Analuminium alloy (UK/IUPAC) oraluminum alloy (NA; seespelling differences) is analloy in whichaluminium (Al) is the predominant metal. The typical alloying elements arecopper,magnesium,manganese,silicon,tin,nickel andzinc. There are two principal classifications, namelycasting alloys and wrought alloys, both of which are further subdivided into the categoriesheat-treatable and non-heat-treatable. About 85% of aluminium is used for wrought products, for example rolled plate, foils andextrusions. Cast aluminium alloys yield cost-effective products due to the low melting point, although they generally have lowertensile strengths than wrought alloys. The most important cast aluminium alloy system isAl–Si, where the high levels of silicon (4–13%) contribute to give good casting characteristics. Aluminium alloys are widely used in engineering structures and components where light weight or corrosion resistance is required.[1]
Alloys composed mostly of aluminium have been very important inaerospace manufacturing since the introduction of metal-skinned aircraft. Aluminium–magnesium alloys are both lighter than other aluminium alloys and much less flammable than other alloys that contain a very high percentage of magnesium.[2]
Aluminium alloy surfaces will develop a white, protective layer ofaluminium oxide if left unprotected byanodizing and/or correct painting procedures. In a wet environment,galvanic corrosion can occur when an aluminium alloy is placed in electrical contact with other metals with more positive corrosion potentials than aluminium, and an electrolyte is present that allows ion exchange. Also referred to as dissimilar-metal corrosion, this process can occur as exfoliation or as intergranular corrosion. Aluminium alloys can be improperly heat treated, causing internal element separation which corrodes the metal from the inside out.[citation needed]
Aluminium alloy compositions are registered withThe Aluminum Association. Many organizations publish more specific standards for the manufacture of aluminium alloy, including theSAE International standards organization, specifically its aerospace standards subgroups,[3] andASTM International.
Aluminium alloys with a wide range of properties are used in engineering structures. Alloy systems are classified by a number system (ANSI) or by names indicating their main alloying constituents (DIN andISO). Selecting the right alloy for a given application entails considerations of itstensile strength,density,ductility, formability, workability,weldability, andcorrosion resistance, to name a few. A brief historical overview of alloys and manufacturing technologies is given in Ref.[4] Aluminium alloys are used extensively in aircraft due to their highstrength-to-weight ratio. Pure aluminium is much too soft for such uses, and it does not have the high tensile strength that is needed for buildingairplanes andhelicopters.
Aluminium alloys typically have anelastic modulus of about 70GPa, which is about one-third of the elastic modulus ofsteel alloys. Therefore, for a given load, a component or unit made of an aluminium alloy will experience a greater deformation in the elastic regime than a steel part of identical size and shape. With completely new metal products, the design choices are often governed by the choice of manufacturing technology. Extrusions are particularly important in this regard, owing to the ease with which aluminium alloys, particularly the Al-Mg-Si series, can be extruded to form complex profiles.
In general, stiffer and lighter designs can be achieved with aluminium alloy than is feasible with steels. For instance, consider the bending of a thin-walled tube: thesecond moment of area is inversely related to the stress in the tube wall, i.e. stresses are lower for larger values. The second moment of area is proportional to the cube of the radius times the wall thickness, thus increasing the radius (and weight) by 26% will lead to a halving of the wall stress. For this reason, bicycle frames made of aluminium alloys make use of larger tube diameters than steel or titanium in order to yield the desired stiffness and strength. In automotive engineering, cars made of aluminium alloys employspace frames made of extruded profiles to ensure rigidity. This represents a radical change from the common approach for current steel car design, which depend on the body shells for stiffness, known asunibody design.
Aluminium alloys are widely used in automotive engines, particularly inengine blocks andcrankcases due to the weight savings that are possible. Since aluminium alloys are susceptible to warping at elevated temperatures, the cooling system of such engines is critical. Manufacturing techniques and metallurgical advancements have also been instrumental for the successful application in automotive engines. In the 1960s, the aluminiumcylinder heads of theChevrolet Corvair earned a reputation for failure and stripping ofthreads, which is not seen in current aluminium cylinder heads.
An important structural limitation of aluminium alloys is their lowerfatigue strength compared to steel. In controlled laboratory conditions, steels display afatigue limit, which is the stress amplitude below which no failures occur – the metal does not continue to weaken with extended stress cycles. Aluminium alloys do not have this lower fatigue limit and will continue to weaken with continued stress cycles. Aluminium alloys are therefore sparsely used in parts that require high fatigue strength in the high cycle regime (more than 107 stress cycles).
Often, the metal's sensitivity to heat must also be considered. Even a relatively routine workshop procedure involving heating is complicated by the fact that aluminium, unlike steel, will melt without first glowing red. Forming operations where a blow torch is used can reverse or remove the effects of heat treatment. No visual signs reveal how the material is internally damaged. Much like welding heat treated, high strength link chain, all strength is now lost by heat of the torch. The chain is dangerous and must be discarded.[citation needed]
Aluminium is subject to internal stresses and strains. Sometimes years later, improperly welded aluminium bicycle frames may gradually twist out of alignment from the stresses of the welding process. Thus, the aerospace industry avoids heat altogether by joining parts with rivets of like metal composition, other fasteners, or adhesives.
Stresses in overheated aluminium can be relieved by heat-treating the parts in an oven and gradually cooling it—in effectannealing the stresses. Yet these parts may still become distorted, so that heat-treating of welded bicycle frames, for instance, can result in a significant fraction becoming misaligned. If the misalignment is not too severe, the cooled parts may be bent into alignment. If the frame is properly designed for rigidity (see above), that bending will require enormous force.[citation needed]
Aluminium's intolerance to high temperatures has not precluded its use in rocketry; even for use in constructing combustion chambers where gases can reach 3500 K. TheRM-81 Agena upper stage engine used a regeneratively cooled aluminium design for some parts of the nozzle, including the thermally critical throat region; in fact the extremely high thermal conductivity of aluminium prevented the throat from reaching the melting point even under massive heat flux, resulting in a reliable, lightweight component.
Because of its high conductivity and relatively low price compared with copper in the 1960s, aluminium was introduced at that time for household electrical wiring in North America, even though many fixtures had not been designed to accept aluminium wire. But the new use brought some problems:
All of this resulted in overheated and loose connections, and this in turn resulted in some fires. Builders then became wary of using the wire, and many jurisdictions outlawed its use in very small sizes, in new construction. Yet newer fixtures eventually were introduced with connections designed to avoid loosening and overheating. At first they were marked "Al/Cu", but they now bear a "CO/ALR" coding.
