Creep in {alpha}-Al{sub 2}O{sub 3} thermally grown on {beta}-NiAl and NiAlPt alloys.
- Materials Science Division
We have measured creep relaxation in {alpha}-Al{sub 2}O{sub 3}, thermally grown on stoichiometric {beta}-NiAl, and on {beta}- and {gamma}{prime}-phase alloys of Ni-Al-Pt at temperatures between 950-1100 C. Creep was monitored using in-situ measurements of strain relaxation in the oxide following the sudden imposition of a stress. A stress was imposed by abruptly changing the sample temperature, exploiting the thermal expansion difference between oxide and substrate. The in-plane elastic strain was obtained using a sin{sup 2}{psi} X-ray diffraction technique exploiting synchrotron radiation. For oxides grown on {beta}-NiAl and Ni-Al-Pt samples, we found that strain relaxation rates are comparable to those observed in fine grained {alpha}-Al{sub 2}O{sub 3} bulk ceramics, when bulk results are extrapolated to the lower temperatures examined here. When Hf was added to the Ni-Al-Pt alloy, creep rates in the thermally grown oxide were substantially slowed. Creep rates at stress levels of 100 MPa, or less, are proportional to on, with n {le} 2, consistent with a diffusional creep mechanism.
- Research Organization:
- Argonne National Lab. (ANL), Argonne, IL (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC); ONR
- DOE Contract Number:
- DE-AC02-06CH11357
- OSTI ID:
- 1009339
- Report Number(s):
- ANL/MSD/JA-68695; TRN: US1101424
- Journal Information:
- Surf. Coating Technol., Vol. 202, Issue 4-7 ; Dec. 2007
- Country of Publication:
- United States
- Language:
- ENGLISH
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