Role of grain size in strength variability of alumina

Journal Article · Fri Jul 01 00:00:00 EDT 1994 · Journal of the American Ceramic Society; (United States)

DOI:https://doi.org/10.1111/j.1151-2916.1994.tb07073.x· OSTI ID:7104070

Kovar, D; Readey, M J ^[1]

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1. Carnegie Mellon Univ., Pittsburgh, PA (United States). Dept. of Materials Science and Engineering

Relationships between grain size and strength variability in alumina were investigated. Results are presented for an ultra-high-purity alumina with a narrow grain size distribution and an equiaxed grain morphology at three grain sizes ranging from 5 to 27 [mu]m. Vickers indentations are used to introduce controlled flaws into the specimens. It is found that increasing the grain size leads to enhanced flaw tolerance owing to a rising R-curve. However, contrary to recent theoretical predictions, no reduction in strength variability is found with increasing grain size. It is proposed that increasing variability in local fracture toughness with grain size offsets any improvement in reliability. This suggests that an upper bound to the reliability of grain-bridging materials may exist.

• DOE Contract Number: AC04-94AL85000
• OSTI ID: 7104070
• Journal Information: Journal of the American Ceramic Society; (United States), Vol. 77:7; ISSN 0002-7820
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALUMINIUM OXIDES
GRAIN SIZE
MECHANICAL PROPERTIES
CERAMICS
FRACTURE PROPERTIES
TENSILE PROPERTIES
ALUMINIUM COMPOUNDS
CHALCOGENIDES
MICROSTRUCTURE
OXIDES
OXYGEN COMPOUNDS
SIZE
360202* - Ceramics
Cermets
& Refractories- Structure & Phase Studies
360203 - Ceramics
Cermets
& Refractories- Mechanical Properties