Duralumin

Duralumin, also called duraluminum, duraluminium or dural is an alloy of aluminium (about 95%), copper (about 4%), and small amounts of magnesium (0.5%-1%) and manganese (less than 1%). It is far better in tensile strength than elemental aluminium, though less resistant to corrosion. Its heat and electrical conductivity are less than that of pure aluminium but much more than that of steel. Duralumin was invented in 1908 by Alfred Wilm during research for the German army. Its first use …

…boot cover (trunk lid) (MG A). Today almost all material that claims to be aluminium is actually an alloy thereof. Pure aluminium is encountered only when corrosion resistance is more important than strength or hardness. Copper-free aluminium is specified for such uses. Conversely, the term "alloy" usually means aluminium alloy. In modern aircraft Duralumin has evolved into the alloys known as 2017, 2117, and 2024. Also, in future, its going to be as important as it is now.