cold drawn 10% Etchant: Scale Line Length:

~ 25Microns


Nominal Composition: Cu 87.1, Al 9.3, Fe 3.6



Rod

Processing: Extruded Etchant: Scale Line Length:

~ 50Microns

Alloy: C62500 Temper: Material: Aluminum bronze, 12.5-13.5 Al




Processing: As quenched from 857C Etchant: Scale Line Length:

~ 25Microns

Alloy: C63000 Temper: Material: Nickel-aluminum bronze, 9.0-11.0

Al, 4.0-5.5 Ni

Nominal Composition: Cu 82.5, Al 9.7, Ni 4.9, Fe 2.9



Rod

Processing: Extruded and cold drawn Etchant: Scale Line Length:

~ 125Microns

Alloy: C63000 Temper: Material: Nickel-aluminum bronze, 9.0-11.0

Al, 4.0-5.5 Ni

Nominal Composition: Cu 82.5, Al 9.7, Ni 4.9, Fe 2.9



Processing: Extruded Etchant: Scale Line Length:

~ 125Microns

Alloy: C63200 Temper: Material: Nickel-aluminum bronze, 8.7-9.5 Al

, 4.0-4.8 Ni

Nominal Composition: Cu 80.4, Al 8.9, Ni 5.0, Fe 4.7, Mn 1.0



Processing: Quenched from 927C and tempered at 705C


~ 500Microns

Alloy: C63200 Temper: Material: Nickel-aluminum bronze, 8.7-9.5 Al

, 4.0-4.8 Ni

Nominal Composition: Cu 80.4, Al 8.9, Ni 5.0, Fe 4.7, Mn 1.0



Cast

Processing: Cast, annealed at 621C and water quenched


~ 500Microns





Cast

Processing: Annealed and furnace cooled Etchant: Scale Line Length:

~ 50Microns





Cast

Processing: Annealed at 621C and water quenched


~ 25Microns





Cast

Processing: Cast and quenched from 913C Etchant: Scale Line Length:

~ 125Microns





Cast

Processing: Cast and heat treated Etchant: Scale Line Length:

~ 250Microns

Alloy: C95500 Temper: Material: Nickel-aluminum bronze, 10-11.5

Al, 3-5.5 Ni, Mn 3.5

Nominal Composition: Cu 78 min, Al 10.0-11.5, Ni 3.0-5.5, Fe 3.0-5.0, Mn 3.5



Cast

Processing: Annealed at 621C and air cooled Etchant: Scale Line Length:

~ 25Microns

Alloy: C95800 Temper: Material: Nickel-aluminum bronze, 9 Al, 4.5

Ni

Nominal Composition: Cu 81.4, Al 8.9.5, Ni 4.7, Fe 4.0, Mn 1.0



Cast


~ 25Microns


Ni




Cast


~ 125Microns


Ni



Copper Nickels

Overview

Copper nickel alloys are very corrosion resistant and thermally stable. The copper nickel alloys contain from 2 to30% nickel depending upon the application. These alloys usually have additions of iron, chromium, niobium, and ormanganese to improve the strength and corrosion resistance. They are virtually immune to stress corrosion cracking and exhibit high oxidation resistance in steam and moist air. The copper nickel alloys have moderate strength evenat elevated temperatures. The higher nickel alloys are well known for their corrosion resistance in sea water andtheir resistance to marine biofouling. The copper nickel alloys are used in applications such as electrical andelectronic products, tubes for condensers in ships and power plants, various marine products including valves,pumps, fittings and sheathing for ship hulls. The wrought alloys are designated as UNS C70100 through C72950.The cast alloys are C96200 to C96900. Cast copper nickel alloys are typically used aboard ships, on offshoreplatforms and in coastal power plants.

Copper nickel alloys are single phase alpha structures because nickel is completely soluble in copper. The as castdendrites are heavily cored, they contain a composition gradient, because the alloys freeze over a wide temperaturerange. The as cast structures consist of alpha dendrites, that have an increasing nickel content from the center tothe edge of the dendrite. The interdendritic regions, being the last liquid to solidify are high in nickel too. Mechanicaltreatments break up the dendritic structure, but even repeated mechanical and thermal treatments do nothomogenize the alloying elements. Segregation of the alloying elements, which starts out as coring of the dendrites,is seen as banding in the wrought microstructures. The microstructure of the wrought materials is similar to that of unalloyed copper, it consists of twinned grains of alpha copper. The banding of the alloying elements shows up asdark rows or stripes across the grains.

