Duralumin

Duralumin was developed by the German metallurgist Alfred Wilm at Dürener Metallwerke AG. In 1903, Wilm discovered that after quenching, an aluminium alloy containing 4% copper would slowly harden when left at room temperature for several days. Further improvements led to the introduction of duralumin in 1909.[1] The name is obsolete today, and mainly used in popular science to describe the Al-Cu alloy system, or ’2000′ series, as designated by the International Alloy Designation System (IADS) originally created in 1970 by the Aluminum Association.

l’origine_ http://classicvintagecycling.tumblr.com/ | en.wikipedia.org/Duralumin