Another way to forestall the heating problem is tocrimp the short "pigtail" of copper wire. A properly done high-pressure crimp by the proper tool is tight enough to reduce any thermal expansion of the aluminium. Today, new alloys, designs, and methods are used for aluminium wiring in combination with aluminium terminations.
Wrought and cast aluminium alloys use different identification systems. Wrought aluminium is identified with a four digit number which identifies the alloying elements.
Cast aluminium alloys use a four to five digit number with a decimal point. The digit in the hundreds place indicates the alloying elements, while the digit after the decimal point indicates the form (cast shape or ingot).
The temper designation follows the cast or wrought designation number with a dash, a letter, and potentially a one to three digit number, e.g. 6061-T6. The definitions for the tempers are:[5][6]
-F : As fabricated
-H : Strain hardened (cold worked) with or without thermal treatment
-O : Full soft (annealed)
-T : Heat treated to produce stable tempers
-W : Solution heat treated only
Note: -W is a relatively soft intermediary designation that applies after heat treat and before aging is completed. The -W condition can be extended at extremely low temperatures but not indefinitely and depending on the material will typically last no longer than 15 minutes at ambient temperatures.
The International Alloy Designation System is the most widely accepted naming scheme for wrought alloys. Each alloy is given a four-digit number, where the first digit indicates the major alloying elements, the second — if different from 0 — indicates a variation of the alloy, and the third and fourth digits identify the specific alloy in the series. For example, in alloy 3105, the number 3 indicates the alloy is in the manganese series, 1 indicates the first modification of alloy 3005, and finally 05 identifies it in the 3000 series.[7]
1000 series are essentially pure aluminium with a minimum 99% aluminium content by weight and can bework hardened.
| Alloy | Al contents | Alloying elements | Uses and refs |
|---|---|---|---|
| 1050 | 99.5 | – | Drawn tube, chemical equipment |
| 1060 | 99.6 | – | Universal |
| 1070 | 99.7 | – | Thick-wall drawn tube |
| 1100 | 99.0 | Cu 0.05–0.20,Fe 0.95 max,Mn 0.05 max,Si 0.95 max,Zn 0.1 max, Residuals: 0.15 max | Universal,holloware |
| 1145 | 99.45 | – | Sheet, plate, foil |
| 1199 | 99.99 | – | Foil[8] |
| 1200 | 99.0 max | (Si +Fe) 1.0 max;Cu 0.05 max;Mn 0.05 max;Zn 0.10 max;Ti 0.05 max; others 0.05 (each) .015 (total) | [9] |
| 1230 (VAD23)# | Si 0.3;Fe 0.3;Cu 4.8–5.8;Mn 0.4–0.8;Mg 0.05;Zn 0.1;Ti 0.15;Li 0.9–1.4;Cd 0.1–0.25 | Tu-144 aircraft[10] | |
| 1350 | 99.5 | – | Electrical conductors |
| 1370 | 99.7 | – | Electrical conductors |
| 1420# | 92.9 | Mg 5.0;Li 2.0;Zr 0.1 | Aerospace |
| 1421# | 92.9 | Mg 5.0;Li 2.0;Mn 0.2;Sc 0.2;Zr 0.1 | Aerospace[11] |
| 1424# | Si 0.08;Fe 0.1;Mn 0.1–0.25;Mg 4.7–5.2;Zn 0.4–0.7;Li 1.5–1.8;Zr 0.07–0.1;Be 0.02–0.2;Sc 0.05–0.08;Na 0.0015 | [10] | |
| 1430# | Si 0.1;Fe 0.15;Cu 1.4–1.8;Mn 0.3–0.5;Mg 2.3–3.0;Zn 0.5–0.7;Ti 0.01–0.1;Li 1.5–1.9;Zr 0.08–0.14;Be 0.02–0.1;Sc 0.01–0.1;Na 0.003;Ce 0.2–0.4;Y 0.05–0.1 | [10] | |
| 1440# | Si 0.02–0.1;Fe 0.03–0.15;Cu 1.2–1.9;Mn 0.05;Mg 0.6–1.1;Cr 0.05;Ti 0.02–0.1;Li 2.1–2.6;Zr 0.10–0.2;Be 0.05–0.2;Na 0.003 | [10] | |
| 1441# | Si 0.08;Fe 0.12;Cu 1.5–1.8;Mn 0.001–0.010;Mg 0.7–1.1;Ti 0.01–0.07;Ni 0.02–0.10;Li 1.8–2.1;Zr 0.04–0.16;Be 0.02–0.20 | Be-103 andBe-200 hydroplanes[10] | |
| 1441K# | Si 0.08;Fe 0.12;Cu 1.3–1.5;Mn 0.001–0.010;Mg 0.7–1.1;Ti 0.01–0.07;Ni 0.01–0.15;Li 1.8–2.1;Zr 0.04–0.16;Be 0.002–0.01 | [10] | |
| 1445# | Si 0.08;Fe 0.12;Cu 1.3–1.5;Mn 0.001–0.010;Mg 0.7–1.1;Ti 0.01–0.1;Ni 0.01–0.15;Li 1.6–1.9;Zr 0.04–0.16;Be 0.002–0.01;Sc 0.005–0.001;Ag 0.05–0.15;Ca 0.005–0.04;Na 0.0015 | [10] | |
| 1450# | Si 0.1;Fe 0.15;Cu 2.6–3.3;Mn 0.1;Mg 0.1;Cr 0.05;Zn 0.25;Ti 0.01–0.06;Li 1.8–2.3;Zr 0.08–0.14;Be 0.008–0.1;Na 0.002;Ce 0.005–0.05 | An-124 andAn-225 aircraft[10] | |
| 1460# | Si 0.1;Fe 0.03–0.15;Cu 2.6–3.3;Mg 0.05;Ti 0.01–0.05;Li 2.0–2.4;Zr 0.08–0.13;Na 0.002;Sc 0.05–0.14;B 0.0002–0.0003 | Tu-156 aircraft[10] | |
| V-1461# | Si 0.8;Fe 0.01–0.1;Cu 2.5–2.95;Mn 0.2–0.6;Mg 0.05–0.6;Cr 0.01–0.05;Zn 0.2–0.8;Ti 0.05;Ni 0.05–0.15;Li 1.5–1.95;Zr 0.05–0.12;Be 0.0001–0.02;Sc 0.05–0.10;Ca 0.001–0.05;Na 0.0015 | [10] | |
| V-1464# | Si 0.03–0.08;Fe 0.03–0.10;Cu 3.25–3.45;Mn 0.20–0.30;Mg 0.35–0.45;Ti 0.01–0.03;Li 1.55–1.70;Zr 0.08–0.10;Sc 0.08–0.10;Be 0.0003–0.02;Na 0.0005 | [10] | |
| V-1469# | Si 0.1;Fe 0.12;Cu 3.2–4.5;Mn 0.003–0.5;Mg 0.1–0.5;Li 1.0–1.5;Zr 0.04–0.20;Sc 0.04–0.15;Ag 0.15–0.6 | [10] |
# Not an International Alloy Designation System name
2000 series are alloyed with copper, can beprecipitation hardened to strengths comparable to steel. Formerly referred to asduralumin, they were once the most common aerospace alloys, but were susceptible tostress corrosion cracking and are increasingly replaced by 7000 series in new designs.
