Low strain rate compressive failure mechanism of coarse grain alumina

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• 作者：Manjima Bhattacharya^a ; Srikanta Dalui^a ; Nitai Dey^a ; Sandip Bysakh^b ; Jiten Ghosh^a ; Anoop Kumar Mukhopadhyay^a ; ^{anoopmukherjee@cgcri.res.in" class="auth_mail" title="E-mail the corresponding author} ; ^{mukhopadhyay.anoop@gmail.com" class="auth_mail" title="E-mail the corresponding author}
• 关键词：Alumina ; Coarse grain ; Strain rate ; Compressive strength ; Failure
• 刊名：Ceramics International
• 出版年：2016
• 出版时间：June 2016
• 年：2016
• 卷：42
• 期：8
• 页码：9875-9886
• 全文大小：3408 K

文摘

The present work reports the dynamic compressive strength (σ_c) of a dense (~95%) coarse grain (~20 μm) alumina measured at ~30 °C as a function of strain rates $\dot{\left(\mathit{\epsilon }\right)}$ ranging from 10⁻⁵ to 5×10⁻¹ s⁻¹. The results showed a unique 40% enhancement of (σ_c) with the increase in $\dot{\left(\mathit{\epsilon }\right)}$. Extensive post mortem examination of fracture fragments obtained from the compressive failure tests by FESEM, TEM and HRTEM confirmed the formation of micro-cracks, shear bands, nanoscale cleavages and dislocations whose recurrence had increased with strain rate. Both shear induced microplasticity and nanoscale cleavages as well as dislocations had occurred concurrently yet independently during compressive fracture of coarse grain alumina even at very low strain rates. Based on these evidences a new compressive failure mechanism of alumina was proposed.