Significance of internal stresses for the martensitic transformation in yttria-stabilized tetragonal zirconia polycrystals during degradation
Various aspects of the tetragonal (t) to monoclinic (m) transformation during degradation have been studied experimentally and theoretically in yttria-stabilized tetragonal zirconia polycrystals (Y-TZP), i.e., polycrystalline t-ZrO/sub 2/ containing Y/sub 2/O/sub 3/ in solution. Transmission electron microscopy (TEM) revealed that protruding grains at the surface of Y-TZP specimens do not transform under corrosive conditions (250/sup 0/C, humid atmosphere) even after n annealing time of 168 h.) Eigenstresses due to anistropic thermal expansion in and around protruding and bulk grains have been calculated for Y-TZP containing 2 and 3 mol% Y/sub 2/O/sub 3/. The prominent role of these stresses on subsequent transformation nucleation during degradation is shown to agree qualitatively with an established free energy concept. The lack of complete transformation of m-ZrO/sub 2/ is attributed to characteristics of the nucleation - and growth- controlled transformation process.
- Research Organization:
- Max-Planck-Institut fur Metallforschung, Institut fur Werkstoffwissenschaften, Stuttgart
- OSTI ID:
- 7067276
- Journal Information:
- J. Am. Ceram. Soc.; (United States), Journal Name: J. Am. Ceram. Soc.; (United States) Vol. 69:7; ISSN JACTA
- Country of Publication:
- United States
- Language:
- English
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360201 -- Ceramics
Cermets
& Refractories-- Preparation & Fabrication
360202* -- Ceramics
Cermets
& Refractories-- Structure & Phase Studies
360203 -- Ceramics
Cermets
& Refractories-- Mechanical Properties
ALLOYS
ANISOTROPY
ANNEALING
CARBON ADDITIONS
CHALCOGENIDES
CHEMICAL REACTIONS
CORROSION
CRYSTAL STRUCTURE
CRYSTALS
ELECTRON MICROSCOPY
EXPANSION
GRAIN SIZE
HEAT TREATMENTS
HIGH TEMPERATURE
IRON ALLOYS
MARTENSITE
MICROSCOPY
MICROSTRUCTURE
NUCLEATION
OXIDES
OXYGEN COMPOUNDS
PHASE TRANSFORMATIONS
POLYCRYSTALS
RESEARCH PROGRAMS
SIZE
STRESSES
THERMAL EXPANSION
TIME DEPENDENCE
TRANSITION ELEMENT COMPOUNDS
TRANSMISSION ELECTRON MICROSCOPY
YTTRIUM COMPOUNDS
YTTRIUM OXIDES
ZIRCONIUM COMPOUNDS
ZIRCONIUM OXIDES