International Research Organization for Advanced Science and Technology
Email address: takashik[at]gpo.kumamoto-u.ac.jp
1. Development of Testing Methods for Micro-Sized Materials
Since thin films are used as structural materials in MEMS (Micro Electro Mechanical System) devices, it is necessary to accurately measure the mechanical properties of thin films in order to improve the reliability and durability of the devices. We are developing testing methods for micron to submicron size components fabricated from thin films. The results obtained will greatly contribute to the development of MEMS devices.
Fig. 1 Examples of micro-sized specimens for tensile, bending, fracture and fatigue tests.
Fig. 2 Micro-materials testing machine developed in our laboratory. We are measuring the deformation, fracture, and fatigue behavior of micro-sized materials using this testing machine.
2. Evaluation of Mechanical Properties of Hierarchical Microstructures in Materials
The mechanical properties of a bulk material depend on the mechanical properties of its microstructure, such as grain size and precipitates, and microstructural control improves the material properties. Therefore, investigating the mechanical properties at such a microscopic level will lead to the development of new materials with superior mechanical properties. In this research, we evaluate the mechanical properties of advanced materials, including high strength steels, Ti alloys and Mg alloys, at the microstructure level to elucidate the deformation and fracture mechanisms and to develop high-strength and high-toughness materials. This laboratory is the only one in the world that conducts such research, and the results are highly anticipated.
Fig. 3 If micro-sized specimens are prepared from micro-constituents in materials, and micromechanical testing is performed for such specimens, the mechanical properties, including grain boundary strength, fracture toughness of precipitate, interfacial strength between matrix and secondary phase, etc., can be measured. The evaluation of mechanical properties of microstructure is essential for the designing high strength material.
Fig.4 Preparation of micro-sized specimens from the constituents of material structure
Fig. 5 Deformation behavior and strain distribution are measured to elucidate deformation and fracture mechanisms.
Grant-in-Aid for Challenging Exploratory Research (The Japan Society for the Promotion of Science), “Development of local strengthening of micro-mechanical components using martensitic transformation induced by focused ion beam irradiation,” April 2021-March 2023
Grant-in-Aid for Scientific Research (A) (The Japan Society for the Promotion of Science), “Elucidation of fatigue crack growth mechanism of martensite steels using micro-mechanical testing technique and application to fatigue strengthening design,” April 2020-March 2025
Grant-in-Aid for Scientific Research (B) (The Japan Society for the Promotion of Science), “Exploration of guiding principles for toughening design of hydrogen-resistant materials using multi-scale mechanical testing,” April 2019-March 2022