{"history":[],"article":{"id":"3c9b740f-529b-4bab-a294-1bba9fcd87ce","title":"Duralumin","slug":"duralumin","content":":::summary\n:::\n\n# \n**Duralumin** (also called ******dural**um**inum**, ******dural**um**inium**, ****dural**um**, ****dural**(l)ium**, or **dural**) is a trade name for one of the earliest types of [age-hardenable](https://bliptext.com/articles/age-hardening) [aluminium–copper alloys](https://bliptext.com/articles/aluminium-copper-alloys).\nThe term is a combination of [Dürener](https://bliptext.com/articles/d-ren) and aluminium.\nIts use as a trade name is obsolete.\nToday the term mainly refers to aluminium-copper alloys, designated as the 2000 series by the international alloy designation system (IADS), as with [2014](https://bliptext.com/articles/2014-aluminium-alloy) and [2024](https://bliptext.com/articles/2024-aluminium-alloy) alloys used in airframe fabrication.\nDuralumin was developed in 1909 in Germany.\nDuralumin is known for its strength and hardness, making it suitable for various applications, especially in the aviation and aerospace industry.\nHowever, it is susceptible to corrosion, which can be mitigated by using alclad-duralum materials.\n# [Fire-damaged Duralumin cross brace from the Zeppelin airship Hindenburg (DLZ129) salvaged from its crash site at Lakehurst Naval Air Station, NJ on May 6, 1937 | upload.wikimedia.org/wikipedia/commons/4/48/DLZ129///spar.jpg]\n# [Corrosion of duralumin | upload.wikimedia.org/wikipedia/commons/0/0b/Corrosion///of///Duralumin.jpg]\n\n# History\nDuralumin was developed by the German metallurgist [Alfred Wilm](https://bliptext.com/articles/alfred-wilm) at private military-industrial laboratory Zentralstelle für wissenschaftlich-technische Untersuchungen (Center for Scientific-Technical Research) in [Neubabelsberg](https://bliptext.com/articles/neubabelsberg).\nIn 1903, Wilm discovered that after [quenching](https://bliptext.com/articles/quenching), an [aluminium alloy](https://bliptext.com/articles/aluminium-alloy) containing 4% copper would harden when left at room temperature for several days.\nFurther improvements led to the introduction of duralumin in 1909.\nThe name, [originally a trade mark](https://bliptext.com/articles/generic-trademark) of Dürener Metallwerke [AG](https://bliptext.com/articles/aktiengesellschaft) which acquired Wilm's patents and commercialized the material, is mainly used in [pop-science](https://bliptext.com/articles/popular-science) to describe all [Al-Cu alloys](https://bliptext.com/articles/al-cu-alloys) system, or '2000' series, as designated through the international alloy designation system originally created in 1970 by the [Aluminum Association](https://bliptext.com/articles/aluminum-association).\n\n# Composition\nIn addition to [aluminium](https://bliptext.com/articles/aluminium), the main materials in duralumin are [copper](https://bliptext.com/articles/copper), [manganese](https://bliptext.com/articles/manganese) and [magnesium](https://bliptext.com/articles/magnesium).\nFor 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.\nAlthough the addition of copper improves strength, it also makes these alloys susceptible to [corrosion](https://bliptext.com/articles/corrosion).\nCorrosion resistance can be greatly enhanced by the metallurgical bonding of a high-purity aluminium surface layer, referred to as [alclad](https://bliptext.com/articles/alclad)-duralum.\n**Alclad** materials are commonly used in the aircraft industry to this day.\n\n# Microstructure\nDuralumin's remarkable strength and durability stem from its unique microstructure, which is significantly influenced by heat treatment processes.\n\n## Initial Microstructure\nSolid 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.\nThis initial state is relatively soft and ductile.\n\n## Heat Treatment and Microstructural Changes\nSolution 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.\nQuenching: Rapid cooling (quenching) after solution annealing freezes the high-temperature solid solution, preventing the precipitation of strengthening phases.\nAging (Precipitation Hardening): During aging, the supersaturated solid solution becomes unstable.\nFine precipitates, such as CuAl2 and Mg2Si, form within the aluminum matrix.\nThese precipitates act as obstacles to dislocation movement, significantly increasing the alloy's strength and hardness.\n\n## Final Microstructure\nThe final microstructure of duralumin consists of a predominantly aluminium matrix dispersed fine precipitates (CuAl2, Mg2Si)\nGrain boundaries.\nThe size, distribution, and type of precipitates play a crucial role in determining the mechanical properties of duralumin.\nOptimal aging conditions lead to the formation of finely dispersed precipitates, resulting in peak strength and hardness.