Dural is the popular word for Duralumin which is an alloy of Aluminium and copper with manganese and magnesium in small quantities thrown in as well
Aluminium makes up about 94% with copper about 4% and thus you get a light but strong alloy. It has one draw back that it suffers from corrosion and that is why you see aircraft that are built from this alloy are painted to prevent the corrosion.
The industry also produced alcad sheet, which uses dural as a core and pure aluminium bonded to both sides, the aluminium in this case giving the protection against corrosion.
Brain hurts now so will stop