本研究是對3Y-TZP與在此材料中添加不同濃度的鈮酸釔試片進行進行單軸向拉伸壓縮循環負載和潛變實驗，試件為承受平面應力負載之薄片。研究材料在拉應力與壓應力狀態下各種韌化機制發生之時機與強度，並且觀察添鈮酸釔濃度的不同對材料的韌化機制有何影響。
先對材料進行拉壓循環負載，並且分析其應力應變曲線圖與波松比變化圖。結果顯示材料在承受拉應力負載過程中，應力應變曲線迴路位置變化大，表示有明顯的相變化發生。但承受壓應力時，相變化發生強度極弱。且隨著循環次數的增加，相變化發生的強度會降低。在3Y氧化鋯中增加鈮酸釔濃度，會促進相變化的發生。但超過某濃度後，增加鈮酸釔濃度反而會抑制相變化的發生。

Specimens of 3Y-TZP doped with various concentrations of YNbO4 were employed to perform cyclic tension-compression loading, interlaced with creeping at diverse stress levels. The specimens are in the form of thin plate, hence ensuring uniformity of stress distribution across the thickness. The occurring intensity and type of toughening mechanisms and the interactions among them are identified at different stress levels. The effect of YNbO4 on toughening mechanisms was detected by differentiating its concentration in the specimens.
The fluctuation of Poisson’s ratio is flabbergastingly huge, say, from –3.87 to 6 for some specimen, when subjected to tensile stress, attributed to intense occurring of phase transformation. Some of the corresponding stress-strain loops in the tensile portion even appear counterclockwise, indicating that energy is released from specimen, contrasting most engineering materials. The stress-strain loops in the tensile portion also exhibit substantial vacillation, implying that tensile stress is prone to trigger phase transformation. The intensity of phase transformation subsides as the cycle number increases. While subjected to compressive stress, the Poisson’s ratio basically stays very close to the elastic Poisson’s ratio, showing that no significant phase transformation takes place. Raising the concentration of YNbO4 facilitates phase transformation, but curbs it when the concentration is beyond a certain value.

1. Srinivasan, G. V., Jue, J.-F., Kuo, S.-Y. ＆ Virkar, A. V. “Ferroelastic domain switching in polydomain tetragonal zirconia single crystals,” J. Am. Ceram. Soc., 72[11], 2098-103, 1989

2. Gibson, I. R. ＆ Irvine, J. T. S. “Qualitative X-ray diffraction analysis of metastable tetragoal (t´) zirconia,” J. Am. Ceram. Soc., 84[3], 615-18, 2001

3. Yuh, S.-D. ＆ Chou, C.-C. “Peculiar stress-induced phase transformation in YNbO4 –modified ZrO2(3Y) using in situ compression-diffraction,”Materials Letters., 52, 69-74, 2002
4.Virkar, A. V. “Role of ferroelasticity in toughening of zirconia ceramics,” Key Engineering Materials., 153/154, 183-210, 1998

5. Fernandez, J. M., Melendo, M. J. ＆ Rodriguez, A. D. “Ferroelasticity of the displacive tetragonal phase in Y2O3 partially stabilized ZrO2 (Y-PSZ) single crystals,” J. Mater. Res., 11[8], 1972-78, 1996

6.Ohtaka, O., Kume, S., Iwami, T. ＆ Urabe, K. “Synthesis of the orthorhombic phase of 2Y-ZrO2,” J. Am. Cerm. Soc., 71[3], 164-66,
1998

7. Kim, D.-J., Jung, H.-J. ＆ Cho, D.-H. “Phase transformation of Y2O3 and Nb2O5 doped tetragonal Zirconia During low temperature aging in air,” Solid State Ionics., 80, 67-73, 1995

8.Kisi, E. H., Howard, C. J. ＆ Hill, R. J. “Crystal structure of orthorhombic zirconia in partially stabilized zirconia,” J. Am. Ceram. Soc., 72[9], 1757-60, 1989

9.Finlayson, T. R., Gross, A. K., Griffiths, J. R. ＆ Kisi, E. H. “Creep of Mg-PSZ at room temperature,” J. Am. Ceram. Soc., 77[3], 617-24, 1994

