Hostname: page-component-848d4c4894-sjtt6 Total loading time: 0 Render date: 2024-06-28T12:33:50.810Z Has data issue: false hasContentIssue false

Microstructural Characterization of Creep Tested Cryomilled NiAl-13vol. % AlN

Published online by Cambridge University Press:  15 February 2011

A. Garg
Affiliation:
NASA Lewis Research Center, Cleveland, OH 44135
J. D. Whittenberger
Affiliation:
NASA Lewis Research Center, Cleveland, OH 44135
B. J. M. Aikin
Affiliation:
Case Western Reserve University, Cleveland, OH 44106
Get access

Abstract

Cryomilling of prealloyed NiAl powders, followed by extrusion, has been used to produce a particulate strengthened NiAl-13vol.% AlN material. At 1300 K, the compressive strain rate-flow stress diagram has two distinct deformation regimes, with the transition occurring near 150 MPa. The low and the high stress regimes have power law creep exponents of ∼ 6.1 and 14.2, respectively. Microstructural characterization of the as-extruded and tested samples has been performed to develop an understanding of the superior mechanical properties of the material. The microstructure of the as-extruded material was inhomogeneous and consisted of mantle regions containing a mixture of small NiAl grains (diameter ∼ 50–150 nm) and fine AlN particles (size ∼ 5–50 nm) that surround larger NiAl grains (diameter ∼ 0.3–8.0 μm) which were mostly particle free. In the low-stress regime, samples tested to steady state exhibited a structure composed of subgrain boundaries in the particle-free NiAl grains. In addition, some of the subgrains had developed a well defined dislocation network. AlN patricles occasionally found within large NiAl grains acted as pinning centers for dislocations. Small NiAl grains and the AlN particles constituting the mantle coarsened during these tests. In the high-stress regime, samples tested to steady state exhibited a high density of dislocations in most of the particle-free NiAl grains. Subgrain boundaries were found occasionally but dislocation networks were rare. The AlN particles had not significantly coarsened due to the shorter times at temperature.

Type
Research Article
Copyright
Copyright © Materials Research Society 1994

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

1. Noebe, R. D., Bowmen, R. R., and Nathal, M. V., Int. Mater. Revs. 38, 193 (1993).Google Scholar
2. Daniel Whittenberger, J., Arzt, Eduart, and Luton, Michael J., J. Mat. Res. 5, 271 (1990).Google Scholar
3. Aikin, B. J. M., Daniel Whittenberger, J., and Hebsur, M. G., in Mechanical Alloying for Structural Applications, edited by deBarbadillo, J. J., Froes, F. H. and Schwarz, R. (ASM International, Materials Park, OH, 1993), pp. 283290.Google Scholar
4. . Daniel, J. Whittenberger in International Symposium on Structural Intermetallics, edited by Darolia, R., Lewandowski, J. J., Liu, C. T., Partin, M. L., Miracle, D. B., and Nathal, M. V. (TMS, Warrendale, PA, 1993), pp. 819828.Google Scholar
5. Mills, M. J. and Miracle, D. B., Acta Metall. Mater. 41, 85 (1993).Google Scholar
6. Forbes, K. R., Glatzel, U., Darolia, R. and Nix, W. D. in High Temperature Ordered Intermetallic Alloys V, edited by Baker, I., Darolia, R., Daniel Whittenberger, J., and Yoo, Man H. ( Mater. Res. Soc. Proc. 288, Pittsburgh, PA, 1993), pp. 4558.Google Scholar
7. Daniel Whittenberger, J., J. Mat. Sci. 22, 394 (1987).Google Scholar