Superalloy for single crystal turbine vanes

Abstract

A nickel-base superalloy that is useful for making single crystal castings exhibiting outstanding stress-rupture properties, creep-rupture properties, and an increased tolerance for grain defects contains, in percentages by weight, from about 4.3% to about 5.3% chromium, (Cr), from about 9% to about 10% cobalt (Co), from about 0.6% to about 0.8% molybdenum (Mo), from about 8.4% to about 8.8% tungsten (W), from about 4.3% to about 4.8% tantalum (Ta), from about 0.6% to about 0.8% titanium (Ti), from about 5.6% to about 5.8% aluminum (Al), from about 2.8% to about 3.1% rhenium (Re), from about 0.9% to about 1.5% hafnium (Hf), from about 0.06% to about 0.08% carbon (C), from about 0.012% to about 0.020% boron (B), from about 0.004% to about 0.010% zirconium (Zr), the balance being nickel and incidental impurities. The nickel-base superalloy provides improved casting yield and reduce component cost due to a reduction in rejectable grain defects as compared with conventional directionally solidified casting alloys and conventional single crystal alloys.

The invention claimed is:  
     
         1 . A nickel-base superalloy comprising, in percentages by weight, from about 4.3% to about 5.3% chromium, (Cr), from about 9.0% to about 10.0% cobalt (Co), from about 0.6% to about 0.8% molybdenum (Mo), from about 8.4% to about 8.8% tungsten (W), from about 4.3% to about 4.8% tantalum (Ta), from about 0.6% to about 0.8% titanium (Ti), from about 5.6% to about 5.8% aluminum (Al), from about 2.8% to about 3.1% rhenium (Re), from about 0.9% to about 1.5% hafnium (Hf), from about 0.06% to about 0.08% carbon (C), from about 0.012% to about 0.020% boron (B), from about 0.004% to about 0.010% zirconium (Zr), the balance being nickel and incidental impurities.  
     
     
         2 . The nickel-base superalloy of  claim 1 , wherein the chromium is present in an amount of from about 4.5% to about 5.1% by weight.  
     
     
         3 . The nickel-base superalloy of  claim 1 , wherein the hafnium is present in an amount from about 0.9% to about 1.3% by weight.  
     
     
         4 . The nickel-base superalloy of  claim 1 , wherein the tantalum is present in an amount of from about 4.4% to about 4.7% by weight.  
     
     
         5 . The nickel-base superalloy of  claim 1 , wherein the chromium is present in an amount of from about 4.5% to about 5.1% by weight, and the hafnium is present in an amount from about 0.9% to about 1.3% by weight.  
     
     
         6 . The nickel-base superalloy of  claim 1 , wherein the chromium is present in an amount of from about 4.5% to about 5.1% by weight, and the tantalum is present in an amount from about 4.4% to about 4.7% by weight.  
     
     
         7 . The nickel-base superalloy of  claim 1 , wherein the hafnium is present in an amount of from about 0.9% to about 1.3% by weight, and the tantalum is present in an amount from about 4.4% to about 4.7% by weight.  
     
     
         8 . The nickel-base superalloy of  claim 1 , wherein the chromium is present in an amount of from about 4.5% to about 5.1% by weight, the hafnium is present in an amount from about 0.9% to about 1.3% by weight, and the tantalum is present in an amount from about 4.4% to about 4.7% by weight.  
     
     
         9 . The nickel-base superalloy of  claim 1 , wherein the total content of tungsten, rhenium, tantalum and molybdenum is from about 16.4% to about 17.0% by weight.  
     
     
         10 . The nickel-base superalloy of  claim 1  comprising, in percentages by weight, about 5% chromium, about 9.3% cobalt, about 0.7% molybdenum, about 8.6% tungsten, about 4.5% tantalum, about 0.7% titanium, about 5.7% aluminum, about 2.9% rhenium, about 1.0% hafnium, about 0.07% carbon, about 0.015% boron, about 0.005% zirconium, the balance being nickel and incident impurities.  
     
     
         11 . A single crystal casting prepared from a nickel-base superalloy comprising, in percentage by weight, from about 4.3% to about 5.3% chromium, (Cr), from about 9.0% to about 10.0% cobalt (Co), from about 0.6% to about 0.8% molybdenum (Mo), from about 8.4% to about 8.8% tungsten (W), from about 4.3% to about 4.8% tantalum (Ta), from about 0.6% to about 0.8% titanium (Ti), from about 5.6% to about 5.8% aluminum (Al), from about 2.8% to about 3.1% rhenium (Re), from about 0.9% to about 1.5% hafnium (Hf), from about 0.06% to about 0.08% carbon (C), from about 0.012% to about 0.020% boron (B), from about 0.004% to about 0.010% zirconium (Zr), the balance being nickel and incidental impurities.  
     
     
         12 . The single crystal casting of  claim 11 , wherein the chromium is present in an amount of from about 4.5% to about 5.1% by weight.  
     
     
         13 . The single crystal casting of  claim 11 , wherein the hafnium is present in an amount of from about 0.9% to about 1.3% by weight.  
     
     
         14 . The single crystal casting of  claim 11 , wherein the tantalum is present in an amount of from about 4.4% to about 4.7% by weight.  
     
     
         15 . The single crystal casting of  claim 11 , wherein the total content of tungsten, rhenium, tantalum and molybdenum is from about 16.4% to about 17.0% by weight.  
     
     
         16 . The single crystal casting of  claim 11 , where 10-50 ppm La, Y, Ce individually or in combination is present to improve bare oxidation resistance and coating performance.  
     
     
         17 . A nickel-base turbine vane, turbine blade, or multiple turbine vane segment cast from a nickel-base superalloy comprising, in percentage by weight, from about 4.3% to about 5.3% chromium, (Cr), from about 9.0% to about 10.0% cobalt (Co), from about 0.6% to about 0.8% molybdenum (Mo), from about 8.4% to about 8.8% tungsten (W), from about 4.3% to about 4.8% tantalum (Ta), from about 0.6% to about 0.8% titanium (Ti), from about 5.6% to about 5.8% aluminum (Al), from about 2.8% to about 3.1% rhenium (Re), from about 0.9% to about 1.5% hafnium (Hf), from about 0.06% to about 0.08% carbon (C), from about 0.012% to about 0.020% boron (B), from about 0.004% to about 0.010% zirconium (Zr), the balance being nickel and incidental impurities.  
     
     
         18 . The turbine vane, turbine blade, or multiple turbine vane segment of  claim 17 , wherein the chromium is present in an amount of from about 4.5% to about 5.1% by weight.  
     
     
         19 . The turbine vane, turbine blade, or multiple turbine vane segment of  claim 17 , wherein the hafnium is present in an amount from about 0.9% to about 1.3% by weight.  
     
     
         20 . The turbine vane, turbine blade, or multiple turbine vane segment of  claim 17 , wherein the tantalum is present in an amount of from about 4.4% to about 4.7% by weight.