
Duralumin (also called duraluminum, duraluminium, duralum, dural(l)ium, or dural) is a trade name for one of the earliest types of
age-hardenable aluminium–copper alloys. The term is a combination of ''
Düren
Düren (; Ripuarian language, Ripuarian: Düre) is a town in North Rhine-Westphalia, Germany, between Aachen and Cologne, on the river Rur (river), Rur.
History
Roman era
The area of Düren was part of Gallia Belgica, more specifically the ter ...
'' and ''aluminium'' . Its use as a trade name is obsolete. Today the term mainly refers to aluminium-copper alloys, designated as the 2000 series by the international alloy designation system (IADS), as with
2014
The year 2014 was marked by the surge of the Western African Ebola epidemic, West African Ebola epidemic, which began in 2013, becoming the List of Ebola outbreaks, most widespread outbreak of the Ebola, Ebola virus in human history, resul ...
and
2024
The year saw the list of ongoing armed conflicts, continuation of major armed conflicts, including the Russian invasion of Ukraine, the Myanmar civil war (2021–present), Myanmar civil war, the Sudanese civil war (2023–present), Sudane ...
alloys used in airframe fabrication.
Duralumin was developed in 1909 in Germany.
Duralumin is known for its strength and hardness, making it suitable for various applications, especially in the aviation and aerospace industry. However, it is susceptible to corrosion, which can be mitigated by using alclad-duralum materials.
History
Duralumin was developed by the German metallurgist
Alfred Wilm at private military-industrial laboratory (Center for Scientific-Technical Research) in
Neubabelsberg. In 1903, Wilm discovered that after
quenching
In materials science, quenching is the rapid cooling of a workpiece in water, gas, oil, polymer, air, or other fluids to obtain certain material properties. A type of heat treating, quenching prevents undesired low-temperature processes, suc ...
, an
aluminium alloy
An aluminium alloy ( UK/IUPAC) or aluminum alloy ( NA; see spelling differences) is an alloy in which aluminium (Al) is the predominant metal. The typical alloying elements are copper, magnesium, manganese, silicon, tin, nickel and zinc. There ...
containing 4% copper would harden when left at room temperature for several days. Further improvements led to the introduction of duralumin in 1909. The name,
originally a trade mark of Dürener Metallwerke
AG which acquired Wilm's patents and commercialized the material, is mainly used in
pop-science
Popular science (also called pop-science or popsci) is an interpretation of science intended for a General reader, general audience. While science journalism focuses on recent scientific developments, popular science is more broad ranging. It ...
to describe all
Al-Cu alloys system, or '2000' series, as designated through the international alloy designation system originally created in 1970 by the
Aluminum Association.
Composition
In addition to
aluminium
Aluminium (or aluminum in North American English) is a chemical element; it has chemical symbol, symbol Al and atomic number 13. It has a density lower than that of other common metals, about one-third that of steel. Aluminium has ...
, the main materials in duralumin are
copper
Copper is a chemical element; it has symbol Cu (from Latin ) and atomic number 29. It is a soft, malleable, and ductile metal with very high thermal and electrical conductivity. A freshly exposed surface of pure copper has a pinkish-orang ...
,
manganese
Manganese is a chemical element; it has Symbol (chemistry), symbol Mn and atomic number 25. It is a hard, brittle, silvery metal, often found in minerals in combination with iron. Manganese was first isolated in the 1770s. It is a transition m ...
and
magnesium
Magnesium is a chemical element; it has Symbol (chemistry), symbol Mg and atomic number 12. It is a shiny gray metal having a low density, low melting point and high chemical reactivity. Like the other alkaline earth metals (group 2 ...
. For instance, Duraluminium 2024 consists of 91-95% aluminium, 3.8-4.9% copper, 1.2-1.8% magnesium, 0.3-0.9% manganese, <0.5% iron, <0.5% silicon, <0.25% zinc, <0.15% titanium, <0.10% chromium and no more than 0.15% of other elements together.
Although the addition of copper improves strength, it also makes these alloys susceptible to
corrosion
Corrosion is a natural process that converts a refined metal into a more chemically stable oxide. It is the gradual deterioration of materials (usually a metal) by chemical or electrochemical reaction with their environment. Corrosion engine ...
. Corrosion resistance can be greatly enhanced by the metallurgical bonding of a high-purity aluminium surface layer, referred to as
alclad-duralum. Alclad materials are commonly used in the aircraft industry to this day.
Microstructure
Duralumin's remarkable strength and durability stem from its unique microstructure, which is significantly influenced by heat treatment processes.
Initial Microstructure
Solid Solution: After initial solidification, duralumin exists as a single-phase solid solution, primarily composed of aluminium atoms with dispersed copper, magnesium, and other alloying elements. This initial state is relatively soft and ductile.
