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Volume 57, Issue 12
Displaying 1-18 of 18 articles from this issue
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Shigeo Sugawara, Jirô Watanabé1993 Volume 57 Issue 12 Pages 1361-1366
Published: 1993
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe dissolution process of (111) faces of Cu crystals in Marukawa’s solution (FeCl3·6H2O 0.88 kmol·m−3, HCl 4.4 kmol·m−3, HBr 0.12 kmol·m−3) was studied. The etching was carried out at 280 K for 10-50 s, and the three-dimensional size of etch pits revealed at screw dislocations and the dissolved thickness of the matrix surface were measured by replica electron microscopy and two-beam interferometry, respectively.
After an initial lapse of 10 s, the width and depth of dislocation etch pits increased linearly with the etching time, while the side slope of etch pits decreased slowly and approached a constant value of 0.1. The dissolved thickness of the matrix surface increased also linearly with the etching time. From the growth rate of etch pits and the removal rate of the matrix surface, the vertical dissolution rate along the dislocation line, vd, and the lateral one, vh, were determined. Using these values, it has been estimated from the spiral theory of crystal dissolution at a screw dislocation site that the spacing of a spiral step is ∼2.1×10−3 μm and that the radius of curvature at a spiral center, which is equal to the size of critical nucleus for two-dimensional nucleation on a stress-free surface, is 1.1×10−4-5.3×10−4 μm. From the nucleation theory of matrix surface dissolution, the rate of two-dimensional nucleation on the dislocation-free surface has been deduced to be 4.3×105 μm−2·s−1.View full abstractDownload PDF (988K) -
Satoru Yamamoto, Toshiyuki Wakabayashi, Hisayoshi Kobayashi1993 Volume 57 Issue 12 Pages 1367-1373
Published: 1993
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSIn the present work, the solid solubility, formation of compounds and strength in Al alloys have been examined by the calculation of energy and Mulliken’s population of cluster models by the extended Hückel method.
The results of the present work are as follows:
(1) The stability of alloy systems and the nature of chemical bonds between the atoms of Al and the alloying elements can be estimated from the cohesive energy, atomic bond populations and atomic populations.
(2) The tendency of mutual solid solubility, insolubility and compound-formation in Al alloys can be judged as follows:
\ oindent(a) In the case of the elements which make compounds and have no mutual solubility with Al, the change of cohesive energy with the composition deviates markedly from lineality and the nature of chemical bonds is ionic or covalent.
\ oindent(b) In the case of the elements which make compounds and have mutual solubility with Al, the change of cohesive energy with the composition deviates a little from lineality and the nature of bonds is a mixture of ionic or covalent and metallic bonds.
\ oindent(c) In the case of elements which make no compounds and have mutual solubility with Al, the cohesive energy changes linearly with the composition and the nature of bonds is the metallic one or its mixture with covalent or ionic bond.
\ oindent(d) In the case of elements which make no compounds and have no mutual solubility with Al, the change of cohesive energy with the composition deviates a little from linearlity and the nature of bonds is anti-bonding.
