Displacive Phase Transformations in Zirconia-Based Ceramics

1986 ◽  
Vol 78 ◽  
Author(s):  
B. C. Muddle
Keyword(s):  
Habit Plane ◽  
Orientation Relationship ◽  
Tetragonal Zirconia ◽  
Formal Theory ◽  
Orthorhombic Phase ◽  
Thin Foil ◽  
Intermediate Stage ◽  
Transformation Toughening ◽  
Stabilized Zirconia ◽  
Partially Stabilized Zirconia

ABSTRACTA review is presented of experimental observations of the mechanism and crystallography of the martensitic tetragonal to monoclinic transformation occurring both in dispersed tetragonal ZrO2 particles in partially stabilized zirconia and in polycrystalline tetragonal zirconia. Preliinary results of determination of the orientation relationship and habit plane for the stress-activated transformation in a CeO2 –stabilized TZP ceramic are reported and compared with predictions of the crystallographic theory for the transformation. This orientation relationship is such that (100)m//(100)t and [001]m//[001]m, and for this variant of the orientation relationship the habit plane is approximately ( 301 )t. These results are in good agreement with theoretical predictions. Progress in the application of the formal theory of martensitic transformations to the transformations in both types of system is examined critically and implications for theories of transformation toughening are discussed.Attention is also given to tetragonal orthorhombic and orthorhombic monoclinic transformations occurring in Zro2 particles in thin foil specimens of partially stabilized zirconia. Formation of a metastable orthorhombic phase appears a possible, but not essential, intermediate stage in the tetragonal to monoclinic transition. However, present evidence strongly suggests that the orthorhombic structure only occurs in those particles experiencing the relaxed matrix constraints typical of thin foil specimens.

Examination of CaO-Dy2O3 for potential use as a high-temperature transformation toughening System

1988 ◽  
Vol 46 ◽  
pp. 790-791
Author(s):  
M. M. Fleming ◽  
W. M. Kriven
Keyword(s):  
High Temperature ◽  
Room Temperature ◽  
Transformation Toughening ◽  
Stabilized Zirconia ◽  
Two Phase ◽  
Volume Increase ◽  
Partially Stabilized Zirconia ◽  
Temperature Transformation ◽  
Fast Quenching ◽  
Potential Use

Similarities exist between the tetragonal to monoclinic transformation of ZrO2 and the monoclinic (B) to cubic (C) transformation of Dy2O3. On cooling the transformation occurs at 1950°C and is accompanied by an 8 % volume increase which causes shattering of bulk specimens. The transformation can be suppressed, however, by minor additions of CaO. An attempt was made to fabricate a “PSD” analogue to partially stabilized zirconia (PSZ).As-received and chemically precipitated powders of pure Dy2O3 were mixed with CaO (0 to 25 mol%), uniaxially and cold isostatically pressed, sealed in small Mo crucibles and sintered at various temperatures (1900° or 1650°C) and times before cooling or subsequent annealing treatments. Some pellets were annealed in the two phase (B + C) region at 1700°C for 2 hours before quenching. Specimens were examined by XRD, TEM, EDS, HVEM, and STEM.A fast quenching in combination with the =8 mol% CaO additions were found to be essential for retention of the high temperature B phase down to room temperature.

Surface Damage of Yttria-Tetragonal Zirconia Polycrystals and Magnesia-Partially-Stabilized Zirconia in Single-Point Abrasion

1995 ◽  
Vol 78 (12) ◽  
pp. 3357-3362 ◽  
Author(s):  
S. A. Syed Asif ◽  
D. Victor Suvisesha Muthu ◽  
Ajay Kumar Sood ◽  
Sanjay Kumar Biswas
Keyword(s):  
Single Point ◽  
Tetragonal Zirconia ◽  
Surface Damage ◽  
Stabilized Zirconia ◽  
Partially Stabilized Zirconia

Terahertz-induced martensitic transformation in partially stabilized zirconia

2021 ◽  
Author(s):  
Masaya Nagai ◽  
Yuhei Higashitani ◽  
Masaaki Ashida ◽  
Koichi Kusakabe ◽  
Hirohiko Niioka ◽  
...  
Keyword(s):  
Martensitic Transformation ◽  
Shear Deformation ◽  
Tetragonal Zirconia ◽  
Thermal Quenching ◽  
Stabilized Zirconia ◽  
Phonon Modes ◽  
Partially Stabilized Zirconia ◽  
Terahertz Pulses ◽  
Transformation Mechanisms ◽  
Local Shear