Heat Treatment and Microstructural Changes
Solution Annealing: Duralumin undergoes solution annealing, a high-temperature heat treatment process that dissolves the alloying elements into the aluminium matrix, creating a homogeneous solid solution.
Quenching: Rapid cooling (quenching) after solution annealing freezes the high-temperature solid solution, preventing the precipitation of strengthening phases.
Aging (Precipitation Hardening): During aging, the supersaturated solid solution becomes unstable. Fine precipitates, such as CuAl2 and Mg2Si, form within the aluminum matrix. These precipitates act as obstacles to dislocation movement, significantly increasing the alloy's strength and hardness.
Final Microstructure
The final microstructure of duralumin consists of a predominantly aluminium matrix dispersed fine precipitates (CuAl2, Mg2Si)
Grain boundaries. The size, distribution, and type of precipitates play a crucial role in determining the mechanical properties of duralumin. Optimal aging conditions lead to the formation of finely dispersed precipitates, resulting in peak strength and hardness.
Applications
Aluminium alloyed with copper (Al-Cu alloys), which can be
precipitation hardened, are designated by the International Alloy Designation System as the 2000 series. Typical uses for
wrought Al-Cu alloys include:
[ASM Handbook. Volume 2, In ''Properties and Selection: Nonferrous alloys and special purpose materials''. ASM, 2002.]
*
2011
The year marked the start of a Arab Spring, series of protests and revolutions throughout the Arab world advocating for democracy, reform, and economic recovery, later leading to the depositions of world leaders in Tunisia, Egypt, and Yemen ...
: Wire, rod, and bar for
screw machine products. Applications where good
machinability and good strength are required.
*
2014
The year 2014 was marked by the surge of the Western African Ebola epidemic, West African Ebola epidemic, which began in 2013, becoming the List of Ebola outbreaks, most widespread outbreak of the Ebola, Ebola virus in human history, resul ...
: Heavy-duty
forging
Forging is a manufacturing process involving the shaping of metal using localized compression (physics), compressive forces. The blows are delivered with a hammer (often a power hammer) or a die (manufacturing), die. Forging is often classif ...
s, plate, and extrusions for aircraft fittings, wheels, and major structural components, space booster tankage and structure, truck frame and suspension components. Applications requiring high strength and hardness including service at elevated temperatures.
*
2017
2017 was designated as the International Year of Sustainable Tourism for Development by the United Nations General Assembly.
Events January
* January 1 – Istanbul nightclub shooting: A gunman dressed as Santa Claus opens fire at the ...
or Avional (France): Around 1% Si.
Good machinability. Acceptable resistance to corrosion in air and mechanical properties. Also called AU4G in France. Used for aircraft applications between the wars in France and Italy. Also saw some use in motor-racing applications from the 1960s, as it is a tolerant alloy that could be press-formed with relatively unsophisticated equipment.
*
2024
The year saw the list of ongoing armed conflicts, continuation of major armed conflicts, including the Russian invasion of Ukraine, the Myanmar civil war (2021–present), Myanmar civil war, the Sudanese civil war (2023–present), Sudane ...
: Aircraft structures, rivets, hardware, truck wheels, screw machine products, and other structural applications.
*
2036
The 2030s (pronounced "twenty-thirties" or "two thousand ndthirties"; shortened to "the '30s" and also known as "The Thirties") is the next decade that will begin on 1 January 2030, and end on 31 December 2039.
Plans and goals
* NASA plans to exe ...
: Sheet for auto body panels
*
2048: Sheet and plate in structural components for aerospace application and military equipment
Aviation

German scientific literature openly published information about duralumin, its composition and heat treatment, before the outbreak of
World War I
World War I or the First World War (28 July 1914 – 11 November 1918), also known as the Great War, was a World war, global conflict between two coalitions: the Allies of World War I, Allies (or Entente) and the Central Powers. Fighting to ...
in 1914. Despite this, use of the alloy outside
Germany did not occur until after fighting ended in 1918. Reports of German use during World War I, even in technical journals such as
''Flight'', could still mis-identify its key alloying component as magnesium rather than copper. Engineers in the UK showed little interest in duralumin until after the war.
