Nickel-Based Superalloys and Articles

Abstract

Rhenium-free nickel based alloys are provided. More particularly, the alloys comprise preferred levels and ratios of elements so as to achieve good high temperature strength of both gamma matrix phase and gamma prime precipitates, as well as good environmental resistance, without using rhenium. When cast and directionally solidified into single crystal form, the alloys exhibit creep resistance substantially equivalent to rhenium-bearing single-crystal alloys. Further, the alloys can be processed by directional solidification into articles in single crystal form or columnar structure comprising fine dendrite arm spacing, e.g., less than 400 μm, if need be, so that further improvements in mechanical properties in the articles can be seen.

1 . A rhenium-free, nickel-based alloy comprising from about 4.0 wt % to about 10 wt % cobalt (Co), from about 4.0 wt % to about 10 wt % chromium (Cr), from about 0.5 wt % to about 2.5 wt % molybdenum (Mo), from about 4.5 wt % to about 9 wt % tungsten (W), from about 4.0 wt % to about 6.5 wt % aluminum (Al), from about 1.5 wt % to about 3.0 wt % titanium (Ti), from about 4.0 wt % to about 9.0 wt % tantalum (Ta), from about 0 wt % to about 1.0 wt % hafnium (Hf), up to about 0.1 wt % carbon (C), up to about 0.01 wt % boron (B), with the remainder being nickel (Ni) and incidental impurities, and wherein:
 Al+0.56Ti is from about 6 wt % to about 8.0 wt %;   Ti/Al is greater than about 0.35;   Al+0.56Ti+0.15Ta+0.15Hf is from about 7 wt % to about 10.0 wt %; and   Mo+0.52W is from about 3.0 wt % to about 5.7 wt %.   
     
     
         2 . The nickel-based alloy of  claim 1 , comprising from about 5.5 wt % to about 8.0 wt % cobalt (Co), from about 6.0 wt % to about 8.5 wt % chromium (Cr), from about 0.5 wt % to about 2.1 wt % molybdenum (Mo), from about 4.5 wt % to about 7.5 wt % tungsten (W), from about 4.5 wt % to about 6.0 wt % aluminum (Al), from about 5.0 wt % to about 7.5 wt % tantalum (Ta), from about 0 wt % to about 0.5 wt % hafnium (Hf). 
     
     
         3 . The nickel-based alloy of  claim 2 , comprising from about 6.0 wt % to about 8.0 wt % cobalt (Co), from about 7.0 wt % to about 8.5 wt % chromium (Cr), from about 1.0 wt % to about 2.0 wt % molybdenum (Mo), from about 4.5 wt % to about 7 wt % tungsten (W), from about 4.5 wt % to about 5.6 wt % aluminum (Al), from about 1.5 wt % to about 2.5 wt % titanium (Ti), and from about 6.0 wt % to about 7.2 wt % tantalum (Ta). 
     
     
         4 . An article comprising a rhenium-free, nickel-based alloy comprising from about 4.0 wt % to about 10 wt % cobalt (Co), from about 4.0 wt % to about 10 wt % chromium (Cr), from about 0.5 wt % to about 2.5 wt % molybdenum (Mo), from about 4.5 wt % to about 9 wt % tungsten (W), from about 4.0 wt % to about 6.5 wt % aluminum (Al), from about 1.5 wt % to about 3.0 wt % titanium (Ti), from about 4.0 wt % to about 9.0 wt % tantalum (Ta), from about 0 wt % to about 1.0 wt % hafnium (Hf), up to about 0.1 wt % carbon (C), up to about 0.01 wt % boron (B), with the remainder being nickel (Ni) and incidental impurities, wherein:
 Al+0.56Ti is from about 6 wt % to about 8.0 wt %;   Ti/Al is greater than about 0.35;   Al+0.56Ti+0.15Ta+0.15Hf is from about 7 wt % to about 10.0 wt %;   Mo+0.52W is from about 3.0 wt % to about 5.7 wt %.   
     
