Volume 20 - Materials Selection and Design Part 7 potx

T7
Solution treated, quenched, and
overaged/stabilized
Wrought products that are overaged to carry them beyond a point of maximum
strength to provide control of some other characteristic, usually corrosion
resistance. Applies to cast products that are artificially aged after solution heat
treatment to provide dimensional and strength stability.
T8
Solution treated, quenched, cold
worked, and artificially aged
Products that are cold worked after solution treatment and the effect of cold work
is recognized in mechanical property limits.
T9
Solution treated, quenched,
artificially aged, and then cold
worked
Products that are cold worked to improve strength.

Table 7 Typical tensile properties of selected 2xxx, 6xxx, and 7xxx aluminum alloy products
Tensile strength

Yield strength

Alloy

Temper Product
(a)

MPa ksi MPa ksi
Elongation
in 50 mm, %

T4 Sheet 250 36 125 18 28
2008
T6 Sheet 300 44 240 35 13
2014
T6, T651 Plate, forging 485 70 415 60 13
T3, T351 Sheet, plate 450 65 310 45 18
T361 Sheet, plate 495 72 395 57 13
T81, T851 Sheet, plate 485 70 450 65 6
2024
T861 Sheet, plate 515 75 490 71 6
2224
T3511 Extrusion 530 77 400 58 16
2324
T39 Plate 505 73 415 60 12
2524
T3, T351 Sheet, plate 450 65 310 45 21
2036
T4 Sheet 340 49 195 28 24
T81, T851 Sheet, plate 455 66 350 51 10
2219
T87 Sheet, plate 475 69 395 57 10
2519
T87 Plate 490 71 430 62 10
T4 Sheet 220 32 125 18 25
6009
T62 Sheet 300 44 260 38 11
T4 Sheet 285 41 165 24 25
6111
T6 Sheet 350 51 310 45 10

T6, T6511 Sheet, plate, extrusion, forging

310 45 275 40 12
6061
T9 Extruded rod 405 59 395 57 12
T5 Extrusion 185 27 145 21 12
6063
T6 Extrusion 240 35 215 31 12
7005
T5 Extrusion 350 51 290 42 13
7049
T73 Forging 540 78 475 69 10
7050
T74, T745X Plate, forging, extrusion 510 74 450 65 13
T651, T6151

Plate 600 87 560 81 11
7150
T77511 Extrusion 650 94 615 89 12
T7751 Plate 640 93 615 89 10
7055
T77511 Extrusion 670 97 655 95 11
T6, T651 Sheet, plate 570 83 505 73 11
7075
T73, T735X Plate, forging 505 73 435 63 13
T7351 Plate 505 73 435 63 15
7475
T7651 Plate 455 66 390 57 15

(a)

Properties of sheet and plate are for the long-transverse direction, and those of extrusions and forgings are for the longitudinal
direction.

Table 8 Typical tensile properties of selected aluminum cast products used in the automotive industry
Tensile strength

Yield strength

Alloy Temper

Casting
process
MPa ksi MPa ksi
Elongation in

20-25 mm, %

354.0
T6 Permanent mold

372 54 255 57 8
Sand 276 40 207 30 6
A356.0

T6
Permanent mold

283 41 207 30 12
365.0
T6 Vacuum die 206 30 139 20 17

The mechanical properties of a casting can vary due to composition, geometry, and fabric
ation process, which are selected based on
design requirements. Properties in certain areas can be adjusted by process and tooling design.
Table 9 Typical tensile properties of selected 3xxx and 5xxx aluminum alloy sheet products

Tensile
strength
Yield
strength
Alloy

Temper

MPa

ksi

MPa

ksi

Elongation
in 50 mm, %

0 100 16 40 6 30
H14 125 18 115 17 9
3003
H18 165 24 150 22 5
O 180 26 70 10 20
H34 240 35 200 29 9

H38 285 41 250 36 5
3004
H19 295 43 285 41 2
O 130 19 55 8 25
3005
H14 180 26 165 24 7
H18 240 35 225 33 4
O 115 17 55 8 24
H25 180 26 160 23 8
3105
H18 215 31 195 28 3
O 125 18 40 6 25
H34 160 23 140 20 8
5005
H38 200 29 185 27 5
O 145 21 55 8 24
H34 190 28 165 24 8
5050
H38 220 32 200 29 6
O 195 28 90 13 25
H34 260 38 215 31 10
5052
H38 290 42 255 37 7
O 180 26 85 12 23
H25 235 34 170 25 11
5252
H28 285 41 240 35 5
O 240 35 115 17 27
H34 290 42 230 33 13
H38 330 48 270 39 10

5154
H112 240 35 115 17 25
5454
O 250 36 115 17 22
H34 305 44 240 35 10
H111 250 36 125 18 18
H112 250 36 125 18 18
O 290 42 150 22 35
H18 435 63 405 59 10
5056
H38 415 60 345 50 15
O 310 45 160 23 24
H112 310 45 165 24 22
5456
H116 350 51 255 37 16
5182
O 275 40 130 19 21

O Temper. Ductility of all aluminum products is highest in this temper. Factors determining properties of annealed
products depend on the alloy system. The annealed strength of unalloyed aluminum, 1xxx series, generally increases and
ductility decreases with increasing impurity level, and the amounts of magnesium and manganese largely determine the
bulk properties of 3xxx and 5xxx products. Strength increases as magnesium (solid-solution strengthening) and manganese
contents (dispersion and solid-solution strengthening) increase. Ultimate tensile strength increases more significantly with
increasing magnesium content than does tensile yield strength because of the potent effect of magnesium on work
hardening. Parts of heat-treatable alloy products that are difficult to form are often formed in the O temper, then heat
treated to a final temper.
H Tempers. Cold working of annealed material to H1 tempers increases the dislocation density. This increases strength,
particularly yield strength, and decreases ductility. In unalloyed aluminum and in alloys containing little magnesium, cold
working produces cells that have walls containing a high density of dislocations enclosing a volume of relatively strain-
free material. In alloys containing sufficient amounts of magnesium, however, the dislocations form a tangled forest. In

highly worked aluminum-magnesium alloys, rearrangement of the dislocation structure occurs over long times at room
temperature. Stabilizing treatments, H3 tempers, prevent loss of strength in certain 3xxx and 5xxx alloys during
subsequent long-time exposure. During partial annealing treatments, H2 tempers, cell walls either form or become more
perfect, and dislocations within the cell migrate to cell boundaries. If the temperature exceeds a critical level, which
depends on alloy content and strain, the cold-worked product will either partially or completely recrystallize. Materials in
H2 tempers provide a combination of strength and ductility generally superior to that of material in H1 tempers. Cold-
worked alloys containing above approximately 3.5% Mg and annealed alloys containing above approximately 4.5% Mg
can also suffer a degradation in corrosion resistance caused by precipitation of a continuous film of Al
3
Mg
2
on grain
boundaries at temperatures between ambient and approximately 205 °C (400 °F). Special H116 and H321 controlled hot-
rolling tempers have been developed that either avoid precipitation of Al
3
Mg
2
on grain boundaries or agglomerate the
precipitate to increase corrosion resistance. For a particular strength level, a higher resistance to stress corrosion is
obtained by increasing magnesium and manganese rather than by increasing work hardening.
W and T Tempers. The highest strengths are obtained by precipitation hardening. The material is held for a sufficient
time above the solvus to dissolve essentially all of the major alloying elements, quenched at a rate to retain most of these
elements in solid solution, then aged either at room temperature (natural aging) or at a modestly elevated temperature
(artificial aging). The highest-strength alloys contain the largest concentration of the major alloying elements. For a
particular alloy system, strength typically increases with increasing alloy content. Most 2xxx and 6xxx wrought alloys and
2xx.x and 3xx.x cast alloys are strengthened during natural aging by Guinier-Preston (G-P) zones, which are precursors to
Al
2
Cu, Al
2

CuMg, Mg
2
Si, or Al
4
CuMg
5
Si
4
phases. Strength of these materials increases for about 4 days, then stabilizes
(T4 temper). In contrast, in 7xxx alloys containing G-P zone precursors to phases such as MgZn
2
, strength continues to
increase indefinitely at room temperature (W temper). The ductility in the freshly quenched (W < h temper) condition is
high enough for many forming operations. Consequently, many parts are formed shortly after quenching from the
solution-heat-treatment temperature. To prevent the formation of large grains during the solution treatment of formed
parts, a critical amount of strain must be avoided. Although this critical strain is alloy dependent, strains near 10% are
particularly troublesome for most alloys. In addition, ductility in the T4 or T3 tempers is sufficiently high that some parts
can be formed successfully in this condition. Strength, particularly yield strength, increases substantially with artificial
aging (T6 temper). This increase is accompanied by a loss in ductility. Strength of materials hardened by Al
2
CuMg,
Al
2
Cu, or Al
2
CuLi precipitates may be increased by cold work prior to artificial aging, T8, treatments. The increase in
strength of these materials is attributed to a refinement of Al
2
CuLi and of the metastable precursors to Al
2

