A nickel-base alloy is disclosed that has the following weight percent composition. C about 0.005 to about 0.06 Cr about 13 to about 17 Fe about 4 to about 20 Mo about 3 to about 9 W up to about 8 Co up to about 12 Al about 1 to about 3 Ti about 0.6 to about 3 Nb up to about 5.5 B about 0.001 to about 0.012 Mg about 0.0010 to about 0.0020 Zr about 0.01 to about 0.08 Si up to about 0.7 P up to about 0.05 and the balance is nickel, usual impurities, and minor amounts of other elements as residuals from alloying additions during melting. The alloy provides a combination of high strength, good creep resistance, and good resistance to crack growth. A method of heat treating a nickel base superalloy to improve the tensile ductility of the alloy is also disclosed. An article of manufacture made from the nickel base superalloy described herein is also disclosed.