\n\n# Applications\nAluminium alloyed with copper (Al-Cu alloys), which can be [precipitation hardened](https://bliptext.com/articles/precipitation-hardening), are designated by the International Alloy Designation System as the 2000 series.\nTypical uses for [wrought](https://bliptext.com/articles/metalworking) Al-Cu alloys include:\n\n## Aviation\nGerman scientific literature openly published information about duralumin, its composition and heat treatment, before the outbreak of [World War I](https://bliptext.com/articles/world-war-i) in 1914.\nDespite this, use of the alloy outside[ Germany](https://bliptext.com/articles/german-empire) did not occur until after fighting ended in 1918.\nReports 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.\nEngineers in the UK showed little interest in duralumin until after the war.\nThe earliest known attempt to use duralumin for a heavier-than-air aircraft structure occurred in 1916, when [Hugo Junkers](https://bliptext.com/articles/hugo-junkers) first introduced its use in the airframe of the [Junkers J 3](https://bliptext.com/articles/junkers-j-3), a single-engined monoplane \"technology demonstrator\" that marked the first use of the Junkers trademark duralumin corrugated skinning.\nThe [Junkers](https://bliptext.com/articles/junkers) company completed only the covered wings and tubular fuselage framework of the J 3 before abandoning its development.\nThe slightly later, solely IdFlieg-designated [Junkers J.I](https://bliptext.com/articles/junkers-j-i) armoured [sesquiplane](https://bliptext.com/articles/biplane) 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](https://bliptext.com/articles/junkers-j-7) single-seat fighter design, which led to the [Junkers D.I](https://bliptext.com/articles/junkers-d-i) low-wing monoplane fighter, introducing all-duralumin aircraft structural technology to[ German military aviation](https://bliptext.com/articles/luftstreitkr-fte) in 1918.\nIts first use in [aerostatic](https://bliptext.com/articles/aerostat) airframes came in rigid [airship](https://bliptext.com/articles/airship) frames, eventually including all those of the \"Great Airship\" era of the 1920s and 1930s: the British-built [R100](https://bliptext.com/articles/r100), the German passenger Zeppelins LZ 127 Graf Zeppelin, LZ 129 Hindenburg, LZ 130 Graf Zeppelin II, and the [U.S. Navy](https://bliptext.com/articles/u-s-navy) [airship](https://bliptext.com/articles/airship)s USS Los Angeles (ZR-3, ex-LZ 126), USS Akron (ZRS-4) and USS Macon (ZRS-5).\n# [Duralumin sample from the 1931 airship USS Akron (ZRS-4) | upload.wikimedia.org/wikipedia/commons/3/32/ZRS-4///USS///Akron///duralumin///sample.jpg]\n# [The first mass-production aircraft to make extensive use of duralumin, the armored Junkers J.I sesquiplane of World War I | upload.wikimedia.org/wikipedia/commons/2/28/Junkers///J.I///-///Ray///Wagner///Collection///Image///%2820821101334%29.jpg]\n\n## Bicycles\nDuralumin was used to manufacture bicycle components and framesets from the 1930s to 1990s.\nSeveral 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](https://bliptext.com/articles/derailleurs), pedals, brakes and handlebars were manufactured by several companies.\nComplete 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.\nOther names that come up here also included: Pierre Caminade, with his beautiful Caminargent creations and their exotic octagonal tubing, and also [Gnome et Rhône](https://bliptext.com/articles/gnome-et-rh-ne), with its deep heritage as an aircraft engine manufacturer that also diversified into motorcycles, velomotors and bicycles after World War Two.\n[Mitsubishi Heavy Industries](https://bliptext.com/articles/mitsubishi-heavy-industries), which was prohibited from producing aircraft during the American occupation of Japan, manufactured the “cross” bicycle out of surplus wartime duralumin in 1946.\nThe “cross” was designed by [Kiro Honjo](https://bliptext.com/articles/kiro-honjo), a former aircraft designer responsible for the [Mitsubishi G4M](https://bliptext.com/articles/mitsubishi-g4m).\nDuralumin use in bicycle manufacturing faded in the 1970s and 1980s.\n[Vitus](https://bliptext.com/articles/vitus-bicycle-company) nonetheless released the venerable “979” frameset in 1979, a “Duralinox” model that became an instant classic among cyclists.\nThe 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.\nThe result was an extremely lightweight but very durable frameset.\nProduction of the Vitus 979 continued until 1992.\n\n## Automotive\nIn 2011, [BBS Automotive](https://bliptext.com/articles/bbs-kraftfahrzeugtechnik) made the RI-D, the world's first production automobile wheel made of duralumin.