The macromechanical characteristics of a material depend on its microstructure mechanical characteristics, such as crystal grain size and precipitates, and the material properties are improved by structural control. Consequently, investigating mechanical characteristics at this kind of micro level leads to the development of new materials. This research evaluates the mechanical properties of advanced magnesium alloys, titanium alloys, nickel alloys, etc. at a microstructural level and elucidates the deformation and fracture mechanisms thereof. Moreover, this research also quantitatively and systematically investigates the effect of the compositional structure of a material on its mechanical properties by performing numerical analysis using crystal plasticity finite element analysis. By integrating experiments and numerical analysis, we are working towards guiding principles for the development and toughening design of innovative structural materials. This laboratory is the only one in the world carrying out this kind of research, and our results are much anticipated.

Improving the strength characteristics of metal materials without sacrificing the excellent ductility thereof is one significant problem when used as structural materials. However, achieving high strength in materials is shown to be closely related to susceptibility to hydrogen embrittlement. High strength is achieved by overlaying various mechanisms, therefore making it difficult to understand the phenomenon of hydrogen embrittlement, which is strongly influenced by the interaction between hydrogen and lattice defects. This research aims to elucidate this mechanism by the use of micro tensile testing technology to observe hydrogen embrittlement behaviour in compositional structural units.

Refinement of crystal grains（PDF／444KB）

Lath martensite is an important structure for achieving high strength in steel and has a complex hierarchical microstructure including packets, blocks, sub-blocks, and laths. For this reason, there is insufficient understanding of the roles of the structural elements with respect to their mechanical properties. We aim to elucidate the toughening mechanism by gathering micro-scale minute test pieces from lath martensite structures, performing tensile and fatigue testing, and studying the effect of the structural elements on the deformation behaviour of martensite.