Nickel-base superalloy

Abstract

A nickel-base alloy that exhibits a desirable balance of mechanical properties, environmental properties, and microstructural stability suitable for gas turbine engine applications. The nickel-base alloy is in the form of a single-crystal casting consisting of, by weight, 5.75% to 6.5% aluminum, 4% to 5% tantalum, 2% to 6% chromium, 5.5% to 7% tungsten, 1.5% to 3% molybdenum, 4% to 5% rhenium, up to 1.0% niobium, 10% to 16% cobalt, up to 1% titanium, 0.01% to 0.05% carbon, up to 0.005% boron, up to 0.01% yttrium, 0.5% to 1.0% hafnium, the balance nickel and incidental impurities. The alloy has a density of not more than 0.320 lbs/in 3 (about 8.87 g/cm 3 ), and contains a combined amount of aluminum, tungsten, molybdenum, niobium, titanium, and hafnium specified relative to the combined amount of tantalum and rhenium.

1 . A single-crystal casting formed of a nickel-base alloy consisting of, by weight: 
 5.75% to 6.5% aluminum;    about 4.0% up to 5.0% tantalum;    2.0% to 6.0% chromium;    5.5% to 7.0% tungsten;    1.5% to 3.0% molybdenum;    4.0% to about 5.0% rhenium;    up to 1.0% niobium;    10.0% to 16.0% cobalt;    up to 1.0% titanium;    0.01% to 0.05% carbon;    up to 0.005% boron;    up to 0.01% yttrium;    0.5% to 1.0% hafnium;    the balance nickel and incidental impurities;    where in the density of the alloy is not greater than 3.20 lb/in 3  and the alloy has a delta ratio of less than one calculated with the formula      (Al+W+Mo+Nb+Ti+Hf−13.15)/(12.6−Ta—Re)    wherein Al, W, Mo, Nb, Ti, Hf, Ta, and Re are the levels of aluminum, tungsten, molybdenum, niobium, titanium, hafnium, tantalum, and rhenium, respectively, in weight percent.    
     
     
         2 . The single-crystal casting according to  claim 1 , wherein the alloy consists of, by weight, 6.0 to 6.25% aluminum, 4.0 to 5.0% tantalum, 2.0 to 6.0% chromium, 5.5 to 7.0% tungsten, 1.5 to 3.0% molybdenum, 4.0 to 5.0% rhenium, 0.5 to 1.0% niobium, 10.0 to 12.0% cobalt, 0.25 to 1.0% titanium, 0.01 to 0.05% carbon, 0.001 to 0.005% boron, 0 to 0.01% yttrium, 0.5 to 1.0% hafnium, the balance nickel and incidental impurities.  
     
     
         3 . The single-crystal casting according to  claim 1 , wherein the alloy consists of, by weight, 6.0 to 6.25% aluminum, 4.0 to 5.0% tantalum, about 4.2% chromium, 6.0 to 7.0% tungsten, about 1.5% molybdenum, 4.0 to 5.0% rhenium, about 0.75% niobium, about 10.0% cobalt, about 0.3% titanium, about 0.03% carbon, about 0.004% boron, about 0.004% yttrium, about 0.6% hafnium, the balance nickel and incidental impurities.  
     
     
         4 . The single-crystal casting according to  claim 1 , wherein the alloy contains of, by weight, about 4.0% tantalum, about 6.0% tungsten, and about 5.0% rhenium.  
     
     
         5 . The single-crystal casting according to  claim 1 , wherein the alloy has a density of 0.315 to 0.319 lb/in 3 .  
     
     
         6 . The single-crystal casting according to  claim 1 , wherein the alloy has a delta ratio of less than 0.9.  
     
     
         7 . The single-crystal casting according to  claim 1 , wherein the casting is a gas turbine engine component.  
     
     
         8 . A single-crystal casting formed of a nickel-base alloy consisting of, by weight: 
 6.00% to 6.25% aluminum;    about 4.0% up to 5.0% tantalum;    2.0% to 6.0% chromium;    about 6.0% up to 7.0% tungsten;    1.5% to 3.0% molybdenum;    4.0% to about 5.0% rhenium;    0.5% to 1.0% niobium;    10.0% to 12.0% cobalt;    0.25% to 1.0% titanium;    0.01% to 0.05% carbon;    0.001% to 0.005% boron;    up to 0.01% yttrium;    0.5% to 1.0% hafnium;    the balance nickel and incidental impurities;    where in the density of the alloy is less than 3.20 lb/in 3  and the alloy has a delta ratio of less than one calculated with the formula      (Al+W+Mo+Nb+Ti+Hf−13.15)/(12.6−Ta—Re)    wherein Al, W, Mo, Nb, Ti, Hf, Ta, and Re are the levels of aluminum, tungsten, molybdenum, niobium, titanium, hafnium, tantalum, and rhenium, respectively, in weight percent.    
     
     
         9 . The single-crystal casting according to  claim 8 , wherein the molybdenum content in the alloy is greater than 2.0 weight percent.  
     
     
         10 . The single-crystal casting according to  claim 8 , wherein the molybdenum content in the alloy is greater than 2.25 weight percent.  
     
     
         11 . The single-crystal casting according to  claim 8 , wherein the alloy has a density of 0.315 to 0.318 lbs/in 3 .  
     
     
         12 . The single-crystal casting according to  claim 8 , wherein the alloy has a delta ratio of less than 0.9.  
     
     
         13 . The single-crystal casting according to  claim 8 , wherein the alloy contains of, by weight, about 4.0% tantalum, about 6.0% tungsten, and about 5.0% rhenium.  
     
     
         14 . The single-crystal casting according to  claim 8 , wherein the casting is a gas turbine engine component.  
     
     
         15 . The single-crystal casting according to  claim 8 , wherein the alloy consists of, by weight, about 6.1% aluminum, about 4.0% tantalum, 4.0 to 4.2% chromium, 5.5 to 6.5% tungsten, 1.50 to 3.0% molybdenum, 4.5 to 5.0% rhenium, about 0.75% niobium, about 10.0% cobalt, 0.3 to 0.5% titanium, about 0.03% carbon, about 0.004% boron, about 0.004% yttrium, about 0.6% hafnium, the balance nickel and incidental impurities.  
     
     
         16 . The single-crystal casting according to  claim 15 , wherein the molybdenum content in the alloy is greater than 2.0 weight percent.  
     
     
         17 . The single-crystal casting according to  claim 15 , wherein the molybdenum content in the alloy is greater than 2.25 weight percent.  
     
     
         18 . The single-crystal casting according to  claim 15 , wherein the alloy has a density of 0.315 to 0.318 lbs/in 3 .  
     
     
         19 . The single-crystal casting according to  claim 15 , wherein the alloy has a delta ratio of less than 0.9.  
     
     
         20 . The single-crystal casting according to  claim 15 , wherein the casting is a gas turbine engine component.