(3) The hardening ability of solute atoms in Al alloys may be attributed to the (covalent+ionic) part in the nature of chemical bonds between Al atoms and solute atoms.View full abstractDownload PDF (687K) -
Toshitada Shimozaki, Yoshinori Wakamatsu, Masami Onishi1993 Volume 57 Issue 12 Pages 1374-1379
Published: 1993
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSNumerical analysis for sequential phase growth behavior in a multi-phase diffusion couple has been proposed on the basis of the finite difference method. An initial concentration-distance curve has been obtained by inserting a new phase thin layer of the linear concentration-distance curve having 5∼10 gridpoints, between existing phase layers. In spite of simple approximations for the initial concentration-distance curve, it was found that the present method is useful for the analysis of the phase growth behavior of the new and existing phases. This method will make it possible to estimate the widths of diffusion layers formed during galvanizing and galvannealing.View full abstractDownload PDF (790K) -
Masakatsu Maeda, Hirotaro Mori, Takao Sakata, Hidehiro Yasuda1993 Volume 57 Issue 12 Pages 1380-1384
Published: 1993
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSBilayer films of Hf(target atom)/SiO2(substrate) and of Au/SiO2 were irradiated with 2 MeV electrons in an ultra-high voltage electron microscope, with the electron beam incident on the target metal layer. With this irradiation, hafnium atoms are successfully implanted into the SiO2 substrate, and nm-sized particles of HfO2 are formed, being dispersed in an amorphous silicon oxide matrix. On the other hand, no evidence for the implantation of gold is obtained even after prolonged irradiation. Based upon these results, the factors controlling the ease with which foreign atoms are successfully implanted into the SiO2 substrate under MeV electron irradiation are discussed.View full abstractDownload PDF (1131K) -
Daisuke Shindo, Jun-ichi Kudoh, Sumio Iijima, Tetsuo Oikawa, Yoshiaki ...1993 Volume 57 Issue 12 Pages 1385-1389
Published: 1993
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSBy using a new quantitative recording material, the imaging plate, electron diffraction patterns were measured quantitatively. In order to evaluate quantitatively the intensity of weak scattering in electron diffraction patterns, a background fitting method was developed and applied to electron diffraction patterns of Ga0.5In0.5P and polyethylene. The background fitting method was successfully carried out with a quadratic function in both cases. It was found that the intensity distribution of diffuse scattering peaks of Ga0.5In0.5P had an asymmetrical shape with higher intensities at larger scattering angle, indicating the existence of static displacement of atoms. Also, in the electron diffraction pattern of polyethylene, decrease of 200 diffraction intensity due to the 200 keV and 100 keV electron irradiation was quantitatively evaluated.View full abstractDownload PDF (1393K) -
Taku Sakai, Hiromi Miura, Takeshi Iwai, Naokuni Muramatsu1993 Volume 57 Issue 12 Pages 1390-1396
Published: 1993
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSHot deformation as well as dynamic recrystallization (DRX) of a commercial Cu-Be25(Cu-1.8Be-0.25Co) alloy were studied by means of tensile testing and microstructural observation at the temperature ranging 923 K to 1123 K under strain rates of 10−5 to 10−1 s−1. The flow curves showed a sharp yield point phenomenon followed by work softening and steady state flow at higher Z (=\dotεexp(Q⁄RT)), although they showed normal yielding, work hardening and then steady state flow at lower Z. DRX took place during work softening or hardening and led to an equilibrium or stable grain structure at high strains. The stable structure, which was dependent on T or \dotε, consisted of a mixture of fine grains and comparatively coarse grains with many sided irregular boundaries at higher Z. In contrast, almost equiaxial grains with smooth or straight boundaries were observed at lower Z. A relationship between the steady state flow stress σs and the stable dynamic grain size Ds is almost the same as that of Cu at higher Z, but it shifted towards a finer grain side at lower Z. Such different types of DRX are discussed by considering the roles of alloying elements of Be and Co. It is concluded that yielding flow can be controlled by the viscous motion of dislocations which drag the solute atmosphere composed of Be atoms, and on the other hand, steady state flow can be controlled by DRX assisted by the volume diffusion of Cu atoms.View full abstractDownload PDF (1369K) -
Nobuya Shinozaki1993 Volume 57 Issue 12 Pages 1397-1403
Published: 1993
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSMuch attention has been paid to utilizing manganese ore in steelmaking because of its inexpensiveness. In order to utilize manganese ore more useful, the simultaneous reactions of dephosphorization and desulfurization of steel by CaF2-CaO-Al2O3 fluxes containing manganese oxide were investigated, and the following results were obtained.
(1) Reactions of dephosphorization, desulfurization, transfer of manganese from flux to liquid iron and distribution of oxygen between flux and iron occurred. These reactions reached an equilibrium within a short period.
(2) As the sum of MnO and FetO contents in flux decreased, in other words, as the sum of CaO and CaF2 contents in flux increased, the phosphate capacity increased and the sulfide capacity slightly decreased.
(3) The activity coefficient of MnO in flux significantly increased with decreasing sum of MnO and FetO contents. It showed a large value from 5 to 6 for the flux containing MnO and FetO less than a few mass%.
