MICROSTRUCTURE EVOLUTION AND SOLUTE SEGREGATION IN DIRECTIONALLY SOLIDIFIED TiAl ALLOYS WITH HIGH Nb CONTENT

doi:10.11900/0412.1961.2014.00703

Acta Metall Sin

2015, Vol. 51

Issue (8): 957-966 DOI: 10.11900/0412.1961.2014.00703

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MICROSTRUCTURE EVOLUTION AND SOLUTE SEGREGATION IN DIRECTIONALLY SOLIDIFIED TiAl ALLOYS WITH HIGH Nb CONTENT

Yong LI¹,Guohuai LIU¹,Zhaodong WANG¹,Tianliang FU¹,Xinzhong LI²,Yanqing SU²,Jingjie GUO²,Hengzhi FU²

1 State Key Laboratory of Rolling and Automation, Northeastern University, Shenyang 110819
2 School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 150001

Cite this article:

Yong LI,Guohuai LIU,Zhaodong WANG,Tianliang FU,Xinzhong LI,Yanqing SU,Jingjie GUO,Hengzhi FU. MICROSTRUCTURE EVOLUTION AND SOLUTE SEGREGATION IN DIRECTIONALLY SOLIDIFIED TiAl ALLOYS WITH HIGH Nb CONTENT. Acta Metall Sin, 2015, 51(8): 957-966.

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Abstract

TiAl-Nb alloys have been determined as the advanced direction for the development of the high temperature TiAl alloys, so being one of the advanced materials for turbines of aircraft engines and gas-burning power-generation plants. However, highly-Nb addition can lead to the complex solidification behavior of TiAl-Nb alloy and multi-phase microstructure, which is important for the mechanical properties during the alloy design. Bridgman type directional solidification experiments were conducted for Ti-46Al-(8, 9, 10)Nb alloy. The effect of the growth rate and Nb content on the microstructure, phase transition and microsegregation was investigated, and finally the selection diagram of the phase transition and the microstructure of the directional solidified TiAl-Nb alloy were obtained. The results show that the planar-cellular-dendritic evolution of solid-liquid interface can be observed with the increase of the growth rate. Meanwhile the fully b phase solidification changes to the peritectic solidification with the increase of the growth rate, and correspondingly the final microstructure is composed of the a₂/g lamellar structure and a multiphase microstructure (B2 phase, a₂/g lamellar structure) respectively. The increase of the b-stabilizer Nb content can promote the fully b phase solidification and the formation of the multiphase microstructure (B2 phase, a₂/g lamellar structure). The contribution of the growth rate and the Nb content to the phase transition and the microstructure is connected with the solute segregation (S-segregation, b-segregation) closely. The increase of the S-segregation amplitude can easily promote the peritectic reaction, which always leads to the highly solute segregation and the concentrated distribution of plenty of B2 phase in the core of the dendrite. b-segregation is the mainly origin of the B2 phase formation, in which the Nb enrichment in the retained b phase directly determines the morphology and the dimension of the B2 phase. Finally according to the selection diagram of the solidification process and the microstructure of the Ti-46Al alloy with the growth rate and the Nb content, the high Nb content and the low growth rate during fully b solidification should be selected for the prefer microstructure with the homogeneous distribution and the low solute segregation.

Key words: TiAl-Nb alloy directional solidification microstructure solute segregation

Fund: Supported by National Natural Science Foundation of China (Nos.51071062, 51274077 and 51271068), Fundamental Research Funds for the Central Universities (No.N140703003) and China Postdoctoral Science Foundation (No.2014M561245)

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	Articles by authors
	Yong LI
	Guohuai LIU
	Zhaodong WANG
	Tianliang FU
	Xinzhong LI
	Yanqing SU
	Jingjie GUO
	Hengzhi FU

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https://www.ams.org.cn/EN/10.11900/0412.1961.2014.00703 OR https://www.ams.org.cn/EN/Y2015/V51/I8/957

Fig.1 Solid/liquid interface morphologies with 8%Nb (a1~e1), 9%Nb (a2~e2), 10%Nb (a3~e3) and growth rates V of 2 μm/s (a1~a3), 3 μm/s (b1~b3), 10 μm/s (c1~c3), 15 μm/s (d1~d3), 70 μm/s (e1~e3) in directional solidified Ti-46Al alloy

Fig.2 Microstructure (a), XRD spectrum (b) and the characteristics of B2 phase distribution (c, d) in directionally solidified Ti-46Al-Nb alloy (Inset in Fig.2c shows SAED pattern of B2 phase)

Table 1 Chemical compositions of the different phases in directionally solidified Ti-46Al-8Nb alloy (atomic fraction / %)