Alloy Family: Copper-nickels Product Form:

Processing: Annealed Etchant: Scale Line Length:

~ 125Microns

Alloy: C70600 Temper: Material: Copper-nickel, 10%

Nominal Composition: Cu 86.5, Ni 9.0-11.0, Fe 1.0-1.8, Zn 1.0, Mn 1.0, Pb 0.05



Processing: Annealed Etchant: Scale Line Length:

~ 25Microns

Alloy: C70600 Temper: Material: Copper-nickel, 10%

Nominal Composition: Cu 86.5, Ni 9.0-11.0, Fe 1.0-1.8, Zn 1.0, Mn 1.0, Pb 0.05



Wrought


~ 25Microns

Alloy: C72500 Temper: Material: Copper-nickel, 10% Ni, 2% Sn

Nominal Composition: Cu 85.35-88.35, Ni 8.5-10.5, Sn 1.2-2.8, Fe 0.6, Zn 0.50, Pb 0.05



Wrought


~ 125Microns

Alloy: C72500 Temper: Material: Copper-nickel, 10% Ni, 2% Sn

Nominal Composition: Cu 85.35-88.35, Ni 8.5-10.5, Sn 1.2-2.8, Fe 0.6, Zn 0.50, Pb 0.05


Nickel Silvers

Overview

Nickel silvers are alloys that contain copper, nickel, and zinc. They are also called nickel brasses, the silver refers totheir attractive silver luster. The nickel silvers have moderately high strength and good corrosion resistance. Thecast nickel silvers are copper, tin, lead, zinc, nickel alloys. They too are named for their silvery luster. They have lowto moderate strength and good aqueous corrosion resistance. They are used in the food and beverage handling equipment, decorative hardware, electroplated table ware, optical and photographic equipment and musicalinstruments. The copper silvers are designated as UNS C73500 through C79800, the cast alloys are UNS C97300to C97800.

The microstructures of the nickel silvers are predominantly single phase solid solution alloys. The wrought nickelsilvers contain between 7 and 20% nickel, and 14 and 46% zinc. The structure of the higher zinc alloys is a twophase structure, similar to that of the high zinc brasses. The nickel is soluble in copper, so it remains in solid solutionwith the copper. Zinc has limited solubility in copper. Alloys with more than approximately 32% zinc consist of alphaand beta phases. These alloys solidify over a wide range of temperatures, the resulting cast microstructure containscored dendrites, or dendrites with a composition gradient across the thickness. The composition of the material inbetween the dendrite arms is rich in zinc and nickel. The wrought structures of the alloys with less than 32% zinc are single phase equiaxed, twinned grains of alpha copper. The two phase alloys contain a mix of alpha and beta grains.

Alloy Family: Nickel-silvers Product Form:

Wrought


~ 125Microns

Alloy: C73500 Temper: Material: Nickel-silver, 72-18

Nominal Composition: Cu 70.5-73.5, Ni 16.5-19.5, Zn 6.15-9.15, Mn 0.50, Fe 0.25, Pb 0.10



Wrought


~ 25Microns


Nominal Composition: Cu 57.0- 61.0, Ni 11.0-13.5, Zn 24.65-31.15, Mn 0.50, Fe 0.25, Pb 0.10



Wrought


~ 125Microns


Nominal Composition: Cu 57.0- 61.0, Ni 11.0-13.5, Zn 24.65-31.15, Mn 0.50, Fe 0.25, Pb 0.10



Cast


~ 250Microns


Nominal Composition: Cu 63-67, Ni 19.0-21.5, Zn 3-9, Sn 3.5-4.5, Pb 3-5, Fe 1.5, Mn 1.0, Sb 0.25, S 0.08



Cast


~ 50Microns


Nominal Composition: Cu 63-67, Ni 19.0-21.5, Zn 3-9, Sn 3.5-4.5, Pb 3-5, Fe 1.5, Mn 1.0, Sb 0.25, S 0.08


Titanium Coppers

Alloy Family: Copper-titanium alloys Product Form:

