巻号一覧
70 巻, 7 号
選択された号の論文の12件中1～12を表示しています
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世利 修美, 廣瀬 史昌2006 年 70 巻 7 号 p. 525-533
発行日: 2006年
公開日: 2006/07/20
ジャーナル フリーIn order to improve corrosion resistance of 2024 aluminum alloy, a preferential removal of CuAl2 intermetallic compound particles on the alloy surface has been studied in trail and error. One of the preferable electrochemical conditions for the CuAl2 preferential removal treatment was a cathodic current density of -2 kAm-2 in a 30 mass%H2SO4 solution for the period of 300 s. By the above treatment, it is shown that the surface with free CuAl2-particles has morphologically and electrochemically performed corrosion-resistant characteristics. The zinc plating on aluminum alloy makes an effective surface modification to obtain 2024 improved corrosion resistant characteristics.
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孫 仁俊, 中野 博昭, 大上 悟, 小林 繁夫, 福島 久哲, 堀田 善治2006 年 70 巻 7 号 p. 534-540
発行日: 2006年
公開日: 2006/07/20
ジャーナル フリーThe effect of equal-channel angular pressing (ECAP) on the pitting corrosion resistance of anodized Al and Al-Mg alloy was investigated by electrochemical techniques in a solution containing 0.25 mol/L of AlCl3 and by surface analysis. The time required before initiating pitting corrosion of anodized Al was longer with ECAP than without, indicating improvement in the pitting corrosion resistance by application of ECAP. However, in anodized Al-Mg alloy, the pitting corrosion occurred earlier with ECAP than without, showing that the corrosion resistance was worse with ECAP than without. SEM and EPMA observation revealed that pitting corrosion of anodized Al occurred around the impurity precipitates and that the size of the impurity precipitate decreased as a result of the ECAP. The improvement in pitting corrosion resistance of anodized Al by ECAP appears to be attributable to a decrease in the size of impurity precipitates. On the other hand, in anodized Al-Mg alloy, cracks occurred in the anodic oxide films during initial corrosion and the cracks were larger with ECAP than without. It is assumed that the pitting corrosion was promoted by the cracks resulted from ECAP.
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南部 智憲, 江崎 尚和, 湯川 宏, 森永 正彦2006 年 70 巻 7 号 p. 541-547
発行日: 2006年
公開日: 2006/07/20
ジャーナル フリーThe local lattice distortion and the chemical bond change in the course of hydrogenation in niobium metal were simulated using the pseudopotential method and the DV-Xα molecular orbital method. The calculated enthalpy changes, ΔH, of hydrogen solution into niobium indicated that hydrogen could be dissolved readily into niobium up to the hydrogen content (H/M) of about 0.7 at 673 K, but further dissolution became difficult, in agreement with the experiment. The local lattice distortion appeared to occur in the niobium lattice so as to suppress the large decrease in the Nb-Nb covalent interaction during hydrogen dissolution, while enhancing the Nb-H interaction.
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宍戸 逸朗, 松尾 明彦, 豊山 裕万, 水野 正隆, 荒木 秀樹, 白井 泰治2006 年 70 巻 7 号 p. 548-553
発行日: 2006年
公開日: 2006/07/20
ジャーナル フリーThe interlayer reaction between Sn-3.0Ag-0.5Cu lead free solder and electrolytic coppers, those include different types of lattice defects analyzed by positron annihilation technique in advance, has been investigated. The copper sample, which has a higher concentration of vacancy clusters, has a higher growth rate of Cu3Sn layer formed on reaction diffusion with the solder, and only for the sample voids was observed in the layer.
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丸野 祐策, 三村 直也, 宮原 広郁, 大城 桂作2006 年 70 巻 7 号 p. 554-561
発行日: 2006年
公開日: 2006/07/20
ジャーナル フリーThe influence of the surface notch size, the SiC particle distribution and the solidification microstructure of the matrix on the fatigue characteristics were investigated, and the parameter governing fatigue was evaluated for SiC particle-reinforced JIS-AC4B alloy composites. 10 to 30% vol 11 μm SiC particles were relatively homogeneously dispersed in an Al-6.79% mass Si-2.93% mass Cu-0.17% mass Mg-0.59% mass Fe matrix alloy through a combination of pressure infiltration and melt stirring casting technique. The matrix microstructure consists of a dendritic alpha phase and eutectic structure. A few intermetallic Fe compounds were observed in the dendritic alpha phase. Furthermore, all composite specimens contained SiC particle clusters. Vickers hardness of composites increased due to the dispersion of SiC particles and age hardening effect, and the hardening ability increased with an increase in the volume fraction of SiC particles. Rotating bending fatigue tests were carried out on both notch-free and notched specimens that were aged to reach their peak hardness. When the stress concentration factor was low, cracks generated from cast defects in the matrix alloy specimen. On the contrary, they generated in boundaries between the SiC particles and the matrix in the composite specimens. Furthermore, the fatigue strength decreased with an increase in the SiC volume fraction. For the notched matrix specimen, in which the stress concentration factor is high, the notch size governed the fatigue strength. However, the cracks generated from the boundaries near SiC particles instead of the notch base in the notched composite specimen. Moreover, it was found that the fatigue limit stress is unchanged in the composite specimen even when the notch is introduced, although the critical stress for crack generation is reduced. Microstructural observations revealed that the cracks are spread and diverted in and around clusters of SiC particles. This suggests that crack propagation resistance is improved by the SiC particles in the notched composite specimen.
