Thin-foil phase transformations of tetragonal ZrO/sub 2/ in a ZrO/sub 2/-8 wt% Y/sub 2/O/sub 3/ alloy

Journal Article · Sat Oct 01 00:00:00 EDT 1988 · J. Am. Ceram. Soc.; (United States)

DOI:https://doi.org/10.1111/j.1151-2916.1988.tb07530.x· OSTI ID:6300678

Bestgen, H; Chaim, R; Heuer, A H

Tetragonal zirconia (t-ZrO/sub 2/) grains in an annealed ZrO/sub 2/-8 wt% Y/sub 2/O/sub 3/ alloy transformed to orthorhombic (o) or mono-clinic (m) symmetry by stresses induced by localized electron beam heating in the transmission electron microscope. Different transformation mechanisms were observed, depending on foil thickness and orientation of individual grains. In thicker grains (greater than or equal to150 nm), the transformation proceeded by a burst-like growth of m laths, and this is believed to approximate bulk behavior. In thinner grains near the edge of the foil, usually those with a (100)/sub t/ orientation perpendicular to the thin-foil surface, continuous growth of an o or m phase with an antiphase-boundary-containing microstructure was observed. The o phase is believed to be a high-pressure polymorph of ZrO/sub 2/, which forms (paradoxically) as a thin-foil artifact because it is less dense than t-ZrO/sub 2/, but more dense than m-ZrO/sub 2/. In some very thin grains, the t ..-->.. m transformation was thermoelastic. Furthermore, a mottled structure often occurred just before the t ..-->.. m or t ..-->.. o transformation, which is attributed to surface transformation. Aside from the lath formation, the observed transformation modes are a result of the reduced constraints in thin foils.

• Research Organization: Ceramic Research Dept., Hoechst A.G., Frankfurt (DE)
• OSTI ID: 6300678
• Journal Information: J. Am. Ceram. Soc.; (United States), Journal Name: J. Am. Ceram. Soc.; (United States) Vol. 71:10; ISSN JACTA
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360202* -- Ceramics
Cermets
& Refractories-- Structure & Phase Studies
656003 -- Condensed Matter Physics-- Interactions between Beams & Condensed Matter-- (1987-)
75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
ANNEALING
BEAMS
BULK DENSITY
CHALCOGENIDES
CRYSTAL LATTICES
CRYSTAL STRUCTURE
DENSITY
ELECTRON BEAMS
ELECTRON MICROSCOPY
FOILS
GRAIN ORIENTATION
HEAT TREATMENTS
HIGH PRESSURE
LEPTON BEAMS
MICROSCOPY
MICROSTRUCTURE
ORIENTATION
ORTHORHOMBIC LATTICES
OXIDES
OXYGEN COMPOUNDS
PARTICLE BEAMS
PHASE TRANSFORMATIONS
PHYSICAL PROPERTIES
SYMMETRY
TETRAGONAL LATTICES
TRANSITION ELEMENT COMPOUNDS
TRANSMISSION ELECTRON MICROSCOPY
YTTRIUM COMPOUNDS
YTTRIUM OXIDES
ZIRCONIUM COMPOUNDS
ZIRCONIUM OXIDES