巻号一覧
49 巻, 2 号
選択された号の論文の8件中1～8を表示しています
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研究論文
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横田 純一, 廣澤 渉一, 里 達雄, 神尾 彰彦1999 年 49 巻 2 号 p. 51-56
発行日: 1999年
公開日: 2007/03/30
ジャーナル フリーThe Monte Carlo computer simulation has been performed to elucidate the effects of the trace-additional elements of Cu and Mg on the δ′ phase precipitation in an Al–Li alloy. The assumed alloy composition in this work was Al–8 mol%Li with additional 0.25 mol%Cu or Mg. The aging temperature employed for the simulation was 463 K. With increasing Monte Carlo step the precipitation of the δ′ phase with the L12-type ordered structure was clearly confirmed in the simulated atom configurations. Based on the simulated atom configurations the solute atom concentration of the matrix, size and number density of the δ′ phase were determined as a function of the Monte Carlo step. While Cu addition to an Al–Li alloy exerts almost no effects on the precipitation of the δ′ phase, Mg addition has the significant effects to accelerate the precipitation of the δ′ phase and also to produce increased number density of the refined δ′ precipitates. These characteristic effects of the additional elements on the δ′ precipitation are closely related with the ordering parameters among quenched-in excess vacancies, Li atoms and trace-additional elements. The computer simulation demonstrates that Mg atoms preferentially exist at the second nearest neighbor positions of the Li atoms and attracts vacancies to form Mg/Li/Vacancy complexes in the alloy containing Mg. These Mg/Li/Vacancy complexes further attract Li atoms and act as the effective nucleation sites for the δ′ phase. This mechanism explains the accelerated precipitation of the δ′ phase in the Al–Li alloys containing Mg.抄録全体を表示PDF形式でダウンロード (1156K) -
細川 裕之, 岩崎 源, 森 隆資, 田形 勉, 馬渕 守, 東 健司1999 年 49 巻 2 号 p. 57-61
発行日: 1999年
公開日: 2007/03/30
ジャーナル フリーDeformation and cavitation characteristics have been investigated at 613∼693 K for Al–4.5 mass%Mg–0.05 mass%Fe and Al–4.5 mass%Mg–0.2 mass%Fe alloys with grain size of 50 μm. The alloys showed strain-rate sensitivity of 0.3 over a strain-rate range from 10−5 s−1 to 10−2 s−1 and elongation-to-failure above 300% at a strain-rate of 1 × 10−3 s−1. The results indicates that the alloys behave like Glass I type which deformation is controlled by dislocation glide dragged by solute atoms. Cavitation was increased by increasing iron content for all strains. Most cavities were nucleated at the interface between ferrous primary crystal and matrix and elongated parallel to the tensile direction. The critical diameter of the primary crystal, above which cavity is nucleated, was 1.5 μm at grain boundary and 0.5 μm at grain interior, which were very close to the theoretical results.抄録全体を表示PDF形式でダウンロード (1130K) -
古俣 和直, 鈴木 孝司, 山田 一雅, 世利 修美1999 年 49 巻 2 号 p. 62-66
発行日: 1999年
公開日: 2007/03/30
ジャーナル フリーIt is well known that elements such as Fe and Si are always contained in an industrial pure aluminum. Some of them dissolve in matrix, others form Al–Fe type or Al–Fe–Si type of the intermetallic compounds. The ratio of Fe/Si in intermetallic compound particles is responsible for the pitting attacks of the aluminum. The degree of the pitting attacks attributes to the preferential dissolution of aluminum and iron in the particles. In this case, the aluminum of the intermetallic compounds is always preferentially dissolved. Then the atmosphere of a particle is changed into low pH by the hydoration of aluminum ions. The higher ratio of Fe/Si is the easier preferential dissolution of iron. The polarization measurements explained that the aluminum and ferrous ions produced by the dissolution make the oxide film around the particle weak and provide a suitable concave for developing the pitting attacks by dissoluting the matrix.抄録全体を表示PDF形式でダウンロード (1056K) -
北澤 君義, 尾角 拓勉1999 年 49 巻 2 号 p. 67-71
発行日: 1999年
公開日: 2007/03/30
