The morphology of γ′ precipitates was quantitatively evaluated for wrought Ni-based superalloy Udimet 720Li by using the absolute moment invariant technique. The diameter of secondary γ′ precipitates, d, increases continuously with the decrease of cooling rate, v, after the solution treatment at 1473 K/1 h along the following equation; d ∝ v^-0.4. It is found that the secondary γ′ precipitates changes from spherical to octo-dendrite in shape with the decrease of cooling rate. In the case of oil-quenched alloy after the solution treatment, the value of d continuously increases with aging time at 1173 K, while the spherical shape remains unchanged during aging. On the contrary, for the furnace-cooled alloy, the shape of secondary γ′ precipitates evolves from octo-dendrite to spherical in shape with aging time under the almost constant value of d.

In this study, evaluation of evolved heat behavior for exothermic sleeve by using the DSC, the XRD, and the TG-DTA measurements. In the results of the DSC measurements, the total evolved heat for the exothermic sleeve was 3.37×10³±210 J/g. The deviation of the evolved heat was caused by the varisized Al particles. In the results of the XRD measurements, it was found that the exothermic heat of the exothermic sleeve was caused by the combustion of the resin, the oxidation of Al and Mg, formation of the melilite, and the oxidation of molten Al particles. In the results of the TG-DTA measurements, it was confirmed that the experimental results of the DSC and the XRD measurements were good consistency with that of the TG-DTA measurement.

Oxygen solid solution has been well known to have a high hardening effect on Ti and its alloys, while it also imposes a serious embrittlement behavior. This study investigated the effect of a rapid cooling process by water quenching (WQ) after heat treatment on the microstructures and mechanical properties of powder metallurgy (PM) α-titanium (Ti) materials with dissolved 0.94 mass% oxygen (O) to clarify their ductility improvement mechanism. The water quenching was applied to PM Ti extruded rod after isothermal annealing at 1173~1373 K. Tensile test results at the ambient temperature indicated that the elongation to failure of the quenched ones at 1223 K and 1273 K was 12.5% and 19.1%, respectively. They are significantly higher than that of as-extruded Ti specimen (6.0%). The Ti-0.94 mass% O materials via the above WQ treatment mainly consisted of equiaxed α-Ti grains, and some martensite phases were also detected at the grain boundaries. They were formed from β phases during phase transformation during WQ due to a lower oxygen content in pre-β phases compared to pre-α phases. The pre-β phase also had a high concentration of dislocation after tensile test. The significantly increased elongation was due to a lower oxygen content phase formation assuming an important role to improve the plastic deformation ability.

High-thermal-conductive heat dissipating sheet is an important material for promoting heat release. In this study, the correlation between the distribution of local thermal diffusivity and volume fraction was discussed. The local thermal diffusivity of the high-thermal-conductive heat dissipating sheet was measured using the laser flash method and the spot periodic heating and infrared radiation thermometer method. The volume fraction of the high-thermal-conductive heat dissipating sheet was evaluated through microscopic observation. It was observed that the local thermal diffusivity of the approximately 0.5 mm-thick high-thermal-conductive heat dissipating sheet measured using the spot periodic heating and infrared radiation thermometer method was close to that measured using the laser flash method. The correlation between the distribution of the local thermal diffusivity and volume fraction was evident.

It is important to obtain the viscosity of a mixed alloy consisting of molten stainless steel and boron-carbide (SUS316L+B₄C alloy) for the improvement of severe accident assessment methodology for sodium-cooled fast reactors. In this study, the viscosities of the molten nickel (Ni) and stainless steel (SUS316L) were measured by the oscillating crucible method to confirm the performance of the viscosity measurement apparatus as a first step. The viscosities of molten Ni and SUS316L melts were measured up to 1823 K. It was found that the measured viscosity values of molten Ni and SUS316L were estimated from the deviation of the experimental data, were ±4% and ±3%, respectively. It was also found that those of molten Ni and SUS316L were close to those of the literature values of molten Ni and similar composite stainless steels. Moreover, we tentatively measured the viscosity of molten SUS316L-5 mass%B₄C alloy. The fitted results of the viscosity for molten Ni and SUS316L were represented as follows.

We have developed a thermally conductive flexible elastomer as a composite materials with slide-ring (SR) materials and boron nitride (BN) particles surface-modified via plasma in solution. This seems to be a promising materials as a flexible insulator for thermal management. Fourier transform infrared spectrum, Raman spectrum, and X-ray diffraction patterns of BN particles indicate that plasma-surface modification introduces OH functional groups on surface of BN particles. Furthermore, X-ray computed tomography of the composite indicates the plasma-surface modification dramatically improves BN dispersibility in SR.