TY - JOUR
T1 - Effect of multi-stage heat treatment on mechanical properties and microstructure transformation of Ti–48Al–2Cr–2Nb alloy
AU - Yim, Seungkyun
AU - Bian, Huakang
AU - Aoyagi, Kenta
AU - Chiba, Akihiko
N1 - Funding Information:
We would like to thank Dr. Makoto Nagasako and Mr. Shun Ito (Analytical Research Core for Advanced Materials, Institute for Materials Research, Tohoku University) for technical support with the TEM observations. This work was partially supported by a Grant-in-Aid for Research Activity Start-up (grant No. 19k23566 ) from JSPS KAKENHI .
Publisher Copyright:
© 2021 Elsevier B.V.
PY - 2021/6/1
Y1 - 2021/6/1
N2 - Refining the grain size of γ-TiAl alloys to improve their strength and ductility is of academic interest. Thus, we report a multi-stage heat treatment method consisting of solution treatment, cyclic heat treatment, annealing, short heat treatment, and aging to refine the microstructure of the Ti–48Al–2Cr–2Nb alloy. The solution-treated microstructure was refined from 1100 to 191 μm by cyclic heat treatment, promoting feathery γ packets. Fine duplex grains below 23 μm were obtained through discontinuous coarsening, which was accelerated in the cyclic-heat-treated alloys owing to the high driving force resulting from the presence of feathery γ packets and fine interlamellar spacing. Through the short heat treatment and aging at single α and α2 + γ fields, a tailored duplex structure with a grain size of 24 μm and interlamellar spacing of 42 nm was achieved. Through microstructure refinement, tensile strength and elongation were improved to 697 MPa and 2.1%, respectively, compared to those of the conventional forged specimen (622 MPa and 1.3%, respectively). We believe that our study provides a simple pathway to refine the grain size and interlamellar spacing of γ-TiAl alloys.
AB - Refining the grain size of γ-TiAl alloys to improve their strength and ductility is of academic interest. Thus, we report a multi-stage heat treatment method consisting of solution treatment, cyclic heat treatment, annealing, short heat treatment, and aging to refine the microstructure of the Ti–48Al–2Cr–2Nb alloy. The solution-treated microstructure was refined from 1100 to 191 μm by cyclic heat treatment, promoting feathery γ packets. Fine duplex grains below 23 μm were obtained through discontinuous coarsening, which was accelerated in the cyclic-heat-treated alloys owing to the high driving force resulting from the presence of feathery γ packets and fine interlamellar spacing. Through the short heat treatment and aging at single α and α2 + γ fields, a tailored duplex structure with a grain size of 24 μm and interlamellar spacing of 42 nm was achieved. Through microstructure refinement, tensile strength and elongation were improved to 697 MPa and 2.1%, respectively, compared to those of the conventional forged specimen (622 MPa and 1.3%, respectively). We believe that our study provides a simple pathway to refine the grain size and interlamellar spacing of γ-TiAl alloys.
KW - Cyclic heat treatment (CHT)
KW - Discontinuous coarsening
KW - Feathery γ
KW - Grain refinement
KW - TiAl alloy
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U2 - 10.1016/j.msea.2021.141321
DO - 10.1016/j.msea.2021.141321
M3 - Article
AN - SCOPUS:85105694505
SN - 0921-5093
VL - 816
JO - Materials Science & Engineering A: Structural Materials: Properties, Microstructure and Processing
JF - Materials Science & Engineering A: Structural Materials: Properties, Microstructure and Processing
M1 - 141321
ER -