Low-density directionally solidified single-crystal superalloys

Abstract

A low-density nickel-base superalloy includes the following elements (percent by weight): 7-13% Chromium, 0-16% Cobalt, 2-5% Titanium, 4.5-7% Aluminium, 0-5% Tantalum, 0-2% Hafnium, 0-3% Tungsten, 0-2% Vanadium, 0-5% Molybdenum, 0.06-0.12% Carbon, 0.01-0.03% Boron, 0.005-0.02% Zirconium, nickel and residual impurities use and to the process for obtaining it. The superalloy has advantageous uses and is obtained by processing.

1 . A nickel-base superalloy comprising the following elements (percent by weight) 
       7-13% Chromium, 
       0-16% Cobalt, 
       2-5% Titanium, 
       4.5-7% Aluminium, 
       0-5% Tantalum, 
       0-2% Hafnium, 
       0-3% Tungsten 
       0-2% Vanadium 
       0-5% Molybdenum 
       0.06-0.12% Carbon, 
       0.01-0.03% Boron, 
       0.005-0.02% Zirconium, 
       Nickel and residual impurities. 
     
     
         2 . A superalloy according to  claim 1 , comprising: 0.07% carbon, 10% chromium, 15% cobalt, 3% molybdenum, 5.5% aluminium, 4% titanium, 1% vanadium, 1.4% hafnium, 0.015% boron and 0.01% zirconium. 
     
     
         3 . A superalloy according to  claim 1 , comprising: 0.07% carbon, 10% chromium, 5% cobalt, 3% molybdenum, 2% tantalum, 4.8% aluminium, 4.7% titanium, 1.4% hafnium, 0.015% boron and 0.01% zirconium. 
     
     
         4 . The use of a nickel-base superalloy according to  claim 1  for obtaining a directionally solidified casting or a casting in single-crystal form. 
     
     
         5 . A process for obtaining a superalloy described in  claim 1  comprising the following steps:
 a) solution heat treatment at a temperature comprised between 1190-1250° C. for 1 to 5 hours   b) intermediate heat treatment at a temperature comprised between 1000-1100° C. for 1 to 5 hours   c) precipitation heat treatment at a temperature comprised between 850-900° C. for 1 to 16 hours   
     
     
         6 . A gas turbine comprising components manufactured with a superalloy according to  claim 1 .