Transformation toughening of ceramics. Annual report No. 2, 1 September 1986-31 August 1987

Technical Report · Thu Oct 01 04:00:00 EDT 1987

OSTI ID:7161203

Marshall, D B

The mechanical properties of high-toughness magnesia-partially-stabilized zirconia were found to be severely degraded by a single cooling cycle between room temperature and 196 C. In-situ Raman spectroscopy and optical interference measurements, and room temperature x-ray diffraction were used to correlate the changes in mechanical properties with structural changes; cooling to temperatures below approximately -100C caused transformation of most of the tetragonal precipitates responsible for toughening to a new phase that was stable with heating to 300 C, but at 400 C it transformed back to the tetragonal structure. After heating to 400 C the original high-toughness mechanical properties were also restored. A new approach for measuring the nature and distribution of strains within transformation zones surrounding cracks in transformation-toughened materials was demonstrated, using Mg-PSZ. The method involves measuring out-of-plane distortions adjacent to a surface-breaking crack and comparing the measurements with computed displacements. The fraction of transformation was found to be strongly varying function of distance from the crack plane.

• Research Organization: Rockwell International Corp., Thousand Oaks, CA (USA). Science Center
• OSTI ID: 7161203
• Report Number(s): AD-A-190399/6/XAB; AFOSRTR-87-1854
• 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
ALKALINE EARTH METAL COMPOUNDS
ALLOYS
CARBON ADDITIONS
CHALCOGENIDES
COOLING
CRACKS
CRYSTAL STRUCTURE
DOCUMENT TYPES
IRON ALLOYS
LASER SPECTROSCOPY
MAGNESIUM COMPOUNDS
MAGNESIUM OXIDES
MARTENSITE
MECHANICAL PROPERTIES
METALLURGICAL EFFECTS
MICROSTRUCTURE
OPTICAL PROPERTIES
OXIDES
OXYGEN COMPOUNDS
PHASE TRANSFORMATIONS
PHYSICAL PROPERTIES
PROGRESS REPORT
RAMAN SPECTROSCOPY
SPECTROSCOPY
STABILIZATION
TRANSITION ELEMENT COMPOUNDS
ZIRCONIUM COMPOUNDS
ZIRCONIUM OXIDES