Thermal Stability of Microstructures in Low-Density Ti2AlNb-Based Alloy Hot Rolled Plate
FENG Aihan1, CHEN Qiang2, WANG Jian3, WANG Hao4, QU Shoujiang1(), CHEN Daolun5()
1School of Materials Science and Engineering, Tongji University, Shanghai 200092, China 2Southwest Technology and Engineering Research Institute, Chongqing 400039, China 3BaoTi Group Co., Ltd., Baoji 721014, China 4Interdisciplinary Center for Additive Manufacturing, School of Materials and Chemistry, University of Shanghai for Science and Technology, Shanghai 200093, China 5Department of Mechanical and Industrial Engineering, Toronto Metropolitan University, Toronto, Ontario M5B 2K3, Canada
Cite this article:
FENG Aihan, CHEN Qiang, WANG Jian, WANG Hao, QU Shoujiang, CHEN Daolun. Thermal Stability of Microstructures in Low-Density Ti2AlNb-Based Alloy Hot Rolled Plate. Acta Metall Sin, 2023, 59(6): 777-786.
Multielement and multiphase intermetallic alloys based on an ordered orthorhombic (O) phase Ti2AlNb, where the presence of a long-range order superlattice structure effectively impedes the movement of dislocations and high-temperature diffusion, are a class of highly promising lightweight high-temperature structural materials for aerospace applications due to their high specific strength and superior fracture toughness. Thermal stability of microstructures in the hot rolled sheet of a low-density Ti2AlNb-based alloy has been investigated in a temperature range from 600oC to 1100oC for 12 h via OM, SEM, XRD, and TEM/STEM. The results showed that the initial Ti2AlNb-based alloy hot rolled sheet consisted of α2, B2, and O phases. Furthermore, the Ti2AlNb-based alloy hot rolled sheet at 600oC for 12 h consisted of α2, B2, and O phases, where the particle shaped α2 phase was distributed in the B2 matrix, and lath-like O phase lay inbetween the α2 particles. The spheroidization of the α2 phase started to occur along with the coarsening and solutionizing of the lath O phase in the B2 matrix at a temperature between 800oC and 900oC for 12 h, while the hot rolled Ti2AlNb-based alloy plate was still composed of α2, B2, and O phases. When the temperature reached 950oC, the O phase disappeared in the B2 matrix. Only α2 + B2 two phases were present in the hot rolled Ti2AlNb-based alloy at 950-1000oC for 12 h, where the α2 phase was spheroidized and tended to distribute surrounding B2 grain boundaries. When the temperature rose to 1100oC, the alloy contained a B2 single phase with only some residual α2 phase. Moreover, the Vickers microhardness contour vs temperature plot revealed that a peak hardness of as high as 509 HV appeared at 600oC due to the presence of numerous fine O laths.
Fund: National Key Research and Development Program of China(2018YFB0704100);National Natural Science Foundation of China(51871168);Southwest Technology and Engineering Research Institute Cooperation Fund(HDHDW5902020102)
Corresponding Authors:
QU Shoujiang, associate professor, Tel:(021)39947690, E-mail: qushoujiang@tongji.edu.cn
CHEN Daolun, professor, Tel: +416-979-5000 (ext.556487), E-mail: dchen@torontomu.ca
Fig.1 Microstructures and selected area electron diffraction (SAED) patterns of hot rolled Ti2AlNb-based alloy plate
Fig.2 OM images of hot rolled Ti2AlNb-based alloy plate after heat treatment at 600oC (a), 800oC (b), 900oC (c), 950oC (d), 1000oC (e), and 1100oC (f) for 12 h and then water quenching
Fig.3 SEM images of hot rolled Ti2AlNb-based alloy plate after heat treatment at 600oC (a), 800oC (b), 900oC (c), 950oC (d), 1000oC (e), and 1100oC (f) for 12 h and then water quenching
Fig.4 XRD spectra of hot rolled Ti2AlNb-based alloys plate before (a) and after heat treatment at 600oC (b), 800oC (c), 850oC (d), 900oC (e), 950oC (f), 1000oC (g), 1050oC (h), and 1100oC (i) for 12 h and then water quenching (Insets in Figs.4c-e show the magnified spectra)
Fig.5 TEM (a) and STEM (b) images of hot rolled Ti2AlNb-based alloy plate after heat treatment at 600oC for 12 h and then water quenching, and corresponding SAED patterns of points I (c) and II (d) in Fig.5a
Phase
Orientation relationship
Ref.
