A molecular dynamics (MD) simulation of the solid-state bonding between single crystals of bcc iron and fcc nickel, i.e., dissimilar components, was conducted by hot-pressing with various initial compressive strains ranging from 14 to 20% and subsequent uncompressed isothermal holding at 873 K. Then, the intrinsic strength of the interfaces with various isothermal holding times was evaluated by uniaxial tensile technique. It was found that the interface separation follows the traction-separation law and that always take place either at the interface or close to the interface. The intrinsic strength of the interface is very low under an as-compressed condition and tends to rapidly increase in the early stage of isothermal holding. In addition, lower intrinsic strength was observed in a specimen with higher initial compressive strain. The significant increase in the intrinsic strength is attributed to the short-range atomic rearrangement of a layer of disordered atoms at the interface, driven by energy stored from the compressive deformation.

We propose a process for the direct synthesis of solar grade Si from a metallurgical Si wafer focusing on the fact that its microstructure is composed of almost pure Si grains and grain boundaries enriched with impurities. Principally, heating a metallurgical grade Si wafer above its eutectic temperature and applying a temperature gradient allows the grain boundaries to be melted and causes them to migrate to the high-temperature direction. The liquid phases are finally terminated at the end surface, resulting in the upgrading of the Si and making it more favorable for solar cells. In the present paper, to determine the purification effect during the liquid phase migration process, thermodynamic assessment was performed using CALPHAD method. Liquid phase migration experiments were also conducted using synthetic MG-Si (Si-Fe alloy) to determine the reaction time for the process. A maximum migration velocity of 8.17 × 10⁻⁷ m/s was obtained at 1623 K, which allows the migration process to be accomplished within 3 min for a 150-μm wafer.

A new methodology for depth profiling of hydrogen in metals is developed applying a tritium imaging plate technique (TIPT) with cross sectional observation. Owing to its high sensitivity and wide dynamic range for tritium detection, depth distribution of hydrogen dissolved in the BCC metals such as tungsten (W) and steels are successfully obtained. The depth distributions enable us to determine reliable lattice diffusion coefficients of hydrogen in W and a ferritic/martensitic steel (F82H) within 20% errors taking into account three dimensional desorption/release from the surfaces of the sample metals. Hydrogen trapped at surface and subsurface are clearly separated from the dissolved one. In BCC metals, since the former could be much larger than the latter, observation of overall hydrogen behavior without knowing detailed depth distributions could lead to wrong estimation of diffusion coefficients and solubility.

Bone tissue has a highly anisotropic microstructure derived from the crystallographic orientation of apatite and the related collagen matrix alignment. Bone is also a highly vascularized tissue; intraosseous vascularization and bone formation are intimately coupled. Meanwhile, the structural relations between intraosseous vascular networks and bone microstructure are as yet unknown, partially due to technical difficulties in visualizing precise intraosseous vasculatures. The aim of this study is to develop a visualization method suitable for the structural analysis of intraosseous vascular networks and to reveal the relations between bone microstructure and the arrangement patterns of intraosseous vasculatures. Three-dimensional vascular networks were successfully visualized, and region-dependent arrangement patterns of blood vessels were clarified using fluorescent dye-conjugated lectin. Interestingly, the anisotropic structural correlation between bone matrix and the vascular system in a region-specific manner was clarified. The obtained results indicate the molecular interactions between the vascular system and bone tissue as a novel contributor for realization of anisotropic bone matrix construct.