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Microstructural development and room temperature tensile property of directionally solidified Ti–47Al alloys by electromagnetic confinement and directional solidification

Published online by Cambridge University Press:  27 April 2018

Yujun Du ,
Jun Shen ,
Yilong Xiong ,
Zhao Shang ,
Ling Qin  and
Hengzhi Fu
Yujun Du*
Affiliation:
State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi’an 710072, China
Jun Shen*
Affiliation:
State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi’an 710072, China
Yilong Xiong
Affiliation:
State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi’an 710072, China
Zhao Shang
Affiliation:
State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi’an 710072, China
Ling Qin
Affiliation:
State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi’an 710072, China
Hengzhi Fu
Affiliation:
State Key Laboratory of Solidification Processing, Northwestern Polytechnical University, Xi’an 710072, China
*
a)Address all correspondence to this author. e-mail: [email protected]
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Abstract

Ti–47Al samples with a diameter of 18 mm are obtained by electromagnetic confinement and directional solidification at different growth velocities. Controlled by a Ti–43Al–3Si seed, the α grains are aligned well and the parallel lamellar microstructure is obtained at the growth velocity of 10 μm/s. With the growth velocity increases to 25 and 50 μm/s, although the lamellar microstructures are still aligned well in the initial transition stage, the lamellar alignment fails due to the nucleation and growth of new β and α grains and then the inclined and perpendicular lamellar microstructures form eventually. The room temperature tensile properties of the different lamellar microstructures are measured and the results show that the desired lamellar microstructure has a tensile strength of 693 MPa and an elongation of 10.0% simultaneously. They are the maximum values that have been reported in binary γ-TiAl alloys so far and are far higher than those of the other two types of lamellar microstructures. The fracture behaviors of the lamellar microstructures are checked by scanning electron microscopy and transmission electron microscopy. Two models are used to illustrate the fracture mechanism of the different lamellar structures.

Keywords

directional solidificationmicrostructureTi
Type
Article
Information
Journal of Materials Research , Volume 33 , Issue 8 , 27 April 2018 , pp. 958 - 966
Copyright
Copyright © Materials Research Society 2018 

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Footnotes

Contributing Editor: Jürgen Eckert

References

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