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Microstructures and High Temperature Tensile Properties of Ti-43Al-4Nb-1.5Mo Alloy in the Canned Forging andHeat Treatment Process |
Tianrui LI1, Guohuai LIU1( ), Mang XU1, Hongzhi NIU2, Tianliang FU1, Zhaodong WANG1, Guodong WANG1 |
1 State Key Laboratory of Rolling and Automation, Northeastern University, Shenyang 110819, China 2 School of Materials Science and Engineering, Northeastern University, Shenyang 110819, China |
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Abstract TiAl alloys are highly promising for high temperature structural application due to their excellent mechanical properties. However, the widespread applications of TiAl alloys have been limited for their low temperature brittleness and poor workability. The further thermo-mechanical treatments is applied for fine microstructures and improved ductility to promote the commercial applications, during which the investigations of hot deformation behavior and microstructural evolution are necessary for the improved microstructure and mechanical properties. The canned forging and subsequent heat treatments of Ti-43Al-4Nb-1.5Mo alloy have been conducted, during which the hot deformation behavior, flow softening mechanism, microstructure evolution and mechanical properties were investigated. The results show that the flow softening process of the canned forging TiAl alloy can be attributed to the soft β phase, α2/γ lamellae decomposition and the dynamic recrystallization induced by dislocation slipping and twinning in γ phase, and the final microstructure is composed of remnant α2/γ lamellae and equiaxed α2, γ and B2 phases. With the increasing heat treatment temperature, the microstructure changes from the multi-phase structure (remnant α2/γ lamellar, equiaxed α2, γ and B2 phases) at 1250 ℃ to the α2/γ lamellar and γ phase at 1285 ℃, and then the fully α2/γ lamellar structure at 1300 ℃, during which the B2 phase is gradually dissolved due to the solution diffusion, and the remnant α2/γ lamellae change to equiaxed α2/γ colonies according to the α2/γ→γ+α2+B2 transition, and the final fully α2/γ lamellar structure is promoted by γ→α transition at high temperature. Moreover, the tensile tests of the hot isostatic pressed (HIPed) samples, canned forged and heat treated samples at 800 ℃ are conducted, in which the fully lamellar structure shows the high properties with the ultimate strength of 663 MPa and the elongation of 26%. The deformation process of the fully α2/γ lamellar can be strengthened by the lamellae twisting, microvoid inhibition and wavy growth of the cracks, leading to the optimal high temperature performance. Moreover, the disordered bcc β phase can promote the deformation during the hot working process at the high temperature (≥1200 ℃), while the hard-brittle B2 phase severely deteriorates the service properties, which should be controlled accurately for the high mechanical properties during the thermo-mechanical processing.
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Received: 17 October 2016
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Fund: Supported by National Key Research and Development Program of China (Nos.2016YFB0301200 and 2016YFB- 0300603), National Natural Science Foundation of China (No.51504060), Fundamental Research Funds for the Central Universities (No.N140703003) and PhD Start-up Foundation of Science Project of Liaoning Province (No.201501150) |
