Duralumin
răl´yəmĭn, dy–), alloy of aluminum (over 90%) with copper (about 4%), magnesium (0.5%–1%), and manganese (less than l%). Before a final heat treatment the alloy is ductile and malleable; after heat treatment a reaction between the aluminum and magnesium produces increased hardness and tensile strength. Because of its lightness and other desirable physical properties, duralumin is widely used in the aircraft industry.