Duralumin

Duralumin is an alloy made up of 90% aluminum, 4% copper, 0.5–1% magnesium, and less than 1% manganese.
It is an extremely hard alloy that is used, for example, in vehicle armour in the defense industry.

 Other website 
Armor-plating composite

Category:Aluminium alloys
Category:Copper alloys
Category:Magnesium alloys
Category:Manganese alloys