(4) Under the present experimental conditions a rapid transfer of sulfur or oxygen between flux and liquid iron occurred at initial period, also the other reactions-that is, dephosphorization and transfer of manganese from flux to iron-proceeded so fast. This phenomenon was presumed to be the interfacial turbulence.View full abstractDownload PDF (709K) -
Mitsuhiro Numata, Motoki Kanamori, Masahito Sugiura, Akio Fuwa1993 Volume 57 Issue 12 Pages 1404-1411
Published: 1993
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSSilicon precipitation reaction was conducted on non-crystalline quartz glass substrate from the hydrogen reduction of Si2Cl6 at temperatures from 873∼1273 K using a horizontal cold wall reactor. The precipitation rate was measured under various experimental conditions and precipitation morphology was observed by X-ray diffraction analysis and SEM. The precipitation rate is one order of magnitude larger than those of other silicon source gases. In the condition when the reaction is controlled by a surface reaction (873∼1073 K), the rate dependence on Si2Cl6 and H2 are proportional to 1/2 order of the former and to the first order of the latter, respectively. From XRD and SEM results, Si precipitated at 1073 K has a preferred crystal orientation in the ⟨110⟩ direction.View full abstractDownload PDF (1458K) -
Masayuki Itagaki, Tooru Tsuru1993 Volume 57 Issue 12 Pages 1412-1420
Published: 1993
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe anodic dissolution mechanism of iron has been investigated using a channel flow double electrode (CFDE) system. The transient current in iron dissolution is separated into partial currents for dissolution of ions and formation of the adsorbed species, using FFT analysis with a dynamic collection number N(ω) of the electrode system. The dissolution of ferrous ions follows the formation of the adsorbed intermediate in the active dissolution potential region. The experimental results support that the anodic dissolution mechanism of iorn in sulfuric acid solution contains two adsorbed species. In the frequency domain, the efficiencies of the formation of adsorbed intermediate on the iron surface Φf(ω) and of the dissolution of ferrous ions Φdiss(ω) are obtained from FFT analysis of current transient curves. The amplitude of Φdiss(ω) decreases and that of Φf(ω) increases with the frequency. The numerical simulations for iron dissolution based on the reaction model involving two adsorbed species have been performed and the results have agreed well with that of the experiment in time and frequency domains.View full abstractDownload PDF (995K) -
Hiroyuki Takeshita, Yoichi Tomii, Toshio Oishi, Katsutoshi Ono1993 Volume 57 Issue 12 Pages 1421-1425
Published: 1993
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSQuantitative analysis of small amounts of oxygen in titanium was carried out by secondary ion mass spectrometry (SIMS). Titanium samples with oxygen concentration of 23, 200, 440, 770 and 1540 mass ppm were prepared. These were bombarded by Cs+ primary ion, and intensities of negative secondary ions such as 16O−, 64(TiO)− and 96(Ti2)− were measured. As the results of preliminary experiments, the changes in primary ion current and vacuum in the sample chamber can influence the accuracy of experimental values.
We found that 64(TiO)− was preferable to 16O− for quantitative determination of oxygen in titanium, although it had lower sensibility. The ion intensity ratio, 64(TiO)−⁄96(Ti2)−, was varied linearly with oxygen concentration and the correlation coefficient was 0.999. The relative standard deviation was less than 12% for the whole range of oxygen concentration studied. But both 16O− and 64(TiO)− were seriously interfered by residual gas and these interfered amounts were found to correspond to 420 ppm 16O− and 290 ppm 64(TiO)−, respectively.View full abstractDownload PDF (583K) -
Yukio Nishikawa, Kunio Tanaka, Yoshikazu Yoshida, Yuji Uesugi1993 Volume 57 Issue 12 Pages 1426-1432
Published: 1993
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe c-axis oriented ZnO films are successfully grown at low substrate temperatures at a high deposition rate, using a KrF excimer laser ablation technique. The influences of substrate temperatures and N2O gas on the structures of the films obtained in a vacuum of 1.3×10−3 Pa and a N2O atmosphere of 1.3 Pa are investigated. Species during laser ablation are also analyzed to discuss the characteristics of the films. The main results obtained are as follws.
