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Title: Microstructure stability and micro-mechanical behavior of as-cast gamma-TiAl alloy during high-temperature low cycle fatigue

This paper systematically investigated the low cycle fatigue deformation of a high Nb-containing TiAl alloy with a nominal chemical composition of Ti-45Al-8.5Nb-0.2W-0.2B-0.02Y at 850 °C by using transmission electron microscopy (TEM), scanning electron microscopy (SEM), and synchrotron-based high-energy X-ray diffraction (HE-XRD) techniques. Cyclic stress-strain (CSS) behavior, lattice strain, and peak broadening of {100} α2, {201} γ, and {202} ωo planes, phase transformations, and crack propagation behavior were obtained for samples with three total strain amplitudes: Δε t/2 = ±0.25%, Δε t/2 = ±0.28%, and Δε t/2 = ±0.30%. At early deformation stages, α 2lamellae transformed into ωo phase with a distinct orientation relationship, and a certain orientation relationship (OR) between them was observed after the following cyclic deformation. Furthermore, γ particles precipitated within the single ω o area. In addition, according to the peak intensity and peak broadening results, the ω o → B2 phase transformation occurred, leading to the appearance of single B2-phase areas. The lattice strains in the ω o phase were always in tension during the cyclic deformation and large differences of the lattice strains were found in the γ phase and α 2 phase, not only the values but also the directions, which resulted in crackmore » nucleated at and propagated along the α 2/γ lamellar interface. Finally, this study provides a better understanding of the low cycle fatigue deformation of TiAl alloys.« less
Authors:
 [1] ;  [1] ;  [1] ;  [1] ;  [2] ;  [3] ;  [1]
  1. Univ. of Science and Technology Beijing (USTB) (China). State Key Lab. for Advanced Metals and Materials
  2. Argonne National Lab. (ANL), Argonne, IL (United States). X-ray Science Division. Advanced Photon Source
  3. Beijing Inst. of Aeronautical Materials (China). National Key Lab. of Science and Technology on Advanced High Temperature Structural Materials
Publication Date:
Grant/Contract Number:
AC02-06CH11357; 51671016; 51401195
Type:
Accepted Manuscript
Journal Name:
Acta Materialia
Additional Journal Information:
Journal Volume: 145; Journal ID: ISSN 1359-6454
Publisher:
Elsevier
Research Org:
Argonne National Lab. (ANL), Argonne, IL (United States); Univ. of Science and Technology Beijing (USTB) (China)
Sponsoring Org:
USDOE; National Natural Science Foundation of China (NNSFC); National Science Foundation for Distinguished Young Scholars (China)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; high Nb-containing TiAl alloys; low cycle fatigue; high-energy X-ray diffraction; phase transformation
OSTI Identifier:
1461317

Ding, Jie, Zhang, Minghe, Ye, Teng, Liang, Yongfeng, Ren, Yang, Dong, Chengli, and Lin, Junpin. Microstructure stability and micro-mechanical behavior of as-cast gamma-TiAl alloy during high-temperature low cycle fatigue. United States: N. p., Web. doi:10.1016/j.actamat.2017.12.040.
Ding, Jie, Zhang, Minghe, Ye, Teng, Liang, Yongfeng, Ren, Yang, Dong, Chengli, & Lin, Junpin. Microstructure stability and micro-mechanical behavior of as-cast gamma-TiAl alloy during high-temperature low cycle fatigue. United States. doi:10.1016/j.actamat.2017.12.040.
Ding, Jie, Zhang, Minghe, Ye, Teng, Liang, Yongfeng, Ren, Yang, Dong, Chengli, and Lin, Junpin. 2017. "Microstructure stability and micro-mechanical behavior of as-cast gamma-TiAl alloy during high-temperature low cycle fatigue". United States. doi:10.1016/j.actamat.2017.12.040. https://www.osti.gov/servlets/purl/1461317.
@article{osti_1461317,
title = {Microstructure stability and micro-mechanical behavior of as-cast gamma-TiAl alloy during high-temperature low cycle fatigue},
author = {Ding, Jie and Zhang, Minghe and Ye, Teng and Liang, Yongfeng and Ren, Yang and Dong, Chengli and Lin, Junpin},
abstractNote = {This paper systematically investigated the low cycle fatigue deformation of a high Nb-containing TiAl alloy with a nominal chemical composition of Ti-45Al-8.5Nb-0.2W-0.2B-0.02Y at 850 °C by using transmission electron microscopy (TEM), scanning electron microscopy (SEM), and synchrotron-based high-energy X-ray diffraction (HE-XRD) techniques. Cyclic stress-strain (CSS) behavior, lattice strain, and peak broadening of {100}α2, {201}γ, and {202}ωo planes, phase transformations, and crack propagation behavior were obtained for samples with three total strain amplitudes: Δεt/2 = ±0.25%, Δεt/2 = ±0.28%, and Δεt/2 = ±0.30%. At early deformation stages, α2lamellae transformed into ωo phase with a distinct orientation relationship, and a certain orientation relationship (OR) between them was observed after the following cyclic deformation. Furthermore, γ particles precipitated within the single ωo area. In addition, according to the peak intensity and peak broadening results, the ωo → B2 phase transformation occurred, leading to the appearance of single B2-phase areas. The lattice strains in the ωo phase were always in tension during the cyclic deformation and large differences of the lattice strains were found in the γ phase and α2 phase, not only the values but also the directions, which resulted in crack nucleated at and propagated along the α2/γ lamellar interface. Finally, this study provides a better understanding of the low cycle fatigue deformation of TiAl alloys.},
doi = {10.1016/j.actamat.2017.12.040},
journal = {Acta Materialia},
number = ,
volume = 145,
place = {United States},
year = {2017},
month = {12}
}