Phase transformation of fully lamellar γ-TiAl alloys inα+γfield①
(Department of Materials Science and Engineering,
Beijing University of Aeronautics and Astronautics, Beijing 100083, P.R.China)
Beijing University of Aeronautics and Astronautics, Beijing 100083, P.R.China)
Abstract: The isothermal phase transformation mechanisms in Ti-46.5Al-2Cr-1.5Nb-1V alloy were studied. The microstructures of the alloy annealed at 1 260℃for different times (2 h, 4 h, 10 h) were observed by using optical microscopy, scanning electron microscopy and transmission electron microscopy. When the annealing time is up to 10h, the primitive large lamellar grains (more than 600μm) transform to small lamellar domains (about 50μm). The small lamellar domains formed from one primitive grain have four kinds of fixed orientations and each orientation has a fixed angle. The lamellar spacing and composition of the small lamellar domains are different from those of the primitive lamellar grains.
Key words: γ-TiAl alloy; phase transformation; microstructure