Impurity effects on the creep of polycrystalline magnesium and aluminum oxides at elevated temperatures. Technical progress report, December 19, 1974--December 18, 1975 [electronic resource].
- Salt Lake City, Utah : University of Utah, 1975. and Oak Ridge, Tenn. : Distributed by the Office of Scientific and Technical Information, U.S. Dept. of Energy.
- Physical Description:
- Pages: 82 : digital, PDF file
- Additional Creators:
- University of Utah and United States. Department of Energy. Office of Scientific and Technical Information
- Work is reported on: 1. Viscous creep of fine-grained MgO doped with iron. 2. The effects of transition metal impurities and grain size on the creep of polycrystalline Al/sub 2/O/sub 3/. 3. The non-viscous creep of large grain size MgO and Al/sub 2/O/sub 3/, pure and doped with transition metal impurities. 4. Stress relaxation tests on polycrystalline MgO and Al/sub 2/O/sub 3/, pure and doped with transition metal impurities. 5. The construction of creep deformation maps for polycrystalline MgO and Al/sub 2/O/sub 3/, pure and doped with iron. 6. Preliminary studies on the effect of grain size on the creep of polycrystalline mullite. Some of the significant findings include: 1. Power law creep (N approx. 3) in polycrystalline MgO is independent of iron doping, grain size, and oxygen partial pressure. 2. Three well-defined regimes have been identified for the diffusional creep of polycrystalline MgO and Al/sub 2/O/sub 3/, pure and doped with transition metal impurities: (1) cation grain boundary diffusion (2) cation lattice diffusion, (3) anion grain boundary diffusion. 3. Coble diffusional creep, which is rate-limited by oxygen grain boundary diffusion, has been identified in reduced iron-doped (2 cation percent) and double doped (1/4 percent Mn and 1/4 percent Ti) polycrystalline Al/sub 2/O/sub 3/. Stress relaxation deformation tests can be used to (1) identify transitions between viscous and non-viscous deformation, and (2) achieve high stresses (approx. 10/sup 3/ kg/cm/sup 2/) and strain rates (1h/sup -1/) without fracture. Good agreement exists between dead-load creep and stress relaxation studies in four point bending. (auth)
- Published through SciTech Connect., 12/01/1975., "coo-1591-29", and Gordon, R.S.
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