| Alloy | Al contents | Alloying elements | Uses and refs |
|---|---|---|---|
| 2004 | 93.6 | Cu 6.0;Zr 0.4 | Aerospace |
| 2011 | 93.7 | Cu 5.5;Bi 0.4;Pb 0.4 | Universal |
| 2014 | 93.5 | Cu 4.4;Si 0.8;Mn 0.8;Mg 0.5 | Universal |
| 2017 | 94.2 | Cu 4.0;Si 0.5;Mn 0.7;Mg 0.6 | Aerospace |
| 2020 | 93.4 | Cu 4.5;Li 1.3;Mn 0.55;Cd 0.25 | Aerospace |
| 2024 | 93.5 | Cu 4.4;Mn 0.6;Mg 1.5 | Universal, aerospace[12] |
| 2029 | 94.6 | Cu 3.6;Mn 0.3;Mg 1.0;Ag 0.4;Zr 0.1 | Alclad sheet, aerospace[13] |
| 2036 | 96.7 | Cu 2.6;Mn 0.25;Mg 0.45 | Sheet |
| 2048 | 94.8 | Cu 3.3;Mn 0.4;Mg 1.5 | Sheet, plate |
| 2055 | 93.5 | Cu 3.7;Zn 0.5;Li 1.1;Ag 0.4;Mn 0.2;Mg 0.3;Zr 0.1 | Aerospace extrusions,[14] |
| 2080 | 94.0 | Mg 3.7;Zn 1.85;Cr 0.2;Li 0.2 | Aerospace |
| 2090 | 95.0 | Cu 2.7;Li 2.2;Zr 0.12 | Aerospace |
| 2091 | 94.3 | Cu 2.1;Li 2.0;Mg 1.5;Zr 0.1 | Aerospace, cryogenics |
| 2094 | Si 0.12;Fe 0.15;Cu 4.4–5.2;Mn 0.25;Mg 0.25–0.8;Zn 0.25;Ti 0.10;Ag 0.25–0.6;Li 0.7–1.4;Zr 0.04–0.18 | [10] | |
| 2095 | 93.6 | Cu 4.2;Li 1.3;Mg 0.4;Ag 0.4;Zr 0.1 | Aerospace |
| 2097 | Si 0.12;Fe 0.15;Cu 2.5–3.1;Mn 0.10–0.6;Mg 0.35;Zn 0.35;Ti 0.15;Li 1.2–1.8;Zr 0.08–0.15 | [10] | |
| 2098 | Si 0.12;Fe 0.15;Cu 2.3–3.8;Mn 0.35;Mg 0.25–0.8;Zn 0.35;Ti 0.10;Ag 0.25–0.6;Li 2.4–2.8;Zr 0.04–0.18 | [10] | |
| 2099 | 94.3 | Cu 2.53;Mn 0.3;Mg 0.25;Li 1.75;Zn 0.75;Zr 0.09 | Aerospace[15] |
| 2124 | 93.5 | Cu 4.4;Mn 0.6;Mg 1.5 | Plate |
| 2195 | 93.5 | Cu 4.0;Mn 0.5;Mg 0.45;Li 1.0;Ag 0.4;Zr 0.12 | Aerospace,[16][17]Space Shuttle Super Lightweight external tank,[18] and theSpaceXFalcon 9[19] andFalcon 1e second stage launch vehicles.[20] |
| 2196 | Si 0.12;Fe 0.15;Cu 2.5–3.3;Mn 0.35;Mg 0.25–0.8;Zn 0.35;Ti 0.10;Ag 0.25–0.6;Li 1.4–2.1;Zr 0.08–0.16[10] | Extrusion | |
| 2197 | Si 0.10;Fe 0.10;Cu 2.5–3.1;Mn 0.10–0.50;Mg 0.25;Zn 0.05;Ti 0.12;Li 1.3–1.7;Zr 0.08–0.15 | [10] | |
| 2198 | Sheet | ||
| 2218 | 92.2 | Cu 4.0;Mg 1.5;Fe 1.0;Si 0.9;Zn 0.25;Mn 0.2 | Forgings, aircraft engine cylinders[21] |
| 2219 | 93.0 | Cu 6.3;Mn 0.3;Ti 0.06;V 0.1;Zr 0.18 | Universal,Space Shuttle Standard Weight external tank |
| 2297 | Si 0.10;Fe 0.10;Cu 2.5–3.1;Mn 0.10–0.50;Mg 0.25;Zn 0.05;Ti 0.12;Li 1.1–1.7;Zr 0.08–0.15 | [10] | |
| 2397 | Si 0.10;Fe 0.10;Cu 2.5–3.1;Mn 0.10–0.50;Mg 0.25;Zn 0.05–0.15;Ti 0.12;Li 1.1–1.7;Zr 0.08–0.15 | [10] | |
| 2224&2324 | 93.8 | Cu 4.1;Mn 0.6;Mg 1.5 | Plate[22] |
| 2319 | 93.0 | Cu 6.3;Mn 0.3;Ti 0.15;V 0.1;Zr 0.18 | Bar and wire |
| 2519 | 93.0 | Cu 5.8;Mg 0.2;Ti 0.15;V 0.1;Zr 0.2 | Aerospace armour plate |
| 2524 | 93.8 | Cu 4.2;Mn 0.6;Mg 1.4 | Plate, sheet[23] |
| 2618 | 93.7 | Cu 2.3;Si 0.18;Mg 1.6;Ti 0.07;Fe 1.1;Ni 1.0 | Forgings |
3000 series are alloyed withmanganese, and can bework hardened.