CuMg and
Al
2
Cu. Additions of silicon and other alloying elements can also serve to refine the size of precipitates in certain 2xxx
alloys. Cold-finishing rod and bar products after artificial aging increases their strength (T9 temper).
The solution treatment, in most cases, is a separate operation. In particular circumstances, however, the heat from a
shaping process may be sufficient to provide solution treatment. These products can be cooled after the shaping process
and subsequently aged to develop useful properties (T5 temper). Some 6xxx alloys attain the same specified properties
whether furnace solution heat treated or cooled from an elevated-temperature shaping process at a rate rapid enough to
maintain sufficient silicon and magnesium in solution. In such cases, the T6 temper designation may be used.
Aluminum Alloy Microstructural Features Not Inferred from the Alloy-Temper
Designation Systems
The alloy designation system defines the alloy content, and the temper-designation system identifies many of the thermal
and mechanical processes that control the microstructure and, hence, the bulk properties of aluminum alloy products.
Nevertheless, many metallurgical features are not specified by these systems. The features include nonmetallic inclusions,
porosity, second-phase particles, grain and dislocation structure, and crystallographic texture.
Inclusions are typically oxides of aluminum and magnesium including spinel, MgAl
2
O
4
. Oxides form on the surface of
molten aluminum and become entrapped when turbulent flow forces them below the surface. Filtration of the molten
metal is used to control inclusions. Inclusions can give rise to problems ranging from pinholes in foil to reduced fatigue
life in structural wrought products and castings.
Porosity reduces ductility and increases susceptibility to the initiation of fatigue cracks. Porosity may arise from either
shrinkage during solidification or from hydrogen. Hydrogen control during solidification is extremely important because
of the ten-fold decrease in the solubility of hydrogen in aluminum as it solidifies. Hydrogen-induced porosity can also
occur in solid aluminum products when they are heated to high temperatures in humid environments. Provided that the
hydrogen content is low enough, most of the porosity can be closed by thermomechanical treatments. Isostatic pressure
can be used to close the pores in castings, and conventional forging and extrusion are effective in healing ingot porosity.

Porosity in thick-rolled products is particularly difficult to close; tensile stresses in the short-transverse direction may
arise during the initial rolling of thick plate because the amount of deformation per pass is limited. This stress causes
pores to enlarge. With additional rolling to thinner plate, the pores heal.
Second-phase particles are divided into four classes based on their mode of formation and their ability to be
dissolved: primary particles, constituents, dispersoids, and precipitates.
Primary Particles. These particles form when some phase other than aluminum solid solution separates first from the
melt. Primary silicon particles form in castings when hypereutectic aluminum-silicon alloys solidify by eutectic
decomposition. Ductility decreases with increasing size of the silicon particles, so size control is important. The coarse,
faceted primary silicon particles are refined to a fine spherulitic structure using additives containing phosphorus. In
certain casting alloys and 8xxx wrought alloys, primary iron-bearing constituents can form if the alloying content is such
that the alloy is hypereutectic. In wrought alloys, macroscopically large, undesirable primary particles of Al
7
Cr, Al
3
Ti, or
Al
3
Zr can form by a peritectic reaction if chemical composition is not closely controlled.
Constituents. These particles may be either intermetallic compounds or essentially pure silicon that forms during
solidification of hypoeutectic aluminum-silicon alloys. They range in size from a few micrometers to tens of micrometers.
Constituents can be classified either as virtually insoluble or soluble. Because the low maximum solid solubility of iron in
aluminum is further reduced by other alloying elements to 0.01 wt% or less, constituents containing iron are insoluble.
Iron-free constituents containing silicon can be either soluble or insoluble depending on the chemical composition of the
alloy. Major alloying elements can combine either with each other or with aluminum to form soluble constituent particles.
Most of these soluble constituents dissolve either during ingot preheating prior to deformation processing or during the
solution heat treatment of cast shapes or wrought products. Constituent size decreases with increasing solidification rate.
In hypoeutectic 3xx.0 and 4xx.0 castings, modification by elements such as strontium significantly refine the flake
structure of the silicon particles to a finer fibrous morphology.
Constituent particles are generally not beneficial and are detrimental to the fatigue resistance and fracture toughness of
high-strength alloy products. These particles fracture at relatively low plastic strains and provide low-energy sites for the

initiation and growth of cracks. Several high-purity (low iron and silicon) versions of 2024 and 7075 have been
commercialized, and the maximum allowable impurity levels of all modern high-strength alloys are significantly lower
than those of older alloys. Despite the harmful effects of constituents in high-strength alloys, the ability of alloy 3004-
H19 to make commercially successful beverage containers relies on careful control of size, volume fraction, and
distribution of Al
12
(Fe,Mn)Si constituent particles. These constituent particles serve to "scour" the die during the drawing
operation so that galling is minimized. Attempts to produce can stock from roll-cast sheet have generally not been
successful because the particle size distribution in roll-cast sheet is not as effective in minimizing galling.
Dispersoids. These form by solid-state precipitation, either during ingot preheating or during the thermal heat treatment
of cast shapes, of slow-diffusing supersaturated elements that are soluble in molten aluminum but which have limited
solubility in solid aluminum. Manganese, chromium, or zirconium are typical dispersoid-forming elements. Unlike the
precipitates that confer precipitation hardening, dispersoids are virtually impossible to dissolve completely, once
precipitated. In addition to providing dispersion strengthening, the size distribution of dispersoids in wrought alloys are a
key factor in controlling degree of recrystallization, recrystallized grain size, and crystallographic texture. Dispersoids in
non-heat-treatable alloys also stabilize the deformation substructure during elevated-temperature exposures, for example,
during paint baking.
In contrast to the commercially significant dispersion strengthening provided by dispersoids in 3xxx and 5xxx alloys, the
level of dispersion strengthening afforded by dispersoids in wrought heat-treatable alloys is trivial. In 2x24 alloys,
Al
20
Cu
2
Mn
3
dispersoids nucleate dislocations at the particle-matrix interface during the quench. These dislocations serve
as nucleation sites for subsequent precipitation. The newer 7xxx alloys contain zirconium, which forms coherent Al
3
Zr
dispersoids while most of the older 7xxx alloys contain Al

12
Mg
2
Cr dispersoids which exhibit incoherent interfaces. The
incoherent interfaces serve to nucleate MgZn
2
precipitates during the quench, so alloys containing these precipitates lose a
great deal of their potential to develop high strength after slow quenching (quench sensitivity). Nucleation is difficult on
coherent interfaces, so the newer alloys are less quench sensitive. A number of casting alloys, and some wrought alloys,
contain elements that can form either constituents or dispersoids depending on the solidification rate.
Precipitates can form during any thermal operation below the solvus. In properly solution-heat-treated products, all
precipitates dissolve during the solution-heat-treatment operation. Depending on quench rate and alloy, precipitates can
form during the quench from the solution-heat-treatment temperature at grain and subgrain boundaries and at particle-
matrix interfaces. These coarse precipitates do not contribute to age hardening and can serve to reduce properties such as
ductility, fracture toughness, and resistance to intergranular corrosion. After the quench, G-P zones form at ambient
temperature (natural aging). These are agglomerates of atoms of the major solute elements with a diffuse, coherent
boundary between the G-P zone and the matrix. During elevated-temperature precipitation heat treatments (artificial
aging) G-P zones may either nucleate metastable precipitates or they may dissolve, and metastable precipitates nucleate
separately. Cold working subsequent to quenching introduces dislocations that may serve to nucleate metastable or
equilibrium precipitates. With prolonged artificial aging, equilibrium precipitates may form. Coarse equilibrium
precipitates form during annealing treatments of heat-treatable alloy products, O temper. They also form during most
thermomechanical treatments prior to solution heat treatment.
Grain Structure. The grain size of aluminum alloy ingots and castings is typically controlled by the introduction of
inoculants that form intermetallic compounds containing titanium and/or boron. During deformation processing, the grain
structure becomes modified. Most aluminum alloy products undergo dynamic recovery during hot working as the
dislocations form networks of subgrains. New dislocation-free grains may form between and following rolling passes
(static recrystallization) or during deformation processing (dynamic recrystallization). During deformation, the crystal
lattice of the aluminum matrix rotates at its interfaces between constituent and coarse precipitate particles. These high-
energy sites serve to nucleate recrystallization. This process is termed particle-stimulated nucleation and is an important
mechanism in the recrystallization process of aluminum. The particle size that will serve as a nucleus decreases as