10.Muddle, B. C. ＆ Hannink, R. H. J. “Phase transformations involving an orthorhombic phase in MgO-partially stabilized zirconia,” The American Ceramic Society , advance in ceramics, 24: science and technology of zirconia ., Ⅲ, 89-120, 1988

11.Burke, D. P. ＆ Rainforth, W. M. “Intermediate rhombohedral (r-ZrO2) phase formation at the surface of sintered Y-TZP's,” Journal of materials science letters., 16, 883-85, 1997

12. Lawson, S. “Environmental degradation of zirconia ceramics,”Journal of the European Ceramic Society., 15, 485-502, 1995

13. Lee, D. Y., Jang, J.-W. ＆ Kim, D.-J. “Raman spectral characterization of existing phase in the ZrO2-Y2O3-Nb2O5 system,” Ceramics International ., 27, 291-98, 2001

14. Kondoh, J., Shiota, H., Kawachi, K. ＆ Nakatani, Toshio “Yttria concentration dependence of tensile strength in yttria stabilized zirconia,” Journal of Alloys and Compounds ., 365, 67-73, 2004

15. Quinn, C. ＆ Wusirika, R. “Twinning in YNbO4,” J. Am. Ceram.

Soc., 74[2], 431-32, 1991

16. Rauchs, G., Fett, T., Munz, D. ＆ Oberacker, R. “Tetragonal to monoclinic phase transformation in CeO2-stabilised zirconia under uniaxial loading,” Journal of the European Ceramic Society., 21, 2229-41, 2001

17.盧宏揚，“氧化鋯結構陶瓷與相轉換韌”，陶業雜誌第四卷第三期

18.周玉， 雷廷權 “陶瓷材料學” 中央圖書出版社,1998

19. Li, J., Zhang, L., Shen, Q. ＆ Hashida, T. “Degradation of yttria stabilized zirconia at 370K under a low applied stress,” Materials Science and Engineering ., A297, 26-30, 2001

20. Chan, C.-J., Lange, F. F. ＆ Ruhle, M. “Ferroelastic domain switching in tetragonal zirconia single crstals microstructural aspects,”J. Am. Ceram. Soc., 74[4], 807-13, 1991

21. Virkar, A. V. ＆ Matsumoto, R. L. k. “Ferroelastic domain switching as a toughening mechanism in tetragonal zirconia,” J. Am. Ceram. Soc., 69[10], C-224-26, 1986

22. Baufeld, B., Baither, D., Messerschmidt, U. ＆ Bartsch, M. “Ferroelastic of t'-zirconia: II, In situ straining in a high-voltage electron microscope,” J. Am. Ceram. Soc., 80[7], 1699-705, 1997

23. Matsui, M., Soma, T., ＆ Oda, I. “Stress-induced transformation and plastic deformation for Y2O3-containing tetragonal zirconia polycrystal ,” J. Am. Ceram. Soc., 69[3], 198-202, 1986

24.Yuh, S. D. ＆ Chou, C. C. “In situ X-ray diffraction investigation of elastic behavior of YNbO4 modified ZrO2(3Y) using synchrotron radiation,” Jpn. J. Appl. Phys., 40, 456-459, 2001

25. Kiguchi, T., Urushihara, W., Saiki, A., Shinozaki, K. ＆ Mizutani, Nobuyasn. “Effect of stress and temperature on ferroelastic domain switching of partially stabilized zirconia pseudo-single crystals,”Journal of the Ceramic Society of Japan,int.Edition, 506-10, 1996

26. Pan, L. S. ＆ Horibe, S. “Anelastic behavior of zirconia ceramics under monotonic and cycle loading,” Acta Metall., 45, 463-69, 1997

27. Li, X., Shih, W. Y., Vartuli, J. S., Milius, D. L., Aksay, I. A. ＆Shih, W. H. “Effect of a transverse tensile stress on the electric field induced domain reorientation in soft PZT : In situ XRD study,” J. Am. Ceram.
Soc., 85[4], 844-50, 2002