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Volume 69, Issue 3
Displaying 1-6 of 6 articles from this issue
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—Problems and Limitations in Taylor's Model—Hirosuke Inagaki2005 Volume 69 Issue 3 Pages 283-290
Published: 2005
Released on J-STAGE: October 12, 2005
JOURNAL FREE ACCESSRecent trends in the field of texture investigations are briefly reviewed. ODF and EBSP analyses have made most significant contribution to the progress in the texture investigations. Owing to the development of these two experimental techniques, we can now not only quantitatively evaluate textures of various materials, but also we can directly correlate the distribution of main texture components with the observed microstructures. As to the theoretical investigations, the development of rolling textures of various metals has been intensively studied by using Taylor's model. In this paper, the validity of the basic assumption of the homogeneous deformation adopted in this model is critically examined in detail. All metallographic observations made on cold rolled pure Fe and Al do not support this assumption. It is strongly suggested that dislocation substructures developed during cold rolling strongly affect the development of cold rolling textures.
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Kinji Saijo, Kazuo Yoshida2005 Volume 69 Issue 3 Pages 291-297
Published: 2005
Released on J-STAGE: October 12, 2005
JOURNAL FREE ACCESSThe influence of atmospheric exposure on the low-temperature bonding of surface-activated aluminum, copper and mild steel sheets was studied in a high vacuum. The previous report showed that tight bonding was achieved in high vacuum with a surface activation bonding technique. However, a considerable amount of residual gases, such as water, hydrocarbons and carbon dioxide, remained in the atmosphere. Therefore the activated surface could immediately be contaminated with these gases.
Bonding strengths were examined after exposure to various air pressures after surface activation. This decreased the bonding strength of Al after a threshold value of approximately 102 Pa•s was reached at various pressures. The bonding strength of Cu was decreased after an exposure of 100 Pa•s. XPS analysis revealed that the activated surface of Al was immediately oxidized by atmospheric exposure. However tight bonding was still attainable up to an exposure of 102 Pa•s. In contrast, the activated surface of Cu was not oxidized by atmospheric exposure, and only adsorption of residual gases was observed, but the bonding strength decreased with a smaller exposure compared with Al.
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Takeshi Ohtomo, Takahiro Ishizaki, Daisuke Ogiwara, Hiroshi Kawarada, ...2005 Volume 69 Issue 3 Pages 298-302
Published: 2005
Released on J-STAGE: October 12, 2005
JOURNAL FREE ACCESSZnTe thin films were electrochemically deposited onto Au-coated Cu substrates from an electrolytic solution containing ZnSO4, TeO2, citric acid and sodium citrate. Effects of deposition potentials and solution's Zn concentrations on the structure, chemical composition and electrical property were investigated. The resistivity, conduction type, carrier density, and carrier mobility were evaluated with a Hall effect measurement apparatus. A film with nearly stoichiometric composition was deposited at -0.80 V vs. Ag /AgCl at 353 K from a solution containing 2.0×10-2 kmol m-3-ZnSO4, 1.0×10-4 kmol m-3-TeO2, 9.0×10-2 kmol m-3-citric acid and 2.1×10-1 kmol m-3-sodium citrate and was well crystallized with cubic preferential orientation along the (111) plane. A resistivity, the carrier density and the carrier mobility were 4.1×102 Ωm, 2.9×1019 m-3 and 5.3×10-4 m2 V-1 s-1, respectively.
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Jyh-Tyng Chou, Ken-ichi Ikeda, Hideharu Nakashima2005 Volume 69 Issue 3 Pages 303-307
Published: 2005
Released on J-STAGE: October 12, 2005
JOURNAL FREE ACCESSFor clarification of the grain boundary energy and the structure of magnesium [1100] symmetric tilt boundaries, the atomic structure was obtained by molecular dynamics simulations. The results are summarized as follows. The grain boundary energy of [1100] symmetric tilt boundary depends on misorientation angle. There is a large energy cusp at the angle which corresponds to (1122) Σ11 symmetric tilt boundary. The boundary is one of the twins. It was found that (1124) Σ10 and (1122) Σ11 boundaries consist of single structural units, while (1126) Σ35b, (2246) Σ59 and (2242) Σ35a boundaries consist of two different structural units, respectively.
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Daigoro Mori, Nobuo Kobayashi, Tamio Shinozawa, Tomoya Matsunaga, Hide ...2005 Volume 69 Issue 3 Pages 308-311
Published: 2005
Released on J-STAGE: October 12, 2005
JOURNAL FREE ACCESSAlthough fuel cell vehicles have great potential as future vehicles, it is also realized that further breakthrough technologies to solve essential problems, such as cost and cruising range to be competitive with internal combustion engine vehicles. We have developed a new type of hydrogen-absorbing alloy tank. The high-pressure metal hydride (MH) tank is designed, based on the 35 MPa cylinder vessel. The heat-exchanger module including hydrogen-absorbing alloy is integrated in the tank. Its advantage over high-pressure cylinder vessel is large hydrogen storage capacity, for example, 7.3 kg at the 180 L tank volume. Cruising range is about 2.5 times longer than that of the same volume 35 MPa cylinder vessel system.
While the conventional hydrogen-absorbing alloy tank has problems in charge and discharge process, the hydrogen charging rate of this system is equal to 35 MPa cylinder without external cooling facility. Furthermore, the hydrogen-absorbing alloy, Ti-Cr-Mn with AB2 laves phase can release hydrogen at 243 K. Its dissociation pressure at 243 K is 0.5 MPa.
High-pressure MH system shows a realistic way to obtain adequate cruising range over 700 km. To develop a practical hydrogen tank for fuel cell vehicles, estimated target of hydrogen storage capacity of alloys is 3-4 mass% and 1600-2400 times as volumetric density.
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Qinglian Zhang, Rongguang Wang, Masahiko Kato, Keijiro Nakasa2005 Volume 69 Issue 3 Pages 312-319
Published: 2005
Released on J-STAGE: October 12, 2005
JOURNAL FREE ACCESSSurfaces of solution-treated SUS304, SUS430, SCM435 and SKD5 steels were sputter-etched by Argon ions in an R.F. magnetron sputtering apparatus for 7.2, 14.4 and 28.8 ks. The observation using FIB and SIM shows that the conical carbides are formed on the surfaces of all the steels examined, and they are growing from the surface towards inside during sputter-etching. The carbides precipitate more along grain boundaries than in grains for SUS430 and SUS304 steels with low carbon content, while they uniformly precipitate in grains for SCM435 and SKD5 steels with high carbon content. The aspect ratios of conical carbides change within the range from 2 to 4 depending on sputter-etching time, sputter voltage, kinds of steels, size and density of carbides. The precipitation of carbides occurs under the balance of carbon diffusion velocity and sputter-etching rate. The size and density of conical carbides increase with increasing sputter-etching time. They eventually disappear, but many small carbides newly precipitate after long time sputter-etching.
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