The films deposited on the glass at the substrate temperatures of 373∼473 K show strong c-axis orientation at a rate of 1 nm/s. Grain sizes of the hexagonal films deposited on the Si (100) substrate are ranging from 4 to 40 nm. Good transparency for visible spectrum ranging from 80 to 85% is obtained with the films deposited in the N2O at the substrate temperatures of 473∼573 K. These films are formed by depositing neutral atoms and ions following laser ablation. But the ZnO molecule does not deposit. In the low N2O pressure of 1.3 Pa, the kinetic energies of atoms and ions do not decrease so much to promote migration of atoms and grow the c-axis oriented transparent ZnO films at low substrate temperatures.View full abstractDownload PDF (908K) -
Gil Geun Lee, Hitoshi Hashimoto, Ryuzo Watanabe1993 Volume 57 Issue 12 Pages 1433-1437
Published: 1993
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSA milling experiment was carried out to investigate the particle coagulation and coating and its spalling-off, which are characteristic to mechanical alloying of ductile powders, using Cu powder as a model material. The milling process was studied by microscopic observations of the morphological evolution of the milled powder and kinetic and dynamic considerations.
The coagulation and coating during milling were analyzed by the Gillespie-Langstroth equation. The analysis showed the rate equation consisted of the coagulation and coating rate terms, and the contribution of the coating increased with milling time. An analysis on the basis of the Hertz and Timoshenko ball impact theory showed that disk-shaped particles, which are the main constituents in the intermediate stage of milling, were formed by breaking-off of the coated films due to tensile stress generated by the impacting action of the milling balls. The experimental observations on the particle diameter and the thickness of the disk-shaped particles were in good agreement with the theoretical estimations.View full abstractDownload PDF (830K) -
Hiroyuki Shirahata, Takashi Murasumi, Michihiko Nagumo1993 Volume 57 Issue 12 Pages 1438-1444
Published: 1993
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSSynthesis of Sm2Fe17Nx was conducted by mechanical alloying mixtures of intermetallic compounds Sm2Fe17 and SmFe3. Effects of the mixing ratio and nitriding conditions on the magnetic properties were examined. Milled powders were subjected to a stabilizing treatment followed by annealing and nitriding. The nitriding temperature, holding time and N2 pressure were systematically varied. Milling of mixtures of intermetallic compounds gave an amorphous Sm-Fe alloy and α-Fe as in the case of milling of elemental metal powders. Optimum magnetic properties were obtained at a composition Sm15Fe85 at which the precipitation of α-Fe, SmO1−xNx and SmFe3 was minimum after nitriding. The increase in the coercivity was parallel to the nitrogen content which increased drastically and then gradually as the nitriding time was extended. It was noted that lattice constants of nitride were constant irrespective of nitrogen content, suggesting that the nitriding conditions affect mainly through the amount of nitride. The optimum nitriding temperature for coercivity was 450°C. The precipitation of α-Fe increased at higher temperatures, while the absorption of nitrogen decreased at lower temperatures. The nitrogen pressure was insensitive to the absorbed nitrogen content. The existence of α-Fe together with SmO1−xNx and Sm2O3 may affect the magnetization curve.View full abstractDownload PDF (605K) -
Hitoshi Yokota, Masazumi Okido, Takeo Oki1993 Volume 57 Issue 12 Pages 1445-1450
Published: 1993
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe interfacial impedance method is widely applied for the analysis of interfacial electrochemical phenomena. In this paper, the wettability of some metals to mercury was measured by means of the interfacial impedance method. The variations of impedance response for metal/mercury/metal with time were measured after dipping a pair of metal electrodes into the liquid mercury. Pb, Zn, Cu, Ni and Fe wet to mercury in the order of their wettability magnitude. The equivalent circuit at the interface between mercury and metals is considered to be a parallel circuit of resistance, Rr, and capacitance, Cdl, from the measurement of frequency response. The improvement of wettability with time leads to the increase of Cdl and the decrease of Rr. The impedance parameter is affected by the surface roughness of the metals. The interfacial wettability can be evaluated by means of the interfacial impedance method which has a small observation error in comparison with the measurement of sessile drop.View full abstractDownload PDF (713K) -