     
         5 . The article of  claim 4 , wherein the nickel-based alloy comprises from about 5.5 wt % to about 8.0 wt % cobalt (Co), from about 6.0 wt % to about 8.5 wt % chromium (Cr), from about 0.5 wt % to about 2.1 wt % molybdenum (Mo), from about 4.5 wt % to about 7.5 wt % tungsten (W), from about 4.5 wt % to about 6.0 wt % aluminum (Al), from about 5.0 wt % to about 7.5 wt % tantalum (Ta), from about 0 wt % to about 0.5 wt % hafnium (Hf). 
     
     
         6 . The article of  claim 5 , wherein the nickel-based alloy comprises from about 6.0 wt % to about 8.0 wt % cobalt (Co), from about 7.0 wt % to about 8.5 wt % chromium (Cr), from about 1.0 wt % to about 2.0 wt % molybdenum (Mo), from about 4.5 wt % to about 7 wt % tungsten (W), from about 4.5 wt % to about 5.6 wt % aluminum (Al), from about 1.5 wt % to about 2.5 wt % titanium (Ti), and from about 6.0 wt % to about 7.2 wt % tantalum (Ta). 
     
     
         7 . The article of  claim 4 , wherein the alloy comprises a dendritic structure. 
     
     
         8 . The article of  claim 7 , wherein the dendritic structure comprises primary dendrite arms having a nominal spacing less than about 400 micrometers. 
     
     
         9 . The article of  claim 8 , wherein the alloy is a single crystal. 
     
     
         10 . The article of  claim 9 , wherein the alloy comprises a directionally solidified microstructure. 
     
     
         11 . The article of  claim 4 , wherein the article is a component of a gas turbine assembly. 
     
     
         12 . The article of  claim 11 , wherein the article comprises a blade, vane, shroud, or combustor component. 
     
     
         13 . A method for manufacturing an article comprising casting into a mold a rhenium-free, nickel-based alloy comprising from about 4.0 wt % to about 10 wt % cobalt (Co), from about 4.0 wt % to about 10 wt % chromium (Cr), from about 0.5 wt % to about 2.5 wt % molybdenum (Mo), from about 4.5 wt % to about 9 wt % tungsten (W), from about 4.0 wt % to about 6.5 wt % aluminum (Al), from about 1.5 wt % to about 3.0 wt % titanium (Ti), from about 4.0 wt % to about 9.0 wt % tantalum (Ta), from about 0 wt % to about 1.0 wt % hafnium (Hf), up to about 0.1 wt % carbon (C), up to about 0.01 wt % boron (B), with the remainder being nickel (Ni) and incidental impurities, wherein:
 Al+0.56Ti is from about 6 wt % to about 8.0 wt %;   Ti/Al is greater than about 0.35;   Al+0.56Ti+0.15Ta+0.15Hf is from about 7 wt % to about 10.0 wt %;   Mo+0.52W is from about 3.0 wt % to about 5.7 wt %; and wherein the article is cast and directionally solidified into a single crystal form or columnar structure and so that the primary dendrite arm spacing within the article is less than about 400 μm.   
     
     
         14 . The method of  claim 13 , comprising from about 5.5 wt % to about 8.0 wt % cobalt (Co), from about 6.0 wt % to about 8.5 wt % chromium (Cr), from about 0.5 wt % to about 2.1 wt % molybdenum (Mo), from about 4.5 wt % to about 7.5 wt % tungsten (W), from about 4.5 wt % to about 6.0 wt % aluminum (Al), from about 5.0 wt % to about 7.5 wt % tantalum (Ta), from about 0 wt % to about 0.5 wt % hafnium (Hf). 
     
     
         15 . The method of  claim 14 , wherein the nickel-based alloy comprises from about 6.0 wt % to about 8.0 wt % cobalt (Co), from about 7.0 wt % to about 8.5 wt % chromium (Cr), from about 1.0 wt % to about 2.0 wt % molybdenum (Mo), from about 4.5 wt % to about 7 wt % tungsten (W), from about 4.5 wt % to about 5.6 wt % aluminum (Al), from about 1.5 wt % to about 2.5 wt % titanium (Ti), and from about 6.0 wt % to about 7.2 wt % tantalum (Ta).