著者

西山 宣正 若井 史博

出版者

日本高圧力学会

雑誌

高圧力の科学と技術 (ISSN:0917639X)

巻号頁・発行日

vol.28, no.3, pp.170-176, 2018 (Released:2018-10-04)

参考文献数

17

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Nanopolycrystalline stishovite was fabricated under high pressure and temperature using Kawai-type apparatus. This material is the hardest oxide as well as one of the toughest ceramics with fracture toughness of about 12 MPa m1/2. We performed X-ray absorption spectroscopy using synchrotron radiation, bending tests using micro-cantilever specimens fabricated by focused ion beam technique, and first-principles calculations for this material. Using the obtained results, we demonstrated that this material is toughened by transformation toughening mechanism by fracture-induced amorphization of stishovite. This toughening mechanism can be a platform to produce new structural materials.

著者

大熊 学 渡辺 修平 篠部 寛 西山 宣正 竹内 晃久 上杉 健太郎 田中 諭 若井 史博

出版者

一般社団法人 粉体粉末冶金協会

雑誌

粉体および粉末冶金 (ISSN:05328799)

巻号頁・発行日

vol.66, no.12, pp.604-610, 2019-12-15 (Released:2019-12-15)

参考文献数

40

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The characterization of the processing-induced defects is a significant step for developing defect-free processing, which is important to the assurance of the mechanical reliability of brittle ceramics. Recent advances in multiscale X-ray computed tomography which consists of micro-CT and nano-CT enables us to observe the three-dimensional (3D) internal structure non-destructively. Micro-CT reveals the distribution of defects in the entire body of a sample, while nano-CT reveals the shape of the identified defect. This powerful imaging tool was used to reveal the complicated 3D morphology of defects evolved during sintering of alumina. The hierarchical packing structure of granules was the origin of several types of strength-limiting defects, which could not be eliminated due to the differential sintering of heterogeneous microstructures. This imaging technique of internal defects provides a link between the processing and the fracture strength for the development of structural materials.