deformation temperature decreases and strain and strain rate increase. Dispersoid particles retard the movement of high-
angle grain boundaries. Consequently, hot-worked structures are resistant to recrystallization and often retain the
dynamically recovered subgrain structure in the interiors of elongated cast grain boundaries. In heat-treated products
containing a sufficient quantity of dispersoids the unrecrystallized structure of hot-worked-plate forgings and extrusions
can be retained after solution heat treatment.
Degree of recrystallization of hot-worked products has an effect on fracture toughness. Unrecrystallized products develop
higher toughness than do products that are either partially or completely recrystallized. This behavior is attributed to
precipitation on the recrystallized high-angle grain boundaries during the quench. These particles increase the tendency
for low-energy intergranular fracture. Products such as sheet, rods, and tubing that are cold rolled invariably recrystallize
during solution heat treatment or annealing to O temper.
Decreasing the grain size can increase strength of 5xxx alloy products in the O temper by 7 to 28 MPa (1 to 4 ksi), but
grain size is not a major factor in increasing strength of other aluminum alloy products. Several measures of formability
are influenced by grain size, however, so grain size is controlled for this reason. One particular use of grain size control is
to produce stable, fine grains, which are essential in developing superplastic behavior in aluminum alloy sheet.
Crystallographic Texture. Cast aluminum ingots and shapes generally have a random crystallographic texture; the
orientation of the unit cells comprising each grain are not aligned. With deformation, however, certain preferred
crystallographic orientations develop. Many of the grains rotate and assume certain orientations with respect to the
direction of deformation. For flat-rolled products and extrusions having a high aspect ratio of width to thickness, the
deformation texture is similar to that in pure fcc metals. These orientations are described by using the Miller indices of the
planes {nnn} in the grains parallel to the plane of the worked product and directions [nnn] parallel to the working
direction. The predominant textures are {110}[112], {123}[634], and {112}[111]. During recrystallization, a high
concentration of grains in the {001}[100] or {011}[100] orientations may develop. Alternatively, if particle-stimulated
nucleation is present to a large extent, the recrystallized texture will be random. Control of crystallographic texture is
particularly important for non-heat-treatable sheet that will be drawn. If texture is not random, ears form during the
drawing process. In extruded or drawn rod or bar, the texture is a dual-fiber texture in which almost all grains are aligned
so that the grain directions are either [001] or [111]. In heat-treatable alloys, texture has the most potent effect on the
properties of extrusions that have the dual-fiber texture. Strengthening by this process is so potent that the longitudinal
yield strengths of extruded products exhibiting this texture are about 70 MPa (10 ksi) higher than strength in the
transverse direction. If this dual-fiber texture is lost by recrystallization, strength in the longitudinal direction decreases to
that in the transverse directions.

References cited in this section
2. H. Baker, Ed., Alloy Phase Diagrams, Vol 3, ASM Handbook, ASM International, 1992
3. J.R. Davis, Ed., ASM Specialty Handbook: Aluminum and Aluminum Alloys, ASM International, 1993
4. D. Altenpohl, Aluminum Viewed from Within, an Introduction to the Metallurgy of Aluminum Fabrication,

Aluminium-Verlag, Dusseldorf, 1982
5. Aluminum Standards and Data, The Aluminum Association, 1993
6. C. Brooks, Heat Treatment, Structure and Properties of Nonferrous Alloys,
American Society for Metals,
1982
7. J. Hatch, Ed., Aluminum: Properties and Physical Metallurgy, American Society for Metals, 1984
8. W.E. Haupin and J.T. Staley, Aluminum and Aluminum Alloys, Encyclopedia of Chemical Technology,

1992
9. Heat Treating of Aluminum Alloys, Heat Treating, Vol 4, ASM Handbook,
ASM International, 1991, p
841-879
10.

W. Petzow and G. Effenberg, Ed.,
Ternary Alloys: A Comprehensive Compendium of Evaluated
Constitutional Data and Phase Diagrams, VCH Verlagsgesellschaft, Weinheim, Germany, 1990
11.

H.W.L. Phillips, Equilibrium Diagrams of Aluminium Alloy Systems,
Aluminum Development Association,
1961
12.

I.J. Polmear, Light Alloys, Metallurgy of the Light Metals, 3rd ed., Arnold, 1995
13.

R.E. Sanders, Jr., S.F. Baumann, and H. Stumpf, Non-Heat-Treatable Aluminum Alloys,
Aluminum Alloys,
Their Physical and Mechanical Properties, Engineering Materials Advisory Services Ltd, 1986, p 1441-
1484
14.

T.H. Sanders, Jr., and J.T. Staley, Review of Fatigue and Fracture Research on High-
Strength Aluminum
Alloys, Fatigue and Microstructure, American Society for Metals, 1979, p 467-522
15.

J.T. Staley, Metallurgical Factors Affecting Strength of High Strength Alloy Products, Pro
ceedings of
Fourth International Conference on Aluminum Alloys,
Norwegian Institute of Technology, Department of
Metallurgy and SINTEF Metallurgy, 1994
16.

E.A. Starke, Jr., and J.T. Staley, Application of Modern Aluminum Alloys to Aircraft, Progr. Aerosp. Sci.,

Vol 32 (No. 2-3), 1996, p 131-172
17.

K.R. Van Horn, Ed., Aluminum, Vol I, Properties, Physical Metallurgy and Phase Diagrams,
American
Society for Metals, 1967
Effects of Composition, Processing, and Structure on Properties of Nonferrous Alloys

Ronald N. Caron, Olin Corporation; James T. Staley, Alcoa Technical Center

Copper and Copper Alloys
After iron and aluminum, copper is the third most-prominent commercial metal because of its availability and attractive
properties: excellent malleability (or formability), good strength, excellent electrical and thermal conductivity, and
superior corrosion resistance (Ref 18, 19, 20, 21, 22, 23, 24, 25). Copper offers the designer moderate levels of density
(8.94 g/cm
3
, or 0.323 lb/in.
3
), elastic modulus (115 GPa, or 17 × 10
6
psi), and melting temperature (1083 °C, or 1981 °F).
It forms many useful alloys to provide a wide variety of engineering property combinations and is not unduly sensitive to
most impurity elements. The electrical conductivity of commercially available pure copper, about 101% IACS
(International Annealed Copper Standard), is second only to that of commercially pure silver (about 103% IACS).
Standard commercial copper is available with higher purity and, therefore, higher conductivity than what was available
when its electrical resistivity value at 20 °C (70 °F) was picked to define the 100% level on the IACS scale in 1913. The
thermal conductivity for copper is also high, 391 W/m · K (226 Btu/ft · h · °F), being directly related to the electrical
conductivity through the Wiedemann-Franz relationship.
Copper and the majority of its alloys are highly workable hot or cold, making them readily commercially available in
various wrought forms: forgings, bar, wire, tube, sheet, and foil. In 1995, copper used in wire and cable represented about
50% of U.S. production and in flat products of various thickness another 15%, rod and bar about 14%, tube about 14.5%,
with foundries using about 5% for cast products, and metal powder manufacturers about 0.6%. Besides the more familiar
copper wire, copper and its alloys are used in electrical and electronic connectors and components, heat-exchanger tubing,
plumbing fixtures, hardware, bearings, and coinage.
As with other metal systems, copper is intentionally alloyed to improve its strength without unduly degrading ductility or
workability. However, it should be recognized that additions of alloying elements also degrade electrical and thermal
conductivity by various amounts depending on the alloying element, its concentration and location in the microstructure
(solid solution or dispersoid). The choice of alloy and condition is most often based on the trade-off between strength and

conductivity. Alloying also changes the color from reddish brown to yellow (with zinc, as in brasses) and to metallic
white or "silver" (with nickel, as in U.S. cupronickel coinage).
Copper and its alloys are readily cast into cake, billet, rod, or plate suitable for subsequent hot or cold processing into
plate, sheet, rod, wire, or tube via all the standard rolling, drawing, extrusion, forging, machining, and joining methods.
Copper and copper alloy tubing can be made by the standard methods of piercing and tube drawing as well as by the
continuous induction welding of strip. Copper is hot worked over the temperature range 750 to 875 °C (1400 to 1600 °F),
annealed between cold working steps over the temperature range 375 to 650 °C (700 to 1200 °F), and is thermally stress
relieved usually between 200 and 350 °C (390 and 660 °F). Copper and its alloys owe their excellent fabricability to the
face-centered cubic crystal structure and its twelve available dislocation slip systems. Many of the applications of copper
and its alloys take advantage of the work-hardening capability of the material, with the cold processing deformation of the
final forming steps providing the required strength/ductility for direct use or for subsequent forming of stamped
components. Copper is easily processible to more than 95% reduction in area. The amount of cold deformation between
softening anneals is usually restricted to 90% maximum to avoid excessive crystallographic texturing, especially in
rolling of sheet and strip.
Although copper obeys the Hall-Petch relationship and grain size can be readily controlled by processing parameters,
work hardening is the only strengthening mechanism used with pure copper. Whether applied by processing to shape and
thickness, as a rolled strip or drawn wire, or by forming into the finish component, as an electrical connector, the amount
of work hardening applied is limited by the amount of ductility required by the application. Worked copper can be
recrystallized by annealing at temperatures as low as 250 °C (480 °F), depending on prior degree of cold work and time at
temperature. While this facilitates processing, it also means that softening resistance during long-time exposures at
moderately elevated temperatures can be a concern, especially in electrical and electronic applications where I
2
R heating
is a factor. For applications above room temperature, but at temperatures lower than those inducing recrystallization in
commercial heat treatments, thermal softening can occur over extended periods and characteristics such as the half-
softening temperature should be considered; that is, the temperature for which the worked metal softens to half its original
hardness after a specific exposure time, usually 1 h.
A more useful engineering property for many electrical contact applications is stress-relaxation resistance, the property
that characterizes the decrease in contact load supported by a mechanical contact over time at a given temperature,
typically measured at room temperature between exposures to elevated temperature (Ref 20). Figure 3 illustrates the

characteristics of the tensile-stress-relaxation property of drawn (worked) copper wire; the degree of relaxation increases
with temperature and time. It also increases with the initial temper or degree of cold work in the material. The mechanism
is the thermally activated and applied-stress directed motion of crystal lattice defects, such as point defects and
dislocations. Consequently, the application of a thermal heat treatment (stabilization anneal) to induce recovery
mechanisms to tie up mobile components of dislocations will improve the stress-relaxation resistance. Alloying elements
also restrict dislocation motion and provide a more potent remedy for improving stress-relaxation resistance of cold-
worked metal in service. For example, the improvement in stress-relaxation resistance obtainable by alloying copper with
5% Sn (alloy C51000) in combination with a low-temperature stabilization heat treatment and as a function of sheet
orientation is illustrated by comparing the alloy data at 93 °C (200 °F) in Fig. 4 with those for copper in Fig. 3.

