Abstract
The microstructure and cellular transition characteristics of an intermetallic Ti-42Al-3Nb-1Mo-0.1B (at.%) alloy were investigated. The as-cast microstructure of the alloy is mainly composed of (α2+γ) lamellar structure and (β+γ) mixture structure, which distributes along the boundaries of the lamellar colonies. In order to study the phase transformation of lamellar structure at aging temperature, a two-step heat treatment was carried out. After the first step of annealing treatment at 1,260 °C, the microstructure with relatively finer lamellar space and (γ+β/B2) mixture structure is obtained. Aging treatment, as the second heat treatment step, has significant influence on the microstructure, attributing to a cellular reaction of α2+γ→ γ+β. With the increase of aging temperature, the (α2+γ) lamellar structure continues to dissolve, whereas the contents of both the equiaxed γ and β/B2 grains continuously increase. Besides, the orientation of lamellae α2, equiaxed γ and equiaxed β/B2 in the cellular transition region follows a specific relationship of {0–11}β<1–11>β//{0001}α2<2-1-10>α2//{1–11}γ<−101>γ.
Article PDF
Similar content being viewed by others
References
Zhang S Z, Zhao Y B, Zhang C J, et al. The microstructure, mechanical properties, and oxidation behavior of beta-gamma TiAl alloy with excellent hot workability. Mater. Sci. Eng. A, 2017, 700: 366–373.
Zhang S Z, Zhang C J, Du Z X, et al. Microstructure and tensile properties of hot forged high Nb containing TiAl based alloy with initial near lamellar microstructure. Mater. Sci. Eng. A, 2015, 642: 16–21.
Yang J R, Cao B, Wu Y L, et al. Continuous cooling transformation (CCT) behavior of a high Nb-containing TiAl alloy. Materialia, 2019, 5: 100169.
Yang J R, Wang X Y, Cao B, et al. Tailoring the microstructure of a β-solidifying TiAl alloy by controlled post-solidification isothermal holding and cooling. Metall. Mater. Trans. A, 2017, 48(10): 1–11.
Schwaighofer E, Clemens H, Mayer S, et al. Microstructural design and mechanical properties of a cast and heat-treated intermetallic multi-phase γ-TiAl based alloy. Intermetallics, 2014, 44: 128–140.
Yang J R, Chen R R, Ding H S, et al. Heat transfer and macrostructure formation of Nb containing TiAl alloy directionally solidified by square cold crucible. Intermetallics, 2013, 42: 184–191.
Clemens H, Wallgram W, Kremmer S, et al. Design of novel β-solidifying TiAl alloys with adjustable β/B2-phase fraction and excellent hot workability. Adv. Eng. Mater., 2008, 10: 707–713.
Wallgram W, Schmölzer T, Cha L. Technology and mechanical properties of advanced γ-TiAl based alloy. Int. J. Mater. Res., 2009, 100(8): 1021–1030.
Clemens H, Chladil H F, Wallgram W, et al. In and ex situ investigations of the β-phase in a Nb and Mo containing γ-TiAl based alloy. Intermetallics, 2008, 16(6): 827–833.
Clemens H, Mayer S. Design, processing, microstructure, properties, and applications of advanced intermetallic TiAl alloys. Adv. Eng. Mater., 2013, 15(4): 191–215.
Imayev V M, Imayev R M, Khismatullin T G. Mechanical properties of the cast intermetallic alloy Ti-43Al-7(Nb, Mo)-0.2B (at.%) after heat treatment. Phys. Metals Metallogr., 2008, 105(5): 484–490.
Gaitzenauer A, Stark A, Gosslar D, et al. Microstructure and texture evolution in an intermetallic β-stabilized TiAl alloy during forging and subsequent isothermal annealing. Adv. Eng. Mater., 2014, 16: 445–451.
Huang J S, Huang L, Zhang Y H, et al. Effect of heat treatment on microstructure of Ti-45Al-7Nb-0.15B–0.7W alloy. T. Mater. Heat Treat., 2006, 27(6): 78–83. (In Chinese)
Wu X H. Review of alloy and process development of TiAl alloys. Intermetallics, 2006, 14: 1114–1122.
Kastenhuber M, Rashkova B, Clemens H, et al. Effect of microstructural instability on the creep resistance of an advanced intermetallic γ-TiAl based alloy. Intermetallics, 2017, 80: 1–9.
Zhang Y, Kou H, Yang G, et al. A two-step heat treatment to eliminate the micro-segregation of Ti-45Al-8.5Nb-0.2W-0.2B-0.02Y alloy. Adv. Eng. Mater., 2016, 18: 1267–1272.
Cha L, Clemens H, Dehm G. Microstructure evolution and mechanical properties of an intermetallic Ti-43.5Al-4Nb-1Mo-0.1B alloy after ageing below the eutectoid temperature. Int. J. Mater. Res., 2011, 102(6): 703–708.