Hitoshi Yokota, Masazumi Okido, Takeo Oki1993 Volume 57 Issue 12 Pages 1451-1455
Published: 1993
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe wettability between Al alloys and graphite was evaluated by means of the interfacial impedance method. The Al alloy and graphite were contacted by centrifugal casting in Ar atmosphere. The electric equivalent circuit at the interface was considered to be a parallel circuit of resistance and capacitance. The improvement of wettability for aluminum to graphite leads to the increase of capacitance in the equivalent circuit. The most effective element to improve wettability was copper. The addition of Mg, Ti and Cr led to the increase of Cdl and the addition of Sn, W, Zn and Cu to the decrease of Cdl with rotation speed increase at the centrifugal casting. Cdl at the interface solid aluminum contacted to graphite was smaller than Cdl at the interface molten aluminum contacted to graphite.View full abstractDownload PDF (481K) -
Fumiyoshi Kirino, Junko Nakamura, Norio Ohta, Fumio Kugiya1993 Volume 57 Issue 12 Pages 1456-1464
Published: 1993
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSMagneto-optical recording materials consisting of NdTbFeCo were studied for high-density recording by short-wavelength lasers. This paper reports the relationship between the layer structure and the magneto-optical characteristics. As the Tb concentration increases in the NdFeCo film, the perpendicular anisotropy increases, but the Kerr rotation angle decreases. As the NdTbFeCo film becomes thinner, the magneto-optical properties such as the Kerr effect and the Faraday effect increase. As a result, a film was obtained with a Kerr rotation angle of 0.5°, with perpendicular magnetization. NdTbFeCo(30 nm)/TbFeCo(80 nm) exchange-coupling double-layer-structure films and (NdTbFeCo(15 nm)/TbFeCo(15 nm))n multi-layer-structure films (n=3) were studied. The coercive force and the perpendicular anisotropy of the NdTbFeCo/TbFeCo double-layer-structure films is larger than that of the single-layered NdTbFeCo films, but it is found that there is a critical temperature at which the exchange coupling ceases. On the other hand, a multi-layer-structure film acts magnetically like a single layer film. This is because the exchange coupling force for the multi-layer-structure films is stronger than that for the double-layer-structure films.View full abstractDownload PDF (849K) -
Shin Fujitani, Hiroshi Nakamura, Yumiko Nakamura, Hiroshi Watanabe, Ta ...1993 Volume 57 Issue 12 Pages 1465-1470
Published: 1993
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSPlateau flatness of the pressure-composition (P-C) isotherm of hydrogen in hydrogen-absorbing alloys is important for achieving high-performance application systems. In this study, the effect of annealing time t on the plateau flatness and micro-structure of an alloy was quantitatively studied.
Samples were prepared by annealing an induction-melted LaNi4.55Al0.45 alloy in the range up to t=259.2 ks in a vacuum at 1323 K. The P-C isotherms at 353 K were analysed with the normal cummulative distribution function model which we developed previously to evaluate the standard deviation σP as the plateau flatness parameter. The homogenizing behaviour of the micro-structure through the annealing was investigated with electron-probe micro analysis and X-ray powder diffraction analysis.
With increasing t, lnσP decreased linearly and the plateau area flattened. The plateau slope was caused by a heterogeneous Al distribution in the dominant phase with high Al concentration area around precipitated AlNi3 phase. A decrease of the half value of the X-ray powder diffraction profile through the annealing showed the homogenization of the micro-structure. The AlNi3 phase was stable through the annealing and therefore, it has no influence on the homogenization.
The homogenizing behaviour was analysed with a non-steady state Al diffusion model where the Al concentration profile in the dominant phase was a cosine function. As a result, an equation to give the linear relation between lnσP and t was found. This equation is helpful for determining manufacturing conditions for a variety of alloys because it includes mean precipitation distance 2l and annealing conditions (time t and temperature T) explicitly.View full abstractDownload PDF (942K) -
Yoshito Takemoto, Moritaka Hida, Akira Sakakibara1993 Volume 57 Issue 12 Pages 1471-1472
Published: 1993
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSDownload PDF (642K)
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