Metal craft production techniques for coin-type medal rewarding contributions manufactured in the Momoyama-era were studied. Reward samples are separated into two types on the basis of production process. One process is casting, and the other is forging. An example of the composition of a casting sample is Ag-Cu alloy, and that of a forged sample is pure Ag. Many voids in cast cultural properties, called eirakutsuho, are observed using X-ray transmission imaging techniques, and indicate the production technique used during this era. Inner stress is measured by the sin²ψ method for identifying X-ray diffraction pattern changes. The inner stress of eirakutsuho manufactured by casting is compressive. This is a solidification contraction that occurs at the time of casting. The metal morphology of cast cultural properties, such as eirakutsuho is of the branch type. A thermal flaw is manufactured at the surface of such a cultural property. A creased metal morphology is formed in production by the forging method. Eirakutsuho manufactured by the forging method is stress free. This result indicates that thermal treatment is used in this manufacture process. A pure Ag is easy to process for forging. Test samples of cultural properties have been found to have been manufactured by forging methods. It is assumed that the jyotagane metal craft technique was used. The inner stress manufactured in this sample prepared by this method is compressive. After annealing, this sample becomes stress free. The result matches the results obtained by measuring the inner stress of cultural properties.

Conductive adhesives are alternatives to solder joints and are of interest because of their high bonding strength, low thermal resistance, and low electrical resistance. In this paper, we focused on the dependence of the metal surface conditions on the surface processing and clarified the effect of different metal surface finishes on the bonding strength and thermal characteristics. The effects of air exposure and silane coupling agent processing on the adhesive strength between the metal and resin were investigated. The thermal resistance after repeated bending was measured to determine the effect of different metal surface finishes on the thermal resistance.

This paper aimed to investigate conditions for pit initiation on type 304 stainless steel under MgCl₂ solution layer in atmospheric environment using a CCD camera system and a surface potential measurement equipment. A droplet of dilute MgCl₂ solution was put on the specimen. The specimen was set in the chamber with a relative humidity of 33% in order to make the droplet dry into the layer. The CCD camera system was employed to observe the change in the shape of the droplet and in the specimen surface during the drying process. In addition, the surface potential measurement equipment was applied for monitoring the surface potential of the specimen with the layer. When the droplet of dilute solution became thin and saturated, pitting corrosion occurred and the surface potential rapidly lowered. By contrast, thick and saturated layer did not induce pitting corrosion and the surface potential indicated the relatively low and steady. Therefore, it was revealed that the atmospheric corrosion occurred on the steel under saturated MgCl₂ solution layer whose thickness less than 0.2 mm.

Additive manufacturing(AM)is the relatively recent process suitable for small - volume production in great varieties. The microstructure of Ti–6Al–4V melted by selective laser melting(SLM)using laser as a heat source and the relationship between the microstructure and mechanical properties were investigated comparing with electron beam melting(EBM)and conventional mill-annealed specimens. The effects of built direction and heat treatment on the tensile and creep properties of Ti–6Al–4V, fabricated by SLM, were also examined. The compositional image in BSE mode and electron backscatter diffraction(EBSD)analysis revealed SLM and EBM specimens were found to consist of acicular α grain transformed from α′ martensite and very fine β distributed in α/α grain boundary. Prior β boundaries were also observed. α+β equiaxed grains were observed in the conventional mill-annealed specimen. Conventional standard heat treatment(954°C/2 h(WQ)+538°C/4 h(AC))improved tensile and creep strengths in the mill-annealed specimen, however it did not improve the strengths in the SLM specimens so much. The tensile and creep strengths were comparable between the horizontal-direction and the vertical-direction specimens, i.e., SLM specimen showed isotropic mechanical properties.

Thermal vacancies in solids have not been treated explicitly in the CALPHAD-type thermodynamic assessments, because it was considered that their contributions to the Gibbs energy were limited (even at the melting point). However, it is necessary for the third generation database for CALPHAD-type thermodynamic calculations. In this paper, it was proposed that an appropriate procedure to set parameters in the CALPHAD-type assessments to reproduce the temperature dependency of thermal vacancy in pure metals and solid solutions.

The factors influencing the tensile deformation behavior and the electrical conductivity of pure copper castings fabricated by an industrial process were investigated. The pure copper castings had sufficient deformation characteristics and electrical conductivity on the practical side. However, the deformation characteristics and the electrical conductivity of the castings were slightly inferior to those of the castings fabricated by laboratory experiments. The oxygen content in the castings fabricated by the industrial process was less than 0.01 mass%, which resulted in the absence of Cu-Cu₂O eutectic phase that exhibits the brittle behavior. On the other hand, observations of the fracture surface and the cross-section of the castings showed the existences of microporosity and two types of inclusions. These may be the factors influencing the decrease in the both tensile strength and uniform elongation. The microporosity were suggested to be caused by higher hydrogen content in the melt and/or by slower cooling rate during solidification. EDX analyses suggested that the inclusions are a kind of slag and straw ashes. Furthermore, phosphorus and iron content in the castings fabricated by the industrial process were higher than those in the castings fabricated by the laboratory experiments. These may be the factors influencing the decrease in electrical conductivity. The above findings indicated the several methods to improve the properties of the castings fabricated by the industrial process.

It has been required to improve the heat efficiency of thermal power generation system for the sake of mitigation of the global warming and resource depletion problems. For improving the heat efficiency, it is effective to increase the steam temperature, and as a result, appropriate heat-resistant alloys are needed. Although SUS304 stainless steel and Ni-based superalloys have been proposed as promising heat-resistant alloys until now, there still remain some concerns such as high-temperature corrosion by flaming gas and erosion by combustion ash. Thus, the present authors propose SiAlON ceramic coating on SUS304 and INCONEL X-750 because SiAlON has excellent heat, wear and corrosion resistances. In the present study, brazed bonding between SiAlON and these heat-resistant alloys was attempted with the applications of Cu and Ag as a soft filler material to reduce the residual stress generated due to the difference in thermal expansion coefficient between SiAlON and the heat-resistant alloys. As for the bonding with the Cu filler, the SiAlON/Cu/SUS joint was successful when the brazing time was short. However, when the brazing time was long (for example, 60 min), Fe-based grains were formed in the Cu filler layer, and the cracks were formed in the SiAlON near the joint interface during cooling in the brazing process. It was considered that the Cu filler was hardened by the formation of the Fe-based grains and could not reduce the residual stress. As for the bonding with the Ag filler, on the other hand, the SiAlON/Ag/SUS joint was successful even for a long brazing time. The SiAlON/Ag/INCONEL joint was also successful. The bending strengths of these SiAlON/Cu/SUS, SiAlON/Ag/SUS and SiAlON/Ag/INCONEL joints were evaluated by a three point bending test, and the results were approximately 200, 270 and 350 MPa, respectively. In all cases fracture occurred in the SiAlON, which means that the SiAlON and the alloys were strongly bonded.