Bolz S, Oehring M, Lindemann J, et al. Microstructure and mechanical properties of a forged β-solidifying y TiAl alloy in different heat treatment conditions. Intermetallics, 2015, 58: 71–83.
Clemens H, Boeck B, Wallgram W, et al. Experimental studies and thermodynamic simulations of phase transformations in Ti-(41–45) Al-4Nb-1Mo-0.1B alloys. MRS Proceedings, 2008, doi:https://doi.org/10.1557/proc-1128-u03-06.
Dong S L, Liu T, Li Y J, et al. Hot deformation processing capability of Fe-contained high Nb TiAl-based alloy. Vacuum, 2019, 159: 391–399.
Takeyama M, Kobayashi S. Physical metallurgy for wrought gamma titanium aluminides: Microstructure control through phase transformations. Intermetallics, 2005, 13(9): 993–999.
Clemens H, Chladil H, Wallgram W, et al. In and ex-situ investigations of the β-phase in a Nb and Mo containing γ-TiAl based alloy. Intermetallics, 2008, 16: 827–833.
Schmoelzer T, Liss K, Zickler G A, et al. Phase fractions, transition and ordering temperatures in TiAl-Nb-Mo alloys: an in-and exsitu study. Intermetallics, 2010, 18(8): 1544–1552.
Schwaighofer E, Rashkova B, Clemens H, et al. Effect of carbon addition on solidification behavior, phase evolution and creep properties of an intermetallic β-stabilized γ-TiAl based alloy. Intermetallics, 2014, 46: 173–184.
Tang B, Cheng L, Kou H C, et al. Hot forging design and microstructure evolution of a high Nb containing TiAl alloy. Intermetallics, 2015, 58: 7–14.
Liss K, Schmoelzer T, Yan K, et al. In situ study of dynamic recrystallization and hot deformation behavior of a multiphase titanium aluminide alloy. J. Appl. Phys., 2009, 106: 1139–1234.
Denquin A, Naka S. Phase transformation mechanisms involved in two-phase TiAl-based alloys — lamellar structure formation. Acta Mater., 1996, 44(1): 343–352.
Tatach-Dumańska M, Zięba P, Pawłowski A, et al. Practical aspects of discontinuous precipitation and dissolution. Mater. Chem. Phys., 2003, 80(2): 476–481.
Wang X P, Zheng Y R. Discontinuous coarsening of Ti3Al+TiAl lamellae. Chin. J. Nonferrous Met., 1998, 8: 233–238.
Wang X P, Zheng Y R. Discontinuous coarsening transformations in TiAl based alloys. J. Mater. Eng., 2000, 7: 20–23.
Shong D S, Kim Y W. Discontinuous coarsening of high perfection lamellae in titanium aluminides. Scripta Metallurgica, 1989, 23(2): 257–261.
Wang Q B, Zhang S Z, Zhang C J, et al. Effect of hot rolling temperature on microstructure evolution, deformation texture and nanoindentation properties of an intermetallic Ti-43Al-9V-0.2Y alloy. Intermetallics, 2020, 117: 106677.
Cheng T T, Loretto M H. The decomposition of the beta phase in Ti-44Al-8Nb and Ti-44Al-4Nb-4Zr-0.2 Si alloys. Acta Mater., 1998, 46(13): 4801–4819.
Chen Y, Cheng L, Sun L Y, et al. Characterization of a new microstructure in a β-solidifying TiAl alloy after air-cooling from a β phase field and subsequent tempering. Metals, 2018, 8: 156–166.
Acknowledgements
This work was financially supported by the National Natural Science Foundation of China (Grant Nos.: 52071228, 51704174, 51801112), the Natural Science Foundation of Shanxi Province (Grant Nos.: 201903D121056 and 201903D421084), and the Shandong Province Key Research and Development Program (Grant No.: 2019GGX102045).
Author information
Authors and Affiliations
Corresponding author
Additional information
Shu-zhi Zhang Born in 1984. He received his Ph.D. degree in materials processing engineering from the Harbin Institute of Technology in 2013. His research interests mainly focus on intermetallic materials, including ordered L10 phase and L12 phase, and their processing technology. To date, he has published more than 60 research papers and holds 10 invent patents of China.
Rights and permissions
About this article
Cite this article
Feng, H., Wang, Qb., Zhang, Sz. et al. Microstructure and cellular transition characteristic of Ti-42Al-3Nb-1Mo-0.1B alloy. China Foundry 17, 423–428 (2020). https://doi.org/10.1007/s41230-020-0086-3
Received:
Accepted:
Published:
Issue Date:
DOI: https://doi.org/10.1007/s41230-020-0086-3