A micromechanics study of competing mechanisms for creep fracture of zirconium diboride polycrystals |
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| Authors: | Chi-Hua Yu Chang-Wei Huang Chuin-Shan Chen Yanfei Gao Chun-Hway Hsueh |
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| Affiliation: | 1. Department of Civil Engineering, National Taiwan University, Taipei, Taiwan;2. Department of Civil Engineering, Chung Yuan Christian University, Chung Li, Taiwan;3. Department of Materials Science and Engineering, University of Tennessee, Knoxville, TN 37996, USA;4. Department of Physics and Astronomy, University of Tennessee, Knoxville, TN 37996, USA;5. Department of Materials Science and Engineering, National Taiwan University, Taipei, Taiwan |
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| Abstract: | A micromechanics model was developed to simulate creep fracture of ceramics at high temperatures and material properties pertinent to zirconium diboride (ZrB2) were adopted in the simulation. Creep fracture is a process of nucleation, growth, and coalescence of cavities along the grain boundaries in a localized and inhomogeneous manner. Based on the grain boundary cavitation process, creep fracture can be categorized into cavity nucleation-controlled and cavity growth-controlled processes. On the other hand, based on the deformation mechanism, the separation between two adjacent grain boundaries can be categorized into diffusion-controlled and creep-controlled mechanisms. In this study, a parametric study was performed to examine the effects of applied stress, cavity nucleation parameter, grain boundary diffusivity, and applied strain rate on cavity nucleation-controlled versus growth-controlled process as well as diffusion-controlled vs. creep-controlled mechanism during creep fracture of ZrB2. |
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| Keywords: | Creep fracture Cavitation Finite element analysis Micromechanics |
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