【開催予告】2026.10.26 -第204回構材ゼミ- Dr. Oriol Gavalda-Diaz (Department of Materials, Imperial College London)
- 日時
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2026年10月26日（月曜日）15:00-16:00
- 場所
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NIMS千現地区 先進構造材料研究棟5階カンファレンスルーム
- 講演題目
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Understanding Fracture and Toughening in Ceramics through Advanced Characterisation and Nanomechanical Testing
- 講演者
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Dr. Oriol Gavalda-Diaz, Associate Professor
Department of Materials, Imperial College London
Abstract:
Ceramics are essential for a wide range of structural and functional applications, particularly in demanding environments, but their inherent brittleness remains a major limitation. Only a very small number of ceramic materials exhibit sufficient toughness to avoid brittle failure under macroscopic tensile loading. Overcoming this limitation requires an understanding of the mechanisms governing crack initiation and propagation, as well as the role of microstructure, interfaces, and local mechanical properties in controlling fracture.
I will show how we combine advanced characterisation techniques with micro- and nanoscale mechanical testing to provide new insights into fracture and toughening mechanisms in ceramics and ceramic composites. I will first present studies of fracture in brittle materials using in-situ scanning and transmission electron microscopy (SEM and TEM), combined with 4D-STEM, to directly investigate crack propagation and the associated nanoscale deformation mechanisms. Examples will include transformation toughening in yttria-stabilised zirconia (YSZ), where local phase transformations at the crack tip can be correlated with crack shielding.
I will then discuss the application of in-situ micromechanical testing to investigate interphases and fibres in SiC-based ceramic matrix composites (CMCs). These approaches enable the quantification of local mechanical properties and the assessment of interphase degradation under extreme environments, including elevated temperatures up to 1000°C. I will highlight how these measurements reveal the influence of temperature, microstructure, and interfacial properties on damage evolution and crack propagation, while also supporting the development of improved interphase concepts for next-generation composites.
Overall, this talk will demonstrate how combining advanced electron microscopy, nanoscale characterisation, and in-situ mechanical testing across different length scales and temperatures can advance our understanding of fracture in ceramics and guide the development of tougher, more reliable structural materials.