Fig. 3 Tensile-stress-
relaxation characteristics of copper alloy C11000. Data are for tinned 30 AWG (0.25 mm
diam) annealed ETP copper wire; initial elastic stress, 89 MPa (13 ksi).

Fig. 4 Anisotropic stress-relaxation behavior in bending for highly cold-
worked C51000 copper alloy strip. Data
are for 5% Sn phosphor bronze cold rolled 93% (reduction in area) to 0
.25 mm (0.01 in.) and heat treated 2 h
at 260 °C (500 °F). Graphs at left are for stress relaxation transverse to the rolling direction; graphs at right,
for stress relaxation parallel to the rolling direction. Initial stresses: as rolled, parallel orienta
tion, 607 MPa (88
ksi); as rolled, transverse orientation, 634 MPa (92 ksi); heat treated, parallel orientation, 641 MPa (93 ksi);
heat treated, transverse orientation, 738 MPa (107 ksi)
Wrought Copper Alloys
The purpose of adding alloying elements to copper is to optimize the strength, ductility (formability), and thermal
stability, without inducing unacceptable loss in fabricability, electrical/thermal conductivity, or corrosion resistance. A list
of selected wrought copper alloy compositions and their properties is given in Table 10. In this table, the alloys are
arranged in their common alloy group: the coppers (99.3% min Cu), the high-coppers (94% min Cu), brasses (copper-
zinc), bronzes (copper-tin, or copper-aluminum, or copper-silicon), copper-nickels, and the nickel silvers (Cu-Ni-Zn).
Composition and property data are given by the Copper Development Association (CDA) and are incorporated in the

ASTM numbering system, wherein alloys numbered by the designations (now UNS) C10100 to C79900 cover wrought
alloys and C80100 to C99900 apply to cast alloys. Copper alloys show excellent hot and cold ductility, although usually
not to the same degree as the unalloyed parent metal. Even alloys with large amounts of solution-hardening elements
zinc, aluminum, tin, silicon that show rapid work hardening are readily commercially processed beyond 50% cold work
before a softening anneal is required to permit additional processing. The amount of cold working and the annealing
parameters must be balanced to control grain size and crystallographic texturing. These two parameters are controlled to
provide annealed strip products at finish gage that have the formability needed in the severe forming and deep drawing
commonly done in commercial production of copper, brass, and other copper alloy hardware and cylindrical tubular
products.
Table 10 Compositions and properties of selected wrought copper alloys
Tensile
strength
Yield strength Alloy UNS
No.
Nominal
composition
Treatment
MPa ksi MPa ksi
Elongation,

%
Rockwell

hardness
Pure copper
OFHC
C10200

99.95 Cu . . . 221-
455

33-
66
69-
365
10-
53
55-4 . . .
High-copper alloys
Annealed 490 71 . . . . . . 35 60 HRB
Beryllium-copper
C17200

97.9Cu-1.9Be-0.2Ni or
Co
Hardened 1400 203 1050 152 2 42 HRC
Brass
Annealed 245 36 77 11 45 52 HRF
Gilding, 95%
C21000

95Cu-5Zn
Hard 392 57 350 51 5 64 HRB
Annealed 280 41 91 13 47 64 HRF
Red brass, 85%
C23000

85Cu-15Zn
Hard 434 63 406 59 5 73 HRB
Annealed 357 52 133 19 55 72 HRF
Cartridge brass,

70%
C26000

70Cu-30Zn
Hard 532 77 441 64 8 82 HRB
Annealed 378 55 119 17 45 80 HRF
Muntz metal
C28000

60Cu-40Zn
Half-hard 490 71 350 51 15 75 HRB
Annealed 350 51 119 17 52 68 HRF
High lead brass
C35300

62Cu-36Zn-2Pb
Hard 420 61 318 46 7 80 HRB
Bronze
Phosphor bronze,
5%
C51000

95Cu-5Sn Annealed 350 51 175 25 55 40 HRB
5%
Hard 588 85 581 84 9 90 HRB
Annealed 483 70 250 36 63 62 HRB
Phosphor bronze,
10%
C52400

90Cu-10Sn
Hard 707 103 658 95 16 96 HRB
Annealed 420 61 175 25 66 49 HRB
Aluminum bronze
C60800

95Cu-5Al
Cold
rolled
700 102 441 64 8 94 HRB
Extruded 690 100 414 60 15 96 HRB
Aluminum bronze
C63000

81.5Cu-9.5Al-5Ni-2.5Fe-
1Mn
Half-hard 814 118 517 75 15 98 HRB
Annealed 441 64 210 31 55 66 HRB
High-silicon bronze
C65500

96Cu-3Si-1Mn
Hard 658 95 406 59 8 95 HRB
Copper nickel
Annealed 385 56 126 18 36 40 HRB
Cupronickel, 30%
C71500

70Cu-30Ni
Cold

rolled
588 85 553 80 3 86 HRB
Nickel silver
Annealed 427 62 196 28 35 55 HRB
Nickel silver
C75700

65Cu-23Zn-12Ni
Hard 595 86 525 76 4 89 HRB

The pure copper alloys, also called the coppers (C10100 to C15900), are melted and cast in inert atmosphere from
the highest-purity copper in order to maintain high electrical conductivity (oxygen-free, or OF, copper, C10200). Copper
is more commonly cast with a controlled oxygen content (0.04% O as in electrolytic tough pitch, or ETP, copper,
C11000) to refine out impurity elements from solution by oxidation. Included in this group are the alloys that are
deoxidized with small addition of various elements such as phosphorus (C12200, Cu-0.03P) and the alloys that use minor
amounts of alloy additions to greatly improve softening resistance, such as the silver-bearing copper alloys (C10500, Cu-
0.034 min Ag) and the zirconium-bearing alloys (C15000 and C15100, Cu-0.1Zr).
High-copper alloys (C16000 to C19900) are designed to maintain high conductivity while using dispersions and
precipitates to increase strength and softening resistance: iron dispersions in Cu-(1.0-2.5)Fe alloys (C19200, C19400),
chromium precipitates in Cu-1Cr (C18200), and the coherent precipitates in the Cu-(0.3-2.0)Be-Co,Ni age-hardening
alloys (C17200, C17410, and C17500).
Brass alloys are a rather large family of copper-zinc alloys. A significant number of these are binary copper-zinc alloys
(C20500 to C28000), utilizing the extensive region of solid solution up to 35% Zn, offering excellent formability with
good work-hardening strength at reasonable cost. The alloys below 15% Zn have good corrosion and stress-corrosion
resistance. Alloys above 15% Zn need a stress-relieving heat treatment to avoid stress corrosion and, under certain
conditions, can be susceptible to dezincification. Alloys at the higher zinc levels of 35 to 40% Zn contain the bcc beta
phase, especially at elevated temperatures, making them hot extrudeable and forgeable (alloy C28000 with Cu-40Zn, for
example). The beta alloys are also capable of being hot worked while containing additions of 1 to 4% Pb, or more
recently bismuth, elements added to provide the dispersion of coarse particles that promote excellent machinability
characteristics available with various commercial Cu-Zn-Pb alloys (C31200 to C38500). The tin-brasses (C40400 to