\nThe company has since made other wheels of duralumin also, such as the RZ-D.","current_revision":null,"created_by":"kACnuQmH5k9Nr5VNVEpVeg7XpvUmMctD","created_at":"2025-01-25T18:27:12.829Z","updated_at":"2025-01-25T18:27:12.829Z","search_vector":"'duralumin':1","search_content":" \n \n\n# \n**Duralumin** (also called ******dural**um**inum**, ******dural**um**inium**, ****dural**um**, ****dural**(l)ium**, or **dural**) is a trade name for one of the earliest types of [age-hardenable](https://bliptext.com/articles/age-hardening) [aluminium–copper alloys](https://bliptext.com/articles/aluminium-copper-alloys).\nThe term is a combination of [Dürener](https://bliptext.com/articles/d-ren) and aluminium.\nIts use as a trade name is obsolete.\nToday the term mainly refers to aluminium-copper alloys, designated as the 2000 series by the international alloy designation system (IADS), as with [2014](https://bliptext.com/articles/2014-aluminium-alloy) and [2024](https://bliptext.com/articles/2024-aluminium-alloy) alloys used in airframe fabrication.\nDuralumin was developed in 1909 in Germany.\nDuralumin is known for its strength and hardness, making it suitable for various applications, especially in the aviation and aerospace industry.\nHowever, it is susceptible to corrosion, which can be mitigated by using alclad-duralum materials.\n# [Fire-damaged Duralumin cross brace from the Zeppelin airship Hindenburg (DLZ129) salvaged from its crash site at Lakehurst Naval Air Station, NJ on May 6, 1937 | upload.wikimedia.org/wikipedia/commons/4/48/DLZ129///spar.jpg]\n# [Corrosion of duralumin | upload.wikimedia.org/wikipedia/commons/0/0b/Corrosion///of///Duralumin.jpg]\n\n# History\nDuralumin was developed by the German metallurgist [Alfred Wilm](https://bliptext.com/articles/alfred-wilm) at private military-industrial laboratory Zentralstelle für wissenschaftlich-technische Untersuchungen (Center for Scientific-Technical Research) in [Neubabelsberg](https://bliptext.com/articles/neubabelsberg).\nIn 1903, Wilm discovered that after [quenching](https://bliptext.com/articles/quenching), an [aluminium alloy](https://bliptext.com/articles/aluminium-alloy) containing 4% copper would harden when left at room temperature for several days.\nFurther improvements led to the introduction of duralumin in 1909.\nThe name, [originally a trade mark](https://bliptext.com/articles/generic-trademark) of Dürener Metallwerke [AG](https://bliptext.com/articles/aktiengesellschaft) which acquired Wilm's patents and commercialized the material, is mainly used in [pop-science](https://bliptext.com/articles/popular-science) to describe all [Al-Cu alloys](https://bliptext.com/articles/al-cu-alloys) system, or '2000' series, as designated through the international alloy designation system originally created in 1970 by the [Aluminum Association](https://bliptext.com/articles/aluminum-association).\n\n# Composition\nIn addition to [aluminium](https://bliptext.com/articles/aluminium), the main materials in duralumin are [copper](https://bliptext.com/articles/copper), [manganese](https://bliptext.com/articles/manganese) and [magnesium](https://bliptext.com/articles/magnesium).\nFor 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.\nAlthough the addition of copper improves strength, it also makes these alloys susceptible to [corrosion](https://bliptext.com/articles/corrosion).\nCorrosion resistance can be greatly enhanced by the metallurgical bonding of a high-purity aluminium surface layer, referred to as [alclad](https://bliptext.com/articles/alclad)-duralum.\n**Alclad** materials are commonly used in the aircraft industry to this day.\n\n# Microstructure\nDuralumin's remarkable strength and durability stem from its unique microstructure, which is significantly influenced by heat treatment processes.\n\n## Initial Microstructure\nSolid 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.\nThis initial state is relatively soft and ductile.\n\n## Heat Treatment and Microstructural Changes\nSolution 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.\nQuenching: Rapid cooling (quenching) after solution annealing freezes the high-temperature solid solution, preventing the precipitation of strengthening phases.\nAging (Precipitation Hardening): During aging, the supersaturated solid solution becomes unstable.\nFine precipitates, such as CuAl2 and Mg2Si, form within the aluminum matrix.\nThese precipitates act as obstacles to dislocation movement, significantly increasing the alloy's strength and hardness.\n\n## Final Microstructure\nThe final microstructure of duralumin consists of a predominantly aluminium matrix dispersed fine precipitates (CuAl2, Mg2Si)\nGrain boundaries.\nThe size, distribution, and type of precipitates play a crucial role in determining the mechanical properties of duralumin.\nOptimal aging conditions lead to the formation of finely dispersed precipitates, resulting in peak strength and hardness.