Low rhenium single crystal superalloy for turbine blades and vane applications

Abstract

A low rhenium nickel-base superalloy for single crystal casting that exhibits excellent high temperature creep resistance, while also exhibiting other desirable properties for such alloys, comprises 5.60% to 5.80% aluminum by weight, 9.4% to 9.9% cobalt by weight, 4.9% to 5.5% chromium by weight, 0.08% to 0.35% hafnium by weight, 0.50% to 0.70% molybdenum by weight, 1.4% to 1.6% rhenium by weight, 8.1% to 8.5% tantalum by weight, 0.60% to 0.80 titanium by weight, 7.6 to 8.0% tungsten by weight the balance comprising nickel and minor amounts of incidental impurity elements.

What is claimed is: 
     
         1 . A nickel-base superalloy for single crystal casting, comprising:
 5.60% to 5.80% aluminum by weight;   9.4% to 9.9% cobalt by weight;   4.9% to 5.5% chromium by weight;   0.08% to 0.35% hafnium by weight;   0.50% to 0.70% molybdenum by weight;   1.4% to 1.6% rhenium by weight;   8.1% to 8.5% tantalum by weight;   0.60% to 0.80 titanium by weight;   7.6 to 8.0% tungsten by weight; and   the balance comprising nickel and minor amounts of incidental elements, the total amount of incidental elements being about 1% or less.   
     
     
         2 . A nickel-base superalloy for single crystal casting according to  claim 1 , in which the incidental elements are present at maximum amounts of 100 ppm carbon, 0.04% silicon, 0.01% manganese, 3 ppm sulfur, 30 ppm phosphorous, 30 ppm boron, 0.10% niobium, 150 ppm zirconium, 0.01% copper, 0.15% iron, 0.10% vanadium, 0.10% ruthenium, 0.15% platinum, 0.15% palladium, 200 ppm magnesium, 5 ppm nitrogen, 5 ppm oxygen, and other trace elements present in amounts of about 25 ppm or less. 
     
     
         3 . A nickel-base superalloy for single crystal casting according to  claim 1 , in which the trace elements are present at maximum amounts of 2 ppm silver, 0.2 ppm bismuth, 10 ppm gallium, 25 ppm calcium, 1 ppm lead, 0.5 ppm selenium, 0.2 ppm tellurium, 0.2 ppm thallium, 10 ppm tin, 2 ppm antimony, 2 ppm arsenic, 5 ppm zinc, 2 ppm mercury, 2 ppm cadmium, 2 ppm germanium, 2 ppm gold, 2 ppm indium, 20 ppm sodium, 10 ppm potassium, 20 ppm barium, 30 ppm phosphorous, 2 ppm uranium, and 2 ppm thorium. 
     
     
         4 . A nickel-base superalloy for single crystal casting according to  claim 1 , in which sulfur is present at a maximum of 0.5 ppm, and lanthanum and/or yttrium are added in an amount targeted to achieve from about 5 ppm to about 80 ppm of total lanthanum and yttrium in a single crystal casting. 
     
     
         5 . A nickel-base superalloy for single crystal casting according to  claim 1 , in which carbon is present in an amount of from 0.02% to 0.05%, and boron is present in an amount of from 40 ppm to 100 ppm. 
     
     
         6 . A nickel-base superalloy for single crystal casting according to  claim 1 , having a density of about 8.90 gms/cc (kg/dm 3 ) or less. 
     
     
         7 . A nickel-base superalloy for single crystal casting according to  claim 1 , having a density of about 8.85 gms/cc (kg/dm 3 ). 
     
     
         8 . A single crystal component cast from an alloy according to  claim 1 . 
     
     
         9 . A single crystal component according to  claim 8  that is a gas turbine component. 
     
     
         10 . A single crystal component according to  claim 8  that is a turbine blade, a vane, or a seal segment for a gas turbine.