Fracture toughness anisotropy and toughening mechanisms of a hot-pressed alumina reinforced with silicon carbide whiskers

Journal Article · Wed Mar 31 23:00:00 EST 1993 · Journal of the American Ceramic Society; (United States)

DOI:https://doi.org/10.1111/j.1151-2916.1993.tb05304.x· OSTI ID:6219137

Hansson, T; Warren, R; Wasen, J ^[1]

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1. Chalmers Univ. of Technology, Goeteborg (Sweden). Dept. of Engineering Metals

The fracture toughness of a hot-pressed alumina and that of a hot-pressed alumina/SiC-whisker composite containing 33 vol% SiC whiskers were measured by four-point bending on single-edge precracked bend bars having sharp precracks created by bridge indentation. Two batches of the composite were examined, one exhibiting a greater degree of whisker clustering than the other. The fracture toughness of the alumina was around 4 MN[center dot]m[sup [minus]3/2] whereas that of the composite varied between 5 and 8 MN[center dot]m[sup [minus]3/2] depending on microstructural uniformity and crack-propagation direction. Crack deflection in combination with a change in fracture from intergranular to transgranular fracture is proposed as an explanation of the superior fracture toughness of SiC-whisker-reinforced alumina as compared to unreinforced alumina. The composite exhibited a variation in fracture toughness with the crack-propagation direction in identical crack planes. This effect could with good accuracy be described in terms of crack deflection for the composite with uniform whisker distribution. However, in the material with whisker clustering the variation of the fracture toughness with crack-growth direction was greater and could not entirely by explained by crack deflection.

• OSTI ID: 6219137
• Journal Information: Journal of the American Ceramic Society; (United States), Journal Name: Journal of the American Ceramic Society; (United States) Vol. 76:4; ISSN 0002-7820; ISSN JACTAW
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360203 -- Ceramics
Cermets
& Refractories-- Mechanical Properties
360603* -- Materials-- Properties
ALUMINIUM COMPOUNDS
ALUMINIUM OXIDES
ANGULAR CORRELATION
ANISOTROPY
CARBIDES
CARBON COMPOUNDS
CHALCOGENIDES
COMPOSITE MATERIALS
CORRELATIONS
CRACK PROPAGATION
CRYSTALS
FABRICATION
FRACTURE MECHANICS
FRACTURE PROPERTIES
HOT PRESSING
MATERIALS
MATERIALS WORKING
MECHANICAL PROPERTIES
MECHANICS
MICROSTRUCTURE
MONOCRYSTALS
OXIDES
OXYGEN COMPOUNDS
PRESSING
REINFORCED MATERIALS
SILICON CARBIDES
SILICON COMPOUNDS
WHISKERS