| Alloy | Al contents | Alloying elements | Uses and refs |
|---|---|---|---|
| 3003 | 98.6 | Mn 1.5;Cu 0.12 | Universal, sheet, rigid foil containers, signs, decorative |
| 3004 | 97.8 | Mn 1.2;Mg 1 | Universal, beverage cans[24] |
| 3005 | 98.5 | Mn 1.0;Mg 0.5 | Work-hardened |
| 3102 | 99.8 | Mn 0.2 | Work-hardened[25] |
| 3103&3303 | 98.8 | Mn 1.2 | Work-hardened |
| 3105 | 97.8 | Mn 0.55;Mg 0.5 | Sheet |
| 3203 | 98.8 | Mn 1.2 | Sheet, high strength foil |
4000 series are alloyed with silicon. Variations of aluminium–silicon alloys intended for casting (and therefore not included in 4000 series) are also known assilumin.
| Alloy | Al contents | Alloying elements | Uses and refs |
|---|---|---|---|
| 4006 | 98.3 | Si 1.0;Fe 0.65 | Work-hardened or aged |
| 4007 | 96.3 | Si 1.4;Mn 1.2;Fe 0.7;Ni 0.3;Cr 0.1 | Work-hardened |
| 4015 | 96.8 | Si 2.0;Mn 1.0;Mg 0.2 | Work-hardened |
| 4032 | 85 | Si 12.2;Cu 0.9;Mg 1;Ni 0.9; | Forgings |
| 4043 | 94.8 | Si 5.2 | Rod, Welding Filler, Brazing Filler |
| 4047 | 85.5 | Si 12.0;Fe 0.8;Cu 0.3;Zn 0.2;Mn 0.15;Mg 0.1 | Sheet, cladding, fillers[26] |
| 4543 | 93.7 | Si 6.0;Mg 0.3 | architectural extrusions |
| 4643 | 93.7 | Si 4.1;Fe 0.8;Mg 0.2;Zn 0.1 | Welding filler for 6000 series |
5000 series are alloyed with magnesium, and offer superb corrosion resistance, making them suitable for marine applications.5083 alloy has the highest strength of non-heat-treated alloys. Most 5000 series alloys includemanganese as well.
| Alloy | Al contents | Alloying elements | Uses and refs |
|---|---|---|---|
| 5005 & 5657 | 99.2 | Mg 0.8 | Sheet, plate, rod |
| 5010 | 99.3 | Mg 0.5;Mn 0.2; | |
| 5019 | 94.7 | Mg 5.0;Mn 0.25; | |
| 5024 | 94.5 | Mg 4.6;Mn 0.6;Zr 0.1;Sc 0.2 | Extrusions, aerospace[27] |
| 5026 | 93.9 | Mg 4.5;Mn 1;Si 0.9;Fe 0.4;Cu 0.3 | |
| 5050 | 98.6 | Mg 1.4 | Universal |
| 5052 & 5652 | 97.2 | Mg 2.5;Cr 0.25 | Universal, aerospace, marine |
| 5056 | 94.8 | Mg 5.0;Mn 0.12;Cr 0.12 | Foil, rod, rivets |
| 5059 | 93.5 | Mg 5.0;Mn 0.8;Zn 0.6;Zr 0.12 | rocket cryogenic tanks |
| 5083 | 94.8 | Mg 4.4;Mn 0.7;Cr 0.15 | Universal, welding, marine |
| 5086 | 95.4 | Mg 4.0;Mn 0.4;Cr 0.15 | Universal, welding, marine |
| 5154 & 5254 | 96.2 | Mg 3.5;Cr 0.25; | Universal, rivets[28] |
| 5182 | 95.2 | Mg 4.5;Mn 0.35; | Sheet |
| 5252 | 97.5 | Mg 2.5; | Sheet |
| 5356 | 94.6 | Mg 5.0;Mn 0.12;Cr 0.12;Ti 0.13 | Rod, MIG wire |
| 5454 | 96.4 | Mg 2.7;Mn 0.8;Cr 0.12 | Universal |
| 5456 | 94 | Mg 5.1;Mn 0.8;Cr 0.12 | Universal |
| 5457 | 98.7 | Mg 1.0;Mn 0.2;Cu 0.1 | Sheet, automobile trim[29] |
| 5557 | 99.1 | Mg 0.6;Mn 0.2;Cu 0.1 | Sheet, automobile trim[30] |
| 5754 | 95.8 | Mg 3.1;Mn 0.5;Cr 0.3 | Sheet, Rod |
6000 series are alloyed with magnesium and silicon. They are easy to machine, areweldable, and can be precipitation hardened, but not to the high strengths that 2000 and 7000 can reach.6061 alloy is one of the most commonly used general-purpose aluminium alloys.
