Some New Aspects in Developing TiAl Based Alloys as Competitive High Temperature Materials

Abstract:

In order to make the TiAl Intermetallics-based materials more competitive with conventional superalloys, further work on microstructure modification and alloying process has been carried out specific to the cast and wrought process, respectively. It is proved that directional lamellar microstructures can be formed in the cast TiAl. Those microstructures have demonstrated preponderant mechanical properties under unidirectional load after the cast porosity being removed by HIP at proper temperatures. This microstructure design specific to the rotating parts has benefited the endurance capacity of cast TiAl turbochargers. On the other hand, the additions of Gd have shown significant effect in refining the lamellar microstructures of forged TiAl alloys but do not bring out the detrimental influence to the tensile ductility. The reason is that the Gd-containing precipitates can greatly impede the growth of  grains while themselves dispersing during the thermal process. Upon those technology advances, the further success of TiAl alloys’ applications is prospected.

• Periodical: Advanced Materials Research (Volume 278)
• Pages: 557-562
• DOI: https://doi.org/10.4028/www.scientific.net/AMR.278.557
• Online since: July 2011
• Authors: Ji Zhang, Di Feng, Fa Jie Yin
• Keywords: Cast, Ingot Metallurgy, Microstructure, Property Analysis, TiAl

References

[1] J. C. Williams, In: Structural Intermetallics 1997, edited by M. V. Nathal, R. Daroila, C. T. Liu, Martin P. L., C. B. Miracle, Wagner R, Yamaguchi M, TMS, Warrendale, PA (1997), p.3.

[2] Y-W. Kim: Acta Metall Mater vol. 40 (1992), p.1121.

[3] T. Tetsui, Advanced Engineering Materials, vol. 3 (2001), p.307.

[4] R.E. Schafrik and S. Walston1, In: Superalloys 2008, edited by R.C. Reed, K.A. Green, P. Caron, T.P. Gabb, M.G. Fahrmann, E.S. Huron and S.A. Woodard, TMS, Warrendale, PA (2008), p.3.

[5] D. M. Dimiduk: Intermetallics vol. 6 (1998), p.613.

[6] M. Yamaguchi, H. Inui and K. Ito: Acta Mater vol. 48 (2000), p.307.

[7] J. Zhang, D. X. Zou, Z. Zhang and Z. Y. Zhong: Acta Metall. Sinica vol. 9(1996), p.571.

[8] B. Godfrey and M. H. Loretto: Intermetallics vol. 4 (1996), p.47.

[9] T.T. Cheng, M.R. Willis and I.P. Jones: Intermetallics vol. 7 (1999), p.89.

[10] W. Li, B. Inkson, Z. Horita, K. Xia: Intermetallics vol. 8 (2000), p.519.

[11] Flemings M C, Solidification Processing, New York: Mcgraw-Hill, 1974: 152.