Skip to main content Accessibility help

Physical and Mechanical Properties of Mo5X3+α (X=Si, B, C) Single Crystals

  • Taisuke Hayashi (a1), Kazuhiro Ito (a1), Katsushi Tanaka (a2) and Masaharu Yamaguchi (a1)


Mo5X3+α (X=Si, B, C) intermetallic compounds such as Mo5SiB2 (D8l), Mo5Si3 (D8m) and Mo5Si3C (D88) have a great potential for ultra-high temperature applications. The present study was undertaken putting greater emphasis on clarifying how their physical and mechanical properties are similar or different in terms of a structure type. Some interesting features are summarized in this paper.

The resistivity of Mo5SiB2, Mo5Si3 and Mo5Si3C single crystals exhibited a negative curvature (d2ρ(T)/dT2<0), with a tendency towards saturation. In the Mo5Si3C with large ρ0 due to impurity carbon atoms, resistivity saturation is pronounced. In contrast, a much higher temperature is required to reach saturation in the Mo5SiB2. The anisotropy ratio of CTE (αca) for the Mo5SiB2 is about 1.2–1.6 and is significantly reduced from about 2 of the Mo5Si3 and Mo5Si3C. On the other hand, the Young's modulus of the Mo5SiB2 is more anisotropic than those of the Mo5Si3 and Mo5Si3C. Plastic anisotropy was observed in the Mo5SiB2, because only slip on [001] {100} is operative at 1500°C. On the contrary, plastic deformation was observed at temperatures above 1300°C for the Mo5Si3C and Mo5Si3. Anisotropy of their plastic deformation was much less than that of the Mo5SiB2, presumably because more than two slip systems can be activated. Creep resistance of the Mo5SiB2 is much better than that of the Mo5Si3 as well as the most advanced materials such as MoSi2 and Si3N4 based structural ceramics.



Hide All
1. Meyer, M.K., Kramer, M.J. and Akinc, M., Adv. Mater. 8, 85 (1996).
2. Meyer, M.K., Akinc, M., J. Am. Ceram. Soc. 79, 938 (1996).
3. Zhu, Q., Shobu, K., Tani, E., Kishi, K. and Umebayashi, S., J. Mater. Sci. 35, 863 (2000).
4. Ito, K., Ihara, K., Tanaka, K., Fujikura, M. and Yamaguchi, M., Intermetallics 9, 591 (2001).
5. Beckman, S., Cook, B.A. and Akic, M., Mater. Sci. Eng. A298, 120 (2001).
6. Ito, K., Hayashi, T., Nakamura, H. and Yamaguchi, M., to be submitted to Intermetallics.
7. Nava, F., Tu, K.N., Thomas, O., Senateur, J.P., Madar, R., Borghesi, A., Guizzetti, G., Gottlieb, U., Laborde, O. and Bisi, O., Mater. Sci. Rep. 9, 141 (1993).
8. Gurvitch, M., Phys. Rev. B24, 7404 (1981).
9. Wilson, A.H., “The Mechanism of Conductivity,” The Theory of Metals, 2nd Ed. (Cambridge Univ. Press, London, 1965) pp. 251299.
10. Chu, F., Thoma, D.J., McClellan, K., Peralta, P. and He, Y., Intermetallics 7, 611 (1999).
11. Fu, C.L. and Wang, X., Phil. Mag. Lett. 80, 683 (2000).
12. Hayashi, T., Ito, K. and Yamaguchi, M., in preparation.
13. Tanaka, K., Onome, H., Inui, H., Yamaguchi, M. and Koiwa, M., Mater. Sci. Eng. A239–240, 188 (1997).
14. Meyer, M.K., Kramer, M.J. and Akinc, M., Intermetallics 4, 273 (1996).
15. Field, R.D., Thoma, D.J., Cooley, J.C., Chu, F., Fu, C.L., Yoo, M.H., Hults, W.L. and Cady, C.M., Intermetallics 9, 863 (2001).
16. Ito, K., Yano, T., Nakamoto, T., Inui, H. and Yamaguchi, M., Intermetallics 4, S119 (1996).
17. Ito, K., Moriwaki, M., Nakamoto, T., Inui, H. and Yamaguchi, M., Mater. Sci. Eng. A233, 33 (1997).
18. Yoshimi, K., Yoo, M.H., Wereszczak, A.A., Borowicz, S.M., George, E.P. and Zee, R.H., Scripta Mater. 45, 1321 (2001).
19. Inui, H., Ishikawa, K. and Yamaguchi, M., Intermetallics 8, 1159 (2000).
20. Mason, D.P. and Van Aken, D.C., Acta. Metall. Mater. 43, 1201 (1995).
21. Umakoshi, Y., Nakashima, T., Nakano, T. and Yanagisawa, E., in High Temperature Silicides and Refractory Alloys, edited by Briant, C.L., Petrovic, J.J., Bewlay, B.P., Vasudevan, A.K. and Lipsitt, H.A. (Mater. Res. Soc. Proc. 322, Pittsburgh, PA, 1994) pp. 920.
22. Sadananda, K., Feng, C.R., Mitra, R. and Deevi, S.C., Mater. Sci. Eng. A261, 223 (1999).

Physical and Mechanical Properties of Mo5X3+α (X=Si, B, C) Single Crystals

  • Taisuke Hayashi (a1), Kazuhiro Ito (a1), Katsushi Tanaka (a2) and Masaharu Yamaguchi (a1)


Full text views

Total number of HTML views: 0
Total number of PDF views: 0 *
Loading metrics...

Abstract views

Total abstract views: 0 *
Loading metrics...

* Views captured on Cambridge Core between <date>. This data will be updated every 24 hours.

Usage data cannot currently be displayed