C49000) contain various tin additions from 0.3 to 3.0% to enhance corrosion resistance and strength in brass alloys.
Besides improving corrosion-resistance properties in copper-zinc tube alloys, such as C44300 (Cu-30Zn-1Sn), the tin
addition also provides for good combinations of strength, formability, and electrical conductivity required by various
electrical connectors, such as C42500 (Cu-10Zn-2Sn). A set of miscellaneous copper-zinc alloys (C66400 to C69900)
provide improved strength and corrosion resistance through solution hardening with aluminum, silicon, and manganese,
as well as dispersion hardening with iron additions.
Bronze alloys consist of several families named for the principal solid-solution alloying element. The familiar tin-
bronzes (C50100 to C54400) comprise a set of good work-hardening, solid-solution alloys containing from nominally
0.8% Sn (C50100) to 10% Sn (C52400), usually with a small addition of phosphorus for deoxidation. These alloys
provide an excellent combination of strength, formability, softening resistance, electrical conductivity, and corrosion
resistance. The aluminum-bronze alloys contain 2 to 15% Al (C60800 to C64200), an element adding good solid-solution
strengthening and work hardening, as well as corrosion resistance. The aluminum-bronzes usually contain 1 to 5% Fe,
providing elemental dispersions to promote dispersion strengthening and grain size control. The silicon-bronze alloys
(C64700 to C66100) generally offer good strength through solution- and work-hardening characteristics, enhanced in
some cases with a tin addition, as well as excellent resistance to stress corrosion and general corrosion.
Cupronickels are copper-nickel alloys (C70100 to C72900) that utilize the complete solid solubility that copper has for
nickel to provide a range of single-phase alloys (C70600 with Cu-10Ni-1.5Fe, and C71500 with Cu-30Ni-0.8Fe, for
example) that offer excellent corrosion resistance and strength. The family of copper-nickel alloys also includes various
dispersion- and precipitation-hardening alloys due to the formation of hardening phases with third elements, such as Ni
2
Si
in C70250 (Cu-3Ni-0.7Si-0.15Mg) and the spinodal hardening obtainable in the Cu-Ni-Sn alloys (C72700 with Cu-10Ni-
8Sn, for example).
Copper-nickel-zinc alloys, also called nickel-silvers, are a family of solid-solution-strengthening and work-hardening
alloys with various nickel-zinc levels in the Cu-(4-26)Ni-(3-30)Zn ternary alloy system valued for their strength,
formability, and corrosion and tarnish resistance, and, for some applications, metallic white color.
Strengthening Mechanisms for Wrought Copper Alloys
Solution Hardening. Copper can be hardened by the various common methods without unduly impairing ductility or
electrical conductivity. The metallurgy of copper alloys is suited for using, singly or in combination, the various common
strengthening mechanisms: solid solution and work hardening, as well as dispersed particle and precipitation hardening.

The commonly used solid-solution hardening elements are zinc, nickel, manganese, aluminum, tin, and silicon, listed in
approximate order of increasing effectiveness. Commercial alloys represent the entire range of available solid-solution
compositions of each element: up to 35% Zn, and up to (and even beyond) 50% Ni, 50% Mn, 9% Al, 11% Sn, and 4% Si.
The relative amount of solution strengthening obtained from each element or particular combination of elements is
determined by the ability of the solute to interfere with dislocation motion and is reflected in the work-hardening rate
starting with the annealed condition, as illustrated by the increase in tensile strength with cold work shown in Fig. 5 and
also Table 10.

Fig. 5 Tensile strength of single-
phase copper alloys as affected by percentage reduction in thickness by rolling
(temper). Curves of lesser slope indicate a low rate of work hardening and a higher capacity for redrawing.
ETP,
electrolytic tough pitch
Work hardening is the principal hardening mechanism applied to most copper alloys, the degree of which depends on
the type and amount of alloying element and whether the alloying element remains in solid solution or forms a dispersoid
or precipitate phase. Even those alloys that are commercially age hardenable are often provided in the mill hardened
tempers; that is, they have been processed with cold work preceding and/or following an age-hardening heat treatment.
For the leaner alloys (below about 12% Zn, or about 3% Al, for example), processing generates dislocations that develop
into entanglements and into cells, with some narrow shear band formation beyond about 65% cold reduction in thickness.
After about 90% cold work, the distinct "copper" or "metal" deformation crystallographic texture begins to develop. With
the richer solid-solution alloys that lower the stacking-fault energy, planar slip is the dominant dislocation mechanism,
with associated higher work hardening. Beyond about 40% cold work in these richer alloys, stacking faults, shear
banding, and deformation twinning become important deformation mechanisms that, beyond 90% cold work, lead to the
"brass" or "alloy" type of crystallographic deformation texture and accompanying anisotropy of properties. The variation
in tensile properties with cold working of an annealed Cu-30 Zn alloy (C26000) is shown in Fig. 6. The degree of work
hardening seen with cold working several selected single-phase copper alloys is illustrated by the cold-rolling curves in
Fig. 5. Many copper alloys are used in wrought forms in a worked temper, chosen for the desired combination of work-
hardened strength and formability, either for direct use in service or for subsequent component fabrication.

Fig. 6 The effect of cold rolling on t

he strength, hardness, and ductility of annealed copper alloy C26000 when
it is cold rolled in varying amounts up to 62% reduction in thickness
Dispersion strengthening is used in copper alloys for hardening, controlling grain size, and providing softening
resistance, as exemplified by iron particles in copper-iron alloys, C19200 or C19400, and in aluminum bronzes, C61300
or C63380. Cobalt silicide particles in alloy C63800 (Cu-2.8Al-1.8Si-0.4Co), for example, provide fine-grain control and
dispersion hardening to give this alloy high strength with reasonably good formability. Alloy C63800 offers an annealed
tensile strength of 570 MPa (82 ksi) and rolled temper tensile strengths of 660 to 900 MPa (96 to 130 ksi). Alloys offering
exceptionally good thermal stability have been developed using powder metallurgy (P/M) techniques to incorporate
dispersions of fine Al
2
O
3
particles (3 to 12 nm in size) in a basically copper matrix, which is finish processed to rod, wire,
or strip products. This family of alloys, C15715 to C15760, can resist softening up to and above 800 °C (1472 °F).
Precipitation Hardening. Age-hardening mechanisms are used in those few but important copper systems that offer a
decreasing solubility for hardening phases. The beryllium-copper system offers a series of wrought and cast age-
hardening alloys, UNS C17000 to C17530 and C82000 to C82800. The wrought alloys contain 0.2 to 2.0% Be and 0.3 to
2.7% Co (or up to 2.2% Ni). They are solution heat treated in the range 760 to 955 °C (1400 to 1750 °F) and age hardened
to produce the beryllium-rich coherent precipitates when aged in the range 260 to 565 °C (500 to 1050 °F), the specific
temperature being chosen for the particular alloy and desired property combination (Fig. 7). The precipitation sequence
during aging consists of the formation of solute-rich G-P zones, followed in sequence by coherent platelets of the
metastable intermediate phases ' and ''. Overaging is marked by the appearance of the B2 ordered equilibrium -
BeCu phase as particles within grains and along grain boundaries, large enough to be seen in the light microscope. The
cobalt and nickel additions form dispersoids of equilibrium (Cu, Co, or Ni)Be that restrict grain growth during solution
annealing in the two-phase field at elevated temperatures (Fig. 7b). A cold-working step following solution annealing is
often used to increase the age-hardening response. Alloy C17200 (Cu-1.8Be-0.4Co), for example, can be processed to
reach high strength: that is, tensile strengths after solutionization (470 MPa, or 68 ksi), after cold rolling to the hard
temper (755 MPa, or 110 ksi), and after aging (1415 MPa, or 205 ksi). While they are commercially available in the heat-
treatble (solutionized) condition, the beryllium-copper alloys are commonly provided in the mill-hardened temper with
the optimal strength/ductility/conductivity combination suitable for the application.

Fig. 7 Phase diagrams for beryllium-copper alloys. (a) Binary composition for high-
strength alloys such as
C17200. (b) Pseudobinary composition for C17510, a high-conductivity alloy containing Cu-1.8Ni-0.4Be
Other age-hardening copper alloys include the chromium-coppers, which contain 0.4 to 1.2% Cr (C18100, C18200, and
C18400); these alloys produce arrays of pure chromium precipitates and dispersoid particles when aged. The Cu-Ni-Si
alloys, C64700 and C70250, age harden by precipitating the Ni
2
Si intermetallic phase (Fig. 8). Compositions in the Cu-
Ni-Sn system, C71900 and C72700, are hardenable by spinodal decomposition, a mechanism that provides high strength
and good ductility through the formation of a periodic array of coherent, fcc solid-solution phases that require the electron
microscope to be seen. Each of these alloys, including the beryllium-coppers can be thermomechanically processed to
provide unique combinations of strength, formability, electrical conductivity, softening resistance, and stress-relaxation
resistance.

Fig. 8 Photomicrograph showing the dispersion of Ni
2
Si precipitates in the q
uenched and aged condition of
copper alloy C64700, Cu-2Ni-0.7Si. Magnification: 500×
Copper Casting Alloys
The copper casting alloys, numbered UNS C80100 to C99900, are available as sand, continuous, centrifugal, permanent
mold, and some die castings (Ref 22, 23). They are generally similar to the wrought counterparts, but they do offer their
own unique composition/property characteristics. For example, they do offer the opportunity to add lead to levels of 25%
that could not be easily made by wrought techniques in order to provide compositions in which dispersions of lead
particles are useful for preventing galling in bearing applications. The copper casting alloys are used for their corrosion
resistance and their high thermal and electrical conductivity. The most common alloys are the general-purpose Cu-5Sn-
5Pb-5Zn alloy (C83600), used for valves and plumbing hardware, and C84400, widely used for cast plumbing system
components. C83600 contains lead particles dispersed about the single-phase matrix and offers good machinability, with
moderate levels of corrosion resistance, tensile strength (240 MPa, or 35 ksi), ductility, and conductivity (15% IACS).

