Jun-ichi Echigoya1, Yuichi Takabayashi2, Ko Sasaki3, Shigeyuki Hayashi3 and Hajime Suto1
1Department of Materials Science, Faculty of Engineering, Tohoku University, Sendai
The microstructure of the Al2O3-ZrO2 eutectic with addition of a small amount of Y2O3 has been studied. The eutectic composition was determined as 59 mol%Al2O3-36.8 mol%ZrO2-4.2 mol%Y2O3. The added Y2O3 (1--5.2 mol%) dissolved only in the ZrO2 phase and changed the crystal structure of this phase from monoclinic to cubic through a tetragonal+cubic mixture with increasing addition of Y2O3. Several orientation relationships were found between the ZrO2 and Al2O3 phases. The Al2O3-ZrO2 eutectic contained twins in the ZrO2 phase. The orientation relationship between monoclinic ZrO2 and Al2O3 can be interpreted to be affected by the thermal expansion coefficient of ZrO2 and Al2O3.
composite materials, eutectic oxide, alumina, zirconia, microstructure, crystallography
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