Ni-BASED COMPOUND SUPERALLOY HAVING EXCELLENT OXIDATION RESISTANCE, METHOD FOR MANUFACTURING THE SAME, AND HEAT-RESISTANT STRUCTURAL MATERIAL

Abstract

The present invention is characterized in including Al: more than 5 at % to 13 at % or less; V: 3 at % or more to 9.5 at % or less; and Ti: 0 at % or more to 3.5 at % or less, with the remainder being Ni and unavoidable impurities, and having a multi-phase microstructure including a primary L1 2 phase and an (L1 2 phase+D0 22 phase and/or D0 24 and/or D0 a phase) eutectoid microstructure.

1 . A Ni-based compound superalloy having excellent oxidation resistance, comprising: Al: more than 5 at % to 13 at % or less; V: 3 at % or more to 9.5 at % or less; and Ti: 0 at % or more to 3.5 at % or less, with the remainder being Ni and unavoidable impurities, and having a multi-phase microstructure comprising a primary L1 2  phase and an (L1 2  phase+D0 22  phase and/or D0 24  and/or D0 a  phase) eutectoid microstructure. 
   
   
       2 . The Ni-based compound superalloy according to  claim 1 , wherein the Ni-based compound superalloy further comprises Nb: 3 at % or more to 9.5 at % or less, and the amount of V is not less than the amount of Nb. 
   
   
       3 . A Ni-based compound superalloy having excellent oxidation resistance, having a multi-phase microstructure comprising a primary L1 2  phase and an (L1 2  phase+D0 22  phase and/or D0 24  and/or D0 a  phase) eutectoid microstructure, which has a composition within the limits which link point A (Al: 14.0 at %, Ti: 0 at %, (V+Nb): 11.0 at %, Ni: 75 at %), point B (Al: 12.5 at %, Ti: 2.8 at %, (V+Nb): 9.8 at %, Ni: 75 at %), point C (Al: 8.0 at %, Ti: 3.8 at %, (V+Nb): 13.3 at %, Ni: 75 at %), point D (Al: 2.3 at %, Ti: 2.0 at %, (V+Nb): 20.8 at %, Ni: 75 at %), and point E (Al: 2.0 at %, Ti: 0 at %, (V+Nb): 23.0 at %, Ni: 75 at %), in the Ni 3 Al—Ni 3 Ti—Ni 3 V pseudo-ternary phase diagram shown in  FIG. 2 . 
   
   
       4 . The Ni-based compound superalloy having excellent oxidation resistance according to  claim 2 , wherein the Ni-based compound superalloy further comprises at least one or more of Co: 15 at % or less and Cr: 5 at % or less. 
   
   
       5 . The Ni-based compound superalloy having excellent oxidation resistance according to  claim 4 , wherein the Ni-based compound superalloy further comprises B: 1000 ppm (weight) or less. 
   
   
       6 . The Ni-based compound superalloy according to  claim 1 , wherein the Ni-based compound superalloy has a dual multi-phase microstructure including the primary L1 2  phase and the (L1 2  phase+D0 22  phase and/or D0 24  and/or D0 a  phase) eutectoid microstructure. 
   
   
       7 . A heat-resistant structural material having excellent oxidation resistance, comprising the Ni-based compound superalloy according to  claim 1 . 
   
   
       8 . A method for manufacturing a Ni-based compound superalloy having excellent oxidation resistance,
 the method comprising: subjecting an alloy material containing Al: more than 5 at % to 13 at % or less; V: 3 at % or more to 9.5 at % or less; and Ti: 0 at % or more to 3.5 at % or less, with the remainder being Ni and unavoidable impurities, to a first heat treatment at a temperature at which a primary L1 2  phase and an Al phase coexist; and   thereafter cooling the alloy material to a temperature at which the primary L1 2  phase and a D0 22  phase and/or a D0 24  phase and/or a D0 a  phase coexist, or further subjecting the alloy material to a second heat treatment at this temperature, thereby converting the Al phase to an (L1 2  phase+D0 22  phase and/or D0 24  phase and/or D0 a  phase) eutectoid microstructure to form a multi-phase microstructure.   
   
   
       9 . The method for manufacturing a Ni-based compound superalloy according to  claim 8 , wherein the alloy material further comprises Nb: 3 at % or more to 9.5 at % or less, and the amount of V is not less than the amount of Nb. 
   
   
       10 . A method for manufacturing a Ni-based compound superalloy having excellent oxidation resistance,
 the method comprising: subjecting an alloy material having a composition within the limits which link point A (Al: 14.0 at %, Ti: 0 at %, (V+Nb): 11.0 at %, Ni: 75 at %), point B (Al: 12.5 at %, Ti: 2.8 at %, (V+Nb): 9.8 at %, Ni: 75 at %), point C (Al: 8.0 at %, Ti: 3.8 at %, (V+Nb): 13.3 at %, Ni: 75 at %), point D (Al: 2.3 at %, Ti: 2.0 at %, (V+Nb): 20.8 at %, Ni: 75 at %), and point E (Al: 2.0 at %, Ti: 0 at %, (V+Nb): 23.0 at %, Ni: 75 at %), in the Ni 3 Al—Ni 3 Ti—Ni 3 V pseudo-ternary phase diagram shown in  FIG. 2 , to a first heat treatment at a temperature at which a primary L1 2  phase and an Al phase coexist; and   thereafter cooling the alloy material to a temperature at which the primary L1 2  phase and a D0 22  phase and/or a D0 24  phase and/or a D0 a  phase coexist, or further subjecting the alloy material to a second heat treatment at this temperature, thereby converting the Al phase to an (L1 2  phase+D0 22  phase and/or D0 24  phase and/or D0 a  phase) eutectoid microstructure to form a multi-phase microstructure.   
   
   
       11 . The method for manufacturing a Ni-based compound superalloy having excellent oxidation resistance according to  claim 8 , wherein the alloy material further comprises at least one or more of Co: 15 at % or less, and Cr: 5 at % or less. 
   
   
       12 . The method for manufacturing a Ni-based compound superalloy having excellent oxidation resistance according to  claim 8 , wherein the alloy material further comprises B: 1000 ppm or less. 
   
   
       13 . The method for manufacturing a Ni-based compound superalloy having excellent oxidation resistance according to  claim 8 , wherein the first heat treatment is carried out at a temperature at which the alloy material is in a first state shown in  FIG. 1 . 
   
   
       14 . The method for manufacturing a Ni-based compound superalloy having excellent oxidation resistance according to  claim 8 , wherein the second heat treatment is carried out at 1173K to 1273K.