The modulated structure formed by isothermal ageing in ZrO2-5.2 mol % Y2O3 alloy

Sakuma, Taketo; Yoshizawa, Yu‐ichi; Sutô, Hajime

doi:10.1007/bf00585753

Cited by 40 publications

(26 citation statements)

References 18 publications

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“…(6) All the experimental results except for the tweed structure have been consistently interpreted within the presently proposed regime of diffusionless transformation from cubic to tetragonal phase. The tweed structure is very similar to those previously observed (8) (10)(21)(22) The contrast was interpreted as arising from either fine precipitates of the tetragonal phase in the cubic matrix(10)(21) or spinodal decomposition toward the tetragonal and the cubic phase(8) (22) Since the tweed structure is often observed in the absence of the herringbone structure and in a more or less aged specimen, it is considered not to be inherent in the herringbone structure. Nevertheless, it is important in the presently proposed model when the tweed structure develops, since if it develops prior to the herringbone structure the parent phase will be no longer the ideal cubic lattice.…”

Section: Surface Reliefsupporting

confidence: 88%

“…A similar structure was also observed in a sintered ZrO2-7 mol% Y2O3(10). Sakuma et al (8) (9) suggested that the structure might be rhombohedral because a similar herringbone structure had been found in the ZrO2-Sc2O3 system(11) (12), in which the crystal structure was rhombohedral. A rhombic structure was also suggested to metastably exist on a ground surface of sintered yttria PSZ (13).…”

mentioning

confidence: 83%

“…Recently Sakuma et al (8) (9) observed a herringbone structure in an as arc-melted ZrO2-3 mol%Y2O3 under TEM. A similar structure was also observed in a sintered ZrO2-7 mol% Y2O3(10).…”

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confidence: 99%

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Structural Study on the Cubic to Tetragonal Transformation in Arc-melted ZrO2-3 mol%Y2O3

et al. 1986

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A herringbone structure observed in an as arc-melted specimen was investigated using XRD, TEM and surface relief study. The specimen was cooled on a water cooled copper hearth and the grain size was approximately 1mm. The results confirmed the crystal structure to be tetragonal (at=0.5100 and ct=0.5166nm, c/a=1.0129). The orientation relation among the different variants of the tetragonal lattice and their arrangement in the herring bone structure were determined; the structure was shown to be suited for accommodation to the cubic (fluorite structure) to tetragonal transformation strain. Surface relief associated with the transformation was also observed and correlated to the transformation strain. From these results, the transformation was suggested to be of diffusionless type (martensitic).

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Section: Surface Reliefsupporting

confidence: 88%

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confidence: 83%

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Structural Study on the Cubic to Tetragonal Transformation in Arc-melted ZrO2-3 mol%Y2O3

et al. 1986

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“…It is to be noted that the <111> direction is elastically-soft in c-ZrO2 (106). This type of microstructure has been found in early stages of isothermal aging of alloys with a certain composition range(105), which is followed by precipitation of ellipsoidal t-ZrO2 in the matrix (103). The present author's group has referred to the microstructure, Fig.…”

Section: Transformationmentioning

confidence: 91%

“…Various precipitate morphologies from cuboids and rectangular plates to irregular equiaxed forms are found in ZrO2-CaO (98). The plate-shaped t-ZrO2 precipitates are often observed in ZrO2-Y2O3(98) (103), an example of which is shown in Fig. 15(103).…”

Section: Transformationmentioning

confidence: 99%

Phase Transformation and Microstructure of Partially-Stabilized Zirconia

Sakuma

1988

Trans. JIM

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Phase transformations and the resultant microstructures of partially-stabilized zirconia (PSZ) are briefly reviewed with a special interest in the nature of phase transformations. The martensitic tetragonal-to-monoclinic transformation, which plays a principal role in toughening of PSZ, accompanies lattice defects such as twins or dislocations in the product phase m-ZrO2. The diffusionless cubicto-tetragonal (c-t) transformation is characterized by two different microstructures; one with the domain structure whose boundaries have curvilinear features showing the contrast of anti-phase domain boundaries in ordered alloys, and the other with thin-plates or 1enticular features. It seems that the diffusionless c-t transformation is always completed by an initial development of domain structure over the entire region of samples. The thin plates or lenticular features may be subsequently formed by the strain accommodation. The nature of the diffusionless c-t transformation is the second order phase transition. The precipitation of t-ZrO2 in the c-ZrO2 matrix is commonly found in alloys heat-treated in the cubic/tetragonal two-phase region. Together with the usual precipitation structures, the modulated or tweed structure is also formed at an early stage of aging. The origin of these microstructures, and the nature of the diffusional reaction or precipitation is discussed in this paper.

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Evolution of Microstructure in Yttria Partially-Stabilized Zirconia

Sakuma¹

1988

Sintering ’87

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The modulated structure formed by isothermal ageing in ZrO2-5.2 mol % Y2O3 alloy

Cited by 40 publications

References 18 publications

Structural Study on the Cubic to Tetragonal Transformation in Arc-melted ZrO<SUB>2</SUB>-3 mol%Y<SUB>2</SUB>O<SUB>3</SUB>

Structural Study on the Cubic to Tetragonal Transformation in Arc-melted ZrO<SUB>2</SUB>-3 mol%Y<SUB>2</SUB>O<SUB>3</SUB>

Phase Transformation and Microstructure of Partially-Stabilized Zirconia

Evolution of Microstructure in Yttria Partially-Stabilized Zirconia

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