[1] | Dimiduk D M.Gamma titanium aluminide alloys——An assessment within the competition of aerospace structural materials[J]. Mater. Sci. Eng., 1999, A263: 281 | [2] | Wu X H.Review of alloy and process development of TiAl alloys[J]. Intermetallics, 2006, 14: 1114 | [3] | Chen Y Y, Su Y J, Kong F T.Research progress in preparation of TiAl interemetallic based compound[J]. Rare Met. Mater. Eng., 2014, 43: 757(陈玉勇, 苏勇君, 孔凡涛. TiAl金属间化合物制备技术的研究进展[J]. 稀有金属材料与工程, 2014, 43: 757) | [4] | Yang R.Advances and challenges of TiAl base alloys[J]. Acta Metall. Sin., 2015, 51: 129(杨锐. 钛铝金属间化合物的进展与挑战[J]. 金属学报, 2015, 51: 129) | [5] | Tetsui T, Shindo K, Kobayashi S, et al.A newly developed hot worked TiAl alloy for blades and structural components[J]. Scr. Mater., 2002, 47: 399 | [6] | Liu G H, Wang Z D, Fu T L, et al.Study on the microstructure, phase transition and hardness for the TiAl-Nb alloy design during directional solidification[J]. J. Alloys Compd., 2015, 650: 45 | [7] | Tetsui T, Shindo K, Kobayashi S, et al.Strengthening a high-strength TiAl alloy by hot-forging[J]. Intermetallics, 2003, 11: 299 | [8] | Kim H Y, Hong S H.Effect of microstructure on the high-temperature deformation behavior of Ti-48Al-2W intermetallic compounds[J]. Mater. Sci. Eng., 1999, A271: 382 | [9] | Kim H Y, Hong S H.High temperature deformation behavior and microstructural evolution of Ti-47Al-2Cr-4Nb intermetallic alloys[J]. Scr. Mater., 1998, 38: 1517 | [10] | Takeyama M, Kobayashi S.Physical metallurgy for wrought gamma titanium aluminides: Microstructure control through phase transformations[J]. Intermetallics, 2005, 13: 993 | [11] | Jiang H T, Zeng S W, Zhao A M, et al.Hot deformation behavior of β phase containing γ-TiAl alloy[J]. Mater. Sci. Eng., 2016, A661: 160 | [12] | Liu B, Liu Y, Li Y P, et al.Thermomechanical characterization of β-stabilized Ti-45Al-7Nb-0.4W-0.15B alloy[J]. Intermetallics, 2011, 19: 1184 | [13] | Lin J P, Zhang L Q, Song X P, et al.Status of research and development of light-weight γ-TiAl intermetallic based compounds[J]. Mater. China, 2010, 29(2): 1(林均品, 张来启, 宋西平等. 轻质γ-TiAl金属间化合物的研究进展[J]. 中国材料进展, 2010, 29(2): 1) | [14] | 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[J]. Adv. Eng. Mater., 2008, 10: 707 | [15] | Tetsui T, Kobayashi T, Harada H.Achieving high strength and low cost for hot-forged TiAl based alloy containing β phase[J]. Mater. Sci. Eng., 2012, A552: 345 | [16] | Chen G L, Xu X J, Teng Z K, et al.Microsegregation in high Nb containing TiAl alloy ingots beyond laboratory scale[J]. Intermetallics, 2007, 15: 625 | [17] | Liu Z C, Lin J P, Li S J, et al.Effects of Nb and Al on the microstructures and mechanical properties of high Nb containing TiAl base alloys[J]. Intermetallics, 2002, 10: 653 | [18] | Kim Y W, Rosenberger A, Dimiduk D M.Microstructural changes and estimated strengthening contributions in a gamma alloy Ti-45Al-5Nb pack-rolled sheet[J]. Intermetallics, 2009, 17: 1017 | [19] | Niu H Z, Kong F T, Chen Y Y, et al.Microstructure characterization and tensile properties of β phase containing TiAl pancake[J]. J. Alloys Compd., 2011, 509: 10179 | [20] | Yang F, Kong F T, Chen Y Y, et al.Effect of heat treatment on microstructure and properties of as-forged TiAl alloy with β phase[J]. Rare Met. Mater. Eng., 2011, 40: 1505 | [21] | 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[J]. Intermetallics, 2014, 44: 128 | [22] | Jin Y G, Wang J N, Yang J, et al.Microstructure refinement of cast TiAl alloys by β solidification[J]. Scr. Mater., 2004, 51: 113 | [23] | Liu G H, Li X Z, Su Y Q, et al.Microstructure, microsegregation pattern and the formation of B2 phase in directionally solidified Ti-46Al-8Nb alloy[J]. J. Alloys Compd., 2012, 541: 275 | [24] | Niu H Z, Chen Y Y, Xiao S L, et al.High temperature deformation behaviors of Ti-45Al-2Nb-1.5V-1Mo-Y alloy[J]. Intermetallics, 2011, 19: 1767 | [25] | Zong Y Y, Wen D S, Liu Z Y, et al.γ-phase transformation, dynamic recrystallization and texture of a forged TiAl-based alloy based on plane strain compression at elevated temperature[J]. Mater. Des., 2016, 91: 321 | [26] | Zhang W J, Lorenz U, Appel F.Recovery, recrystallization and phase transformations during thermomechanical processing and treatment of TiAl-based alloys[J]. Acta Mater., 2000, 48: 2803 | [27] | Peng Y B, Chen F, Wang M Z, et al.Relationship between mechanical properties and lamellar orientation of PST crystals in Ti-45Al-8Nb alloy[J]. Acta Metall. Sin., 2013, 49: 1457(彭英博, 陈锋, 王敏智等. Ti-45Al-8Nb合金PST晶体片层取向与力学性能的关系[J]. 金属学报, 2013, 49: 1457) |
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