Fig.3 Longitudinal macrostructures and corresponding microstructures of directionally solidified Ti-46Al-Nb alloy with different Nb contents and growth rates

(a) macrostructure of Ti-46Al-8Nb alloy, V=2 μm/s

(b~d) microstructures of Ti-46Al-8Nb alloy, V=2 μm/s

(e) macrostructure of Ti-46Al-8Nb alloy, V=3 μm/s

(f~h) microstructures of Ti-46Al-8Nb alloy, V=3 μm/s

(i) macrostructure of Ti-46Al-10Nb alloy, V=30 μm/s

(j~l) microstructures of Ti-46Al-10Nb alloy, V=30 μm/s, inset in Fig.3l show the locally magnified image

Fig.4 Solute segregations (a1~c1) and line scan EDS along the black line (a2~c2) during the different phase transition processes of directionally solidified Ti-46Al-8Nb alloy in L+b region (a1, a2), L+b+a region (b1, b2) and a₂/g+B2 region (c1, c2)

Fig.5 Solute segregation and microstructure evolution during the phase transition process of L→L+b→L+b+a (a1~c1) and L→L+b→b+a (a2~c2) in directionally solidified Ti-46Al-Nb alloy at V=5 μm/s

Fig.6 Selection diagram of the phase transition and the final microstructure with the evolution of the Nb content and the growth rate in directionally solidified Ti-46Al-Nb alloy

[1]	Loria E A. Intermetallics, 2000; 8: 1339
[2]	Luo W Z, Shen J, Li Q L, Man W W, Fu H Z. Acta Metall Sin, 2007; 43: 897 (罗文忠, 沈军, 李庆林, 满伟伟, 傅恒志. 金属学报, 2007; 43: 897)
[3]	Dimiduk D M. Mater Sci Eng, 1999; A263: 281
[4]	Chen Y Y, Kong F T. Acta Metall Sin, 2008; 44: 551 (陈玉勇, 孔凡涛. 金属学报, 2008; 44: 551)
[5]	Li X Z, Fan J L, Su Y Q, Liu D M, Guo J J, Fu H Z. Intermetallics, 2012; 27: 38
[6]	Wu X. Intermetallics, 2006; 14: 1114
[7]	Li H Z, Li Z, Zhang W, Wang Y, Liu Y, Wang H J. J Alloys Compd, 2010; 508: 359
[8]	Wang Y H, Lin J P, He Y H, Wang Y L, Chen G L. J Alloys Compd, 2008; 456: 297
[9]	Chen G L, Wang X T, Ni K Q, Hao S M, Cao J X, Zhang X. Intermetallics, 1996; 4: 13
[10]	Chen G L, Sun Z Q, Zhou X. Corros Sci, 1992; 11: 939
[11]	Nakamura H, Takeyama M, Yamabe Y, Kikuchi M. Scr Mater, 1993; 28: 997
[12]	Leonard K J, Vasudevan V K. Intermetallics, 2000; 8: 1257
[13]	Chen G L, Zhang W J, Liu Z C, Li S J, Kim Y W. Gamma Titanium Aluminizes 1999. Lerotto: TMS, 1999: 371
[14]	Liu G H, Li X Z, Su Y Q, Liu D M, Guo J J, Fu H Z. J Alloys Compd, 2012; 541: 275
[15]	Chen G L, Xu X J, Teng Z K, Wang Y L, Lin J P. Intermetallics, 2007; 15: 625
[16]	Ding X F, Lin J P, Zhang L Q, Wang H L, Hao G J, Chen G L. J Alloys Compd, 2010; 506: 115
[17]	Perdrix F, Trichrt M F, Bonnentien J L, Cornet M, Bigot J. Intermetallics, 1999; 7: 1323
[18]	Ding X F, Lin J P, Zhang L Q, Song X P, Chen G L. Mater Des, 2011; 32: 395
[19]	Clemens H, Kestler H. Adv Eng Mater, 2000; 2: 551
[20]	Imayev R M, Imayev V M, Oehring M. Intermetallics, 2007; 15: 451
[21]	Niu H Z, Chen Y Y, Xiao S L, Xu L J. Intermetallics, 2012; 31: 225
[22]	Yu R, He L L, Cheng Z Y, Zhu J, Ye H Q. Intermetallics, 2002; 10: 661
[23]	Trivedi R. J Cryst Growth, 1980; 49: 219
[24]	Kerr H W, Cisse J, Bolling G F. Acta Metall, 1974; 22: 677
[25]	Kim M C, Oh M H, Lee J H, Inui H, Yamaguchi M, Wee D M. Mater Sci Eng, 1997; A239-240: 570

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