| Alloy | Al contents | Alloying elements | Uses and refs |
|---|---|---|---|
| 6005 | 98.7 | Si 0.8;Mg 0.5 | Extrusions, angles |
| 6005A | 96.5 | Si 0.6;Mg 0.5;Cu 0.3;Cr 0.3;Fe 0.35 | |
| 6009 | 97.7 | Si 0.8;Mg 0.6;Mn 0.5;Cu 0.35 | Sheet |
| 6010 | 97.3 | Si 1.0;Mg 0.7;Mn 0.5;Cu 0.35 | Sheet |
| 6013 | 97.05 | Si 0.8;Mg 1.0;Mn 0.35;Cu 0.8 | Plate, aerospace, smartphone cases[31][32] |
| 6022 | 97.9 | Si 1.1;Mg 0.6;Mn 0.05;Cu 0.05;Fe 0.3 | Sheet, automotive[33] |
| 6060 | 98.9 | Si 0.4;Mg 0.5;Fe 0.2 | Heat-treatable |
| 6061 | 97.9 | Si 0.6;Mg 1.0;Cu 0.25;Cr 0.2 | Universal, structural, aerospace |
| 6063 & 646g | 98.9 | Si 0.4;Mg 0.7 | Universal, marine, decorative |
| 6063A | 98.7 | Si 0.4;Mg 0.7;Fe 0.2 | Heat-treatable |
| 6065 | 97.1 | Si 0.6;Mg 1.0;Cu 0.25;Bi 1.0 | Heat-treatable |
| 6066 | 95.7 | Si 1.4;Mg 1.1;Mn 0.8;Cu 1.0 | Universal |
| 6070 | 96.8 | Si 1.4;Mg 0.8;Mn 0.7;Cu 0.28 | Extrusions |
| 6081 | 98.1 | Si 0.9;Mg 0.8;Mn 0.2 | Heat-treatable |
| 6082 | 97.5 | Si 1.0;Mg 0.85;Mn 0.65 | Heat-treatable |
| 6101 | 98.9 | Si 0.5;Mg 0.6 | Extrusions |
| 6105 | 98.6 | Si 0.8;Mg 0.65 | Heat-treatable |
| 6111 | 98.4 | Cu 0.7;Mg 0.75;Si 0.85 | Precipitation hardening;[34] used for automotive paneling.[35][36]Corrosion resistance. |
| 6113 | 96.8 | Si 0.8;Mg 1.0;Mn 0.35;Cu 0.8;O 0.2 | Aerospace |
| 6151 | 98.2 | Si 0.9;Mg 0.6;Cr 0.25 | Forgings |
| 6162 | 98.6 | Si 0.55;Mg 0.9 | Heat-treatable |
| 6201 | 98.5 | Si 0.7;Mg 0.8 | Rod |
| 6205 | 98.4 | Si 0.8;Mg 0.5;Mn 0.1;Cr 0.1;Zr 0.1 | Extrusions |
| 6262 | 96.8 | Si 0.6;Mg 1.0;Cu 0.25;Cr 0.1;Bi 0.6;Pb 0.6 | Universal |
| 6351 | 97.8 | Si 1.0;Mg 0.6;Mn 0.6 | Extrusions |
| 6463 | 98.9 | Si 0.4;Mg 0.7 | Extrusions |
| 6951 | 97.2 | Si 0.5;Fe 0.8;Cu 0.3;Mg 0.7;Mn 0.1;Zn 0.2 | Heat-treatable |
7000 series are alloyed with zinc, and can beprecipitation hardened to the highest strengths of any aluminium alloy. Most 7000 series alloys include magnesium and copper as well.
| Alloy | Al contents | Alloying elements | Uses and refs |
|---|---|---|---|
| 7005 | 93.3 | Zn 4.5;Mg 1.4;Mn 0.45;Cr 0.13;Zr 0.14;Ti 0.04 | Extrusions |
| 7010 | 93.3 | Zn 6.2;Mg 2.35;Cu 1.7;Zr 0.1; | Aerospace |
| 7022 | 91.1 | Zn 4.7;Mg 3.1;Mn 0.2;Cu 0.7;Cr 0.2; | plate, molds[37][38] |
| 7034 | 85.7 | Zn 11.0;Mg 2.3;Cu 1.0 | Ultimate tensile strength 750 MPa[39] |
| 7039 | 92.3 | Zn 4.0;Mg 3.3;Mn 0.2;Cr 0.2 | Aerospace armour plate |
| 7049 | 88.1 | Zn 7.7;Mg 2.45;Cu 1.6;Cr 0.15 | Universal, aerospace |
| 7050 | 89.0 | Zn 6.2;Mg 2.3;Cu 2.3;Zr 0.1 | Universal, aerospace |
| 7055 | 87.2 | Zn 8.0;Mg 2.3;Cu 2.3;Zr 0.1 | Plate, extrusions, aerospace[40] |
| 7065 | 88.5 | Zn 7.7;Mg 1.6;Cu 2.1;Zr 0.1 | Plate, aerospace[41] |
| 7068 | 87.6 | Zn 7.8;Mg 2.5;Cu 2.0;Zr 0.12 | Aerospace, Ultimate tensile strength 710 MPa |
| 7072 | 99.0 | Zn 1.0 | Sheet, foil |
| 7075 & 7175 | 90.0 | Zn 5.6;Mg 2.5;Cu 1.6;Cr 0.23 | Universal, aerospace, forgings |
| 7079 | 91.4 | Zn 4.3;Mg 3.3;Cu 0.6;Mn 0.2;Cr 0.15 | - |
| 7085 | 89.4 | Zn 7.5;Mg 1.5;Cu 1.6 | Thick plate, aerospace[42] |
| 7090 | Al-Zn-Mg-Cu with Co 1.5% | high strength, ductility and resistance to stress corrosion cracking[43] | |
| 7091 | Al-Zn-Mg-Cu with Co 0.4% | high strength, ductility and resistance to stress corrosion cracking[43] | |
| 7093 | 86.7 | Zn 9.0;Mg 2.5;Cu 1.5;O 0.2;Zr 0.1 | Aerospace |
| 7116 | 93.7 | Zn 4.5;Mg 1;Cu 0.8 | Heat-treatable |
| 7129 | 93.2 | Zn 4.5;Mg 1.6;Cu 0.7 | - |
| 7150 | 89.05 | Zn 6.4;Mg 2.35;Cu 2.2;O 0.2;Zr 0.1 | Aerospace |
| 7178 | 88.1 | Zn 6.8;Mg 2.7;Cu 2.0;Cr 0.26 | Universal, aerospace |
| 7255 | 87.5 | Zn 8.0;Mg 2.1;Cu 2.3;Zr 0.1 | Plate, aerospace[44] |
| 7475 | 90.3 | Zn 5.7;Mg 2.3;Si 1.5;Cr 0.22 | Universal, aerospace |
8000 series are alloyed with other elements which are not covered by other series.Aluminium–lithium alloys are an example.[45]
| Alloy | Al content | Alloying elements | Uses and refs |
|---|---|---|---|
| 8006 | 98.0 | Fe 1.5;Mn 0.5; | Universal, weldable |
| 8009 | 88.3 | Fe 8.6;Si 1.8;V 1.3 | High-temperature aerospace[46] |
| 8011 | 98.7 | Fe 0.7;Si 0.6 | Work-hardened |
| 8014 | 98.2 | Fe 1.4;Mn 0.4; | universal[47] |
| 8019 | 87.5 | Fe 8.3;Ce 4.0;O 0.2 | Aerospace |
| 8025 | Si 0.05;Fe 0.06–0.25;Cu 0.20;Mg 0.05;Cr 0.18;Zn 0.50;Ti 0.005–0.02;Li 3.4–4.2;Zr 0.08–0.25 | [10] | |
| 8030 | 99.3 | Fe 0.5;Cu 0.2 | wire[48] |
| 8090 | Si 0.20;Fe 0.30;Cu 1.0–1.6;Mn 0.10;Mg 0.6–1.3;Cr 0.10;Zn 0.25;Ti 0.10;Li 2.2–2.7;Zr 0.04–0.16 | [10] | |
