Abstract: Aluminum based alloy primarily for use in aircraft and aerospace components consists essentially of the composition: 2.60 to 3.30 weight percent copper, 0.0 to 0.50 weight percent manganese, 1.30 to 1.65 weight percent lithium, 0.0 to 1.8 percent magnesium, and from 0.0 to 1.5 weight percent of grain refinement elements selected from the group consisting of zirconium, and chromium. Up to about 0.5 wt. % zinc and up to about 1.5 wt. % titanium may also be present. Minor impurities may also be present. These alloys exhibit an improved combination of characteristics including low density, high strength, high corrosion resistance and good fracture toughness.

Abstract: A method of adding alloying elements, including highly reactive metals such s lithium, to molten aluminum so that the normally occurring oxidation reaction of such elements with the atmosphere is minimized. After adding all alloying elements, except the highly reactive metals, to the molten aluminum, and after the alloyed melt has been subjected to a degassing and filtering process, the reactive metals are introduced in a mixing crucible as the final step prior to the casting operation. The desired concentration of reactive metal in the melt is achieved by controlling the relative amounts of reactive metal and alloyed melt. Uniformity of the mixture is controlled by mechanical stirring. The alloyed metal is then cast into ingots.