While the Cu-Sn-Pb-(and/or Zn) casting alloys have only moderate strength, the cast manganese and aluminum bronzes
offer higher tensile strengths, 450 to 900 MPa (65 to 130 ksi). As with the wrought alloys, the cast aluminum-bronze
alloys commonly contain an iron addition (0.8 to 5.0%) to provide iron-rich particles for grain refinement and added
strength. In addition, at aluminum levels in the range 9.5 to 10.5% (or 8.0 to 9.5% Al with nickel or manganese additions)
the alloys are heat treatable for added strength. Depending on the section thickness and cooling rate of the casting, as well
as the alloy composition and heat treatments, the microstructures can be rather complex. The aluminum-bronzes can be
annealed completely or partially in the field and quenched to form martensite with needles. Aging these alloys will
temper the martensite by precipitation fine needles. One of the aluminum-bronze alloys, Cu-10.5Al-5Fe-5Ni, for
example, is used for its combination of high strength and good corrosion resistance. Through heat treatment, the
intermetallic -phase, with its complex composition (Fe,Ni,Cu)Al and CsCl crystal structure, provides a strengthening
component in any of its morphologies: as globular particles, fine precipitates, or as a component of cellular eutectoid
colonies.
Copper Alloy Powders
Unique structural components are commercially made of copper and its alloys by P/M methods. Copper and prealloyed
powders are made by reduction of oxides, or by atomization, wherein the solidification of liquid droplets from a pour
stream is broken up by an impinging jet of a liquid or gas. Self-lubricating sintered bronze bearings are deliberately not
pressed and sintered to 100% density in order to maintain an interconnected porosity to serve as an oil reservoir. The P/M
technique is uniquely suited to permit the addition of up to about 1.5% graphite in these bearings. Likewise, various
multiphase P/M copper alloys containing a mixture of hard and soft phases in a copper matrix (Cu-7Sn-3Fe-6Pb-6
graphite-3SiO
2
, for example) are made for friction materials. The combination of thermal stability, wear resistance, and
sliding friction properties make these materials suitable for use in clutch plates, and so forth. Various structural parts are
made of bronze, brass, and nickel-silver alloys. In addition, P/M techniques are used to prepare the initial stages of the
oxide-dispersion-strengthened (ODS) copper alloys, which are fabricated into finished forms by standard wrought
methods to provide good softening resistance with excellent thermal or electrical conductivity. These ODS materials are
prepared by internal oxidation of powder copper-aluminum alloy to form a dispersion of fine Al
2
O
3

particles, about 3 to
12 nm in size.

References cited in this section
18.

Properties of Pure Metals, Properties and Selection: Nonferrous Alloys and Special-Purpose Materials,
Vol
2, ASM Handbook, ASM International, 1990, p 1099-1201
19.

D.E. Tyler and W.T. Black, Introduction to Copper and Copper Alloys, Pro
perties and Selection:
Nonferrous Alloys and Special-Purpose Materials, Vol 2, ASM Handbook, ASM International, 1990, p 216-
240
20.

D.E. Tyler, Wrought Copper and Copper Alloy Products,
Properties and Selection: Nonferrous Alloys and
Special-Purpose Materials, Vol 2, ASM Handbook, ASM International, 1990, p 241-264
21.

P. Robinson, Properties of Wrought Coppers and Copper Alloys,
Properties and Selection: Nonferrous
Alloys and Special-Purpose Materials, Vol 2, ASM Handbook, ASM International, 1990, p 265-345
22.

R.F. Schmidt and D.G. Schmidt, Selection and Application of Copper Alloy Castings,
Properties and
Selection: Nonferrous Alloys and Special-Purpose Materials, Vol 2, ASM Handbook,

ASM International,
1990, p 346-355
23.

A. Cohen, Properties of Cast Copper Alloys, Properties and Selection: Nonferrous Alloys and Special-
Purpose Materials, Vol 2, ASM Handbook, ASM International, 1990, p 356-391
24.

E. Klar and D.F. Berry, Copper P/M Products, Properties and Selection: Nonferrous Alloys and Special-
Purpose Materials, Vol 2, ASM Handbook, ASM International, 1990, p 392-402
25.

J.C. Harkness, W.D. Speigelberg, and W.R. Cribb, Beryllium-Copper and Other Beryllium-
Containing
Alloys, Properties and Selection: Nonferrous Alloys and Special-Purpose Materials, Vol 2,
ASM
Handbook, ASM International, 1990, p 403-427
Effects of Composition, Processing, and Structure on Properties of Nonferrous Alloys
Ronald N. Caron, Olin Corporation; James T. Staley, Alcoa Technical Center

Nickel and Nickel Alloys
Nickel and nickel alloys are used in the chemical processing, pollution control, power generation, electronic, and
aerospace industries, taking advantage of their excellent corrosion, oxidation, and heat resistance (Ref 18, 26, 27, 28, 29,
30, 31, 32). Nickel is ductile and can be made by the conventional processing methods into cast, P/M, and various
wrought products: bar/wire, plate/sheet, and tube. Commercially pure nickel has moderately high values of melting
temperature (1453 °C, or 2647 °F), density (8.902 g/cm
3
, or 0.322 lb/in.
3
), and elastic modulus (204 GPa, or 30 × 10

6
psi).
It is ferromagnetic, with a Curie temperature of 358 °C (676 °F) and good electrical (25% IACS) and thermal
conductivity (82.9 W/m · K, or 48 Btu/ft · h · °F). Elemental nickel is used principally as an alloying element to increase
the corrosion resistance of commercial iron and copper alloys; only about 13% of annual consumption is used in nickel-
base alloys. Approximately 60% is used in stainless steel production, with another 10% in alloy steels and 2.5% in copper
alloys. Nickel is also used in special-purpose alloys: controlled expansion, electrical resistance, magnetic, and shape
memory alloys.
Effects of Alloying Elements in Nickel Alloys
Nickel has an fcc crystal structure, to which it owes its excellent ductility and toughness. Because nickel has extensive
solid solubility for many alloying elements, the microstructure of nickel alloys consists of the fcc solid-solution austenite
( ) in which dispersoid and precipitate particles can form. Nickel forms a complete solid solution with copper and has
nearly complete solubility with iron. It can dissolve about 35% Cr, about 20% each of molybdenum and tungsten, and
about 5 to 10% each of aluminum, titanium, manganese, and vanadium. Thus, the tough, ductile fcc matrix can dissolve
extensive amounts of elements in various combinations to provide solution hardening as well as improved corrosion and
oxidation resistance. The degree of solution hardening has been related to the atomic size difference between nickel and
the alloying element, and therefore the ability of the solute to interfere with dislocation motion. Tungsten, molybdenum,
niobium, tantalum, and aluminum, when aluminum is left in solution, are strong solution hardeners, with tungsten,
niobium, tantalum, and molybdenum also being effective at temperatures above 0.6 T
m
(T
m
= melting temperature), where
diffusion-controlled creep strength is important. Iron, cobalt, titanium, chromium, and vanadium are weaker solution-
hardening elements. Aluminum and titanium are usually added together to form the age-hardening precipitate, Ni
3
(Al,Ti).
Gamma Prime ( ') Precipitation. Gamma-prime ( '), Ni
3
(Al,Ti), and the closely related '', Ni

3
Nb, are the major
precipitation-hardening phases in nickel alloys. These precipitates are based on the intermetallic compound, Ni
3
Al, which
has an fcc L1
2
ordered crystal structure with a lattice parameter differing from the nickel austenite ( ) matrix by 1%.
This misfit allows the homogeneous nucleation and growth of rather stable arrays of coherent precipitates (Fig. 9).
Strengthening is provided in part by the hindrance to dislocations moving across the - ' interface and, more
importantly, as they cut across the ordered precipitate, where they must split into partials to maintain the ordered crystal
structure. Moreover, Ni
3
Al is one of the unique phases that show a significant increase in flow stress with temperature. In
particular, the yield strength increases over the range 300 °C (572 °F) to above 900 °C (1650 °F), showing a broad peak at
about 600 °C (1110 °F).


Fig. 9 Replica electron micrograph of the nickel alloy Udimet 700 (Ni-15Cr-17Co-5Mo-3.5Ti-4Al-
0.06C) in the
solution-annealed and aged condition, showing precipitation of carbide at grain boundaries and arrays of
'
within grains of the solid-solution matrix. 4500×
In addition, some alloying elements can partition to ', affecting the interface mismatch and precipitate-coarsening
kinetics as well as contributing a solution-hardening component to strength, with titanium being the most effective at
room and elevated temperatures. However, titanium, niobium, and tantalum can influence mechanical properties still
further by encouraging the formation of other similar types of precipitates. With higher titanium content, ' will
transform to the hexagonal close-packed (hcp) -phase, Ni
3
Ti, which has an acicular or cellular morphology. With

increased amounts of niobium, ' transforms to the commercially important metastable body-centered tetragonal (bct)
phase '. A decrease in hardening will result if the equilibrium orthorhombic phase, Ni
3
Nb, is allowed to form. The
actual phases precipitated and their effectiveness in hardening the microstructure are dependent on the alloy composition,
the applied heat treatments, the resulting precipitate volume fraction, and the service conditions.
Carbides. Although not a carbide former, nickel dissolves many elements that readily form the carbides seen in nickel
alloys (MC, M
6
C, M
7
C
3
, M
23
C
6
). The MC carbides (where M = W, Ta, Ti, Mo, Nb) are usually large, blocky, and
undesirable. The M
6
C carbides (M = Mo, W) can precipitate as small platelets in the grains or as blocky particles in
boundaries useful for grain control, but deleterious for ductility and stress rupture properties. The M
7
C
3
(M = Cr) can be
useful when precipitated as discrete particles, but more so are grain boundary particles of M
23
C
6

(M = Cr, Mo, W), where
they can enhance creep rupture properties (Fig. 10). If carbides are allowed to agglomerate or form grain-boundary films
during heat treatment or in service at elevated temperatures, they can seriously impair ductility and cause embrittlement.
As in stainless steels, precipitation of chromium carbides at boundaries can lead to intergranular corrosion due to the
chromium-depleted zone alongside the grain boundary becoming anodic to the rest of the grains. This grain-boundary
sensitization is controlled in several ways: (1) by avoiding the chromium-carbide aging temperature range (425 to 760 °C,
or 800 to 1400 °F) during processing, (2) with stabilization heat treatments to tie up carbon with more stable carbide
formers (niobium, tantalum, titanium), and (3) by reducing the carbon level in the base alloy.

