Acoustic Emission and Microcracking in Sapphire, Sintered Al2O3, Al/Al2O3 Composite, and Aluminum |
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| Authors: | Else Breval Varanasi Srikanth Eleswarapu C Subbarao |
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| Affiliation: | Intercollege Materials Research Laboratory, The Pennsylvania State University, University Park, Pennsylvania 16802 |
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| Abstract: | A range of materials with brittle to ductile behavior (single-crystal and polycrystalline alumina, aluminum/alumina composite, and metallic aluminum) were investigated by acoustic emission (AE) methods for microcracking during hardness indentations or cooling from elevated temperatures (800°C). During indentation, the extent of crack formation (and the AE counts) decreased in the following order: sapphire, sintered alumina, aluminum/alumina composite with no microcracking in metallic aluminum. During cooling from 800°C, polycrystalline alumina exhibited more extensive microcracking than the aluminum/alumina composite, suggesting that the metallic phase in the aluminum/alumina composite absorbs stresses more than the glassy boundary phase in sintered alumina. |
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