Duralumin

Duralumin was developed by the German metallurgist Alfred Wilm at private military-industrial laboratory Zentralstelle für wissenschaftlich-technische Untersuchungen [de] (Center for Scientific-Technical Research) in Neubabelsberg.

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.

Corrosion resistance can be greatly enhanced by the metallurgical bonding of a high-purity aluminium surface layer, referred to as alclad-duralum.

[3][4] Duralumin's remarkable strength and durability stem from its unique microstructure, which is significantly influenced by heat treatment processes.

Optimal aging conditions lead to the formation of finely dispersed precipitates, resulting in peak strength and hardness.

Typical uses for wrought Al-Cu alloys include:[5] German scientific literature openly published information about duralumin, its composition and heat treatment, before the outbreak of World War I in 1914.

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.

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, which was prohibited from producing aircraft during the American occupation of Japan, manufactured the “cross” bicycle out of surplus wartime duralumin in 1946.