| 8091 | Si 0.30;Fe 0.50;Cu 1.0–1.6;Mn 0.10;Mg 0.50–1.2;Cr 0.10;Zn 0.25;Ti 0.10;Li 2.4–2.8;Zr 0.08–0.16 | [10] | |
| 8093 | Si 0.10;Fe 0.10;Cu 1.6–2.2;Mn 0.10;Mg 0.9–1.6;Cr 0.10;Zn 0.25;Ti 0.10;Li 1.9–2.6;Zr 0.04–0.14 | [10] | |
| 8176 | 99.3 | Fe 0.6;Si 0.1 | electrical wire[49] |
| Alloy | Si | Fe | Cu | Mn | Mg | Cr | Zn | V | Ti | Bi | Ga | Pb | Zr | Limits†† | Al | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Each | Total | |||||||||||||||
| 1050[50] | 0.25 | 0.40 | 0.05 | 0.05 | 0.05 | 0.05 | 0.03 | 99.5 min | ||||||||
| 1060 | 0.25 | 0.35 | 0.05 | 0.028 | 0.03 | 0.03 | 0.05 | 0.05 | 0.028 | 0.03 | 0.03 | 0.03 | 0.03 | 0.028 | 99.6 min | |
| 1100 | 0.95 Si+Fe | 0.05–0.20 | 0.05 | 0.10 | 0.05 | 0.15 | 99.0 min | |||||||||
| 1199[50] | 0.006 | 0.006 | 0.006 | 0.002 | 0.006 | 0.006 | 0.005 | 0.002 | 0.005 | 0.002 | 99.99 min | |||||
| 2014 | 0.50–1.2 | 0.7 | 3.9–5.0 | 0.40–1.2 | 0.20–0.8 | 0.10 | 0.25 | 0.15 | 0.05 | 0.15 | remainder | |||||
| 2024 | 0.50 | 0.50 | 3.8–4.9 | 0.30–0.9 | 1.2–1.8 | 0.10 | 0.25 | 0.15 | 0.05 | 0.15 | remainder | |||||
| 2219 | 0.2 | 0.30 | 5.8–6.8 | 0.20–0.40 | 0.02 | 0.10 | 0.05–0.15 | 0.02–0.10 | 0.10–0.25 | 0.05 | 0.15 | remainder | ||||
| 3003 | 0.6 | 0.7 | 0.05–0.20 | 1.0–1.5 | 0.10 | 0.05 | 0.15 | remainder | ||||||||
| 3004 | 0.30 | 0.7 | 0.25 | 1.0–1.5 | 0.8–1.3 | 0.25 | 0.05 | 0.15 | remainder | |||||||
| 3102 | 0.40 | 0.7 | 0.10 | 0.05–0.40 | 0.30 | 0.10 | 0.05 | 0.15 | remainder | |||||||
| 4043 | 4.5–6.0 | 0.80 | 0.30 | 0.05 | 0.05 | 0.10 | 0.20 | 0.05 | 0.15 | remainder | ||||||
| 5005 | 0.3 | 0.7 | 0.2 | 0.2 | 0.5–1.1 | 0.1 | 0.25 | 0.05 | 0.15 | remainder | ||||||
| 5052 | 0.25 | 0.40 | 0.10 | 0.10 | 2.2–2.8 | 0.15–0.35 | 0.10 | 0.05 | 0.15 | remainder | ||||||
| 5083 | 0.40 | 0.40 | 0.10 | 0.40–1.0 | 4.0–4.9 | 0.05–0.25 | 0.25 | 0.15 | 0.05 | 0.15 | remainder | |||||
| 5086 | 0.40 | 0.50 | 0.10 | 0.20–0.7 | 3.5–4.5 | 0.05–0.25 | 0.25 | 0.15 | 0.05 | 0.15 | remainder | |||||
| 5154 | 0.25 | 0.40 | 0.10 | 0.10 | 3.10–3.90 | 0.15–0.35 | 0.20 | 0.20 | 0.05 | 0.15 | remainder | |||||
| 5356 | 0.25 | 0.40 | 0.10 | 0.10 | 4.50–5.50 | 0.05–0.20 | 0.10 | 0.06–0.20 | 0.05 | 0.15 | remainder | |||||
| 5454 | 0.25 | 0.40 | 0.10 | 0.50–1.0 | 2.4–3.0 | 0.05–0.20 | 0.25 | 0.20 | 0.05 | 0.15 | remainder | |||||
| 5456 | 0.25 | 0.40 | 0.10 | 0.50–1.0 | 4.7–5.5 | 0.05–0.20 | 0.25 | 0.20 | 0.05 | 0.15 | remainder | |||||
| 5754 | 0.40 | 0.40 | 0.10 | 0.50 | 2.6–3.6 | 0.30 | 0.20 | 0.15 | 0.05 | 0.15 | remainder | |||||
| 6005 | 0.6–0.9 | 0.35 | 0.10 | 0.10 | 0.40–0.6 | 0.10 | 0.10 | 0.10 | 0.05 | 0.15 | remainder | |||||
| 6005A† | 0.50–0.9 | 0.35 | 0.30 | 0.50 | 0.40–0.7 | 0.30 | 0.20 | 0.10 | 0.05 | 0.15 | remainder | |||||
| 6060 | 0.30–0.6 | 0.10–0.30 | 0.10 | 0.10 | 0.35–0.6 | 0.05 | 0.15 | 0.10 | 0.05 | 0.15 | remainder | |||||
| 6061 | 0.40–0.8 | 0.7 | 0.15–0.40 | 0.15 | 0.8–1.2 | 0.04–0.35 | 0.25 | 0.15 | 0.05 | 0.15 | remainder | |||||
| 6063 | 0.20–0.6 | 0.35 | 0.10 | 0.10 | 0.45–0.9 | 0.10 | 0.10 | 0.10 | 0.05 | 0.15 | remainder | |||||
| 6066 | 0.9–1.8 | 0.50 | 0.7–1.2 | 0.6–1.1 | 0.8–1.4 | 0.40 | 0.25 | 0.20 | 0.05 | 0.15 | remainder | |||||
| 6070 | 1.0–1.7 | 0.50 | 0.15–0.40 | 0.40–1.0 | 0.50–1.2 | 0.10 | 0.25 | 0.15 | 0.05 | 0.15 | remainder | |||||
| 6082 | 0.7–1.3 | 0.50 | 0.10 | 0.40–1.0 | 0.60–1.2 | 0.25 | 0.20 | 0.10 | 0.05 | 0.15 | remainder | |||||
| 6105 | 0.6–1.0 | 0.35 | 0.10 | 0.10 | 0.45–0.8 | 0.10 | 0.10 | 0.10 | 0.05 | 0.15 | remainder | |||||
| 6162 | 0.40–0.8 | 0.50 | 0.20 | 0.10 | 0.7–1.1 | 0.10 | 0.25 | 0.10 | 0.05 | 0.15 | remainder | |||||
| 6262 | 0.40–0.8 | 0.7 | 0.15–0.40 | 0.15 | 0.8–1.2 | 0.04–0.14 | 0.25 | 0.15 | 0.40–0.7 | 0.40–0.7 | 0.05 | 0.15 | remainder | |||
| 6351 | 0.7–1.3 | 0.50 | 0.10 | 0.40–0.8 | 0.40–0.8 | 0.20 | 0.20 | 0.05 | 0.15 | remainder | ||||||
| 6463 | 0.20–0.6 | 0.15 | 0.20 | 0.05 | 0.45–0.9 | 0.05 | 0.05 | 0.15 | remainder | |||||||
| 7005 | 0.35 | 0.40 | 0.10 | 0.20–0.70 | 1.0–1.8 | 0.06–0.20 | 4.0–5.0 | 0.01–0.06 | 0.08–0.20 | 0.05 | 0.15 | remainder | ||||
| 7022 | 0.50 | 0.50 | 0.50–1.00 | 0.10–0.40 | 2.60–3.70 | 0.10–0.30 | 4.30–5.20 | 0.20 | 0.05 | 0.15 | remainder | |||||
| 7068 | 0.12 | 0.15 | 1.60–2.40 | 0.10 | 2.20–3.00 | 0.05 | 7.30–8.30 | 0.01 | 0.05–0.15 | 0.05 | 0.15 | remainder | ||||
| 7072 | 0.7 Si+Fe | 0.10 | 0.10 | 0.10 | 0.8–1.3 | 0.05 | 0.15 | remainder | ||||||||
