日本金属学会誌

J. Japan Inst. Metals, Vol. 56, No. 7 (1992),
pp. 764-769

numerical simulation of formation process of transformed zone and r-curve behavior in partially stabilized zirconia

Kensuke Kageyama1, Manabu Enoki1 and Teruo Kishi1

1Research Center for Advanced Science and Technology, The University of Tokyo, Tokyo

Abstract:

Numerical simulation of the shape and width of the transformed zone and R-curve behavior in partially stabilized zirconia was carried out. The toughening mechanism by transformation has been theoretically studied by McMeeking et al. However, the result by their model is not coincident with the experimental data in Ce-TZP by Yu et al. because they assumed that the transformation volume fraction is low and the stress field is generated only from the main crack tip. In this paper, we assume that the stress filed is generated from both main crack tip and transformed particles, and that the transformation distribution is discontinuous by each particle. As a result, we have two formation processes of the transformed zone. In the case of the low transformation volume fraction, the R-curve behavior agrees with the analysis by McMeeking et al. and the width of the transformed zone with crack extension is almost constant. In the case of the high fraction, however, the transformed zone extends and elongates along the crack tip, and the shape changes and the width of the transformed zone extends discontinuously. It demonstrates a step-like R-curve behavior.


(Received 1992/01/16)

Keywords:

transformation, toughening, R-curve behavior, stress intensity factor, partially stabilized zirconia, numerical simulation


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