Kyushu University · Engineering
Professor Hiroyuki Toda's research lab specializes in advanced X-ray microtomography and in-situ characterization of metallic materials, focusing on the three-dimensional visualization and mechanical analysis of microstructural evolution under load. The lab employs synchrotron radiation to achieve ultra-high-resolution 3D imaging, enabling the observation of nanoscale features such as precipitates, cracks, voids, and hydrogen micropores in real time. Key research directions include in-situ fatigue and fracture behavior, hydrogen-induced damage, stress corrosion cracking, and strain mapping using digital volume correlation and microstructural tracking techniques. The lab's work bridges the gap between microstructure and mechanical performance, offering new insights into failure mechanisms in engineering alloys.
Figures are computed from collected data and may differ slightly.
Synchrotron X-ray microtomography has been utilized for the in-situ observation of steady-state plane-strain fatigue crack growth. A high-resolution experimental configuration and phase contrast imaging technique have enabled the reconstruction of crack images with an isotropic voxel with a 0.7 µm edge. The details of a crack are readily observed, together with evidence of the incidence and mechanical influence of closure. After preliminary investigations of the achievable accuracy and reproduci
The single-distance phase retrieval technique was applied to contrast-enhanced imaging of the dual-phase microstructure of a ferrite/martensite dual-phase with only 1.4% difference in density between the two phases. Each high-resolution absorption-contrast image was registered with a corresponding phase-contrast image, to analyse damage evolution behaviour. The loading step at which each microvoid was nucleated was identified by tracking the microvoid throughout tension, together with its nuclea
Al-10Mg alloys, which are highly susceptible to SCC, were prepared with various β precipitate morphologies. Interrupted in-situ tensile tests were conducted under synchrotron X-ray radiation, employing a recently developed X-ray microtomography technique that combines high-energy, applicability to metallic materials, and ultra-high resolution. Preferential dissolution of the β phase along grain boundaries, and incidental intergranular and transgranular fracture, were observed in 3D. A drastic de
Microtomography combined with hard x-ray imaging microscopy has been employed to observe nanoscopic features in a material, which has, to date, only been done by the transmission electron microscopy (TEM). Here, the authors show a characteristic microstructure in an aluminum alloy, such as a slant gap between growing precipitates that impinge on each other due to the presence of a solute-depleted zone. Such observation is not possible by conventional projection microtomography even using the hig
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