Ni-based single crystal alloy

Abstract

Disclosed is a single crystal alloy consisting essentially of, by weight, 0.06-0.09% carbon, 0.016-0.035% B, 0.2-0.4% Hf, 0-0.02% Zr, 6.5-8.5% Cr, 0.4-1.0% Mo, 5.5-9.5% W, 1.2-3.1% Re, 8-10% Ta, 0.3-1.0% Nb, 0-0.4% Ti, 4.7-5.4% Al, 0.5-5.0% Co, 0.1-5% Fe, and the balance of Ni and unavoidable impurities. The alloy is free from solidification cracks during casting a large-sized blade of gas turbines, has grain boundary strength sufficient for assuring the reliability during operation, and further has excellent oxidation resistance to a high combustion gas temperature while having excellent high-temperature strength comparable to that of a conventional single crystal alloy.

1 . A Ni-based single crystal alloy consisting essentially of, by weight, from not less than 0.06% to not more than 0.09% carbon, from not less than 0.016% to not more than 0.035% B, from not less than 0.2% to not more than 0.4% Hf, from inclusive zero to not more than 0.02% Zr, from not less than 6.5% to not more than 8.5% Cr, from not less than 0.4% to not more than 1.0% Mo, from not less than 5.5% to not more than 9.5% W, from not less than 1.2% to not more than 3.1% Re, from not less than 8% to not more than 10% Ta, from not less than 0.3% to not more than 1.0% Nb, from inclusive zero to not more than 0.4% Ti, from not less than 4.7% to not more than 5.4% Al, from not less than 0.5% to not more than 5.0% Co, from not less than 0.1% to not more than 5% Fe, and the balance of Ni and unavoidable impurities. 
     
     
         2 . A Ni-based single crystal alloy according to  claim 1 , which consists essentially of, by weight, from not less than 0.06% to not more than 0.08% carbon, from not less than 0.2% to not more than 0.3% Hf, from not less than 6.9% to not more than 7.3% Cr, from not less than 0.7% to not more than 1.0% Mo, from not less than 7.0% to not more than 9.0% W, from not less than 1.2% to not more than 1.6% Re, from not less than 8.5% to not more than 9.5% Ta, from not less than 0.6% to not more than 1.0% Nb, from not less than 4.9% to not more than 5.2% Al, from not less than 0.8% to not more than 1.2% Co, and the balance of Ni and unavoidable impurities. 
     
     
         3 . A Ni-based single crystal alloy according to  claim 1 , which contains, by weight, from not less than 0.5% to not more than 3% Fe. 
     
     
         4 . A Ni-based single crystal alloy according to  claim 1 , which consists essentially of, by weight, from not less than 0.06% to not more than 0.08% carbon, from not less than 0.2% to not more than 0.3% Hf, from not less than 6.9% to not more than 7.3% Cr, from not less than 0.7% to not more than 1.0% Mo, from not less than 7.0% to not more than 9.0% W, from not less than 1.2% to not more than 1.6% Re, from not less than 8.5% to not more than 9.5% Ta, from not less than 0.6% to not more than 1.0% Nb, from not less than 4.9% to not more than 5.2% Al, from not less than 0.8% to not more than 1.2% Co, from not less than 0.5% to not more than 3% Fe, and the balance of Ni and unavoidable impurities. 
     
     
         5 . A Ni-based single crystal alloy according to  claim 1 , which contains, by weight, from not less than 1% to not more than 3% Fe. 
     
     
         6 . A Ni-based single crystal alloy according to  claim 1 , which further contains, by weight, from 0.01% to not more than 0.2% Si. 
     
     
         7 . A Ni-based single crystal alloy according to  claim 1 , which further contains, by weight, from 0.05% to not more than 0.15% Si. 
     
     
         8 . A casting made of a Ni-based alloy having the alloy composition as defined in  claim 1 .