Phase equilibria in Ti3Al-Nb alloys at 1000 °C
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Titanium aluminides are considered to be the future high-temperature structural materials for turbine applications. Major focus is on α2Ti3Al based and γTiAl based alloys. Niobium additions to Ti3Al alloys is found to improve the room-temperature ductility. Thus phase equilibria in Ti-Al-Nb system is of practical significance with regard to their processing and high-temperature phase stability characteristics. In the present research, four alloys with compositions Ti-22Al-12Nb, Ti-21A1-16Nb, Ti-20Al-20Nb, and Ti-25Al-25Nb (all in atom percent) were equilibrated at 1000 °C for 225 hours and then quenched in water. The quenched alloys were characterized for phase relations by optical microscopy, X-ray diffraction (XRD), and electron probe microanalysis (EPMA). Based on the phase analysis, the ternary isotherm of the Ti-Al-Nb system at 1000 °C was constructed on the Ti3Al-rich side. The orthorhombic Ti2AlNb phase was observed in the sample with Ti-25Al-25Nb composition signifying the presence of this phase at 1000 °C.
KeywordsPhase Equilibrium Niobium Elemental Powder Titanium Aluminides Niobium Content
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- 90Moz:.B. Mozer, L.A. Bendersky, W.J. Boettinger, and R.G. Rowe,scz: Metall. Mater., 24,2363–2368 (1990).Google Scholar
- 90Red:.R.G. Reddy and L. Brewer, presentation at the High Temperature Science and Technology Symposium, LBL, University of California, Berkeley, CA, October 1990.Google Scholar
- 91 Ben:.
- 91Hoe:.D.T. Hoelzer and F. Ebrahimi,Proc. High Temperature Niobium Alloys, J. J. Stephens and I. Ahmad, Ed., TMS, Warrendale, PA, 105- 119(1991).Google Scholar
- 91Kim:.Y.W. Kim and F.H. Froes,Proc. High Temperature Aluminides and Intermetallics, S. H. Whang, C. T. Liu, D. P. Pope, and J. O. Stiegler, Ed.,TMS, Warrendale, PA, 465–492(1991).Google Scholar
- 91Lar:.J.M. Larsen, K.A. Williams, S.J. Balsone, and M.A. Stucke,Proc. High Temperature Aluminides and Intermetallics, S. H. Whang, C. T. Liu, D. P. Pope, and J. O. Stiegler, Ed., TMS, Warrendale, PA, 521–556(1991).Google Scholar
- 91Nis:.Y. Nishiyama, T. Miyashita, S. Isobe, and T. Noda,Proc. High Temperature Aluminides and Intermetallics, S. H. Whang, C. T. Liu, D. P. Pope, and J. O. Stiegler, Ed., TMS, Warrendale, PA, 557–584 (1991).Google Scholar
- 91Per:.J.H. Perepezko, Y.A. Chang, L.E. Seitzman, J.C. Lin, N.R. Bonda, T.J. Jewett, and J.C. Mishurda,Proc. High Temperature Alu- minides andlntermetallics, S. H. Whang, C.T.Liu, D. P. Pope, and J. O. Stiegler, Ed., TMS, Warrendale, PA, 19–47 (1991).Google Scholar
- 92Row:.R.G. Rowe,Adv. Mater. Process., 141(3), 33 (1992).Google Scholar
- 94Kuml:.S.G.Kumar and R.G. Reddy, paper submitted for publication.Google Scholar
- 94Kum2:.S.G. Kumar and R.G. Reddy, presentation at ASM-TMS Materials Week, Rosemont, IL, October 1994.Google Scholar