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岡安 和人, 福富 洋志2006 年 70 巻 7 号 p. 562-567
発行日: 2006年
公開日: 2006/07/20
ジャーナル フリーUniaxial compression tests were conducted on Al-3 mass%Mg alloy under various amounts of strain, strain rates and temperatures. High temperature yielding phenomena are seen at the temperatures higher than 623 K and strain rates ranging from 1.0×10-4 s-1 to 1.0×10-3 s-1. Texture examination elucidated that fiber textures are constructed in all the deformation conditions. The main components of the fiber textures are {011} and {001}. The transition of the main component from {011} to {001} with an increase in strain is seen in some deformation conditions. It is considered that orientation stability for crystal slip deformation as well as the rapid recovery during the deformation of the grains close to {001} orientation made it possible to grow by consuming the other deformed grains with the orientations such as {011}, resulting in the development of {001} texture with an increase in strain. In addition, it is suggested that new grain formation in dynamic recrystallization also contribute the development of {001} texture.
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半谷 禎彦, 吉田 俊介, 北原 総一郎, 天田 重庚2006 年 70 巻 7 号 p. 568-571
発行日: 2006年
公開日: 2006/07/20
ジャーナル フリーThe pore defects inside die casting have an influence on the mechanical properties or air leakage efficiency of products. In these days, the classification of these pore defects is not clearly determined, and accurate measures to reduce these pore defects in the production field are carried out by trial-and-error processes. The accurate classification of pore defects leads to the accurate clarification of the direct cause of these defects. For this purpose, it is necessary to estimate pore defects quantitatively, instead of qualitatively. We propose the fractal dimension as the quantitative indicator of the classification of pore defects. In this study, we examined the fractal analysis of the shapes of “blow hole” and “shrinkage porosity”, and the validity of applying fractal dimensions to pore defects is investigated. The fractal dimensions for shapes of boundary lines for “blow hole” and “shrinkage porosity” are about 1.05~1.09 and about 1.15~1.17, respectively. Therefore, it is shown that the quantitative classification of “blow hole” and “shrinkage porosity” using fractal dimensions is definitely feasible.
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坂口 信人, 新家 光雄, 赤堀 俊和, 戸田 裕之2006 年 70 巻 7 号 p. 572-578
発行日: 2006年
公開日: 2006/07/20
ジャーナル フリーTi-XNb-10Ta-5Zr alloys were fabricated based on Ti-30Nb-10Ta-5Zr alloy, which was the composition that simplified that of Ti-29Nb-13Ta-4.6Zr alloy for biomedical applications. The tensile deformation mechanisms of the Ti-25Nb-10Ta-5Zr, Ti-30Nb-10Ta-5Zr, and Ti-35Nb-10Ta-5Zr alloys were investigated using X-ray diffraction analysis under several loading conditions.
Under loading conditions, the X-ray diffraction peaks of all specimens in this study shift to higher angles than those obtained under non-loading conditions. In the crystal orientation of Ti-30Nb-10Ta-5Zr alloy, in which the lattice strain has reached the maximum elastic lattice strain, plastic deformation (for example slip) is moved with elastic deformation. Therefore, the elastic modulus of this alloy appears to decrease in terms of strain over a proportional limit. Thus, the elastic deformation behavior of the Ti-30Nb-10Ta-5Zr alloy does not obey Hooke's law.
