Hiroshi Anada

Electrical properties of organic electroluminescent devices with aluminium alloy cathode

Abstract Organic electroluminescent devices with an aluminium alloy cathode, consisting of aluminium-lithium, aluminium-calcium or aluminium-magnesium, have been examined. From the temperature dependence of the current-voltage characteristics in metal/aluminium complex (Alq 3 )/metal structure devices, the carrier-injection mechanism in the higher current range is ascribed to thermionic (Schottky) emission and the carrier-conduction mechanism of the Alq 3 layer in the lower current range is observed to be three-dimensional variable-range hopping.

Alloying effects on hydrogen gettering properties for Zr-Al system

This paper discusses alloying effects on absorption and desorption kinetics of deuterium for Zr-Al alloys, studied with mass analyzed thermal desorption spectroscopy using a conventional high vacuum system. It is found that the absorption rate of deuterium was proportional to the 1/2 power of deuterium gas pressure. On the other hand, the desorption process obeyed the second order kinetics with respect to the amount of absorbed deuterium. The temperature dependence of the rate constants revealed that the activation energies for both the absorption and desorption processes were lowered by the increase in the Al content in the alloys. Through potential diagrams for the absorption and desorption of deuterium, it was also found that the heat of deuterium (hydrogen) solution decreased with increasing Al composition. In addition, the x-ray diffraction spectroscopy showed the formation of a Zr{sub 4}Al{sub 3} phase in the Zr{sub 3}Al{sub 2} sample owing to repeated absorption and desorption cycles. The results suggest that the electronic factors, for example, work function, electron density, d-band character and so on, play an important role for the alloying effects rather than crystallographic structures.

Superplastic Deformation of a Mg-8% Li Alloy Processed at Room Temperature by ECAP

Significant phase refinement and dispersion were achieved in a cast Mg-8% Li alloy through processing by ECAP using a die having an internal channel angle of 135° and a pressing temperature of 293 K. Following extrusion and subsequent ECAP through 4 passes, the alloy exhibited superplasticity at a testing temperature of 473 K. A maximum fracture elongation of 1610% was attained with an initial strain rate of 1.5 x 10 -4 s -1 . The strain rate sensitivities under the optimum superplastic conditions were measured as about 0.6. The maximum elongation achieved in this investigation is very high by comparison with most Mg alloys tested in tension at similar temperatures and strain rates.

The Effect of Grain Size and Amount of β Phase on the Properties of Back-Torsion Working in 60/40 Brass

It was limited to 60/40 brass and the adjustment of grain size was performed, thereafter, it was processed by one way torsion working and back-torsion working. The effect of both workings on the work hardening and the surface roughness of 60/40 brass were investigated. The quenched material has excellent surface roughness in comparison with the furnace-cooled material both after and before workings. It seemed that a little difference in their grain size (15-55μm) affects the restoration ratio of surface roughness. For the back-torsion worked material, as the grain size is coarse, the amount of hardening increases. If the β phase ratio is more, it is easy to become hardened. Inversely, if the β phase ratio is less, it obtains the maximum amount of hardening.

Titatium-Flake Reinforced Aluminum-Matrix Composite Prepared from Multilayered Foils by Cold Pressure Welding

In the present work, pure aluminium foils 92 μm thick and pure titanium foils of three thicknesses were alternately multilayered and then pressed at high pressure at room temperature to fabricate aluminium matrix al/ti composites of three volume fractions by a simple method. The composites were examined by optical and scanning electron microscopy and by nominal compressive stress-displacement curves. Tensile and bending properties were investigated. Tensile strengths of the composites were compared with the values estimated from the rule of mixtures on the flake-reinforced composite

High temperature tensile properties of a Mg-8%Li alloy shear-strained by torsion working and ECAP

High temperature tensile test was performed by using a Mg-8%Li alloy to give an equal shearing strain by torsion working and ECAP under the various strain rates at 473 K. Elongation to failure of Mg-8%Li alloy strained by torsion working was bigger than that of same alloy strained by ECAP. The difference of elongation to failure showed that it originates in the formation of cavity, shape of a phase and width of a and βphases measured vertically in the tensile direction.

The Influence of Strain on Semi-Solid Behavior in AC4C Aluminum Alloy Billet by One Way Torsion Working

This study was investigated about that behavior of α phase during recrystallization process and the influence of the amount of strain on semi-solid structure of AC4C aluminum alloy which was processed by one way torsion working. AC4C aluminum alloy billets having a diameter of 35mm and a length of 400mm were torsioned by a single side torsion machine. The maximum strain (γmax) of the specimens in this experiment was 0.88. The specimens were etched for the microstructure observation by optical microscope. The casting material (γ＝0) and the torsion material (γ＝0.73) were remained dendrite structure from room temperature to 565°C. The casting materials had grain-shaped structure when they reached to 585°C which is an eutectic temperature in this alloy. However the torsion working material had it when they reached to 577°C from eutectic temperature on down. In semi-solid region, the structure of the torsion working material was finer than that of casting material and became a more grain-shaped structure. The casting material which was heated to the eutectic temperature was changed to dendrite structure again. However the torsion working material was remained grain-shaped structure.

Influence of the Cooling Rate on the Iron Solubility in High Purity Aluminum Maked by the Melt Spinning Method Using the Rotating Single Roller

It makes use of that excellent nature, high purity aluminum is being used as a function material in the electron, the high technology industry and information. Generally that material is molded as a slab, and processed through such as metal rolling is given after that, and it is being made. It is increase demand that it use for condenser. Condenser capacity is increase by making a (100) oriented cube texture crystal. It is known effective to increase a solid solubility of iron to aluminum that make increase the condenser capacity. Therefore, the cooling rate of Al-10,100 and 1000ppm content Fe was controlled by single roller equipment. Research was done about the relations of the amount of solid solubility of iron to aluminum and the cooling rate. It is result that the amount of solid solubility of iron to aluminum becomes 800ppm at the cooling rate of 2×103 K/s. When the cooling rate rises, the amount of solid solubility increases. The change appears in the separation thing as well because the amount of iron changes by this when the cooling rate is high. When iron is solid solubled in aluminum, it is bigger than the case of solid solubility formed by other general metal elements. Hardness is four times rose more than pure aluminum by solid solubility of iron to aluminum about 800ppm.

Multiplication process of twin bounderies in feathery crystal.

Feathery crystals formed in Al-5 mass%Mg alloys unidirectionally solidified were microscopically observed at intervals of about ten micronmeters for examining multiplication of twin boundaries. Two types of site for multiplication of feathery crystals are found. Type I is that a new twin boundary originates at a site separating from preexisting twin boundaries. And type II is that a new twin crystal originates at a site on the subgrain boundary generated in either individual of a preexisting twin crystal. These types of twin multiplication have particular features of the variations of length and spacing of twin boundaries.