High temperature oxidation resistant co-based gamma/gamma prime alloys DMREF-Co
A series of alloys of Co, Ni, Al, W, Ta, and Cr, wherein the alloy comprises a solid solution of gamma and gamma prime alloy phases, the Ni content is greater than 25% at. %, the Al content is greater than 10 at. %, the Cr content is greater than 2 at. %, and the Ni:Co ratio is between 0.5 and 1.5. In one or more examples, the alloy further comprises one or more of C, B, and a reactive element metal. Embodiments of the alloy simultaneously possess a high solvus temperature, a high fraction of the strengthening γ′-L1 2 phase, good oxidation resistance and highly favorable solidification characteristics.
1. A composition of matter, comprising:
an alloy of Co, Ni, Al, Ta, and Cr, wherein:
the alloy comprises a solid solution of gamma and gamma prime alloy phases,
the Ni content is at least 25% at. %,
the Al content is at least 10 at. %,
the Cr content is at least 2 at. %,
the Ni:Co ratio is between 0.5 and 1.5, and
further comprising:
a W content in a range of 0 to 2 at. %, and
the Ta content in a range of 2.5-5 at. %, wherein:
the alloy is able to generate a protective aluminum oxide layer upon exposure to air, and
the alloy is characterized by having a γ′ solvus greater than 1100° C. and a solidus of 1343° C. or less.
2. The composition of matter of claim 1 , wherein:
the Ni content is in a range of 25 at. % to 40 at. %,
the Al content is in a range of 12 at. % to 16 at. %, and
the Cr content is in a range of 2 at. % to 8 at. %, and
the Ta content is in a range of 3-5 at. %.
3. The composition of matter of claim 2 , wherein the alloy further comprises at least one of C, B, Y or Hf.
4. The composition of matter of claim 3 , wherein:
the B content is in a range of 0.01 to 0.1 at. %,
the Y content is in a range of 0.001 to 0.004, and
the Hf content is in a range of 0.02 to 0.08 at. %.
5. The composition of matter of claim 3 , wherein:
the Ni content is in a range of 36-38 at. %,
the Al content is in a range of 12-14 at. %,
the Cr content is in a range of 5-7 at. %,
the Ta content is in a range of 3-5 at. %,
the W content is in a range of 0.5-2 at. %,
the B content is in a range of 0.01-0.1 at. %,
the Y content is in a range of 0.001-0.004 at. %,
the Hf content is in a range of 0.02-0.08 at. %, and
the Co content is the remainder.
6. The composition of matter of claim 2 , wherein
the alloy further comprises at least one of C, B, or a reactive element metal.
7. The composition of matter of claim 2 , wherein the alloy further comprises carbon (C).
8. The composition of matter of claim 1 , wherein
the Co content is in a range of 38-40 at. %,
the Ni content is in a range of 37-39 at. %,
the Al content is in a range of 12-14 at. %,
the Cr content is in a range of 5-7 at. %,
the Ta content is in a range of 3-4 at. %, and
the W content is in a range of 0.5-2 at. %.
9. The composition of matter of claim 8 , wherein the alloy maintains its strengthening precipitates above a temperature of 1190° C. and is able to generate the protective aluminum oxide layer upon exposure to the air at 1100° C.
10. The composition of matter of claim 8 , wherein the alloy maintains a creep rupture strength of 248 MPa at 982° C. and 310 MPa at a temperature of 900° C.
11. A powder material for additive manufacturing comprising the composition of matter of claim 8 , and wherein the alloy has increased crack resistance under melting conditions used during the additive manufacturing, as compared to a nickel based superalloy PWA 1480.
12. The composition of matter of claim 1 , further comprising at least one of Ti and Nb, wherein the Ti or Nb content is up to 4 at. %.
13. A gas turbine component comprising the composition of matter of claim 1 .
14. A cast and wrought piece comprising the composition of matter of claim 1 wherein
the Ni content is in a range of 25 at. % to 40 at. %,
the Al content is in a range of 10 at. % to 16 at. %,
the Cr content is in a range of 2 at. % to 8 at. %, and
the Ta content is in a range of 3-5 at. %.
15. A 3D printed alloy or a powder for additive manufacturing consisting of the composition of matter of claim 1 .
16. The composition of matter of claim 1 , wherein the alloy is characterized by having 98° C.≤(solidus—γ′ solvus)≤143° C. and a time to rupture of at least 1 hour under a stress of 248 MPa at 982° C. and the stress of 310 MPa at a temperature of 900° C., as measured using a Larson Miller analysis.
17. A method of fabricating a composition of matter, comprising:
melting Co, Ni, Al, Ta, and Cr together so as to form an alloy;
further forming the alloy so as to form a formed alloy;
heat treating the formed alloy so as to obtain a heat treated alloy;
performing an ageing treatment of the heat treated alloy so as to obtain an aged alloy, wherein:
the aged alloy comprises a solid solution of gamma and gamma prime alloy phases,
the Ni content is at least 25% at. %,
the Al content is at least 10 at. %,
the Cr content is at least 2 at. %, and
the Ni:Co ratio is between 0.5 and 1.5,
further comprising a W content in a range of 0 to 2 at. % and the Ta content in a range of 2.5-5 at. %, wherein:
the alloy is able to generate a protective aluminum oxide layer upon exposure to air, and
the alloy is characterized by having a γ′ solvus greater than 1100° C. and a solidus of 1343° C. or less.
18. The method of claim 17 , wherein:
the Ni content is in a range of 25 at. % to 40 at. %,
the Al content is in a range of 10 at. % to 16 at. %,
the Cr content is in a range of 2 at. % to 8 at. %, and
the Ta content is in a range of 3-5 at. %.
19. The method of claim 17 , wherein the forming forms the alloy into a powder.
20. The method of claim 19 , further comprising processing the powder using powder metallurgy so as to obtain a part.
21. The method of claim 20 , wherein the processing comprises additive manufacturing.
22. The method of claim 17 , wherein the forming comprises casting the alloy so as to form a casted alloy.
23. The method of claim 22 , further comprising working the casted alloy so as to form a cast and wrought piece.
24. The method of claim 23 , wherein the forming comprises solidifying the alloy into an ingot.
25. The method of claim 24 , wherein the forming further comprises forging the ingot, extruding the ingot, or rolling the ingot.
26. The method of claim 17 , wherein the forming comprises growing the alloy so as to obtain a single crystal.
27. A composition of matter, comprising:
an alloy of Co, Ni, Al, Ta, and Cr, wherein:
the alloy comprises a solid solution of gamma and gamma prime alloy phases,
36 at. %≤Ni content≤38 at. %,
12 at. %≤Al content≤14 at. %,
5 at. %≤Cr content≤7 at. %,
3 at. %≤Ta content≤5 at. %,
0.5 at. %≤W content≤2 at. %;
the alloy further comprises at least one of C, B, Y or Hf,
the Co comprises the remainder, and
the alloy is characterized by having a γ′ solvus greater than 1100° C. and a solidus of 1343° C. or less.
28. A powder material for additive manufacturing comprising the composition of matter of claim 27 .
29. The composition of matter of claim 27 , wherein the alloy comprises the C, B, and Hf.
30. The composition of matter of claim 27 , wherein the alloy comprises the C and Hf.
31. The composition of matter of claim 27 , wherein the alloy comprises the C, B, Hf, and Y.