| 7075 | 0.40 | 0.50 | 1.2–2.0 | 0.30 | 2.1–2.9 | 0.18–0.28 | 5.1–6.1 | 0.20 | 0.05 | 0.15 | remainder | |||||
| 7079 | 0.3 | 0.40 | 0.40–0.80 | 0.10–0.30 | 2.9–3.7 | 0.10–0.25 | 3.8–4.8 | 0.10 | 0.05 | 0.15 | remainder | |||||
| 7116 | 0.15 | 0.30 | 0.50–1.1 | 0.05 | 0.8–1.4 | 4.2–5.2 | 0.05 | 0.05 | 0.03 | 0.05 | 0.15 | remainder | ||||
| 7129 | 0.15 | 0.30 | 0.50–0.9 | 0.10 | 1.3–2.0 | 0.10 | 4.2–5.2 | 0.05 | 0.05 | 0.03 | 0.05 | 0.15 | remainder | |||
| 7178 | 0.40 | 0.50 | 1.6–2.4 | 0.30 | 2.4–3.1 | 0.18–0.28 | 6.3–7.3 | 0.20 | 0.05 | 0.15 | remainder | |||||
| 8176[49] | 0.03–0.15 | 0.40–1.0 | 0.10 | 0.03 | 0.05 | 0.15 | remainder | |||||||||
| Alloy | Si | Fe | Cu | Mn | Mg | Cr | Zn | V | Ti | Bi | Ga | Pb | Zr | Limits†† | Al | |
| Each | Total | |||||||||||||||
| †Manganese plus chromium must be between 0.12 and 0.50%. ††This limit applies to all elements for which no other limit is specified on a given row, because no column exists or because the column is blank. | ||||||||||||||||
The Aluminum Association (AA) has adopted a nomenclature similar to that of wrought alloys.British Standard and DIN have different designations. In the AA system, the second two digits reveal the minimum percentage of aluminium, e.g. 150.x correspond to a minimum of 99.50% aluminium. The digit after the decimal point takes a value of 0 or 1, denoting casting and ingot respectively.[1] The main alloying elements in the AA system are as follows:[51]
| Alloy type | Temper | Tensile strength (min) inksi (MPa) | Yield strength (min) in ksi (MPa) | Elongation in 2 in % | |
|---|---|---|---|---|---|
| ANSI | UNS | ||||
| 201.0 | A02010 | T7 | 60.0 (414) | 50.0 (345) | 3.0 |
| 204.0 | A02040 | T4 | 45.0 (310) | 28.0 (193) | 6.0 |
| 242.0 | A02420 | O | 23.0 (159) | N/A | N/A |
| T61 | 32.0 (221) | 20.0 (138) | N/A | ||
| A242.0 | A12420 | T75 | 29.0 (200) | N/A | 1.0 |
| 295.0 | A02950 | T4 | 29.0 (200) | 13.0 (90) | 6.0 |
| T6 | 32.0 (221) | 20.0 (138) | 3.0 | ||
| T62 | 36.0 (248) | 28.0 (193) | N/A | ||
| T7 | 29.0 (200) | 16.0 (110) | 3.0 | ||
| 319.0 | A03190 | F | 23.0 (159) | 13.0 (90) | 1.5 |
| T5 | 25.0 (172) | N/A | N/A | ||
| T6 | 31.0 (214) | 20.0 (138) | 1.5 | ||
| 328.0 | A03280 | F | 25.0 (172) | 14.0 (97) | 1.0 |
| T6 | 34.0 (234) | 21.0 (145) | 1.0 | ||
| 355.0 | A03550 | T6 | 32.0 (221) | 20.0 (138) | 2.0 |
| T51 | 25.0 (172) | 18.0 (124) | N/A | ||
| T71 | 30.0 (207) | 22.0 (152) | N/A | ||
| C355.0 | A33550 | T6 | 36.0 (248) | 25.0 (172) | 2.5 |
| 356.0 | A03560 | F | 19.0 (131) | 9.5 (66) | 2.0 |
| T6 | 30.0 (207) | 20.0 (138) | 3.0 | ||
| T7 | 31.0 (214) | N/A | N/A | ||
| T51 | 23.0 (159) | 16.0 (110) | N/A | ||
| T71 | 25.0 (172) | 18.0 (124) | 3.0 | ||
| A356.0 | A13560 | T6 | 34.0 (234) | 24.0 (165) | 3.5 |
| T61 | 35.0 (241) | 26.0 (179) | 1.0 | ||
| 443.0 | A04430 | F | 17.0 (117) | 7.0 (48) | 3.0 |
| B443.0 | A24430 | F | 17.0 (117) | 6.0 (41) | 3.0 |
| 512.0 | A05120 | F | 17.0 (117) | 10.0 (69) | N/A |
| 514.0 | A05140 | F | 22.0 (152) | 9.0 (62) | 6.0 |
| 520.0 | A05200 | T4 | 42.0 (290) | 22.0 (152) | 12.0 |
| 535.0 | A05350 | F | 35.0 (241) | 18.0 (124) | 9.0 |
| 705.0 | A07050 | T5 | 30.0 (207) | 17.0 (117)† | 5.0 |
| 707.0 | A07070 | T7 | 37.0 (255) | 30.0 (207)† | 1.0 |
| 710.0 | A07100 | T5 | 32.0 (221) | 20.0 (138) | 2.0 |
| 712.0 | A07120 | T5 | 34.0 (234) | 25.0 (172)† | 4.0 |
| 713.0 | A07130 | T5 | 32.0 (221) | 22.0 (152) | 3.0 |
| 771.0 | A07710 | T5 | 42.0 (290) | 38.0 (262) | 1.5 |
| T51 | 32.0 (221) | 27.0 (186) | 3.0 | ||
| T52 | 36.0 (248) | 30.0 (207) | 1.5 | ||
| T6 | 42.0 (290) | 35.0 (241) | 5.0 | ||
| T71 | 48.0 (331) | 45.0 (310) | 5.0 | ||
| 850.0 | A08500 | T5 | 16.0 (110) | N/A | 5.0 |
| 851.0 | A08510 | T5 | 17.0 (117) | N/A | 3.0 |
| 852.0 | A08520 | T5 | 24.0 (165) | 18.0 (124) | N/A |
| †Only when requested by the customer | |||||
Titanium alloys, which are stronger but heavier than Al-Sc alloys, are still much more widely used.[57]
The main application of metallic scandium by weight is inaluminium–scandium alloys for minor aerospace industry components. These alloys contain between 0.1% and 0.5% (by weight) of scandium. They were used in the Russian military aircraftMiG-21 andMiG-29.[56]
Some items of sports equipment, which rely on high performance materials, have been made with scandium–aluminium alloys, includingbaseball bats,[58]lacrosse sticks, as well as bicycle[59] frames and components, and tent poles.
