Abstract: The present invention is directed to the achievement of increased gas turbine engine efficiencies through further improvements in nickel-base superalloys used to make parts and components for gas turbine engines. The present invention comprises nickel-base superalloys for producing single crystal articles having a significant increase in temperature capability, based on stress rupture strength and low and high cycle fatigue properties, over single crystal articles made from current production nickel-base superalloys. Further, because of their superior resistance to degradation by cyclic oxidation, and their resistance to hot corrosion, the superalloys of this invention possess a balance in mechanical and environmental properties which is unique and has not heretofore been obtained.