Microstructure evolution and hot deformation behavior of spray-deposited TiAl alloys
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ARTICLE Microstructure evolution and hot deformation behavior of spray-deposited TiAl alloys Yandong Jia and Long Xu Laboratory for Microstructures, Institute of Materials, Shanghai University, Shanghai 200444, China
Pan Maa) School of Materials Engineering, Shanghai University of Engineering Science, Shanghai 201620, China
Konda Gokuldoss Prashanth Department of Manufacturing and Civil Engineering, Norwegian University of Science and Technology, Gjøvik 2815, Norway; Erich Schmid Institute of Materials Science, Austrian Academy of Sciences, Leoben A-8700, Austria; and Department of Mechanical and Industrial Engineering, Tallinn University of Technology, Tallinn 19086, Estonia
Chenghui Yao School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 151001, China
Gang Wangb) Laboratory for Microstructures, Institute of Materials, Shanghai University, Shanghai 200444, China (Received 13 May 2018; accepted 29 June 2018)
Ti–Al alloys are established as promising candidates for aerospace applications due to their lightweight, good elevated temperature strength, and decent corrosion resistance. In this study, a Ti–51Al (at.%) alloy is fabricated by spray deposition. The effects of temperature and strain rate on the deformation behavior of the spray-deposited Ti–Al alloy are investigated. The microstructural evolution of the Ti–Al alloy with different deformation temperatures is discussed in detail. A strain-dependent constitutive equation was proposed to predict the flow stresses at the elevated temperatures for the spray-deposited Ti–Al alloy. The microstructure of the as-deposited Ti–51Al alloy exhibits a a2/c lamellar-structure with average size 25 6 2 lm, due to the high cooling rate observed during solidification. The lamellar structure is embedded on a c matrix. The amount of the a2/c lamellar-structure reduces gradually with increasing the hot deformation temperature. After hot isostatic pressing at 1523 K, the microstructure is mainly comprised of the c matrix.
I. INTRODUCTION
The c-TiAl-based alloys have been considered as promising candidates for aerospace, automotive, and energy industries, due to their excellent combination properties, i.e., low density, good elevated temperature strength, good corrosion resistance, and excellent creep properties.1–5 However, poor room temperature ductility and high sensitivity of flow stress toward higher temperatures limit their wide application.6,7 Moreover, the preparation of c-TiAl alloys by ingot metallurgy exhibit several disadvantages, including coarse-grained lamellae and macrosegregation that result in low mechanical properties. In addition, it is difficult to carry postprocessing processes (like thermomechanical processing) on these c-TiAl alloys.8,9 Selective laser melting is an advanced additive manufacturing technique, which offers
Address all correspondence to these authors. a) e-mail: [email protected] b) e-mail: [email protected] DOI: 10.1557/jmr.2018.249 J. Mater. Res., 2018
a great potential for producing complex-shaped parts
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