Twinning and Microcracking Associated with Monoclinic Zirconia in the Eutectic System Zirconia–Mullite |
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| Authors: | Vinayak P Dravid &#; Michael R Notis &#; Charles E Lyman |
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| Affiliation: | Department of Materials Science and Engineering, Lehigh University, Bethlehem, Pennsylvania 18015 |
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| Abstract: | Crystallography and morphology of twins and microcracks in the eutectic system mullite–zirconia are discussed in view of the tetragonal-to-monoclinic transformation and associated toughening mechanisms. Specific twin relationships were observed in monoclinic ZrO2. Highly symmetric and crystallographically well-defined microcracks were observed at the mullite–ZrO2 interface. Microdiffraction revealed closely related crystallography of monnoclinic twins and microcracks. The number of twin variants depend on the monoclinic ZrO2 particle size. A method to calculate twinning shear strain using microcrack morphology is suggested. This parameter is essential in several fracture-mechanics calculations. |
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