Evidence of grain-boundary-sliding-induced cavitation in ceramics under compression

Journal Article · Thu Jul 01 04:00:00 EDT 1993 · Journal of the American Ceramic Society; (United States)

DOI:https://doi.org/10.1111/j.1151-2916.1993.tb06631.x· OSTI ID:6464560

Blanchard, C R; Chan, K S ^[1]

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1. Southwest Research Inst., San Antonio, TX (United States)

Detailed microscopy of two crept aluminas, one with (AD99) and one without (Lucalox) a grain boundary glassy phase, has been performed to determine the pertinent damage mechanisms during creep. Evidence is presented for a nucleation-controlled cavitation process where creep cavities nucleate primarily on two-grain facets, followed by cavity growth and coalescence to form grain-facet-sized cavities and microcracks. A variety of creep cavity morphologies were observed in Lucalox, including spheroidal and irregularly shaped cavities. The latter finding implies a strong influence of crystallographic orientation and the corresponding surface energy of the cavitated planes on the cavity shaped. In contrast, classical spheroidal cavities were observed in AD99 due to the presence of a viscous phase along grain boundaries. Direct evidence for grain boundary sliding as the process driving force for cavitation in Lucalox is presented together with evidence for the nucleation of creep cavities at grain boundary ledges. These findings are compared to the grain boundary sliding (GBS) and small-angle neutron scattering (SANS) measurements performed previously on the same systems. Based on this study, the cavity nucleation process in the glassy-phase- and non-glassy-phase-containing aluminas is apparently similar as both involve the nucleation of rows of equally sized and equally spaced cavities.

• DOE Contract Number: FG05-84ER45063
• OSTI ID: 6464560
• Journal Information: Journal of the American Ceramic Society; (United States), Journal Name: Journal of the American Ceramic Society; (United States) Vol. 76:7; ISSN 0002-7820; ISSN JACTAW
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360203* -- Ceramics
Cermets
& Refractories-- Mechanical Properties
ALUMINIUM COMPOUNDS
ALUMINIUM OXIDES
CAVITATION
CHALCOGENIDES
CREEP
FAILURES
GRAIN BOUNDARIES
GRAIN ORIENTATION
MECHANICAL PROPERTIES
MICROSCOPY
MICROSTRUCTURE
MORPHOLOGY
NUCLEATION
ORIENTATION
OXIDES
OXYGEN COMPOUNDS
SCATTERING
SMALL ANGLE SCATTERING