Rhenium-free single crystal superalloy for turbine blades and vane applications

Abstract

A rhenium-free 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 5.85% aluminum, 9.4% to 9.9% cobalt, 5.0% to 6.0% chromium, 0.08% 0.35% hafnium, 0.50% to 0.70% molybdenum, 8.0% to 9.0% tantalum, 0.60% to 0.90% titanium, 8.5% to 9.8% tungsten, the balance comprising nickel and minor amounts of incidental elements.

What is claimed is: 
     
         1 . A nickel-base superalloy for single crystal casting comprising:
 5.60% to 5.85% aluminum by weight;   9.4% to 9.9% cobalt by weight;   5.0% to 6.0% chromium by weight;   0.08% to 0.35% hafnium by weight;   0.50% to 0.70% molybdenum by weight;   8.0% to 9.0% tantalum by weight;   0.60% to 0.90% titanium by weight;   8.5% to 9.8% 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 by weight.   
     
     
         2 . A nickel-base superalloy for single crystal casting according to  claim 1 , in which the incidental elements are controlled to maximums of 100 ppm carbon, 0.04% silicon, 0.01% manganese, 3 ppm sulfur, 30 ppm phosphorous, 30 ppm boron, 0.1% niobium, 150 ppm zirconium, 0.15% rhenium, 0.01% copper, 0.15% iron, 0.1% vanadium, 0.1% ruthenium, 0.15% platinum, 0.15% palladium, 200 ppm magnesium, 5 ppm nitrogen, and 5 ppm oxygen, each of any other incidental elements being present as a trace element at a maximum of about 25 ppm. 
     
     
         3 . A nickel-base superalloy for single crystal casting according to  claim 2 , in which the trace elements are controlled to maximums 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, 10 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 , containing a maximum amount of sulfur of 0.5 ppm, and further comprising an amount of lanthanum and yttrium that is targeted to achieve a total lanthanum and yttrium content that is from about 5 ppm to 80 ppm in a single crystal casting. 
     
     
         5 . A nickel-base superalloy for single crystal casting according to  claim 1 , containing from 0.02% to 0.05% carbon by weight, and from 40 ppm to 100 ppm boron. 
     
     
         6 . A nickel-base superalloy for single crystal casting according to  claim 1 , having a density about 8.8 gms/cc (kg/dm 3 ). 
     
     
         7 . A single crystal component cast from an alloy according to  claim 1 . 
     
     
         8 . A single crystal component according to  claim 7  that is a gas turbine component. 
     
     
         9 . A single crystal component according to  claim 7  that is a blade, a vane, or a seal segment for a gas turbine.