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Title: Enhanced high-temperature tensile property by gradient twin structure of duplex high-Nb-containing TiAl alloy

Abstract

A pre-deformation process was employed for a TiAl alloy via high-temperature torsion, in which the stability of the constituent phases was tailored, resulting in enhanced hardening capability and ductility via a gradient microstructure. A sample with a pre-torsion of 360° exhibited a yield strength of 475 MPa and an ultimate tensile strength of 592 MPa, with a tensile ductility of 47% at 850 °C. The tensile properties were significantly enhanced compared with the as-forged sample, which exhibited values of 395 MPa, 494 MPa, and 4.6%, respectively. The physical mechanisms for the significant enhancement of the mechanical property of the TiAl alloys were studied in-depth via of transmission electron microscopy, electron-backscattered diffraction, and high-energy X-ray diffraction techniques. The high strength is mainly attributed to the twin structure formed during torsion, while high fracture elongation correlates to the recrystallization of the γ phase at twin-twin sections and the load partitioning regulated by a hierarchical microstructure. When the tensile micro-strains along the loading direction and transverse direction in the γ phase of the pre-deformed TiAl alloy, a higher mechanical performance was obtained. Moreover, the fracture mode of the pre-torsional tensile sample is a combination of pores and cleavage facets which resulted from themore » microstructure after torsion. Finally, the gradient twin structure approach in this study provides a strategy for developing TiAl alloys with exceptionally high-temperature tensile property, and the results of the micromechanical behavior-microstructure-property relationship may improve the understanding of the plastic deformation of TiAl alloys.« less

Authors:
 [1];  [2]; ORCiD logo [2];  [3];  [4];  [2]
  1. Univ. of Science and Technology, Beijing (China). State Key Lab. for Advanced Metals and Materials; China Jiliang Univ., Hangzhou (China)
  2. Univ. of Science and Technology, Beijing (China). State Key Lab. for Advanced Metals and Materials
  3. Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source (APS), X-ray Science Division
  4. Beijing Inst. of Aeronautical Materials, Beijing (China). National Key Lab. of Science and Technology on Advanced High Temperature Structural Materials
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States)
Sponsoring Org.:
USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22). Scientific User Facilities Division; National Natural Science Foundation of China (NNSFC)
OSTI Identifier:
1505178
Grant/Contract Number:  
AC02-06CH11357
Resource Type:
Accepted Manuscript
Journal Name:
Acta Materialia
Additional Journal Information:
Journal Volume: 161; Journal Issue: C; Journal ID: ISSN 1359-6454
Publisher:
Elsevier
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; High Nb-containing TiAl alloys; High-energy X-ray diffraction; gradient structure; γ recrystallization

Citation Formats

Ding, Jie, Zhang, Minghe, Liang, Yongfeng, Ren, Yang, Dong, Chengli, and Lin, Junpin. Enhanced high-temperature tensile property by gradient twin structure of duplex high-Nb-containing TiAl alloy. United States: N. p., 2018. Web. doi:10.1016/j.actamat.2018.09.007.
Ding, Jie, Zhang, Minghe, Liang, Yongfeng, Ren, Yang, Dong, Chengli, & Lin, Junpin. Enhanced high-temperature tensile property by gradient twin structure of duplex high-Nb-containing TiAl alloy. United States. doi:10.1016/j.actamat.2018.09.007.
Ding, Jie, Zhang, Minghe, Liang, Yongfeng, Ren, Yang, Dong, Chengli, and Lin, Junpin. Fri . "Enhanced high-temperature tensile property by gradient twin structure of duplex high-Nb-containing TiAl alloy". United States. doi:10.1016/j.actamat.2018.09.007. https://www.osti.gov/servlets/purl/1505178.
@article{osti_1505178,
title = {Enhanced high-temperature tensile property by gradient twin structure of duplex high-Nb-containing TiAl alloy},
author = {Ding, Jie and Zhang, Minghe and Liang, Yongfeng and Ren, Yang and Dong, Chengli and Lin, Junpin},
abstractNote = {A pre-deformation process was employed for a TiAl alloy via high-temperature torsion, in which the stability of the constituent phases was tailored, resulting in enhanced hardening capability and ductility via a gradient microstructure. A sample with a pre-torsion of 360° exhibited a yield strength of 475 MPa and an ultimate tensile strength of 592 MPa, with a tensile ductility of 47% at 850 °C. The tensile properties were significantly enhanced compared with the as-forged sample, which exhibited values of 395 MPa, 494 MPa, and 4.6%, respectively. The physical mechanisms for the significant enhancement of the mechanical property of the TiAl alloys were studied in-depth via of transmission electron microscopy, electron-backscattered diffraction, and high-energy X-ray diffraction techniques. The high strength is mainly attributed to the twin structure formed during torsion, while high fracture elongation correlates to the recrystallization of the γ phase at twin-twin sections and the load partitioning regulated by a hierarchical microstructure. When the tensile micro-strains along the loading direction and transverse direction in the γ phase of the pre-deformed TiAl alloy, a higher mechanical performance was obtained. Moreover, the fracture mode of the pre-torsional tensile sample is a combination of pores and cleavage facets which resulted from the microstructure after torsion. Finally, the gradient twin structure approach in this study provides a strategy for developing TiAl alloys with exceptionally high-temperature tensile property, and the results of the micromechanical behavior-microstructure-property relationship may improve the understanding of the plastic deformation of TiAl alloys.},
doi = {10.1016/j.actamat.2018.09.007},
journal = {Acta Materialia},
number = C,
volume = 161,
place = {United States},
year = {2018},
month = {9}
}

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