Ceramics is a general term for inorganic materials other than metals that have excellent hardness, wear resistance, heat resistance, corrosion resistance, and have unique dielectric properties. They are used in various applications, from everyday items such as pottery and glass to industrial parts such as refractories and cutting tools as well as high-tech industrial components such as electronic parts, semiconductor materials, and manufacturing equipment. In recent years, the demand for ceramics as a structural material has been increasing in fields where it is expected to be used in harsh environments, such as the aerospace domain. However, ceramics are brittle and have low reliability as a material; hence, their range of applications is still limited compared to that of metals.
A research group made up of Professor Hidehiro Yoshida, Lecturer Hiroshi Masuda, and Graduate Student Yuta Aoki of the Graduate School of Engineering, and Associate Professor Eita Tochigi of the Institute of Industrial Science at the University of Tokyo, discovered that a fine composite structure consisting of alumina (Al2O3) ceramics, which is a high-strength material with brittleness when used alone, and gadolinium-aluminum perovskite (GdAlO3; GAP) ceramics, shows improved plastic deformability and suppressed brittle fracture. If it is possible to intrinsically improve the plastic deformability of ceramics by activating dislocation glide and suppressing material fracture, this development is expected to lead to the realization of highly reliable ceramics, greatly expanding their applications as structural materials. The results were published in Nature Communications.
Provided by the University of Tokyo
The research group hypothesized that activating dislocation glide by creating an interface between different ceramic materials might lead to an intrinsic improvement in their plastic deformability. In this research, a mixed powder consisting of Al2O3 and gadolinium oxide (Gd2O3) ceramics was melted and rapidly cooled and solidified to prepare a eutectic material resembling a mustard-filled lotus root, wherein fine rod-shaped GAP crystals of approximately 100-nm diameter were arranged in the Al2O3 crystals. Micropillar compression tests were conducted for this material at room temperature to evaluate its microscopic mechanical response and compare the material with Al2O3 and GAP single-crystal materials. The single-crystal materials did not deform plastically at all and fractured, whereas the Al2O3-GAP eutectic bent and deformed plastically without fracturing. Transmission electron microscopy analysis of the eutectic after deformation revealed dislocation motion in Al2O3, which does not occur at room temperature.
This is a groundbreaking achievement in that the preparation of an interface between different phases promotes dislocation glide in the material, drawing out plastic deformability from a combination of hard and brittle materials and generating a material that is hard and yet not brittle. In the future, if the research group can clarify the mechanisms underlying the formation and glide of dislocations that are responsible for the plastic deformation of the ceramics as well as the effects of the microstructure and material selection on the mechanical response of the resulting ceramics, it is expected that the group will be able to discover new material design guidelines that will draw out the hidden plastic deformability of ceramics and realize ceramics as excellent structural materials exhibiting environmental resistance and high reliability.
Journal Information
Publication: Nature Communications
Title: Overcoming the intrinsic brittleness of high-strength Al2O3-GdAlO3 ceramics through refined eutectic microstructure
DOI: 10.1038/s41467-024-53026-6
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