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Volume 53, Issue 4
Displaying 1-18 of 18 articles from this issue
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Tohru Yamasaki, Yoshikiyo Ogino1989 Volume 53 Issue 4 Pages 359-366
Published: 1989
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSFe90−xBxSi10 amorphous alloys containing 10∼17 at%B were studied by 57Fe Mössbauer spectroscopy. The internal magnetic field distribution which was derived from the observed spectrum by a Fourier analysis was approximated by a sum of three Gaussian lines with the average internal fields of about 15.9 MA/m (component A), 19.9 MA/m (component B) and 23.9 MA/m (component C). With increasing boron content, the component A increases and the component C decreases. The intensity of the component A sharply increases from the composition of about 13 at% boron which is slightly higher than the eutectic composition. The component B increases to a maximum at about 13 at% boron and then decreases at higher boron contents. The compositional dependence of the fraction and the average internal field of each structural component suggests that the components A and B have Fe2B-like and Fe3B-like short range orders, respectively, and the component C has a lower boron content and a relatively high Si content of about 9 at%. The results of DSC and Mössbauer effect measurements on annealing Fe80B10Si10 and Fe76B14Si10 amorphous alloys suggest that the nucleations of the Fe2B intermatallic compound and the α-Fe(Si) solid solution take place in the regions of components A and C, respectively.View full abstractDownload PDF (1074K) -
Hisami Yumoto, Yoshihiko Gotoh, Naohiro Igata1989 Volume 53 Issue 4 Pages 367-371
Published: 1989
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSCd or Zn fine crystals having the shape of whisker or polyhedrons were grown by a physical vapor deposition method. Their growth mechanism was VLS (Vapor-Liquid-Solid) growth. The nucleation of the crystal growth occurred in the eutectic alloy droplet (homogeneous nucleation) and did not occur at the interface between the droplet and a glass substrate (heterogeneous nucleation). The purpose of the present study was to explain this reason.
In order to decide the nucleation type (homogeneous or heterogeneous), we introduced the parameter Y defined as Y=γSG−(γLG+γSL), where γSG, γLG and γSL are the interfacial tensions between the crystal and the glass, between the liquid and the glass, and between the crystal and the liquid, respectively. When Y>0, the nucleation was homogeneous. When Y<0, it became heterogeneous.
In the case of VLS-grown Cd or Zn crystals, it was found from the data on the surface tension that the parameter Y was positive. Therefore, it was concluded that the nucleation of the Cd or Zn crystals was homogeneous.View full abstractDownload PDF (1106K) -
Hiromitsu Ino, Katsuro Oda, Kiyoshi Umezu1989 Volume 53 Issue 4 Pages 372-377
Published: 1989
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSA Mössbauer effect study has been done for Fe-9.0 at%N austenite in order to clarify the interaction between interstitial atoms in the fcc lattice and the nitrogen atom distribution among the octahedral sites. Mössbauer spectra were decomposed into three components; one singlet γ0, and two sets of doublet γ1 and γ2, with a different quadrupole splitting, 0.39 mm/s and 0.70 mm/s, respectively. The ratio of Fe atoms among three components was determined by extrapolating the intensity of each component to zero sample thickness. It is concluded that N-Fe-N type dumb-bell configuration is preferentially formed in the Fe-N austenite as a result of both the repulsive and attractive interactions between 1st and 2nd neighboring nitrogen atoms, respectively. The critical temperature for the Fe4N type of ordering in the fcc solid solution is estimated to be about 150 K.View full abstractDownload PDF (641K) -
Yoshinori Wakamatsu, Masami Onishi, Toshitada Shimozaki1989 Volume 53 Issue 4 Pages 378-387
Published: 1989
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSKidson’s simultaneous equations describing positions of phase boundaries in a multi-phase diffusion couple were numerically solved for various diffusion conditions. Based on the calculated results, the relation between layer growth rates of intermediate phases and the three controlling factors pointed out by Seith, i.e., interdiffusion coefficient, solubility range of each phase and miscibility gap between adjacent phases, was examined in detail.
