Transformation toughening in the alumina-chromia/ziroconia-hafnia system
Thesis/Dissertation
·
OSTI ID:5144108
Fracture toughness, strength, and elastic modulus of Al/sub 2/O/sub 3/-Cr/sub 2/O/sub 3/ (matrix)/ZrO/sub 2/-HfO/sub 2/ (dispersed phase) composites were measured. The fracture toughness generally increased with increasing dispersed phase volume fraction for samples with 5 m/o Cr/sub 2/O/sub 3/ in the matrix. A similar trend was observed in the 20 m/o Cr/sub 2/O/sub 3/ samples at low volume fractions of ZrO/sub 2/-HfO/sub 2/. At high volume fractions the toughness decreased. Strength and elastic modulus remained nearly constant up to 10-12.5 v/o dispersed phase and then decreased. Chromia additions to the matrix increased the dispersed phase particle size and decreased the retained tetragonal fraction. Fracture toughness increased initially and peaked at 10 m/o CrO/sub 3/. Strength, elastic modulus and fracture toughness degradation was observed in the high chromia containing samples due to high monoclinic zirconia volume fractions causing extensive microcracking. Hafnia additions had little effect on the strength and elastic modulus for low ZrO/sub 2/-HfO/sub 2/ contents. For large ZrO/sub 2/-HfO/sub 2/ contents, the strength and elastic modulus increased with increasing hafnia content due to a decrease in the transformation volume change, causing less microcracking.
- Research Organization:
- Michigan Univ., Ann Arbor (USA)
- OSTI ID:
- 5144108
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
36 MATERIALS SCIENCE
360203 -- Ceramics
Cermets
& Refractories-- Mechanical Properties
360303* -- Composite Materials-- Mechanical Properties-- (-1987)
ALUMINIUM COMPOUNDS
ALUMINIUM OXIDES
CHALCOGENIDES
CHROMIUM COMPOUNDS
CHROMIUM OXIDES
COMPOSITE MATERIALS
DISPERSIONS
ELASTICITY
FRACTURE PROPERTIES
HAFNIUM COMPOUNDS
HAFNIUM OXIDES
MATERIALS
MATRIX MATERIALS
MECHANICAL PROPERTIES
OXIDES
OXYGEN COMPOUNDS
REFRACTORY METAL COMPOUNDS
TENSILE PROPERTIES
TRANSITION ELEMENT COMPOUNDS
YIELD STRENGTH
ZIRCONIUM COMPOUNDS
ZIRCONIUM OXIDES
360203 -- Ceramics
Cermets
& Refractories-- Mechanical Properties
360303* -- Composite Materials-- Mechanical Properties-- (-1987)
ALUMINIUM COMPOUNDS
ALUMINIUM OXIDES
CHALCOGENIDES
CHROMIUM COMPOUNDS
CHROMIUM OXIDES
COMPOSITE MATERIALS
DISPERSIONS
ELASTICITY
FRACTURE PROPERTIES
HAFNIUM COMPOUNDS
HAFNIUM OXIDES
MATERIALS
MATRIX MATERIALS
MECHANICAL PROPERTIES
OXIDES
OXYGEN COMPOUNDS
REFRACTORY METAL COMPOUNDS
TENSILE PROPERTIES
TRANSITION ELEMENT COMPOUNDS
YIELD STRENGTH
ZIRCONIUM COMPOUNDS
ZIRCONIUM OXIDES