Titanium aluminum intermetallic compound based alloy and method of fabricating a product from the alloy

Abstract

A titanium aluminum intermetallic compound based alloy superior in creep strength and low cycle fatigue strength made by casting. The alloy has lamellar structure. A volume ratio of non-lamellar structure of the alloy is equal to or less than 3 volume percent. Diameters of lamellar grains included in the alloy are equal to or less than 200 μm. Lamellar spacing of the lamella structure included in the alloy is equal to or less than 2 μm.

What is claimed is:  
     
         1 . A titanium aluminum intermetallic compound based alloy, wherein a volume ratio of non-lamellar structure is equal to or less than 3 volume percent, and diameters of lamellar grains are equal to or less than 200 μm, and a lamellar spacing of lamellar structure is equal to or less than 2 μm.  
     
     
         2 . The titanium aluminum intermetallic compound based alloy according to  claim 1 , comprising boron.  
     
     
         3 . The titanium aluminum intermetallic compound based alloy according to  claim 2 , wherein a boron concentration is in the range of 0.2 to 1.2 atomic percent.  
     
     
         4 . An titanium aluminum intermetallic compound based alloy comprising (measured in atomic percent): 
 43-48% aluminum;    2.0-5.0% niobium;    0.2-1.2% tungsten;    0.1-1.0% nickel;    0.2-1.2% boron; and    a remainder including titanium plus impurities.    
     
     
         5 . The titanium aluminum intermetallic compound based alloy according to  claim 4 , further comprising manganese.  
     
     
         6 . The titanium aluminum intermetallic compound based alloy, according to  claim 4 , wherein a manganese concentration is in the range of 0.2 to 1.2 atomic percent.  
     
     
         7 . The titanium aluminum intermetallic compound based alloy, according to  claim 4 , further comprising chromium.  
     
     
         8 . The titanium aluminum intermetallic compound based alloy according to  claim 7 , wherein a chromium concentration is in the range of 0.2 to 1.2 atomic percent.  
     
     
         9 . The titanium aluminum intermetallic compound based alloy according to  claim 4 , further comprising silicon.  
     
     
         10 . The titanium aluminum intermetallic compound based alloy according to  claim 9 , wherein a silicon concentration is in the range of  0 . 1  to 1.0 atomic percent.  
     
     
         11 . The titanium aluminum intermetallic compound based alloy according to  claim 4 , further comprising carbon.  
     
     
         12 . The titanium aluminum intermetallic compound based alloy according to  claim 11 , wherein a carbon concentration is in the range of 0.1 to 0.5 atomic percent.  
     
     
         13 . A method of fabricating a product from titanium aluminum intermetallic compound based alloy comprising: 
 casting an titanium aluminum intermetallic compound based alloy into a product;    executing hot isostatic pressing on said product;    heat-treatment of said product in a nonoxidizing environment after said hot isostatic pressing;    rapidly cooling said product after said heat-treating.    
     
     
         14 . The method according to  claim 13 , wherein said product is heated at 1320° to 1370° C. during said heat-treatment.  
     
     
         15 . The method according to  claim 14 , wherein said product is cooled to 1000° C. at a cooling rate of 30° to 100° C./min. during said rapid cooling.  
     
     
         16 . The method according to  claim 15 , further comprising: 
 second heat-treatment of said product after said rapid cooling; and    slowly cooling said product after said second heat-treatment.    
     
     
         17 . The method according to  claim 16 , wherein said product is heated at 900° to 1050° C. during said second heat-treatment.  
     
     
         18 . The method according to  claim 16 , wherein said product is cooled at a cooling rate equal to or less than 10° C./min. during said slowly cooling.  
     
     
         19 . The method according to  claim 13 , wherein said titanium aluminum intermetallic compound based alloy includes boron.  
     
     
         20 . The method according to  claim 19 , wherein a boron concentration of said titanium aluminum intermetallic compound based alloy is in the range of 0.2 to 1.2 atomic percent.