ジャーナル フリーAlthough the CNC incremental forming process permits thin shell parts of great depth to be formed with multi tool-path schedules, the process causes remarkable thinning to the thin shell parts. In order to suppress the thinning, a new CNC incremental forming process with ORIGAMI method, in which a shell is formed from a flat blank by means of pre-bending (ORIGAMI process) and subsequent incremental stretch-expanding, has been developed. Automotive trunk-lid type panels are formed from aluminum and its alloy blanks by means of the process, and the influence of tool-path schedules, materials properties and forming conditions on the minimum wall-thickness of the panel are examined. It is found that there is a linear relationship between the amount of thinning and the height of stretch-expanding, since the straining in the stretch-expanding process is in plane strain. Experimental results show that the process is suitable for suppression of the thinning.抄録全体を表示PDF形式でダウンロード (842K) -
北澤 君義, 中島 明1999 年 49 巻 2 号 p. 72-76
発行日: 1999年
公開日: 2007/03/30
ジャーナル フリーA process of CNC incremental forming in which a cylindrical shell is formed a flat blank by means of conical incremental stretching and subsequent reverse incremental drawing, has the advantage of adaptability to small-lot production of cylindrical shell parts. Although the forming limit has been reported for the conical incremental stretching, the limit has not been illuminated previously for the cylindrical incremental drawing. Here we report the forming limit in the cylindrical incremental drawing of aluminum sheets. It is found that the forming limit is governed by occurrence of versatile rupture modes, and these rupture modes are avoidable by controlling the tool-path schedule in the process. Furthermore, experimental results show that the tool-path pitch is a dominant parameter in determining the success or failure of the process, because the excessive tool-path pitch forms the excess metal into a plastic hinge line in the vicinity ahead of the tool, and thus adds resistance to incremental drawing flow, which promotes rupture.抄録全体を表示PDF形式でダウンロード (1543K) -
徳勢 允宏, 内田 浩, 松永 賢二, 和久 芳春1999 年 49 巻 2 号 p. 77-82
発行日: 1999年
公開日: 2007/03/30
ジャーナル フリーβ–Si3N4 whisker preforms are directly formed from amorphous Si3N4 (obtained by imido process) with addition of yttrium oxide by baking under specially controlled conditions. Their volume fraction is only 13%, but their flexural strength is more than 10 MPa. In-situ formed β–Si3N4 whisker preform is used for the reinforcement of 6061 and 7075 aluminum alloys by vertical squeeze casting. Even for a whisker volume fraction of 13%, the in-situ preforms have no cracks nor deformation. On the other hand, the filtration β–Si3N4 whisker preforms with a volume fraction of 25% have some cracks or deformation. Therefore in-situ formed β–Si3N4 whisker preforms are suitable for squeeze casting. Aluminum alloy composites have high flexural strength from room temperature to 573 K. Also the rotary bending fatigue tests show that fatigue properties of 6061 and 7075 aluminum alloy are much improved by reinforcement of β–Si3N4 whiskers. The SEM observation of fracture surface, revealed that β–Si3N4 whiskers has good compatibility with 6061 and 7075 aluminum alloys.抄録全体を表示PDF形式でダウンロード (1288K) -
川井 五作, 小川 恒一, 越智 秀, 時末 光1999 年 49 巻 2 号 p. 83-88
発行日: 1999年
公開日: 2007/03/30
ジャーナル フリーFriction welding of various aluminum alloy pipes to SUS304 stainless steel pipe was carried out making clear weldability at dissimilar material pipe. A1050/SUS304, A5052/SUS304, A5056/SUS304, A6061/SUS304 and A6063/SUS304 joints showed good weldability and the maximum joint efficiencies of these joints in tensile test were about 91%, 71%, 60%, 79% and 97%, respectively. In these cases, the formation of Al13Fe4 intermetallic compound was induced by the interdiffusion through the weld interface. On the other hand, other joints had poor weldability. In the cases of A2011/SUS304, A2017/SUS304 and A2024/SUS304 joints, CuAl2 and Al7Cu2Fe were observed on the friction surface, and the maximum joint efficiencies of these joints were about 26%, 39% and 32%, respectively. For the case of A7075/SUS304 joint, Al23CuFe4 was observed on the friction surface, and the maximum joint efficiency was about 37%.抄録全体を表示PDF形式でダウンロード (1001K)
解説
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長尾 彰英, 倉本 繁, 菅野 幹宏1999 年 49 巻 2 号 p. 89-96
発行日: 1999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 (1711K)
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