Cast


~ 25Microns

Alloy: Temper: Material: Copper-4 Ti

Nominal Composition: Cu, 4Ti



Cast

Processing: Cold worked and aged Etchant: Scale Line Length:

~ 50Microns





Cast


~ 500Microns





Cast


~ 25Microns

Alloy: Temper: Material: Copper-5 Ni-2.5 Ti

Nominal Composition: Cu, 5 Ni, 2.5 Ti



Cast


~ 125Microns

Alloy: Temper: Material: Copper-5 Ni-2.5 Ti

Nominal Composition: Cu, 5 Ni, 2.5 Ti


Copper Tin Alloys

Overview

Copper tin alloys or tin bronzes are known for their corrosion resistance. Tin bronzes are stronger and more ductilethan red and semi red brasses. They have high wear resistance and low friction coefficient against steel. Tinbronzes, with up 15.8% tin, retain the structure of alpha copper. The tin is a solid solution strengthener in copper, even though tin has a low solubility in copper at room temperature. The room temperature phase transformationsare slow and usually do not occur, therefore these alloys are single phase alloys. The tin bronzes are used in bearings, gears, piston rings, valves and fittings. The cast tin bronzes are designated by UNS C90200 throughC91700. Lead is added to tin bronzes in order to improve machinability and pressure tightness. Lead decreases thetensile strength and ductility of the tin bronzes, but the composition can be adjusted to balance machinability andstrength requirements. High leaded tin bronzes are primarily used for sleeve bearings. These alloys have a slow failmechanism that temporarily prevents galling and seizing. The slow fail mechanism works by lead seeping out of thealloy and smearing over the surface of the journal. The cast leaded tin bronzes are designated as UNS C92200through C94500.

The microstructure of the cast tin bronzes consists of cored dendrites, they have a composition gradient of increasing tin as they grow. The last liquid to solidify is enriched with tin upon cooling, and forms alpha and deltaphases. The alpha and delta phases fill in the areas between the dendrite arms. the microstructure of the leaded tin bronzes are similar to the nonleaded materials with the addition of lead particles in the inter-dendritic boundaries. The lead is practically insoluble in solid copper and it solidifies last as almost pure lead in the grain boundaries.

Alloy Family: Copper-tin alloys Product Form:

Cast


~ 50Microns

Alloy: C90700 Temper: Material: Tin bronze

Nominal Composition: Cu 88-90, Sn 10-12, Pb .50, Zn .50, Ni .50, P .30, Sb .20, Fe .15, S .05, Al .005



Cast


~ 50Microns

Alloy: C90700 Temper: Material: Tin bronze

Nominal Composition: Cu 88-90, Sn 10-12, Pb .50, Zn .50, Ni .50, P .30, Sb .20, Fe .15, S .05, Al .005



Cast


~ 25Microns

Alloy: C93200 Temper: Material: High leaded tin bronze, 6-8 Pb

Nominal Composition: Cu 81-85, Pb 6-8, Sn 6.3-7.5, Zn 2-4, Ni 1.0, Sb .35, Fe .2, P .15, Al .15, Si .005



Cast


~ 125Microns


Nominal Composition: Cu 81-85, Pb 6-8, Sn 6.3-7.5, Zn 2-4, Ni 1.0, Sb .35, Fe .2, P .15, Al .15, Si .005



Cast


~ 25Microns


Nominal Composition: Cu 78-82, Pb 8-11, Sn 9-11, Zn 0.8, Ni 1.0, Sb .55, Fe .15, P .15, Al .15, S 0.8



Continous cast


~ 250Microns





Continous cast


~ 25Microns




Leaded Coppers

Overview

Lead is frequently added to copper alloys to increase their machinability. The role of lead in copper alloys is two fold,it acts as a lubricant and, in the free machining grades, the lead assists in chip break up. Lead is added to manycopper alloys, making all types of free machining alloys. Lead does not affect the structure and properties of copperbecause it is practically insoluble in solid copper. The pure copper solidifies first, leaving the lead to solidify last as almost pure lead globules at the grain boundaries or in the inter dendritic regions. The size and concentration of leadparticles depends upon the concentration of lead in the alloy. Leaded coppers are categorized as low lead alloys, or free machining alloys and high lead alloys. In the free machining alloys, the lead acts as chip breaker and lubricantmaking these alloys easier to machine than their non leaded counter parts. The high leaded copper alloys are used in bearing applications. In the bearing materials, the lead acts as a solid lubricant and the copper is the load bearingsupport. Lead is added to many of the copper alloys producing free machining brasses, bronzes and other copperalloys. The free machining brasses and other alloys are presented in the sections with the specific alloy types. Thecast, high leaded copper alloys used for bearings are presented in this section. They are designated by UNSC98200 through C98840.

