US Patent 7494552 Al-Cu alloy with high toughness

Disclosed is an Al—Cu alloy of the AA2000-series alloys with high toughness and an improved strength, including the following composition (in weight percent) Cu 4.5-5.5, Mg 0.5-1.6, Mn≦0.80, Zr≦0.18, Cr≦0.18, Si≦0.15, Fe≦0.15, the balance essentially aluminum and incidental elements and impurities, and wherein the amount (in weight %) of magnesium is either: (a) in a range of 1.0 to 1.6%, or alternatively (b) in a range of 0.50 to 1.2% when the amount of dispersoid forming elements such as Cr, Zr or Mn is controlled and (in weight %) in a range of 0.10 to 0.70%.