Fig. 10 Photomicrograph of the nickel alloy Udimet 700 (Ni-15Cr-17Co-5Mo-3.5Ti-4Al-0.06C) in the solution-
annealed and aged condition, showing precipitation of M
23
C
6
carbide at grain boundaries and arrays of
' within
grains of the solid-solution matrix. 1000×
Nickel Alloys
Nickel is alloyed to extend the good corrosion resistance and good heat resistance of elemental nickel. Even with
extensive amounts of alloying elements, the tough, ductile fcc austenitic matrix is preserved. It is convenient to describe
nickel alloys by grouping them into their two broad application areas: corrosion resistance, especially in aqueous
environments, and heat resistance. Naturally, this artificial separation should not be considered a rigid barrier as the
corrosion-resistant alloys have good strength above room temperature and the heat-resistant alloys have good corrosion
resistance. The unique, special-property alloys, many of which are also used for their good corrosion and heat resistance
as well as high strength, are described separately.
Corrosion-Resistant Nickel Alloys. A list of selected corrosion-resistant nickel alloys with nominal values of
mechanical properties is given in Table 11. The commercially pure nickel grades, Nickel 200 to 205, are highly resistant
to many corrosive media, especially in reducing environments, but also in oxidizing environments where they can
maintain the passive nickel oxide surface film. They are used in the chemical processing and electronics industries. They
are hot worked at 650 to 1230 °C (1200 to 2250 °F), annealed at 700 to 925 °C (1300 to 1700 °F), and are hardened by

cold working. For processed sheet, for example, the tensile properties in the annealed condition (460 MPa, or 67 ksi,
tensile strength; 148 MPa, or 22 ksi, yield strength; and 47% elongation) can be increased by cold rolling up to 760 MPa
(110 ksi) tensile strength, 635 MPa (92 ksi) yield strength, and 8% elongation. Because of its nominal 0.08% C content
(0.15% max), Nickel alloy 200 (UNS No 2200) should not be used above 315 °C (600 °F), because embrittlement results
from the precipitation of graphite in the temperature range 425 to 650 °C (800 to 1200 °F). The more widely used low-
carbon alloy Nickel 201 (UNS No 2201), with 0.02% max C, can be used at temperatures above 290 °C (550 °F). Higher-
purity nickel is commercially available for various electrical applications.
Table 11 Compositions and properties of selected corrosion-resistant nickel-base alloys
Ultimate
tensile
strength
Yield
strength
(0.2% offset)
Alloy Nominal composition, wt %
MPa ksi MPa ksi
Elongation in

50 mm (2 in.),
%
Rockwell
hardness
Commercially pure and low-alloy nickels
Nickel 200
99.0% Ni 462 67 148 21.5 47 109 HB
Nickel 201
99.0% Ni 403 58.5 103 15 50 129 HB
Nickel 211
Ni-4.75Mn-0.75Fe 530 77 240 35 40 . . .
Duranickel 301

Ni-4.5Al-0.5Ti 1170 170 862 125 25 30-40 HRC
Nickel-copper alloys
Alloy 400
Ni-31Cu-2.5Fe 550 80 240 35 40 110-150
HB
Alloy K-500
Ni-30Cu-2Fe-1.5Mn-2.7Al-0.6Ti 1100 160 790 115 20 300 HB
Nickel-molybdenum and nickel-silicon alloys
Hastelloy B
Ni-28Mo-5.5Fe-2.5Co
Sheet
834 121 386 56 63 92 HRB
Investment
cast
586 85 345 50 10 93 HRB
Hastelloy D
Ni-9.25Si-3Cu-1.5Co 793 115 . . . . . . . . . 30-39 HRC
Nickel-chromium-iron alloys
Alloy 600
Ni-15Cr-8Fe 655 95 310 45 40 75 HRB
Alloy 800
Ni-21Cr-39.5Fe-0.4Ti-0.4Al 600 87 295 43 44 138 HB
Alloy 617
Ni-22Cr-3Fe-12Co-9Mo-1Al 755 110 350 51 58 173 HB
Alloy 690
Ni-29Cr-9Fe 725 105 348 50 41 88 HRB
Alloy 751
Ni-15Cr-7Fe-1Nb-2Ti 1310 190 976 142 22 352 HB
Nickel-chromium-molybdenum alloys
Alloy C-276

Ni-15.5Cr-16Mo-5.5Fe-3.75W-1.25Co + V 785 114 372 54 62 209 HB
Alloy 625
Ni-21.5Cr-9Mo-3.65Nb + Ta-2.5Fe 930 135 517 75 42.5 190 HB
Nickel-chromium-iron-molybdenum-copper alloys
Hasteloy G
Ni-22.25 Cr-19.5Fe-6.5Mo-2Cu +
Co,Nb,Ta
690 100 320 47 50 79 HRB
Alloy 825
Ni-21.5Cr-30Fe-3Mo-2.25Cu + Al 690 100 310 45 45 . . .

The low-alloy nickels contain 94% min Ni. The 5% Mn solid-solution addition in Nickel 211 protects against sulfur in
service environments. As little as 0.005% S can cause liquid embrittlement at unalloyed nickel grain boundaries in the
range between 640 and 740 °C (1185 and 1365 °F). Duranickel, alloy 301 (Ni-4.5Al-0.6Ti), offers the corrosion
resistance of commercially pure nickel with the strengthening provided by the precipitation of '. There is sufficient
alloying additions in alloy 301 to lower the Curie temperature, making the alloy weakly ferromagnetic at room
temperature.
The nickel-copper alloys are strong and tough, offering corrosion resistance in various environments, including brine and
sulfuric and other acids, and showing immunity to chloride-ion stress corrosion. They are used in chemical processing and
pollution control equipment. Capable of precipitating ', Ni
3
(Al,Ti), with its 2.7Al-0.6Ti alloy addition, alloy K-500 adds
an age-hardening component to the good solution strengthening and work-hardening characteristics already available with
the nominal 30% Cu in alloy 400. The composition of these alloys can be adjusted to decrease the Curie temperature to
below room temperature.
The Ni-Cr-Fe(-Mo) alloys might simply be thought of as nickel-base analogs of the iron-base austenitic stainless steel
alloys, with an interchange of the iron and nickel contents. In these commercially important alloys the chromium content
in general ranges from 14 to 30% and iron from 3 to 20%. With a well-maintained Cr
2
O

3
surface film, these alloys offer
excellent corrosion resistance in many severe environments, showing immunity to chloride-ion stress-corrosion cracking.
They also offer good oxidation and sulfidation resistance with good strength at elevated temperatures. These nickel-rich
Ni-Cr-Fe alloys have maximum operating temperatures in the neighborhood of 1200 °C (2200 °F). Alloy 600 (UNS
N06600, with Ni-15Cr-8Fe) is a single-phase alloy that can be used at temperatures from cryogenic to 1093 °C (2000 °F).
The modest yield strength of strip in the annealed condition (207 to 310 MPa, or 30 to 45 ksi) can be readily work
hardened by cold rolling to reach yield strengths of 827 to 1100 MPa (120 to 160 ksi) and can retain most of this strength
up to about 540 °C (1000 °F).
The Ni-Cr-(Fe)-Mo alloys consist of a large family of alloys that are used in the chemical processing, pollution control,
and waste treatment industries to utilize their excellent heat and corrosion resistance. Alloys in this commercially
important family, such as C-276 and alloy 625, are made even more versatile by their excellent welding characteristics
and the corrosion resistance of welded structures. The molybdenum additions to these alloys improve resistance to pitting
and crevice corrosion. Aluminum improves the protective surface oxide film, and the carbide formers titanium and
niobium are used to stabilize the alloys against chromium-carbide sensitization. Even with the low-level additions of
aluminum and titanium to alloy 800, for example, small amounts of ' can form in service during exposure to elevated
temperatures. The high molybdenum and silicon additions in Hastelloy B and D promote good corrosion resistance in the
presence of hydrochloric and sulfuric acids.
Heat-Resistant Nickel Alloys. Chemical compositions of selected heat-resistant superalloys are given in Table 12. A
glance at this list reveals that these nickel-containing materials include nickel-, iron-nickel-, or cobalt-base alloys. They
can be made by wrought and P/M methods, and also with castings produced with carefully controlled conditions to
provide the desired polycrystal, or elongated (directionally solidified), or single-crystal grain structure for improved
elevated-temperature mechanical properties. The majority of the nickel-base superalloys utilize the combined
strengthening of a solution-hardened austenite matrix with ' precipitation. The niobium-rich, age-hardening precipitate,
'', offers the ease of heat treatment and weldability that has made alloy 718 the most important nickel-base superalloy
for aerospace and nuclear structural applications. Alloy 718 is a high-strength, corrosion-resistant alloy that is used at
temperatures from -250 to 700 °C (-423 to 1300 °F). Some of the alloys, Hastelloy X for example, obtain additional
strengthening from carbide precipitation instead of '. Others, MA 754 for example, utilize P/M techniques involving
mechanical alloying (Ref 27) to achieve a dispersion of about 1 vol% of very fine (25 nm) inert oxide particles, such as
Y

