巻号一覧
52 巻, 3 号
選択された号の論文の7件中1～7を表示しています
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研究論文
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樫原 恵蔵, 田中 弘, 田上 稔, 岡田 達也, 猪子 富久治2002 年 52 巻 3 号 p. 101-107
発行日: 2002年
公開日: 2007/03/30
ジャーナル フリーIn order to clarify the effect of piled-up dislocations on the strain induced boundary migration (SIBM), deformation and recrystallization experiments were performed using an aluminum bicrystal specimen with twin boundary at initial orientation. During the deformation to 20% strain, inhomogeneous deformation took place near the grain boundary (GB). Two kinds of dislocations, edge and screw ones, were piled up against the GB in one component crystal. In the other crystal, edge dislocations were piled up against it. After the annealing, the SIBM was recognized along the original GB. The interaction of the piled-up dislocations was considered to occur at the GB, and it would influence the recrystallization behavior. Since the screw dislocations in one crystal were transmitted during the deformation to the other crystal through the GB because of the special orientation and geometric conditions, they could not be retained stably near or at the GB. In contrast, the edge dislocations introduced into the GB in both crystals were accumulated each other near or at the GB, thereby the component of tilt boundary took part in the original twin boundary. Therefore, it was understood that the SIBM resulted from the annihilation and rearrangement of these dislocations.抄録全体を表示PDF形式でダウンロード (1982K) -
畑中 伸夫, 山口 克彦, 高倉 章雄, 飯塚 高志2002 年 52 巻 3 号 p. 108-114
発行日: 2002年
公開日: 2007/03/30
ジャーナル フリーCutting of an aluminum sheet (A1100P–H12) by indentation of wedge shape punches is investigated as a process to achieve burr-free-cutting. Numerical simulations of the cutting process are done using a rigid plastic finite element code developed by the authors. The modified Cockcroft and Latham expression is used as a fracture criterion and is linked with the simulation. Stress and strain distributions at the deformation region of the sheet are calculated and compared with the fracture threshold. The effects of nose angle and radius of the wedge shape punch on the cut edge profile are discussed based on the calculated results. To confirm the results of the finite element simulations, cutting experiments are also carried out and the shape of the cut edge is observed using an optical or a scanning electron microscope. The experimental result shows that the shape of cut edge is divided into four modes depending on the wedge angle α and nose radius r of punch. When the punch of r = 0.1 mm and α = 30 degree is used a sheet is separated by cutting, while when α = 60 and 90 degree ductile fracture occurs due to the secondary tensile force induced by the wedge indentation, and when α = 120 degree brittle fracture occurs due to the excessive work hardening during compression. When the nose radius of punch is increased from 0.1 mm to 0.5 mm, the deformation of sheet material between upper and lower punches becomes compression rather than cutting. Therefore, when punches of r = 0.5 mm are used, the separated surface has a very thin flash. These experimental results can be explained well by the simulation results.抄録全体を表示PDF形式でダウンロード (2293K) -
小野 幸子, 木島 秀夫, 増子 曻2002 年 52 巻 3 号 p. 115-121
発行日: 2002年
公開日: 2007/03/30
ジャーナル フリーFormation behavior of anodic oxide films on magnesium in fluoride electrolytes was investigated with attention to the effects of anodizing voltage, pH and aluminum content. In the range of formation voltage between 2 V and 100 V, porous film was formed in alkaline fluoride solution associated with high current density at around 5 V and at breakdown voltage. The critical voltage of breakdown to allow maximum current flow was approximately 60 V and relatively independent on substrate purity. Barrier films or semi-barrier films, which were composed of hydrated outer layer and inner layer, were formed at the other voltages. A peculiar phenomenon of high current density at around 5 V, which may be caused by trans-passive state, was not observed for anodizing in acidic fluoride solutions. In the case of AZ91D, the critical voltage increased to 70 V and peculiar phenomenon at 5 V was not observed, so that only barrier films were formed at less than the critical breakdown voltage. When AlO2− ion was added in the electrolytes, the critical voltage remarkably increased and current density effectively decreased with increasing AlO2− content. The passivation effect of aluminum addition in the electrolytes is more remarkable than the addition in magnesium substrates. The depth profiles of constituent elements showed that aluminum migrated into oxide film to reach near oxide/substrate interface. Atomic ratio of aluminum to magnesium increased with increasing voltage to attain 1/3 at 80 V and crystalline MgAl2O4 and MgO were found in the film.抄録全体を表示PDF形式でダウンロード (2779K) -
渡辺 健彦, 柳沢 敦, 須永 史朗, 平石 誠2002 年 52 巻 3 号 p. 122-125
発行日: 2002年
公開日: 2007/03/30
ジャーナル フリーIn the ultrasonic welding process, it is well known that the bonding between both faying surfaces can be completed by rubbing them for short duration such as one second at room temperature. In this study, the atomic interaction (chemical bonding) across the interface between aluminum and alumina ceramic, which was ultrasonically welded for short time of 1.5 s, was analysed by means of Auger electron spectroscopy in order to clarify whether the chemical bonding can be achieved or not across the interface. The Auger spectra analyses results suggested the chemical bonding between Al and O existed across the aluminum-alumina interface welded ultrasonically for short time of 1.5 s, and aluminum was chemically bonded to alumina.抄録全体を表示PDF形式でダウンロード (453K) -
飛田 守孝, 今田 光一, 榊原 精, 竹元 嘉利2002 年 52 巻 3 号 p. 126-130
発行日: 2002年
公開日: 2007/03/30
ジャーナル フリーSurface and interior precipitations of Mg–6 mass%Al alloy were morphologically studied by SPM observation with AFM and KFM modes, TEM and XRD methods. The hardness increment due to the precipitation was negligibly small. According to AFM contrast the precipitates on the surface were identified as droplet-like particles (1~4 μm); on the other hand the ones formed in the alloy as needle-like (~1 μm). It was confirmed by XRD that both types of the precipitates had γ–structure (Al12Mg17), and the peak height of the surface precipitates was about 3 times as high as that of the interior ones. The droplet-like precipitates projecting from the surface had a higher KFM electric potential than that of the matrix solid solution, however the precipitates embedded in either the surface layer or the matrix had a lower KFM electric potential.抄録全体を表示PDF形式でダウンロード (2977K) -
小川 欽也2002 年 52 巻 3 号 p. 131-135
発行日: 2002年
公開日: 2007/03/30
ジャーナル フリーTensile strength of 6061–O aluminum alloy is presently investigated in the wide ranges of temperature from 77 to 473 K, and of strain rate from 10−4 to 103 s−1. At high strain rates a split-Hopkinson pressure bar method is adapted. Temperature and strain rate effects on the stress are not significant at around the room temperature, while the stress greatly depends on the temperature and strain rate with increase of strain in the low temperature range. The thermally activated process concept well describes the temperature and strain rate effects on the stress. Comparing with the effects on the stress in 6061–T6 aged material, athermal component of the stress is significantly reduced due to the largely dispersed precipitates in the present materials, while the temperature and strain rate effects are almost identical in both materials. The dislocation intersection is most plausible deformation mechanism for thermally activated process in 6000 aluminum alloy independent of the aging treatment.抄録全体を表示PDF形式でダウンロード (828K)
解説
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松田 健二, 里 達雄2002 年 52 巻 3 号 p. 136-147
発行日: 2002年
公開日: 2007/03/30
ジャーナル フリーPDF形式でダウンロード (6517K)
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