B2/α2
[31]
B2/O
[30,31]
α2/O
[1,3,8]
Table 1 Summaries of orientation relationships among α2, B2, and O phases[1,3,8,30,31]
Fig.6 TEM (a) and STEM (b) images of hot rolled Ti2AlNb-based alloy plate after heat treatment at 850oC for 12 h and then water quenching, and corresponding SAED patterns of points I (c), II (d), III (e), and IV (f) in Fig.6b
Fig.7 TEM image (a) of hot rolled Ti2AlNb-based alloy plate after heat treatment at 900oC for 12 h and then water quenching, and corresponding SAED patterns of points I (b), II (c), and III (d) in Fig.7a
Fig.8 TEM (a) and STEM (b) images of hot rolled Ti2AlNb-based alloy plate after heat treatment at 1000oC for 12 h and then water quenching, and corresponding SAED patterns of points I (c), II (d), III (e), and IV (f) in Fig.8a
Fig.9 Microhardnesses of hot rolled Ti2AlNb-based alloy plate as a function of heat treatment temperature
Heat treatment
Phase constituent
XRD
SEM
TEM
As-rolled
B2 + O + α2
B2 + O + α2
B2 + α2
600oC, 12 h, WQ
B2 + O + α2
B2 + O + α2
B2 + O + α2
800oC, 12 h, WQ
B2 + O + α2
B2 + O + α2
-
850oC, 12 h, WQ
B2 + O + α2
B2 + O + α2
B2 + O + α2
900oC, 12 h, WQ
B2 + O + α2
B2 + O + α2
B2 + O + α2
950oC, 12 h, WQ
B2 + α2
B2 + α2
-
1000oC, 12 h, WQ
B2 + α2
B2 + α2
B2 + α2
1050oC, 12 h, WQ
B2 + α2
B2 + α2
-
1100oC, 12 h, WQ
B2 + α2
B2 + α2
-
Table 2 Summaries of phase constituents of hot rolled Ti2AlNb-based alloy plate before and after heat treatment according to XRD, SEM, and TEM analyses
1
Banerjee D, Gogia A K, Nandi T K, et al. A new ordered orthorhombic phase in a Ti3Al-Nb alloy [J]. Acta Metall., 1988, 36: 871
doi: 10.1016/0001-6160(88)90141-1
Qu S J, Feng A H, Shagiev M R, et al. Superplastic behavior of the fine-grained Ti-21Al-18Nb-1Mo-2V-0.3Si intermetallic alloy [J]. Lett. Mater., 2018, 8: 567
doi: 10.22226/2410-3535
4
Zhu H P, Qu S J, Qi G Y, et al. High temperature oxidation behavior of as-rolled Ti2AlNb-based alloy [J]. Chin. J. Rare Met., 2016, 40: 104
Xiang J M, Mi G B, Qu S J, et al. Thermodynamic and microstructural study of Ti2AlNb oxides at 800oC [J]. Sci. Rep., 2018, 8: 12761
doi: 10.1038/s41598-018-31196-w
pmid: 30143715
6
Zhang Y L, Feng A H, Qu S J, et al. Microstructure and low cycle fatigue of a Ti2AlNb-based lightweight alloy [J]. J. Mater. Sci. Technol., 2020, 44: 140
doi: 10.1016/j.jmst.2020.01.032
7
Feng A H, Li B B, Shen J. Recent advances on Ti2AlNb-based alloys [J]. J. Mater. Metall., 2011, 10: 30
Shen J, Feng A H. Recent advances on microstructural controlling and hot forming of Ti2AlNb-based alloys [J]. Acta Metall. Sin., 2013, 49: 1286
doi: 10.3724/SP.J.1037.2013.00607
Zhang H Y, Yan N, Liang H Y, et al. Phase transformation and microstructure control of Ti2AlNb-based alloys: A review [J]. J. Mater. Sci. Technol., 2021, 80: 203
doi: 10.1016/j.jmst.2020.11.022
11
Ravi C, Vajeeston P, Mathijaya S, et al. Electronic structure, phase stability, and cohesive properties of Ti2XAl (X = Nb, V, Zr) [J]. Phys. Rev., 1999, 60B: 15683
12
Pathak A, Singh A K. A first principles study of Ti2AlNb intermetallic [J]. Solid State Commun., 2015, 204: 9
doi: 10.1016/j.ssc.2014.12.002
13
Morris M A, Morris D G. Strain localization, slip-band formation and twinning associated with deformation of a Ti-24at.%Al-11at.%Nb alloy [J]. Philos. Mag., 1991, 63A: 1175
