Low coefficient of thermal expansion alloys

Abstract

A low coefficient of thermal expansion high strength alloy and methods of formation thereof, the alloy including: chromium 7 wt. % to 10 wt. %; molybdenum 20 wt. % to 25 wt. %; tungsten 4 wt. % to 7 wt. %; aluminum 0.5 wt. % to 2 wt. %; titanium 0.5 wt. % to 2 wt. %; boron 0.005 wt. % to 0.05 wt. %; niobium ≤3.9 wt. % tantalum ≤3.9 wt. % vanadium 0.1 wt. % to 4 wt. %; niobium, tantalum, and vanadium, in combination 0.1 wt. % to 4 wt. %; silicon <0.5 wt. %; zirconium <0.5 wt. %; hafnium <0.5 wt. %; yttrium <0.5 wt. %; copper <0.1 wt. %; manganese <0.1 wt. %; phosphorus <0.1 wt. %; sulfur <0.1 wt. %; iron <5 wt. %; cobalt ≤15 wt. %; balance nickel, cobalt and nickel, in combination 50 wt. % to 70 wt. %, and aluminum and titanium, in combination ≥1.4 wt. %.

What is claimed is: 
     
         1 . A low coefficient of thermal expansion high strength alloy, comprising:
 chromium 7 wt. % to 10 wt. %;   molybdenum 20 wt. % to 25 wt. %;   tungsten 4 wt. % to 7 wt. %;   aluminum 0.5 wt. % to 2 wt. %;   titanium 0.5 wt. % to 2 wt. %;   boron 0.005 wt. % to 0.05 wt. %;   niobium ≤3.9 wt. %   tantalum ≤3.9 wt. %   vanadium 0.1 wt. % to 4 wt. %;   niobium, tantalum, and vanadium, in combination 0.1 wt. % to 4 wt. %;   silicon <0.5 wt. %;   zirconium <0.5 wt. %;   hafnium <0.5 wt. %;   yttrium <0.5 wt. %;   copper <0.1 wt. %;   manganese <0.1 wt. %;   phosphorus <0.1 wt. %;   sulfur <0.1 wt. %;   iron <5 wt. %;   cobalt ≤15 wt. %;   balance nickel,   cobalt and nickel, in combination 50 wt. % to 70 wt. %, and   aluminum and titanium, in combination ≥1.4 wt. %.   
     
     
         2 . The alloy of  claim 1 , comprising:
 cobalt 5 wt. % to 15 wt. %.   
     
     
         3 . The alloy of  claim 1 , comprising:
 vanadium and niobium, in combination 0.5 wt. % to 4 wt. %.   
     
     
         4 . The alloy of  claim 1 , comprising:
 vanadium 0.5 wt. % to 4 wt. %.   
     
     
         5 . The alloy of  claim 1 , comprising:
 vanadium and titanium, in combination 0.8 wt. % to 3.5 wt. %.   
     
     
         6 . The alloy of  claim 1 , comprising:
 tungsten 5.5 wt. % to 7 wt. %.   
     
     
         7 . The alloy of  claim 1 , comprising:
 molybdenum 21 wt. % to 24 wt. %.   
     
     
         8 . The alloy of  claim 1 , comprising:
 molybdenum and (tungsten)/2, in combination 24 wt. % to 27 wt. %.   
     
     
         9 . The alloy of  claim 1 , wherein a ratio of molybdenum wt. % to tungsten wt. % is selected from a range of 3.6 to 4.2. 
     
     
         10 . The alloy of  claim 1 , comprising:
 titanium and aluminum, in combination 1.4 wt. % to 4 wt. %.   
     
     
         11 . The alloy of  claim 1 , wherein a ratio of titanium wt. % to aluminum wt. % is ≥0.4. 
     
     
         12 . The alloy of  claim 1 , further comprising:
 carbon 0.005 wt. % to 0.05 wt. %.   
     
     
         13 . The alloy of  claim 1 , wherein a coefficient of thermal expansion of the alloy is less than 8×10 −6  inch/(inch ° F.) between room temperature to 1400° F. 
     
     
         14 . The alloy of  claim 1 , wherein a yield strength of the alloy is higher than 85 ksi at 1400° F. 
     
     
         15 . The alloy of  claim 1 , wherein an ultimate tensile strength of the alloy is higher than 120 ksi at 1400° F. 
     
     
         16 . The alloy of  claim 1 , comprising more than 4 vol. % gamma-prime and gamma double prime phases in combination. 
     
     
         17 . The alloy of  claim 1 , comprising less than 5 vol % eta and delta phases in combination. 
     
     
         18 . The alloy of  claim 1 , comprising 4 vol. %-12 vol. % mu and P phases in combination. 
     
     
         19 . The alloy of  claim 1 , comprising at least 25 vol. % Ni2M phase, wherein M is selected from the group consisting of Cr, Mo, W, and V. 
     
     
         20 . A method of manufacturing a low coefficient of thermal expansion high strength alloy, the method comprising:
 melting a plurality of elements comprising the composition of  claim 1 ,   homogenizing the plurality of elements;   hot working the plurality of elements at a first temperature, wherein at least one of mu phase or P phase are present at the first temperature; and   solution and age the plurality of elements at a second temperature to precipitate out γ′ and/or γ″ phases and Ni2M phase, wherein the second temperature is higher than or equal to an intended service temperature.   
     
     
         21 . The method of  claim 20 , wherein the intended service temperature is at least 1400° F.