| Microstructures of TiAl alloys can he divided into four groups; near-γ, duplex, nearly-lamellar and fully-lamellar. Depending on heat treatment temperature and time, these structures can be formed. The duplex microstructure, the finest microstructure, can be formed by heat treatment in an α+γ field. In this study, heat treatment conditions for the formation of duplex microstructures were studied. The TiAl alloys were cast in a plasma arc melting system. The effects of recrystallization time in the α+γ field and the addition of a third element, such as Mn or Zr on the microstructures were investigated. The fully-lamellar microstructure which has smooth grain boundaries resulted in low fracture strain. Recrystallization time in the α+r field decreased with the addition of Mn, but increased with the addition of Zr. |
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