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Microstructures and mechanical properties of NiAl–Ni2AlHf alloys

Published online by Cambridge University Press:  31 January 2011

M. Takeyama  and
C. T. Liu
M. Takeyama
Affiliation:
Metals and Ceramics Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6115
C. T. Liu
Affiliation:
Metals and Ceramics Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6115
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Abstract

The microstructure and mechanical properties of several Ni–Al–Hf alloys in the composition range between NiAl (β) and Ni2AlHf (Heusler phase) have been studied. The volume fraction of Heusler phase, Vf, in these alloys varies from about 15 to 96%. The lattice misfit between the β and Heusler phases in two-phase alloys is larger than 5%, indicating no coherency between them. The yield strength increases with increasing Vf at all temperatures to 1000°C. Compressive ductilities of 4 and 7% were obtained for the alloy with Vf of 15% at room temperature and 500°C, respectively, but they decreased to 0% with increasing Vf to 96%. The corresponding fracture mode is basically transgranular cleavage. However, all the alloys can be deformed extensively without fracture at 1000°C. The hardness of the Heusler alloy is very high (8.3 GPa) at room temperature, and it decreases gently with temperature to 600°C, followed by a rapid decrease to 1000°C. The brittleness and high hardness of the Ni2AlHf Heusler phase at low temperatures are interpreted in terms of internal lattice distortion resulting from its crystal structure. The thermally activated process of deformation takes place above 600°C, which is responsible for the rapid drop of the hardness of the alloys.

Type
Articles
Information
Journal of Materials Research , Volume 5 , Issue 6 , June 1990 , pp. 1189 - 1196
Copyright
Copyright © Materials Research Society 1990

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References

REFERENCES

1Stoloff, N. S., Koch, C. C., Liu, C.T., and Izumi, O., High Temperature Ordered Intermetallic Alloys II (Materials Research Society, Pittsburgh, PA, 1987), Vol. 81.Google Scholar
2Liu, C.T., Taub, A. I., Stoloff, N. S., and Koch, C. C., High Temperature Ordered Intermetallic Alloys III (Materials Research Society, Pittsburgh, PA, 1989), Vol. 133.Google Scholar
3Pascoe, R.T. and Newey, C.W., Metal Sci. J. 2, 138 (1968).CrossRefGoogle Scholar
4Hahn, K. H. and Vedula, K., Scripta Metall. 23, 7 (1989).CrossRefGoogle Scholar
5Strutt, P. R., Polvani, R. S., and Ingram, J. C., Metall. Trans. A 7A, 23 (1976).CrossRefGoogle Scholar
6Polvani, R. S., Tzeng, W-S., and Strutt, P.R., Metall. Trans. A 7A, 33 (1976).CrossRefGoogle Scholar
7Strutt, P. R. and Kear, B. H., in High Temperature Ordered Intermetallic Alloys I (Materials Research Society, Pittsburgh, PA, 1985), Vol. 39, p. 279.Google Scholar
8Yamaguchi, M., Umakoshi, Y., and Yamane, T., Phil. Mag. A 50, 205 (1984).CrossRefGoogle Scholar
9Umakoshi, Y., Yamaguchi, M., and Yamane, T., Phil. Mag. A 52, 357 (1985).CrossRefGoogle Scholar
10Whittenberger, J. D., Viswanadham, R. K., Mannan, S. K., and Kumar, K. S., in High Temperature Ordered Intermetallic Alloys III (Materials Research Society, Pittsburgh, PA, 1989), Vol. 133.Google Scholar
11Vedula, K., Pathare, V., Aslandis, I., and Titram, R.H., in High Temperature Ordered Intermetallic Alloys I (Materials Research Society, Pittsburgh, PA, 1985), Vol. 39, p. 411.Google Scholar
12Nash, P. and West, D. R. F., Metal Science 15, 347 (1981).CrossRefGoogle Scholar
13Cullity, B. D., Elements of X-ray Diffraction (Addison-Wesley Publishing Company Inc., Reading, MA, 1978), 2nd ed., p. 411.Google Scholar
14Boettinger, W. J., Bendersky, L.A., Biancaniello, F. S., and Cahn, J.W., Mater. Sci. Eng. 98, 273 (1988).CrossRefGoogle Scholar
15Nash, P. and Liang, W.W., Metall. Trans. A 16A, 319 (1985).CrossRefGoogle Scholar
16Laves, F., Theory of Alloy Phases (American Society for Metals, Metals Park, OH, 1956), p. 124.Google Scholar
17Villars, P. and Calvert, L. D., Pearson's Handbook of Crystallographic Data for Intermetallic Phases (American Society for Metals, Metals Park, OH, 1985).Google Scholar
18Takeyama, M. and Liu, C.T., Oak Ridge National Laboratory (1989) (unpublished research).Google Scholar
19Pak, H-R., Chen, C-W., Inal, O.T., Okazaki, K., and Suzuki, T., Mater. Sci. Eng. (1989) (in press).Google Scholar
20Taub, A.I. and Fleischer, R.L., Science 243, 616 (1989).CrossRefGoogle Scholar
21Atkins, A. G., in The Science of Hardness Testing and its Research Application, edited by Westbrook, J. H. and Conrad, H. (American Society for Metals, Metals Park, OH, 1973), p. 223.Google Scholar
22Hancock, G. F. and McDonnel, B. R., Phys. Status Solidi (A) 4, 143 (1971).CrossRefGoogle Scholar