U.S. gunmakerSmith & Wesson produces revolvers with frames composed of scandium alloy and cylinders of titanium.[60]
Due to its light-weight and high strength, aluminium alloys are desired materials to be applied in spacecraft, satellites and other components to be deployed in space. However, this application is limited by theenergetic particle irradiation emitted by theSun. The impact and deposition of solar energetic particles within the microstructure of conventional aluminium alloys can induce the dissolution of most common hardening phases, leading to softening. The recently introduced crossover aluminium alloys[61][62] are being tested as a surrogate to 6xxx and 7xxx series in environments where energetic particle irradiation is a major concern. Such crossover aluminium alloys can be hardened via precipitation of a chemical complex phase known as T-phase in which the radiation resistance has been proved to be superior than other hardening phases of conventional aluminium alloys.[63][64]
The following aluminium alloys are commonly used in aircraft and otheraerospace structures:[65][66]
Note that the termaircraft aluminium oraerospace aluminium usually refers to 7075.[67][68]
4047 aluminium is a unique alloy used in both the aerospace and automotive applications as a cladding alloy or filler material. As filler, aluminium alloy 4047 strips can be combined to intricate applications to bond two metals.[69]
6951 is a heat treatable alloy providing additional strength to the fins while increasing sag resistance; this allows the manufacturer to reduce the gauge of the sheet and therefore reducing the weight of the formed fin. These distinctive features make aluminium alloy 6951 one of the preferred alloys for heat transfer and heat exchangers manufactured for aerospace applications.[70]
6063 aluminium alloys are heat treatable with moderately high strength, excellent corrosion resistance and good extrudability.They are regularly used as architectural and structural members.[71]
The following list of aluminium alloys are currently produced,[citation needed] but less widely[citation needed] used:
These alloys are used for boat building and shipbuilding, and other marine and salt-water sensitive shore applications.[72]
4043, 5183, 6005A, 6082 also used in marine constructions and off shore applications.
6111 aluminium and2008 aluminium alloy are extensively used for external automotivebody panels, with5083 and5754 used for inner body panels. Bonnets have been manufactured from2036,6016, and 6111 alloys. Truck and trailer body panels have used5456 aluminium.
Automobile frames often use5182 aluminium or5754 aluminium formed sheets,6061 or6063 extrusions.
Wheels have been cast fromA356.0 aluminium or formed 5xxx sheet.[73]
Engine blocks andcrankcases are often cast made of aluminium alloys. The most popular aluminium alloys used for cylinder blocks are A356, 319 and to a minor extent 242.
Aluminium alloys containingcerium are being developed and implemented in high-temperature automotive applications, such ascylinder heads andturbochargers, and in other energy generation applications.[74] These alloys were initially developed as a way to increase the usage of cerium, which is over-produced in rare-earth mining operations for more coveted elements such asneodymium anddysprosium,[75] but gained attention for its strength at high temperatures over long periods of time.[76] It gains its strength from the presence of an Al11Ce3intermetallic phase which is stable up to temperatures of 540 °C, and retains its strength up to 300 °C, making it quite viable at elevated temperatures. Aluminium–cerium alloys are typically cast, due to their excellent casting properties, although work has also been done to show that laser-basedadditive manufacturing techniques can be used as well to create parts with more complex geometries and greater mechanical properties.[77] Recent work has largely focused on adding higher-order alloying elements to the binary Al-Ce system to improve its mechanical performance at room and elevated temperatures, such asiron,nickel,magnesium, orcopper, and work is being done to understand the alloying element interactions further.[78]
6061 aluminium and6351 aluminium are widely used in breathing gas cylinders forscuba diving andSCBA alloys.[79]
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