Patent ID: 11920219
Assignee: NATIONAL INSTITUTE FOR MATERIALS SCIENCE
Field: Materials, metallurgy (Chemistry)
Classification: CPC C  B  F | IPC B  C

Claim 3:
4. A method for producing a TiAl-based alloy, the method comprising:
a step of hot-forging a TiAl-based alloy base material as the temperature of the TiAl-based alloy base material is held in a coexistence temperature range of an α phase and a β phase; and
a heat treating step of holding the TiAl-based alloy material obtained by hot-forging in a temperature range of 1210 to 1240° C. for 0.75 to 4 hours and then cooling the TiAl-based alloy material at a cooling rate of 1.5 to 8° C./min,
wherein the TiAl-based alloy base material subjected to the step of hot-forging comprises:
Al: 41.2 to 42.8 at %;
Fe: 0 to 2.0 at %;
Ni: 0 to 2.0 at %;
Mo: 0 to 1.7 at %;
W: 0 to 1.7 at %;
Cr: 0 to 4.0 at %;
Mn: 0 to 5.0 at %;
V: 0 to 8 at %;
Nb: 0 to 8 at %;
C: 0.35 to 0.65 at %; and
a remainder consisting of Ti and inevitable impurities,
an alloy element parameter P obtained by Equation (1) below is in a range of 1.2 to 1.8,

P=(41.5−Al)/3+Fe+Ni+Mo+W+0.5Cr+0.4Mn+0.2V+0.2Nb—C  (1), and

the produced TiAl-based alloy has a microstructure consisting of a γ phase of 7 to 25 area %, a β phase of 0.5 to 4.5 area %, and a lamellar structure occupying a remaining part.