Compressive Strength of Polycrystalline Alumina.
Interim rept. 4 Apr 75-31 Mar 76,
SOUTHWEST RESEARCH INST SAN ANTONIO TEX
Pagination or Media Count:
The compressive strength of polycrystalline alumina at 23C is found to be strain rate and temperature sensitive, but insensitive to environment. Scanning electron microscopy of specimens loaded to near failure indicates the basis of the thermally-activated process which controls failure to be localized plasticity in the form of twinning and, possibly, slip. The interaction of these deformation bands with grain boundaries causes the initiation of microcracks. Higher stresses produce still more twinslip nucleated microcracks, which finally coalesce at failure. Twinning occurs at stresses below 50 of the failure strength and may play a role in crack nucleation during indentation and impact loading. It is suggested that twinning also may be related to the tensile failure of alumina.
- Ceramics, Refractories and Glass