Creep in protective {alpha}-Al{sub 2}O{sub 3} thermally grown on {beta}-NiAl.
The authors report systematic measurements of creep relaxation in {alpha}-Al{sub 2}O{sub 3}, thermally grown in air on (100) single crystals of stoichiometric {beta}-NiAl, at temperatures between 950 and 1100 C. Creep was monitored using time dependent in situ measurements of strain relaxation in the oxide following imposition of a stress resulting from a sudden temperature change. The in-plane elastic strain was obtained using a sin{sup 2} {psi} x-ray diffraction technique exploiting synchrotron radiation. The authors found that strain relaxation rates were comparable to those observed in fine grained {alpha}-Al{sub 2}O{sub 3} ceramics when the latter results were extrapolated to the lower temperatures examined here. Creep rates at stress levels of 100 MPa, or less, are proportional to {sigma}{sup n}, with n - 2, consistent with a diffusional creep mechanism.
- Research Organization:
- Argonne National Lab. (ANL), Argonne, IL (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC)
- DOE Contract Number:
- DE-AC02-06CH11357
- OSTI ID:
- 1000657
- Report Number(s):
- ANL/MSD/JA-57771; TRN: US1100159
- Journal Information:
- Appl. Phys. Lett., Vol. 90, Issue Mar. 2007
- Country of Publication:
- United States
- Language:
- ENGLISH
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