The microstructure of the leaded copper alloys is similar to the structure of the unalloyed copper materials with theaddition of almost pure lead particles in the grain boundaries. The size and amount of lead particles in the structuresdepends on the concentration of lead in the alloy. The microstructure of the as cast copper lead alloys consists ofpure alpha copper dendrites, with lead globules in the boundaries between the dendrites. The higher the leadcontent of the alloy the more lead globules present in the structure. In the wrought structures, the lead is present as discrete particles between the alpha copper grains.

Alloy Family: Copper-lead alloys Product Form:

Cast


~ 500Microns

Alloy: Temper: Material: Copper-4.5 Pb

Nominal Composition: Cu, 4.5Pb



Cast


~ 50Microns





Cast


~ 50Microns





Cast


~ 250Microns

Alloy: Temper: Material: Copper-35 Pb

Nominal Composition: Cu 35.2Pb

Description: Unetched



Cast


~ 50Microns

Alloy: Temper: Material: Copper-35 Pb

Nominal Composition: Cu 35.2Pb


Grain Size Comparisons

Alloy Family: Product Form:

Processing: Grain size 0.010 mm Etchant: Scale Line Length:

~ 500Microns

Alloy: Temper: Material:




~ 500Microns





~ 500Microns





~ 500Microns





~ 500Microns





~ 500Microns





~ 500Microns





~ 500Microns





~ 500Microns





~ 500Microns





~ 500Microns





~ 500Microns





~ 500Microns



General, Atomic and Crystallographic Properties and Features of Copper

Source: "Properties of Copper and Copper Alloys at Cryogenic Temperatures" by N.J. Simon, E.S. Drexler, and R.P. Reed ( NIST MN 177)

General and Atomic Properties of Copper

Atomic Number 29 Atomic Weight 63.546 Atomic Diameter 2.551 x 10-10m Melting Point 1356 K Boiling Point 2868 K Density at 293 K 8.94 x 103 kg/m3 Electronic Structure 3d104s Valence States 2,1 Fermi Energy 7.0 eV Fermi Surface spherical, necks at [111] Hall Coefficient -5.12 x 10-11 m3/(A.S) Magnetic State diamagnetic Heat of Fusion 134 J/g Heat of Vaporization 3630 J/g Heat of Sublimation @ 1299 K 3730 J/g

Crystallographic Features of Copper

Type of Structure A1 Space Group Oh

5 - Fm3m Crystal Structure face-centered cubic Number of Atoms per Unit Cell 4 Lattice Parameters at 293 K 3.6147 x 10-10 m Distance of Closest Atomic Approach (Burgers vector) at 293

2.556 x 10-10m

Goldschmidt Atomic Radii (12-fold coordination)

1.28 x 10-10m

Atomic Volume 1.182 10-29m3

European 'CEN' Standard Designations In this document:

The CEN standards being produced for European materials are being adopted without modification by all European countries. They are being dual numbered and published in each country by the relevant national standards organisation. Conflicting national standards must be withdrawn within six months. The standards include all materials already in common use in Europe and have a new designation system to give a common terminology in all countries.

Describing materials by a recognised designation system is very important in order that orders can be placed with a clear understanding that correct materials will be procured. Such systems are an essential part of material standardisation common to all countries. There are, however, many different systems in use throughout the world. There are three basic types of designations based either on terms, symbols or numbers. For European CEN standards, a numbering system has been developed that can be easily understood by personnel with or without computers and that has a common meaning across all countries and all languages. This systems does not conflict with any others in use elsewhere in the world.

