Transformation toughening of ceramics. Final report, 1 September 1985-31 August 1988

Technical Report · Thu Dec 01 04:00:00 EST 1988

OSTI ID:6052966

Marshall, D B

The results of a three-year study, aimed at understanding factors that dictate microstructural evolution and mechanical properties of transformation toughened ceramics, are summarized. Large crack-growth resistance curves (rather than single-valued toughness) were discovered in toughened zirconia, and these were shown to be responsible for strength-toughness relations, damage tolerance, and other mechanical properties. New insight was gained into mechanisms of controlling grain growth during processing, and a method for forming high strength, fine-grained ZrO/sub 2/ fibers was discovered. In the final year's work, reported in detail here, a new tetragonal-to-orthorhomic phase transformation at low temperatures was discovered and shown to have a dramatic effect on mechanical properties. New methods were applied to measure the amount and location of phase transformation within crack tip zones and to quantify crack tip shielding, evaluate stability and reversibility of the martensitic transformation, and to determine the net transformation strain that gives to toughening. Finally, crack growth under cyclic loading was demonstrated to be important in zirconia materials.

• Research Organization: Rockwell International Corp., Thousand Oaks, CA (USA). Science Center
• OSTI ID: 6052966
• Report Number(s): AD-A-204687/8/XAB; SC-5444.FR
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360202* -- Ceramics
Cermets
& Refractories-- Structure & Phase Studies
360203 -- Ceramics
Cermets
& Refractories-- Mechanical Properties
ALLOYS
CARBON ADDITIONS
CERAMICS
CHALCOGENIDES
CRACK PROPAGATION
CRACKS
CRYSTAL STRUCTURE
DAMAGE
DOCUMENT TYPES
FIBERS
FRACTURE PROPERTIES
GRAIN GROWTH
IRON ALLOYS
LOW TEMPERATURE
MARTENSITE
MATERIALS
MECHANICAL PROPERTIES
MICROSTRUCTURE
OXIDES
OXYGEN COMPOUNDS
PHASE TRANSFORMATIONS
PROGRESS REPORT
TRANSITION ELEMENT COMPOUNDS
ZIRCONIUM COMPOUNDS
ZIRCONIUM OXIDES