The earliest known attempt to use duralumin for a heavier-than-air aircraft structure occurred in 1916, when
Hugo Junkers
Hugo Junkers (3 February 1859 – 3 February 1935) was a German aircraft engineer and aircraft designer who pioneered the design of all-metal airplanes and flying wings. His company, Junkers Flugzeug- und Motorenwerke AG (Junkers Aircraft and ...
first introduced its use in the airframe of the
Junkers J 3, a single-engined monoplane "technology demonstrator" that marked the first use of the Junkers trademark duralumin corrugated skinning. The
Junkers
Junkers Flugzeug- und Motorenwerke AG (JFM, earlier JCO or JKO in World War I, English language, English: Junkers Aircraft and Motor Works) more commonly Junkers , was a major German aircraft manufacturer, aircraft and aircraft engine manufactu ...
company completed only the covered wings and tubular fuselage framework of the J 3 before abandoning its development. The slightly later, solely
''IdFlieg''-designated Junkers J.I
The Junkers J.I (manufacturer's name J 4) was a German Idflieg aircraft designation system, "J-class" armored sesquiplane of World War I, developed for low-level attack aircraft, ground attack, Aerial reconnaissance, observation and liaison airc ...
armoured
sesquiplane
A biplane is a fixed-wing aircraft with two main wings stacked one above the other. The first powered, controlled aeroplane to fly, the Wright Flyer, used a biplane wing arrangement, as did many aircraft in the early years of aviation. While a ...
of 1917, known to the factory as the Junkers J 4, had its all-metal wings and horizontal stabilizer made in the same manner as the J 3's wings had been, like the experimental and airworthy all-duralumin
Junkers J 7 single-seat fighter design, which led to the
Junkers D.I low-wing monoplane fighter, introducing all-duralumin aircraft structural technology to
German military aviation in 1918.
Its first use in
aerostat
An aerostat (, via French) or lighter-than-air aircraft is an aircraft that relies on buoyancy to maintain flight. Aerostats include unpowered balloons (free-flying or tethered) and powered airships.
The relative density of an aerostat as a ...
ic airframes came in rigid
airship
An airship, dirigible balloon or dirigible is a type of aerostat (lighter-than-air) aircraft that can navigate through the air flying powered aircraft, under its own power. Aerostats use buoyancy from a lifting gas that is less dense than the ...
frames, eventually including all those of the "Great Airship" era of the 1920s and 1930s: the British-built
R100, the German passenger Zeppelins
LZ 127 ''Graf Zeppelin'',
LZ 129 ''Hindenburg'',
LZ 130 ''Graf Zeppelin II'', and the
U.S. Navy airships
USS ''Los Angeles'' (ZR-3, ex-LZ 126),
USS ''Akron'' (ZRS-4) and
USS ''Macon'' (ZRS-5).
Bicycles
Duralumin was used to manufacture bicycle components and framesets from the 1930s to 1990s. Several companies in Saint-Étienne, France stood out for their early, innovative adoption of duralumin: in 1932, Verot et Perrin developed the first light alloy crank arms; in 1934, Haubtmann released a complete crankset; from 1935 on, Duralumin freewheels,
derailleurs
Shimano 600 front derailleur (1980)
A derailleur () is a variable-ratio bicycle gearing system consisting of a chain, multiple sprockets of different sizes, and a mechanism to move the chain from one sprocket to another.
Modern front and re ...
, pedals, brakes and handlebars were manufactured by several companies.
Complete framesets followed quickly, including those manufactured by: Mercier (and Aviac and other licensees) with their popular Meca Dural family of models, the Pelissier brothers and their race-worthy La Perle models, and Nicolas Barra and his exquisite mid-twentieth century “Barralumin” creations. Other names that come up here also included: Pierre Caminade, with his beautiful Caminargent creations and their exotic octagonal tubing, and also
Gnome et Rhône, with its deep heritage as an aircraft engine manufacturer that also diversified into motorcycles, velomotors and bicycles after World War Two.
Mitsubishi Heavy Industries
is a Japanese Multinational corporation, multinational engineering, electrical equipment and electronics corporation headquartered in Tokyo, Japan. MHI is one of the core companies of the Mitsubishi Group and its automobile division is the prede ...
, which was prohibited from producing aircraft during the American occupation of Japan, manufactured the “cross” bicycle out of surplus wartime duralumin in 1946. The “cross” was designed by
Kiro Honjo, a former aircraft designer responsible for the
Mitsubishi G4M.
Duralumin use in bicycle manufacturing faded in the 1970s and 1980s.
Vitus nonetheless released the venerable “979” frameset in 1979, a “Duralinox” model that became an instant classic among cyclists. The Vitus 979 was the first production aluminium frameset whose thin-wall 5083/5086 tubing was slip-fit and then glued together using a dry heat-activated epoxy. The result was an extremely lightweight but very durable frameset. Production of the Vitus 979 continued until 1992.
Automotive
In 2011,
BBS Automotive made the RI-D, the world's first production automobile wheel made of duralumin. The company has since made other wheels of duralumin also, such as the RZ-D.
References
{{Authority control
Aluminium–copper alloys
Products introduced in 1909
Aerospace materials