14
Kazantseva N V, Demakov S L, Popov A A. Microstructure and plastic deformation of orthorhombic titanium aluminides Ti2AlNb. III. Formation of transformation twins upon the B2→Ophase transformation [J]. Phys. Met. Metallogr., 2007, 103: 378
doi: 10.1134/S0031918X07040102
15
Kazantseva N V, Demakov S L, Popov A A. Microstructure and plastic deformation of orthorhombic titanium aluminides Ti2AlNb. IV. Formation of the transformation twins upon the α2→O phase transformation [J]. Phys. Met. Metallogr., 2007, 103: 388
doi: 10.1134/S0031918X07040114
16
Liang X B, Zhou J J, Zhang J W, et al. High cycle fatigue at high temperatures of the lamellar microstructure of Ti-22Al-25Nb alloy [J]. Titanium Ind. Prog., 2019, 36(2): 20
Luo C, Zhang Y, Wang X Y, et al. Effect of heat treatment on microstructure and properties of cast Ti-22Al-25Nb alloy [J]. Aerosp. Manuf. Technol., 2020, (2): 18
Li B B. Plate preparation, microstructure and mechanical properties of low-density Ti2AlNb-based alloys [D]. Harbin: Harbin Institute of Technology, 2011
Chen Z. Research on microstructure and mechanical properties of Ti2AlNb-based alloy fabricated by multiple isothermal forging [D]. Harbin: Harbin Institute of Technology, 2013
Zhou Y, Cao J X, Huang X, et al. Microstructure evolution and comprehensive mechanical properties of β/B2 processed Ti-22Al-23Nb-2(Mo, Zr) alloy [J]. J. Aeronaut. Mater., 2020, 40(4): 25
Li J J, Zeng W D, Xue C. Effects of hot deformation parameters on lamellar microstructure evolution of Ti2AlNb based alloy [J]. Chin. J. Nonferrous Met., 2014, 24: 1998
Boehlert C J, Majumdar B S, Seetharaman V, et al. Part I. The microstructural evolution in Ti-Al-Nb O + bcc orthorhombic alloys [J]. Metall. Mater. Trans., 1999, 30A: 2305
25
Boehlert C J. The phase evolution and microstructural stability of an orthorhombic Ti-23Al-27Nb alloy [J]. J. Phase Equilib., 1999, 20: 101
doi: 10.1007/s11669-999-0007-z
26
Boehlert C J, Miracle D B. Part II. The creep behavior of Ti-Al-Nb O + bcc orthorhombic alloys [J]. Metall. Mater. Trans., 1999, 30A: 2349
27
Boehlert C J. Microstructure, creep, and tensile behavior of a Ti-12Al-38Nb (at.%) beta+orthorhombic alloy [J]. Mater. Sci. Eng., 1999, A267: 82
28
Boehlert C J. Part III. The tensile behavior of Ti-Al-Nb O + bcc orthorhombic alloys [J]. Metall. Mater. Trans., 2001, 32A: 1977
29
Lin P, He Z B, Yuan S J, et al. Instability of the O-phase in Ti-22Al-25Nb alloy during elevated-temperature deformation [J]. J. Alloys Compd., 2013, 578: 96
doi: 10.1016/j.jallcom.2013.05.018
30
Bendersky L A, Boettinger W J, Roytburd A. Coherent precipitates in the b.c.c./orthorhombic two-phase field of the Ti-Al-Nb system [J]. Acta Metall. Mater., 1991, 39: 1959
doi: 10.1016/0956-7151(91)90165-W
31
Muraleedharan K, Gogia A K, Nandy T K, et al. Transformations in a Ti-24Al-15Nb alloy: Part I. Phase equilibria and microstructure [J]. Metall. Trans., 1992, 23A: 401
32
Popov A A, Illarionov A G, Grib S V, et al. Phase and structural transformations in the alloy on the basis of the orthorhombic titanium aluminide [J]. Phys. Met. Metallogr., 2008, 106: 399
doi: 10.1134/S0031918X08100104
33
Kazantseva N V, Lepikhin S V. Study of the Ti-Al-Nb phase diagram [J]. Phys. Met. Metall., 2006, 102: 169
doi: 10.1134/S0031918X06080084
