Superalloy forming highly adherent chromia surface layer

Abstract

A nickel-based superalloy that forms a chromia scale in an oxidizing environment is disclosed. The alloy provides good oxidation resistance at temperatures below 900° C. in a dry or moist atmosphere. The superalloy is suited for components of gas or steam turbine engines including blades and vanes.

1 . A nickel-based superalloy expressed in weight percentages consisting essentially of:
 10 to 25 Cr;   5 to 25 Co;   2.0 to 6.0 Mo;   0.5 to 4.0 Al;   1.0 to 4.0 Ti;   0 to 3 Hf;   0 to 10 Fe;   0 to 1 Si;   0 to 0.10 B;   0 to 0.20 Zr;   0 to 0.20 C;   0 to 0.5 at least one rare earth element selected from the group consisting of Y, La, Ce, Nb, Dy, Pr, Sm, and Gd;   less than 100 ppm S; and   balance formed from Ni.   
     
     
         2 . The superalloy of  claim 1 , wherein the superalloy expressed in weight percentages consisting essentially of:
 18 to 21 Cr;   12.0 to 15.0 Co;   3.5 to 5.0 Mo;   1.2 to 1.6 Al;   2.75 to 3.25 Ti;   0 to 0.5 Hf;   0 to 2 Fe;   0 to 0.5 Si;   0.003 to 0.010 B;   0.02 to 0.08 Zr;   0.03 to 0.10 C;   0 to 0.2 of at least one rare earth element selected from the group consisting of Y, La, Ce, Nb, Dy, Pr, Sm, and Gd;   less than 10 ppm S; and   the balance formed from Ni.   
     
     
         3 . The superalloy of  claim 1 , wherein the superalloy expressed in weight percentages consisting essentially of:
 18.5 Cr;   13.0 to 14.0 Co;   4.0 to 4.4 Mo;   1.30 to 1.50 Al;   2.80 to 3.20 Ti;   0.05 to 0.15 Hf;   0 to 0.2 Fe;   0.05 to 0.15 Si;   0.008 B;   0.06 Zr;   0.07 C;   0.02 of a mixture of at least one rare earth element selected from the group consisting of Y, La, Ce, Nb, Dy, Pr, Sm, and Gd;   with less than 4 ppm S; and   the balance formed from Ni.