Historical

There are many numbering systems in existence of recognised significance throughout the world. Many of these are the subject of extensive trade references and have been based on carefully conceived concepts. Many other designations are also well established and, by virtue of their long history of usage, have become very well known to the individuals and areas of commerce in which they are employed. Some confusion can be caused when they are used outside the usual sphere of influence.

One of the biggest, most well-known, systems is the Unified Numbering System developed by the National Bureau of Standards in the USA. This predominates throughout most ASTM (American Society for Testing and Materials)Standards used extensively through North America and significantly in other parts of the world by organisations with North American connections. The administration of this system is based in North America. It has proved impossible to adopt it to a system suitable for other national and international preferences. Similar considerations apply to other national systems.

A common designation system used within International Standards Organisation (ISO) is a compositional system described in ISO 1190 Pt 1, based on the element symbols and the descending order of magnitude of alloying elements. For example, a leaded brass containing 60% copper and 2% lead is designated CuZn38Pb2. This system is easy to use by humans but can be unwieldy when used to describe complex alloys with many alloying elements. It can be difficult to sort and index using computer programs. It has, however, been widely adopted throughout Europe during the last 20 years or so as many countries have been adapting ISO Standards with modifications for use as national standards. It is also now common practice in European technical meetings for materials to be referred to by this compositional designation. The use of common names or trade names causes confusion to those unfamiliar with them.

Some time ago the International Standards Organisation (ISO) published Technical Report No TR 7003 "International Numbering System for Metals". This gave a very logical system by which designations could be established with an alpha-numerical series of numbers easily understood by computers. For ISO purposes, there was not much impetus towards its adoption. With the onset of the mandatory nature of the European CEN standards, this attitude has changed. This has resulted in discussions to formulate a European Numbering System.

Designation Requirements

During discussions in working groups and committees preparing the standards, it became obvious that agreement on a computer-friendly numbering system was essential. It was agreed that there was a need to keep a designation simple, and to be able to define the material as closely as possible including, if achievable, composition, form (type of wrought product or casting) and main mandatory properties (such as tensile strength, hardness or proof stress). The possibility of using a simple numbering system was considered but proved impractical because of the limited number of variations possible. It was agreed, therefore, that an alpha-numerical system would be used. In a six digit system there is a possibility of only one million variations in an all-numerical system, whereas in an alpha-numerical system of three letters and three digits, not only can the letters appear to be more meaningful but over 12 million combinations are possible.

CEN numbering system for copper and copper alloys

Having agreed to use a basic six-digit system, CEN/TC 132 agreed to use C as the first letter to indicate a copper alloy. A second letter was introduced to indicate the material state (i.e. W for a wrought material, B for ingots, C for castings and M for master alloys). Three numbers are then used to identify the material and a final third letter is used to identify the classification of individual copper material groups and to enlarge the capacity. This also prevents confusion with the existing BSI designations and the old C/three-digit CDA numbers administered by Copper Development Association, New York.

This system will cater for both CEN materials and other non-standardised materials, but initial allocations have been made for the numbers to ensure a minimum of confusion within CEN preferred materials. This means that not every material sub-group starts at number '1'. As an example, while coppers do commence at 001, miscellaneous copper alloys start at 100, copper aluminium alloys start at 300, copper zinc alloys at 500 and so on, as shown in Table 1, below.

The lack of overlap in preferred number series ensures that common materials in differently lettered material groups will not normally share the same number. There will, however, be many spare numbers available in reserve.

Temper Designations

For temper designations CEN TC 133 covering copper and copper alloys has agreed to use a system similar to that already established by DIN indicating the minimum value of specified properties. For example, tensile strength R 250 indicates the minimum of 250 N/mm² while a hardness of H090 indicates a value of 90 (Vickers for wrought materials and Brinell for cast) and Y140 indicates a minimum 0.2% proof stress of 140 N/mm². This meets the requirements of the wide variety of customers who have individual needs for special properties to ensure fitness for purpose but do not need to know the way in which a temper was originally produced.

Table 3: Letter Symbols for property designations

A Elongation B Spring bending limit G Grain size H Hardness (Brinell for castings, Vickers for wrought products) M (as) Manufactured, i.e. without specified mechanical propertiesR Tensile strength Y 0.2% proof stress

Microstructures of Copper Alloys

Documents

scale line

gamma double

continuous

free machining

achieve maximum

wide freezing

international

coarse grained