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古田 忠彦, 倉本 繁, 陳 栄, Junghwang Hwang, 西野 和彰, 斎藤 卓, 池田 勝彦2006 年 70 巻 7 号 p. 579-585
発行日: 2006年
公開日: 2006/07/20
ジャーナル フリーEffect of oxygen on phase stability and elastic deformation behavior after cold working of Ti-Nb-Ta-Zr-O alloys were investigated by employing tensile test, microstructure observations, in-situ XRD analysis, and electrical resistivity measurements. The specimens were Ti-36%Nb-2%Ta-3%Zr-0.35%O (mass%) alloy (Gum Metal) and the reference alloys having lower and higher oxygen contents (from 0.07% to 0.93%) than that in Gum Metal. Pseudo-elastic deformation with rearrangements of α″ variants was observed in the specimen with 0.07% oxygen content. As the oxygen content was increased, the generation of α″ was suppressed and yield strength was increased. The elastic behavior in Gum Metal with 0.35% oxygen content showed non-linearity, with the slope of the stress-strain curve in the elastic region continuously decreasing with stress increase. In-situ XRD measurements during tensile loading in Gum Metal showed that all β peaks shift monotonically to higher 2θ angles with increasing tensile strain up to 2.7%. This result indicates that elastic behavior in Gum metal is not accompanied by phase transformation, such as stress-induced α″. The higher oxygen content alloy with 0.93% had linear elastic deformation behavior and a yield strength of about 1600 MPa. Additionally, the starting temperature of athermal ω formation was lowered with increasing oxygen and cold working.
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梅川 翔悟, 井野 博満2006 年 70 巻 7 号 p. 586-591
発行日: 2006年
公開日: 2006/07/20
ジャーナル フリーThe aim of this study is to examine the effect of doped N and Au on the lattice parameter and the magnetic properties of FCC Fe-Cu alloys, prepared by mechanical alloying. By the measurements of X-ray diffraction, it is shown that both N and Au extend the FCC lattice. The magnetic moment and the Curie temperature of Fe-Cu-N alloys decreased drastically with increasing N content, but the magnetic moment and the Curie temperature of Fe-Au-Cu-N alloys increased with increasing Au. Analysis based on a molecular field approximation shows the exchange integral is not affected by the addition of Au, but strongly affected by the addition of N. The fact is interpreted as the result that the latter changes not only the lattice parameter but also the band structure of the alloys.
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森 信幸, 中原 義昭, 深町 星児, 向田 昌志, 大城 桂作2006 年 70 巻 7 号 p. 592-598
発行日: 2006年
公開日: 2006/07/20
ジャーナル フリーThe growth process of RE123 (REBa2Cu3O7-x, RE=Nd and Sm) crystals in the atmosphere of Ar-1%O2 were observed in-situ to investigate the nucleation and growth process of faceted RE123 crystals from the liquid +422(Nd4Ba2Cu2O10) or 211(Sm2BaCuO5) on MgO(100) substrate through a peritectic reaction by using high temperature optical microscope with zoom lens. The nucleated faceted 123 crystals grew at a rate depended on the undercooling(ΔT). Growth rate(u) and incubation time (tinc) for nucleation were obtained from the changes in position of faceted interface during isothermal solidification. Growth rate u(m/s) was approximated by the following relation: u=Ag(ΔTr2/η(T)), where η(T) was the viscosity, ΔT=Tp-T, ΔTr=ΔT/Tp, T was temperature, Tp was peritectic temperature, Ag was a constant: Ag=0.60×106 for Nd and Ag=1.8×10-5 for Sm. Nucleation rate(Iv) was obtained from the relationship between the number of nucleated crystals(n) and time(t). Iv(m-3 s-1) was approximated by Iv=An(1/η(T)) exp (-B/ΔTr2), where An and B were constants: An=3.5×107, B=1.5×10-3 for Nd, and An=12.5×107, B=3.2×10-3 for Sm.
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高平 信幸, 田中 敏宏2006 年 70 巻 7 号 p. 599-605
発行日: 2006年
公開日: 2006/07/20
ジャーナル フリーThe authors have found that liquid metals droplet wetted and spread very widely on solid substrates of Fe in reduced atmosphere after the surface oxidation of the surfaces. This unusual wetting is caused by capillary penetration into porous layer formed on the iron sample that is reduced after oxidized in air. In order to find adequate conditions for the unusual wetting behavior, we have investigated the effect of iron substrate on reduced porous morphology of oxidized iron. Pores in the porous iron layers of all samples with iron substrates are connected 3-dimensionally each other, while those of porous iron films of some samples without substrates were isolated partially and were not connected entirely in the film. Adequate porous iron layers for the unusual wetting were obtained mainly from the condition on the reduction of oxidized iron layer formed on the surface of iron substrates rather than the reduction of oxidized iron film without iron substrates.
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