Tial intermetallic casting alloy

Abstract

The present disclosure relates to the technical field of TiAl intermetallic foundry alloys. More particularly, it relates to such an alloy comprising: 44≤Al≤47 at. %; 0<Zr<2 at. %; 1≤W≤2 at. %; and only one of the following elements: 0.5≤V≤2 at. %; 0.5≤Cr≤2 at. %; 0<Nb<4 at. %.

1 . A TiAl intermetallic foundry alloy comprising:
 44≤Al≤47 at. %;   0<Zr<2 at. %;   1≤W≤2 at. %; and   only one of the following elements:   0.5≤V≤2 at. %;   0.5≤Cr≤2 at. %;   0<Nb<4 at. %.   
     
     
         2 . The alloy according to  claim 1 , comprising less than 0.1 at. % of Si, C and B in total. 
     
     
         3 . The alloy according to  claim 1 , comprising:
 44≤Al≤46 at. %;   0<Zr<2 at. %;   1≤W≤2 at. %; and   0.5≤V≤2 at. %.   
     
     
         4 . The alloy according to  claim 1 , comprising:
 44≤Al≤46 at. %;   0<Zr<2 at. %;   1≤W≤2 at. %; and   0.5≤Cr≤2 at. %.   
     
     
         5 . The alloy according to  claim 1 , comprising:
 45≤Al≤47 at. %;   0<Zr<2 at. %;   1≤W≤2 at. %; and   0<Nb<4 at. %.   
     
     
         6 . The alloy according to  claim 1 , comprising a β phase fraction of less than 1 vol. %. 
     
     
         7 . The alloy according to  claim 1 , having a single-phase domain at a temperature below 1350° C. 
     
     
         8 . The alloy according to  claim 1 , having a conventional elastic limit Rp 0.2  of between 400 and 700 MPa at a temperature between 25 and 900° C. 
     
     
         9 . The alloy according to  claim 1 , comprising at least 20% α 2  phase by volume. 
     
     
         10 . A part for a turbine produced in the alloy according to  claim 1 . 
     
     
         11 . A method for manufacturing the alloy according to  claim 1 , comprising, in the following order:
 casting a mixture of precursors of Ti, Al, Zr, W and only one of the elements V, Cr and Nb;   homogenizing at a temperature between 1200° C. and 1500° C., for a time between 1 hr and 15 hr;   optionally ageing at a temperature below the homogenization temperature at a temperature between 700° C. and 1200° C. for 3 hr to 15 hr; and   controlled cooling.   
     
     
         12 . The method according to  claim 11 , wherein said homogenizing at a temperature of 1200° C. and 1500° C. includes homogenizing at a temperature of 1250° C. and 1350° C. 
     
     
         13 . The method according to  claim 11 , wherein said homogenizing at a temperature of 1200° C. and 1500° C. for a time of between 1 hr and 15 hr includes homogenizing at a time between 1 hr and 10 hr. 
     
     
         14 . The method according to  claim 11 , wherein said optionally ageing at a temperature below the homogenization temperature at a temperature between 700° C. and 1200° C. includes optionally ageing at a temperature between 850° C. and 1100° C. 
     
     
         15 . The method according to  claim 11 , wherein said optionally ageing at a temperature below the homogenization temperature at a temperature between 700° C. and 1200° C. for 3 hr to 15 hr includes optionally ageing for a time between 4 hr to 10 hr. 
     
     
         16 . The method according to  claim 11 , wherein said homogenizing and optionally ageing occurs under neutral gas pressure. 
     
     
         17 . The alloy according to  claim 3 , wherein Al at. % is 44.5≤Al≤45.5 at. %. 
     
     
         18 . The alloy according to  claim 4 , wherein Al at. % is 44.5≤Al≤45.5 at. %. 
     
     
         19 . The alloy according to  claim 5 , wherein Al at. % is 44.5≤Al≤45.5 at. %. 
     
     
         20 . The alloy according to  claim 1 , wherein the single-phase domain is at a temperature below 1300° C.