The magnetic field effect on phase formations of ferromagnetic Mn-Al (τ-phase) was evaluated. The transformation from ε-phase with hcp-structure to τ-phase was accelerated by annealing in magnetic field. With in-field annealing at 623 K, the magnetization of the sample annealed at 15 T was a maximum of 72.2 A･m²/kg at 1.5 T, which was over 4 times larger than that annealed in a zero field. Meanwhile, the precipitation of non-ferromagnetic β-phase was suppressed by in-field annealing. Magnetic field-induced acceleration of ε-τ transformation and suppression of τ-β transformation were due to the gain of Zeeman energy of τ-phase.

In this study, the optimal parameters for aerosol deposition (AD) of mullite coating and the microstructure change of mullite coating after heat exposure in an air were investigated. Mullite, which is one of the component materials for environmental barrier coatings was deposited on glass, Al₂O₃ and Si by AD method. In order to produce a homogeneous mullite coating, the angle of the gas flow direction from the nozzle to the substrate plane should be 60°. Deposition rate increased with increasing gas flow rate, when the gas flow rate was in the range from 18 to 36 L/min. Further increase of the gas flow rate resulted in the formation of heterogeneous coating. The mullite coating formed by the optimized parameters was almost dense and crystalline. The chemical composition of the mullite coating was almost the same as the composition of the mullite raw powder used for the deposition. The coating was composed of mullite single phase. Delamination was not observed at the interface between the Si substrate and the mullite coating. Since the interface showed undulation, it was considered that the substrate and the coating were bonded due to the anchor effect. Heat exposure was carried out at 1573 K in a specimen in which the mullite coating was deposited on the Si substrate. When the specimen was heat exposed for 10 h, coating at the surface side and the coatings at the central part and near the interface between the substrate and the coating were composed of (Al₂O₃ + mullite) and (SiO₂ + mullite) two-phase state, respectively. Further heat exposure formed an altered layer near the interface. The layer was composed of (SiO₂ + mullite) two-phase state containing more than 80 mol％ of SiO₂. The thickness of the layer increased with increasing heat exposure time. Formation of the altered layer was due to the diffusion of Al present in the mullite coating to the coating surface and the diffusion of Si into the coating from the Si substrate.

The three-dimensional morphology and thickness of the C15–Al₂Ca Laves phase, which precipitated within the primary α-Mg grains, were investigated for the Mg–5Al–1.5Ca alloy over-aged at 523 K for 100 h using the high-resolution transmission electron microscopy (HRTEM). The C15–Al₂Ca phase precipitated with a hexagonal plate-like morphology along the (0001)_α basal plane of the α-Mg matrix phase, where the sides of the hexagonal plates were parallel to the second columnar plane {1120}_α of the α matrix. The typical coffee bean contrast was clearly visible around the precipitates, indicative of coherent precipitation of the C15–Al₂Ca phase. The thickness of the C15–Al₂Ca precipitates, which corresponds to the six layers of (111)_C15 plane composed of Ca atoms, was evaluated to be approximately 1.5 nm.

As a fundamental study on the adhesion of Ni-plating on aluminum alloys, various molecular dynamics simulations are performed on Ni/Al infinite laminate structure under tension, by changing mixing concentration of Ni and Al at the interface. The adhesion shows the highest at the perfect (001) Ni/Al interface while it decreases with the rate of random mixing in Ni/Al phases (10％, 30％ and 50％ substitution in each phase). Especially the 50％ substitution in Al phase remarkably decreases the adhesion compare to the same substitution in Ni phase. The (111) interface shows weaker adhesion than (001) for perfect Ni/Al interface, and the substitution doesn't largely affect to the adhesion reduction as the (001) interface. The (001) interfaces are always ruptured in brittle manner near the interface in Al side, and few Ni atoms are observed on the fracture surface. The (111) interfaces shows shear-lip breakage by void formation and growth in Al side further away from the interface. We obtained simple conclusion that the Ni/Al interface is inherently strong and the delamination never takes place at the interface, since the surface energy and elastic coefficients of Ni are much larger than Al. The large reduction of adhesion by atom mixing in the (001) interfaces can be explained with the initial misfit at the interface while it doesn't largely affect to the close-packed (111) interface. Assuming various phenomena in real Ni-plating, we also performed simulations with Ni₃Al and NiAl interlayer, (001)-(110) surfaces combination; and all results in the same story above mentioned. Finally, we performed calculations on Ni-P system, and revealed that the surface energy of amorphous Ni-P is close to that of Al. Thus interfacial delamination can be occurred between the amorphous Ni-P plating and aluminum base.

Co-Ni spinel ferrite particles were synthesized via chemical co-precipitation and subsequently performed hydrothermal treatment at different temperatures. Fine particles of size with a few nanometers and spherical or cubic particles of size approximately 30 nm, which are responsible for magnetic properties, were obtained. The crystallite size obtained using the Scherrer equation was 24-27 nm and showed no dependency on the hydrothermal treatment temperature unlike the apparent particle size observed using transmission electron microscopy. The coercive force showed a remarkable increase with the decrease in the hydrothermal treatment temperature from 141 kA/m at 240℃ to 400 kA/m at 100-120℃, in contrast to the decrease in magnetization from 60.0 Am²/kg at 240℃ to 37.2 Am²/kg at 100℃. The specific composition of the Co-Ni spinel ferrite particles is expected to affect the high coercive force and the remarkable dependency of the coercive force on the hydrothermal treatment temperature.

In this study, the effects of bending and tension deformation on the texture formation and room temperature formability of Mg-3.0 mass％Al-1.0 mass％Zn-0.3 mass％Mn (AZ31B) alloy sheets were investigated. Bending and tension deformation was conducted in one to nine passes through the die with a 45° angled channel with and without rotating the sheets. The sheets that were subjected to bending and tension deformation through more than three passes exhibited a rolling direction (RD)-split texture, where the basal pole inclined toward the RD, and its inclination angle tended to increase with an increase in the number of passes. When the bending and tension deformation was conducted in six passes through the die by rotating the sheet 180° relative to the RD axis, the sheet exhibited superior room temperature formability (7.0 of the Erichsen value). The yield stress and Lankford value of the sheet subjected to bending tension deformation were closely related to the distribution of the basal pole. The results suggest that recrystallization nucleated at secondary twins as well as lattice rotation likely caused the formation of the RD-split texture.