Abstract Martensitic crystal structures are usually obtained by rapid thermal quenching of certain alloys, which induces stress and subsequent shear deformation. Here, we demonstrate that it is also possible to intentionally excite a suitable transverse acoustic phonon mode to induce a local shear deformation. We irradiate the surface of a partially stabilized zirconia plate with intense terahertz pulses and verify martensitic transformation from the tetragonal to the monoclinic phases by Raman spectroscopy and the observed destructive spallation of the zirconia microcrystals. We calculate the phonon modes in tetragonal zirconia and determine the effective channel that triggers the transformation. This mode can be excited via the Klemens process. Since terahertz pulses can induce a specific local shear deformation beyond thermal equilibrium, they can be used to elucidate phase transformation mechanisms with dynamical approaches. Terahertz-induced martensitic transformation is considered to be useful for material strengthening and shape memory ceramics.

Pitfalls of local and quantitative phase analysis in partially stabilized zirconia

2012 ◽  
Vol 45 (6) ◽  
pp. 1136-1144 ◽  
Author(s):  
Stefan Martin ◽  
Harry Berek ◽  
Christos G. Aneziris ◽  
Ulrich Martin ◽  
David Rafaja
Keyword(s):  
Phase Transformation ◽  
Phase Analysis ◽  
Tetragonal Zirconia ◽  
Quantitative Phase Analysis ◽  
Local Concentration ◽  
Stabilized Zirconia ◽  
Concentration Gradients ◽  
Continuous Transition ◽  
Partially Stabilized Zirconia ◽  
Quantitative Phase

The addition of selected elements into the host structure of ZrO2stabilizes the tetragonal and cubic phases of zirconia, which are, in their undoped binary form, only stable at high temperatures. From the crystallographic point of view, the increasing amount of the stabilizer causes a continuous transition of the tetragonal zirconia to its cubic modification. In partially stabilized zirconia, local concentration gradients of the stabilizer are frequently present as a consequence of the production process, which results in a coexistence of zirconia domains having different degrees of tetragonality. The presence of the local concentration gradients in such samples and the continuous nature of the phase transformation are features important for many technological applications, but their analysis is not straightforward. Furthermore, these features complicate the quantitative phase analysis in partially stabilized zirconia. For the example of zirconia partially stabilized by magnesium, this contribution illustrates the capabilities and limitations of X-ray and electron backscatter diffraction. In particular, the ability of these experimental methods to reveal the gradual lattice distortion that is associated with the cubic to tetragonal phase transformation in zirconia and the reliability of the quantitative phase analysis are discussed. In this context, it is shown to what extent the choice of the microstructure model influences the result of the phase analysis.

A Study of Rhombohedral Phase in Y2 O3 -Partially Stabilized Zirconia

1986 ◽  
Vol 78 ◽  
Author(s):  
Jukishige Kitano ◽  
Y. Mori ◽  
A. Ishitani ◽  
T. Masaki
Keyword(s):  
Heat Treatment ◽  
Phase Transformation ◽  
Hot Isostatic Pressing ◽  
Tetragonal Zirconia ◽  
Rhombohedral Phase ◽  
X Ray Diffraction ◽  
Stabilized Zirconia ◽  
Partially Stabilized Zirconia ◽  
X Ray ◽  
The Stability

ABSTRACTTetragonal to rhombohedral phase transformation was studied by X-ray diffraction technique on the ground surfaces of tetragonal zirconia polycrystals (Y-TZP) and partially stabilized zirconia (Y-PSZ) with 2.0 to 5.0 mol% Y2 O3 contents prepared by hot isostatic pressing. The rhombohedral phase increased with increase of Y2 O3 content from 2.0 to 5.0 mol%, and also with the increase of HIPing temperature from 1400 to 1600°C. The stability of the phase was also studied with regard to the surface finish and annealing. The subsequent heat treatment of the samples was found to promote the reverse rhombohedral to tetragonal transformation.

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