Effects of Heat Treatment on Unique Layered Microstructure and Tensile Properties of TiAl Fabricated by Electron Beam Melting

Abstract:

In the present study, effects of heat treatment on microstructures and tensile properties of the cylindrical bars of Ti-48Al-2Cr-2Nb (at.%) alloy with unique layered microstructure consisting of equiaxed γ grains region (γ band) and duplex-like region fabricated by electron beam melting (EBM) were investigated. We found that it is possible to control width of the γ bands (W_γ) by heat treatments at 1100°C and 1190°C. The W_γ increases with decreasing heat treatment temperature. The bars heat-treated at 1190°C exhibit high elongation of 2.9% at room temperature (RT) with maintaining high strength. The RT elongation increases with increasing the W_γ because of increasing deformable regions. In contrast, the RT elongation of the bars decreases with increasing the W_γ when W_γ is very large. This is because the large γ band leads intergranular fracture. These results indicate that there is appropriate width for the γ band to obtain excellent tensile properties at RT.

• Periodical: Materials Science Forum (Volume 941)
• Pages: 1366-1371
• DOI: https://doi.org/10.4028/www.scientific.net/MSF.941.1366
• Online since: December 2018
• Authors: Masahiro Sakata, Jong Yeong Oh, Ken Cho, Hiroyuki Y. Yasuda*, Mitsuharu Todai, Takayoshi Nakano, Ayako Ikeda, Minoru Ueda, Masao Takeyama
• Keywords: Additive Manufacturing (AM), Electron Beam Melting, Microstructure, Tensile Properties, Titanium Aluminide

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