Abstract
The operative and controlling mechanisms of steady-state creep in hot-pressed AIN have been determined both from kinetic data within the temperature and constant compressive stress ranges of 1470 to 1670 K and 100 to 370 MPa, respectively, and from the microstructural results of TEM. No secondary phases were detected in the bulk or at the grain boundaries using Raman spectroscopy and HREM. The stress exponent was ~1.0 at all temperatures. The activation energies ranged between 558 and 611 kJ/mol. The most prominent microstructural features of the crept samples were elongated grains, strain whorls, and triple-point folds. Dislocations were generated only at the strain whorls in order to relieve the localized stress caused by intraboundary mechanical interaction among the grains. They contributed little to the observed deformation. The controlling mechanism for creep was diffusion-accommodated grain-boundary sliding. This mechanism was accompanied in parallel by relatively small amounts of unaccommodated grain-boundary sliding. Cavitation was not observed.
| Original language | English |
|---|---|
| Pages (from-to) | 1101-1108 |
| Number of pages | 8 |
| Journal | Journal of Materials Research |
| Volume | 8 |
| Issue number | 5 |
| DOIs | |
| State | Published - May 1993 |
| Externally published | Yes |
Funding
The authors are pleased to acknowledge the support of this research by the Army Research Office through Grant No. DAALOG-89-K-0131. The electron microscopy was supported as part of the Ceramic Technology for Advanced Heat Engines Program of the Advanced Materials Development Program and partially performed in the HTML User Facility, both sponsored by the United States Department of Energy, Assistant Secretary for Conservation and Renewable Energy, Office of Transportation Technologies, under Contract DE-AC05-84OR021400 managed by Martin Marietta Energy Systems, Inc. The material used in this study was developed and provided by Dr. W. Rafaniello of Dow Chemical Co. through research sponsored by the United States Department of Energy as part of the Ceramic Technology for Advanced Heat Engines Program under Contract DE-AC05-84OR021400 with Martin Marietta
| Funders | Funder number |
|---|---|
| Assistant Secretary for Conservation and Renewable Energy | |
| HTML | |
| Martin Marietta | |
| Office of Transportation Technologies | DE-AC05-84OR021400 |
| U.S. Department of Energy | |
| Army Research Office | DAALOG-89-K-0131 |