Properties of interface materials used as boundaries to sever environments seem to be gradually varied along to the distance from surface. The material integrity might be influenced by the surface property degradation. Target vessel materials applied to the spallation neutron source will be exposed to proton and neutron irradiation and mercury immersion environments. In order to evaluate the surface degradation due to such environment, triple ions beam irradiation and mercury immersion tests were carried out. The mechanical properties of the gradient surface layer were evaluated by the indentation technique with the inverse analysis using the multi-layer model. As a result, it was confirmed that the ductility loss is enhanced by the irradiation and the mercury immersion.

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The solid lubricating layer with dispersed diamond nanoparticles were fabricated with the Al-Si-Cu-Mg alloy. A solid lubricating layer was made on the surface of the axle by dynamic compaction at 773K in vacuum. The mechanical properties and microstructures of the solid lubricating layer were examined. A density measurement revealed that the layer has a relative density of 0.93-1.00. The Vickers hardness of the layer was more than 80 HV. Pores were not observed in the layer. This technique is one of the promising techniques to produce solid lubricating layers.

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The present paper investigates a process of laser sintering of titanium sheets toward the fabrication of porous artificial bones. The novelty lies in the use of a titanium powder sheet mixed with an organic binder and the application of selective laser sintering to the fabrication of a laminated porous structure. An alternate Nd: YAG laser irradiation with high and low average powers (15W and 1.5W, respectively) results in the suppression of distortion of the sintered part as well as increases in mechanical properties. The titanium specimen with 3×30×3 (height) mm³ has a porosity of 67% and a maximum shape error of less than 10%. A bending strength of 121.5 MPa and a Young's modulus of 11.3 GPa are attainable in the direction perpendicular to the lamination, whereas those in the laminating direction are 35.9 MPa and 1.9 GPa, respectively. It is crucial to improve bonding strength between the sintered sheets toward around 100 MPa for human bones.

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Fine powders of intermetallic compound NiAl were produced through organometallic precursors. The bulk NiAl and NiAl/Al₂O₃ were obtained by sintering of the powders. The pore density of sintered materials was less than 3%. The cyclic oxidation tests revealed the good oxidation resistance of sintered NiAl. The sintered NiAl exhibited excellent ductility compared with cast one at room temperature and NiAl/Al₂O₃ showed high strength at elevated temperature.

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The mechanical properties of cortical bone are a consequence of the interaction between the mineral and collagen components. Small variations in the amount of mineral present in a section of bone can have a large influence on its mechanical properties. Studies have shown the correlations between Vickers microhardness and mineral content, and Vickers microhardness and elastic modulus using three-point and four-point bending tests. However, the precise nature of statistical relationship has yet to be established. Nanoindentation, which evolved from Vickers microhardness test, allows for measurement of mechanical properties of cortical bone at the nanometer scale. The nanoindentation technique has been applied to estimate mechanical properties of bone at a microscopic length scale, overcoming the limitations of traditional mechanical tests for small specimens. In this study, the relationships between mechanical properties measured by nanoindentation and volumetric Bone Mineral Density (vBMD) measured by peripheral Quantitative Computed Tomography (pQCT) in femoral cortical bone from a variety of ages of rats were investigated. The specimen of rat cortical bone used here was Haversian bone. Experimentally measured elastic modulus was correlated with vBMD (r=0.80). It was found that a good correlation also existed between hardness and vBMD (r=0.81).

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Acetabular prosthesis loosening is one of the primary failure factors for long-term total hip arthroplasties. Loosening is associated with structural characteristics of the implant-bone system and the operative procedure. In order to improve the service life of the cup, it is important to develop the material, design, fixation mechanism, etc. and to assess the mechanical behavior around the cup. The measurement of deformation at cancellouse bone with porous structure is generally difficult by the contact measurement techniques. In this study, electronic speckle interferometry, which can provide the detailed displacement distribution over the entire visual field, was assessed for its applicability to measure the displacement. In this report, the strength of cancellous bone was examined. In the displacement distribution for the transverse direction of the implant, the interference fringe patterns showed the discontinuity of deformation at the boundary regions of cup, bone cement and cancellous bone. It was shown that the experimental results were also similar to those by finite element model.

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In order to conduct the water tank experiment that resembles the Katmandu valley, the dominant dimensionless parameters of both the flow field and the dispersion field were extracted by the numerical simulation. The dimensionless parameters in both atmospheric stability and instability condition were defined by the ratio of the mountain height to the mixing height and to the inversion height, respectively. The water tank experiment based on these dimensionless parameters of the Katmandu valley agreed with the numerical simulation reasonably. This result suggested that these dimensionless parameters can be applicable for the flow and dispersion phenomenon in the valley.

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