Nickel Based Superalloys and Articles

Abstract

Nickel based alloys are provided comprising from about 7.0 weight percent (wt %) to about 12.0 wt % chromium, from about 0.1 wt % to about 5 wt % molybdenum, from about 0.2 wt % to about 4.5 wt % titanium, from about 4 wt % to about 6 wt % aluminum, from about 3 wt % to about 4.9 wt % cobalt, from about 6.0 wt % to about 9.0 wt % tungsten, from about 4.0 wt % to about 6.5 wt % tantalum, from about 0.05 wt % to about 0.6 wt % hafnium, up to about 1.0 wt % niobium, up to about 0.02 wt % boron, and up to about 0.1 wt % carbon, with the remainder being nickel and incidental impurities. The alloys may be cast, directionally solidified and heat treated to provide articles having a gamma prime fraction of greater than about 50%.

1 . A method of making a cast and heat treated article having a gamma prime volume fraction comprising:
 providing a nickel-based alloy comprising about 7.0 wt % to about 12.0 wt % chromium, about 0.1 wt % to about 5 wt % molybdenum, about 0.2 wt % to about 4.5 wt % titanium, about 4 wt % to about 6 wt % aluminum, about 3 wt % to about 4.9 wt % cobalt, about 6.0 wt % to about 9.0 wt % tungsten, about 4.0 wt % to about 6.5 wt % tantalum, about 0.05 wt % to about 0.6 wt % hafnium, niobium present in an amount of up to about 1.0 wt %, boron present in an amount of up to about 0.02 wt %, and carbon present in an amount of up to about 0.1 wt %, remainder being nickel and incidental impurities;   melting and directionally solidifying the alloy to produce an article; and   heat treating the article at about 2260° F. to about 2400° F. to form a heat treated article having a gamma prime volume fraction of greater than about 50%.   
     
     
         2 . The method of  claim 1  wherein the carbon is present in an amount of about 0.04 wt % to about 0.1 wt. %. 
     
     
         3 . The method of  claim 1  wherein the alloy has an aluminum to titanium ratio of greater than about 1. 
     
     
         4 . A method of making a cast and heat treated article having a gamma prime volume fraction comprising: providing a nickel-based alloy comprising about 9.0 wt % to about 11.0 wt % chromium, about 0.5 wt % to about 3.0 wt % molybdenum, about 0.5 wt % to about 3.5 wt % titanium, about 4 wt % to about 6 wt % aluminum, about 3.5 wt % to about 4.25 wt % cobalt, about 6.0 wt % to about 9.0 wt % tungsten, about 4.0 wt % to about 6.5 wt % tantalum, about 0.05 wt % to about 0.5 wt % hafnium, niobium in an amount of up to about 1.0 wt %, boron in an amount of up to about 0.01 wt %, and carbon present in an amount of up to about 0.07 wt %, balance being nickel and incidental impurities;
 melting and directionally solidifying the alloy to produce an article; and   heat treating the article in a vacuum to form a heat treated article having a gamma prime volume fraction of greater than about 50%.   
     
     
         5 . The method of  claim 1  wherein the gamma prime fraction is greater than 60%. 
     
     
         6 . The method of  claim 4  wherein the gamma prime fraction is greater than 60%. 
     
     
         7 . The method of  claim 1  wherein the alloy is substantially free of rhenium. 
     
     
         8 . The method of  claim 4  wherein the alloy is substantially free of rhenium. 
     
     
         9 . The method of  claim 1  wherein the alloy comprises about 9.59 wt % to about 9.78 wt % chromium, about 0.74 wt % to about 1.5 wt % molybdenum, about 0.82 wt. % to about 4.5 wt % Ti, about 4.13 wt % to about 4.71 wt % aluminum, about 3.93 wt % to about 4.01 wt % cobalt, about 6.02 wt % to about 8.85 wt % tungsten, about 5.90 wt % to about 6.01 wt % tantalum, about 0.15 wt % hafnium, about 0.50 wt % niobium, about 0.01 wt % boron, and about 0.04 wt. % carbon, remainder being nickel and incidental impurities. 
     
     
         10 . The method of  claim 9  wherein the alloy comprises titanium present in an amount of about 2.62 wt. % to about 3.44 wt. %. 
     
     
         11 . The method of  claim 1  wherein the heat treating is performed by heating in a vacuum for 2 to 4 hours. 
     
     
         12 . The method of  claim 4  wherein the heat treating is performed by heating in a vacuum for 2 to 4 hours. 
     
     
         13 . The method of  claim 1  wherein the article is a component of a gas turbine engine.