Low thermal expansion NI-base superalloy

Abstract

A low thermal expansion Ni-base superalloy contains, by weight % (hereinafter the same as long as not particularly defined), C: 0.15% or less; Si: 1% or less; Mn: 1% or less; Cr: 5 to 20%; at least one of Mo, W and Re of Mo+½ (W+Re) of 10 to 25%; Al: 0.2 to 2%; Ti: 0.5 to 4.5%; Fe of 10% or less; at least one of B: 0.02% and Zr: 0.2% or less; a remainder of Ni and inevitable impurities; wherein the atomic % of Al+Ti is 2.5 to 7.0.

What is claimed is:  
     
         1 . A low thermal expansion Ni-base superalloy comprising, by weight % (hereinafter the same as long as not particularly defined), 
 C: 0.15% or less;    Si: 1% or less;    Mn: 1% or less;    Cr: 5 to 20%;    at least one of Mo, W and Re of Mo+½ (W+Re) of 10 to 25%;    Al: 0.2 to 2%;    Ti: 0.5 to 4.5%;    Fe of 10% or less;    at least one of B: 0.02% and Zr: 0.2% or less;    a remainder of Ni and inevitable impurities;    wherein the atomic % of Al+Ti is 2.5 to 7.0.    
     
     
         2 . The low thermal expansion Ni-base superalloy according to  claim 1 , wherein the amount of Cr is from 5 to 10 (exclusive) %.  
     
     
         3 . The low thermal expansion Ni-base superalloy according to  claim 2 , further comprising at least one of Nb and Ta in Nb+½ Ta: 1.5% or less; wherein the atomic % of Al+Ti+Nb+Ta is 2.5 to 7.0.  
     
     
         4 . The low thermal expansion Ni-base superalloy according to  claim 1 , wherein the amount of at least one of Mo, W and Re of Mo+½ (W+Re) is from 17 (exclusive) to 25%.  
     
     
         5 . Thelow thermal expansion Ni-base superalloy according to  claim 4 , further comprising at least one of Nb and Ta in Nb+½ Ta: 1.5% or less; wherein the atomic % of Al+Ti+Nb+Ta is 2.5 to 7.0.  
     
     
         6 . The low thermal expansion Ni-base superalloy according to  claim 1 , wherein the amount of Al is from 0.2 to 0.4 (exclusive) %.  
     
     
         7 . The low thermal expansion Ni-base superalloy according to  claim 6 , further comprising at least one of Nb and Ta in Nb+½ Ta: 1.5% or less; wherein the atomic % of Al+Ti+Nb+Ta is 2.5 to 7.0.  
     
     
         8 . The low thermal expansion Ni-base superalloy according to  claim 1 , wherein the amount of Ti is from 3.5 (exclusive) to 4.5%.  
     
     
         9 . The low thermal expansion Ni-base superalloy according to  claim 8 , further comprising at least one of Nb and Ta in Nb+½ Ta: 1.5% or less; wherein the atomic % of Al+Ti+Nb+Ta is 2.5 to 7.0.  
     
     
         10 . The low thermal expansion Ni-base superalloy according to any one of  claims 1  to  9 , wherein a part of Ni is replaced by Co of 5% or less.  
     
     
         11 . The low thermal expansion Ni-base superalloy according to  claim 1 , wherein an average expansion coefficient at a temperature from room temperature to 700° C. is 14.0×10 −6 /° C. or less.