Nickel-based alloy

Abstract

Adding silicon, in a defined range of weight percentage, to the composition of a known nickel-based alloy improves oxidation, hot corrosion and dwell crack growth resistance without the detrimental effects on the thermal stability of the microstructure and on other material properties that have been found with known alloys. In a particular preferred embodiment the alloy has the following composition (in weight percent): chromium 14.6-15.4%; cobalt 18-19%; molybdenum 4.75-5.25%; aluminium 2.8-3.2 titanium 3.4-3.8%; tantalum 1.8-2.2%; hafnium 0.4-0.6%; carbon 0.020-0.034%; boron 0.005-0.025%; silicon 0.2-0.6%; the remainder being nickel and incidental impurities.

1 . A nickel-based alloy including between 0.2 wt % and 0.6 wt % silicon to improve oxidation resistance, dwell crack growth resistance and hot corrosion resistance without detrimental effect on other mechanical properties of the alloy. 
     
     
         2 . An alloy as claimed in  claim 1 , further including at least one of the following:
 hafnium <=0.75 wt %;   zirconium <=0.1 wt %;   magnesium <=0.03 wt %;   sulphur <=5 ppm;   phosphorous <10 ppm.   
     
     
         3 . An alloy as claimed in  claim 1  having the following composition in weight percent:
 chromium 14.6-15.4%; 
 cobalt 18-19%; 
 molybdenum 4.75-5.25%; 
 aluminium 2.8-12%; 
 titanium 3.4-3.8%; 
 tantalum 1.8-2.2%; 
 hafnium 0.4-0.6%; 
 carbon 0.020-0.034%; 
 boron 0.005-0.025%; 
 silicon 0.2-0.6%; 
 the remainder being nickel and incidental impurities. 
 
     
     
         4 . An alloy as claimed in  claim 1 , having the following composition in weight percent:
 chromium 15%;   cobalt 18.5%;   molybdenum 5%;   aluminium 3%;   titanium 3.6%;   tantalum 2%;   hafnium 0.5%;   carbon 0.027%;   boron 0.015%;   silicon 0.2-0.6%;   the remainder being nickel and incidental impurities.   
     
     
         5 . An alloy as claimed in  claim 1 , having the following composition in weight percent:
 chromium 15%;   cobalt 18.5%;   molybdenum 5%;   aluminium 3%;   titanium 3.6%;   tantalum 2%;   hafnium 0.5%;   carbon 0.027%;   boron 0.015%;   silicon 0.2%;   the remainder being nickel and incidental impurities.   
     
     
         6 . An alloy as claimed in  claim 1 , having the following composition in weight percent:
 chromium 15%;   cobalt 18.5%;   molybdenum 5%;   aluminium 3%;   titanium 3.6%;   tantalum 2%;   hafnium 0.5%;   carbon 0.027%;   boron 0.015%;   silicon 0.5%;   the remainder being nickel and incidental impurities.   
     
     
         7 . A component fanned of an alloy as claimed in  claim 1 . 
     
     
         8 . A component as claimed in  claim 7 , the component being a disc for a gas turbine engine. 
     
     
         9 - 10 . (canceled) 
     
     
         11 . A component formed of an alloy as claimed in  claim 2 . 
     
     
         12 . A component formed of an allay as claimed in  claim 3   
     
     
         13 . A component fanned of an alloy as claimed in  claim 4 . 
     
     
         14 . A component formed of an alloy as claimed in  claim 5 . 
     
     
         15 . A component formed of an alloy as claimed in  claim 6 . 
     
     
         16 . A component as claimed in  claim 11 , the component being a disc for a gas turbine engine. 
     
     
         17 . A component as claimed in  claim 12 , the component being a disc for a gas turbine engine. 
     
     
         18 . A component as claimed in  claim 13 , the component being a disc for a gas turbine engine. 
     
     
         19 . A component as claimed in  claim 14 , the component being a disc for a gas turbine engine. 
     
     
         20 . A component as claimed in  claim 15 , the component being a disc for a gas turbine engine.