Tetragonal phase in yttria partially stabilized zirconia

Thesis/Dissertation · Wed Jan 01 00:00:00 EST 1986

OSTI ID:6952593

Lanteri, V

The microstructure of the tetragonal phase in yttria partially stabilized zirconia (Y-PSZ) is very sensitive to cooling rates. With fast cooling rates a displacive, but non-martensitic, transformation occurs resulting in the formation of a tetragonal solid solution (t'-ZrO/sub 2/) with the same yttria content as the parent cubic phase (c-ZrO/sub 2/). The microstructure is characterized by the presence of antiphase domain boundaries (APB's) resulting from the loss of symmetry during the transformation, and by 90/sup 0/ twins formed mechanically to relieve the transformation strains. With slow cooling rates, the equilibrium tetragonal solid solution (t-ZrO/sub 2/) starts to precipitate; at room temperature the material has a tweed-like microstructure. After lengthy annealings at high temperatures in the two phase field (t + c), t-ZrO/sub 2/ coarsens in a cubic matrix which can again undergo a displacive transformation upon cooling depending on its rate. t-ZrO/sub 2/ has a particular microstructure consisting of large colonies of twin related variants. Each colony is formed by stacking plates of two tetragonal variants sharing the same (101) habit plane, with their c-axes about 90/sup 0/. The microstructure effectively reduces the overall strain energy.

• Research Organization: Case Western Reserve Univ., Cleveland, OH (USA)
• OSTI ID: 6952593
• Resource Relation: Other Information: Thesis (Ph. D.)
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
YTTRIUM OXIDES
METALLURGICAL EFFECTS
ZIRCONIUM OXIDES
TETRAGONAL LATTICES
MICROSTRUCTURE
STABILIZATION
CHALCOGENIDES
CRYSTAL LATTICES
CRYSTAL STRUCTURE
OXIDES
OXYGEN COMPOUNDS
TRANSITION ELEMENT COMPOUNDS
YTTRIUM COMPOUNDS
ZIRCONIUM COMPOUNDS
360202* - Ceramics
Cermets
& Refractories- Structure & Phase Studies