2
O
3
, to promote higher elevated-temperature tensile and stress-rupture strength.
Table 12 Chemical compositions of selected superalloys
Composition, wt % Alloy
(a)

Ni Cr Fe Co Mo

W Nb

Ti Al C Mn Si B Other
Wrought alloys
Waspaloy
58.0

19.5

. . . 13.5

4.3 . . . . . .

3.0

1.3 0.08 . . . . . . 0.006

. . .
Udimet 700
55.0

15.0

. . . 17.0

5.0 . . . . . .

3.5

4.0 0.06 . . . . . . 0.030

. . .
Hastelloy X
47.0

22.0

18.5

1.5 9.0 0.6 . . .

. . .

. . . 0.10 0.5 0.5 . . . . . .
A-286
26.0

15.0

54.0

. . . 1.3 . . . . . .

2.0

0.2 0.05 1.3 0.5 0.015

. . .
Incoloy 901
42.5

12.5

36.0

. . . 5.7 . . . . . .

2.8

0.2 0.05 0.1 0.1 0.015

. . .
Inconel 718
52.5

19.0

18.5

. . . 3.0 . . . 5.1

0.9

0.5 0.04 0.2 0.2 . . . . . .
Incoloy 903
38.0

. . . 42.0

15.0

. . . . . . 3.0

1.4

0.9 . . . 0.8 1.0 . . . . . .
Incoloy 909
38.0

. . . 42.0

13.0

. . . . . . 4.7

1.5

0.03

. . . . . . 0.4 . . . . . .

Haynes 188
22.0

22.0

3.0 bal . . . 14.0

. . .

. . .

. . . 0.10 1.25

0.35

. . . . . .
Haynes 25 (L-
605)
10.0

20.0

3.0 bal . . . 15.0

. . .

. . .

. . . 0.10 1.5 1.0 . . . 0.05 La
Cast alloys

MAR-M-200(P)
bal 9.0 . . . 10.0

. . . 12.5

1.8

2.0

5.0 0.15 . . . . . . 0.015

0.05 Zr
B-1900 (P)
bal 8.0 . . . 10.0

6.0 . . . . . .

1.0

6.0 0.10 . . . . . . 0.015

4.3Ta, 0.08 Zr
Nimocast 90 (P)
bal 19.5

1.5 18.0

. . . . . . . . .

2.4

1.4 0.06 . . . . . . . . . . . .
MAR-M-509 (P)
10.0

24.0

1.0 bal . . . 7.0 . . .

0.2

. . . 0.60 . . . . . . . . . 7.5 Ta
FSX-414 (P)
10.5

29.5

2.0 bal . . . 7.0 . . .

. . .

. . . 0.25 . . . . . . 0.012

. . .
MAR-M-247 (DS)

bal 8.0 . . . 10.0

0.6 10.0

. . .

1.0

5.5 0.15 . . . . . . 0.015

3.0 Ta, 0.03 Zr, 1.5 Hf
CM 247 LC (DS)
bal 8.0 . . . 9.0 0.5 10.0

. . .

0.7

5.6 0.07 . . . . . . 0.015

3.2 Ta, 0.010 Zr, 1.4
Hf
PWA 1484 (SC)
bal 5.0 . . . 10.0

2.0 6.0 . . .

. . .

5.6 . . . . . . . . . . . . 9.0 Ta, 3.0 Re, 0.1 Hf
CMSX-4
bal 6.0 . . . 9.0 0.6 6.0 . . .

1.0

5.6 . . . . . . . . . . . . 7 Ta, 3 Re, 0.1 Hf
Powder metallurgy alloys
MA754
bal 20.0

. . . . . . . . . . . . . . .

0.5

0.3 0.05 . . . . . . . . . 0.6 Y
2
O
3

MA 6000
bal 15.0

. . . 2.0 2.0 4.0 . . .

2.5

4.5 0.05 . . . . . . 0.1 2Ta
MERL 76
bal 12.2

. . . 18.2

3.2 . . . 1.3

4.3

5.0 0.025

. . . . . . 0.02 0.3 Hf, 0.06 Zr
Rene' 95
bal 12.8

. . . 8.1 3.6 3.6 3.6

2.6

3.6 0.08 . . . . . . 0.01 0.053 Zr

(a)
P, polycrystalline casting; DS, directionally solidified casting; SC, single-crystal casting; bal, balance

The iron-base Fe-Ni-Cr heat-resistant alloys are extensions of the iron-base stainless steels with higher nickel and
additions of other alloying elements. Retaining the fcc iron-nickel austenite matrix, these alloys (alloys A-286 and 901,
for example) are workable into various wrought forms and are capable of precipitation hardening with '. Alloys 903 and
909 are controlled thermal expansion Fe-Ni-Co-base alloys that are capable of age hardening with Ni
3
(Nb,Ti)
precipitation and are designed to have high strength and low coefficient of thermal expansion for applications in gas
turbine rings and seals up to 650 °C (1200 °F) (Ref 26). These alloys are hot worked at about 870 to 1120 °C (1600 to
2050 °F) and solution heat treated at 815 to 980 °C (1500 to 1800 °F). The standard aging treatment consists of 720 °C
(1325 °F) for 8 h, furnace cool at 55 °C (100 °F)/h to 620 °C (1150 °F) for 8 h, followed by air cooling. Alloy 909 in the
as-hardened condition, for example, retains much of its room-temperature yield strength (1070 MPa, or 155 ksi) at 540 °C
(1000 °F), namely, 895 MPa (130 ksi) (Ref 30).
Specialty Nickel Alloys. Unique combinations of properties are available with other nickel-base alloys for special

applications. While some of these properties are also available to some extent with alloys described above, the alloys
described below were developed to promote their rather unique properties.
There are many electrical resistance alloys used for resistance heating elements. They can contain 35 to 95% Ni, but
invariably contain greater than 15% Cr to form an adherent surface oxide to protect against oxidation and carburization at
temperatures up to 1000 to 1200 °C (1850 to 2200 °F) in air. Examples are Ni-20Cr (UNS N06003), Ni-15Cr-25Fe (UNS
N06004), and Ni-20Cr-3Al-3Fe. These alloys are single-phase austenite and have the needed properties for heating
elements: desirably high, reproducible electrical resistance; low thermal expansion to minimize thermal fatigue and
shock; good creep strength; strong and ductile for fabrication (Ref 27, 28).
The ferromagnetic characteristics of nickel allow formulation of nickel-base alloys for corrosion-resistant soft magnets
for a variety of applications, typified by Ni-5Mo-16Fe. Low thermal expansion characteristics are shown by Fe-(36-
52)Ni-(0-17)Co alloys, making these materials useful for glass-to-metal sealing and containment equipment for liquefied
natural gas, for example. The controlled thermal expansion alloys, typified by alloy 903 (Ni-42Fe-15Co + Nb,Al,Ti), are
also '-precipitation hardenable, offering high strength and low, relatively constant thermal expansion coefficient for
applications up to about 650 °C (1200 °F). With nearly 50-50 at.%, nickel forms a shape memory intermetallic alloy with
titanium, which offers 8% of reversible strain via a thermoelastic martensitic transformation, along with good ductility
and corrosion resistance.
The L1
2
intermetallic compound, Ni
3
Al, has been the focus of development work to create a strong, corrosion-resistant
material for elevated-temperature applications. Wrought and cast beryllium-nickel alloys are commercially available
(UNS N03360 with Ni-2Be-0.5Ti, for example) and respond to processing and age-hardening heat treatments as readily
as the beryllium-copper alloys, but offer higher strength with better resistance to thermal softening and stress relaxation
(Ref 25, 29, 30, 31, 32).

References cited in this section
18.

Properties of Pure Metals, Properties and Selection: Nonferrous Alloys and Special-Purpose Materials,

Vol
2, ASM Handbook, ASM International, 1990, p 1099-1201
25.

J.C. Harkness, W.D. Speigelberg, and W.R. Cribb, Beryllium-Copper and Other Beryllium-
Containing
Alloys, Properties and Selection: Nonferrous Alloys and Special-Purpose Materials, Vol 2,
ASM