\n\n# Applications\nAluminium alloyed with copper (Al-Cu alloys), which can be [precipitation hardened](https://bliptext.com/articles/precipitation-hardening), are designated by the International Alloy Designation System as the 2000 series.\nTypical uses for [wrought](https://bliptext.com/articles/metalworking) Al-Cu alloys include:\n\n## Aviation\nGerman scientific literature openly published information about duralumin, its composition and heat treatment, before the outbreak of [World War I](https://bliptext.com/articles/world-war-i) in 1914.\nDespite this, use of the alloy outside[ Germany](https://bliptext.com/articles/german-empire) did not occur until after fighting ended in 1918.\nReports 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.\nEngineers in the UK showed little interest in duralumin until after the war.\nThe earliest known attempt to use duralumin for a heavier-than-air aircraft structure occurred in 1916, when [Hugo Junkers](https://bliptext.com/articles/hugo-junkers) first introduced its use in the airframe of the [Junkers J 3](https://bliptext.com/articles/junkers-j-3), a single-engined monoplane \"technology demonstrator\" that marked the first use of the Junkers trademark duralumin corrugated skinning.\nThe [Junkers](https://bliptext.com/articles/junkers) company completed only the covered wings and tubular fuselage framework of the J 3 before abandoning its development.\nThe slightly later, solely IdFlieg-designated [Junkers J.I](https://bliptext.com/articles/junkers-j-i) armoured [sesquiplane](https://bliptext.com/articles/biplane) 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](https://bliptext.com/articles/junkers-j-7) single-seat fighter design, which led to the [Junkers D.I](https://bliptext.com/articles/junkers-d-i) low-wing monoplane fighter, introducing all-duralumin aircraft structural technology to[ German military aviation](https://bliptext.com/articles/luftstreitkr-fte) in 1918.\nIts first use in [aerostatic](https://bliptext.com/articles/aerostat) airframes came in rigid [airship](https://bliptext.com/articles/airship) frames, eventually including all those of the \"Great Airship\" era of the 1920s and 1930s: the British-built [R100](https://bliptext.com/articles/r100), the German passenger Zeppelins LZ 127 Graf Zeppelin, LZ 129 Hindenburg, LZ 130 Graf Zeppelin II, and the [U.S. Navy](https://bliptext.com/articles/u-s-navy) [airship](https://bliptext.com/articles/airship)s USS Los Angeles (ZR-3, ex-LZ 126), USS Akron (ZRS-4) and USS Macon (ZRS-5).\n# [Duralumin sample from the 1931 airship USS Akron (ZRS-4) | upload.wikimedia.org/wikipedia/commons/3/32/ZRS-4///USS///Akron///duralumin///sample.jpg]\n# [The first mass-production aircraft to make extensive use of duralumin, the armored Junkers J.I sesquiplane of World War I | upload.wikimedia.org/wikipedia/commons/2/28/Junkers///J.I///-///Ray///Wagner///Collection///Image///%2820821101334%29.jpg]\n\n## Bicycles\nDuralumin was used to manufacture bicycle components and framesets from the 1930s to 1990s.\nSeveral 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](https://bliptext.com/articles/derailleurs), pedals, brakes and handlebars were manufactured by several companies.\nComplete 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.\nOther names that come up here also included: Pierre Caminade, with his beautiful Caminargent creations and their exotic octagonal tubing, and also [Gnome et Rhône](https://bliptext.com/articles/gnome-et-rh-ne), with its deep heritage as an aircraft engine manufacturer that also diversified into motorcycles, velomotors and bicycles after World War Two.\n[Mitsubishi Heavy Industries](https://bliptext.com/articles/mitsubishi-heavy-industries), which was prohibited from producing aircraft during the American occupation of Japan, manufactured the “cross” bicycle out of surplus wartime duralumin in 1946.\nThe “cross” was designed by [Kiro Honjo](https://bliptext.com/articles/kiro-honjo), a former aircraft designer responsible for the [Mitsubishi G4M](https://bliptext.com/articles/mitsubishi-g4m).\nDuralumin use in bicycle manufacturing faded in the 1970s and 1980s.\n[Vitus](https://bliptext.com/articles/vitus-bicycle-company) nonetheless released the venerable “979” frameset in 1979, a “Duralinox” model that became an instant classic among cyclists.\nThe 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.\nThe result was an extremely lightweight but very durable frameset.\nProduction of the Vitus 979 continued until 1992.\n\n## Automotive\nIn 2011, [BBS Automotive](https://bliptext.com/articles/bbs-kraftfahrzeugtechnik) made the RI-D, the world's first production automobile wheel made of duralumin.\nThe company has since made other wheels of duralumin also, such as the RZ-D.","revisionCount":0},"hasMore":false,"nextCursor":null}