There exists an obvious quantitative relation between the layer growth rates of intermediate phases and the interdiffusion coefficients \ ildeD or the solubility ranges ΔN. Between the layer growth rates and miscibility gaps, however, such a distinct relation can not be found. If the miscibility gap is excluded from the factors controlling the layer growth rates of intermediate phases, the average composition within each phase N may be regarded as an alternative factor.
Effect of these factors including the average phase composition on the layer growth rates of intermediate phases should be evaluated synthetically. It is concluded that any intermediate phase formed in a multi-phase diffusion couple grows more rapidly as the value of ΔN\ ildeD⁄{N(1−N)}2⁄3 becomes greater. The ratio of layer growth rates between the two given intermediate phases can be approximately expressed in terms of the ratio of the above value.View full abstractDownload PDF (1418K) -
Masamichi Miki, Tohru Yamasaki, Naoki Ueyama, Yoshikiyo Ogino1989 Volume 53 Issue 4 Pages 388-392
Published: 1989
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe Relation between the formation and growth of grain-boundary cells at each individual grain-boundary and the character (Σ value) of its boundary in a Ni-16 mass%Sn alloy on aging at 823 K after quenching from 1273 K was investigated by means of SEM-ECP measurement and optical microscopic observation.
The formation and growth of cells at CSL boundaries with low Σ values were suppressed as compared with those at random boundaries (Σ≥31). Especially, no cells were observed at twin boundaries (Σ=3). However, at some of the random boundaries, cells were scarcely observed. This fact suggest that the formation and growth of cells relate not only to the Σ value of the grain-boundary but also to the inclination of the boundary and the grain-boundary structure (atomic arrangement in the grain-boundary).View full abstractDownload PDF (1140K) -
Kazuo Saito, Atsushi Takei, Masahiro Tosa, Kazuhiro Yoshihara, Masaya ...1989 Volume 53 Issue 4 Pages 393-398
Published: 1989
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSTo examine the effect of ion implantation into substrates prior to ceramic coating, Ti ions were implanted into the substrates of pure iron, SUS304 and 0.1%C steel, and TiC films were deposited on these pretreated substrates by an activated reaction evaporation method. It was found that in pure Fe and SUS304 an amorphous surface layer was created after a critical dose of 5×1016 Ti ions/cm2. TEM observations and indentation-fracture tests revealed that the frequency of microcracking or exfoliation of TiC films was significantly reduced by Ti ion implantation of the substrates. For 0.1%C steel, however, the Ti ion implanted surface layer still remained crystalline and exhibited no improved adhesion to TiC films. The AES analysis showed that carbon atoms diffused readily into the amorphous surface layers, resulting in the creation of a ductile transition layer of Ti-rich TiC phase at the TiC-substrate interface. Thus, the adhesion improvement of TiC films is thought to result from the amorphous transformation of substrate surfaces and the specific structure relaxation in the amorphous layer may be effective in relieving complex strains, themally or mechanically induced at the TiC/substrate interface.View full abstractDownload PDF (1899K) -
Sumiko Sanuki, Noriko Minami, Satoshi Sunada, Koichi Arai1989 Volume 53 Issue 4 Pages 399-406
Published: 1989
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe feasibility of the electrolytic silver recovery process from the oxidative leaching residue of Cu-anode slime was investigated from the electrochemical and kinetic points of view based on the experimental results of the leaching test, the stoichiometry of the electrolytic silver recovery, the determination of the rest potentials and the cathodic polarization curves for the Pt electrode in the Na2S2O3 solution containing Ag(S2O3)23−, Cu(S2O3)25− and Pb(S2O3)22− ions.
The experimental results are summarized as follows:
(1) The leaching rate of Ag component from the oxidative leaching residue of Cu-anode slime in a Na2S2O3 solution is fast, and the fractional leaching ratio of Ag reaches 0.94 for the retention time of 3.6 ks at 313 K. However, the dissolution ratios of Cu and Pb species from the leaching residue are rather small.
(2) The electrochemical reaction for the Ag deposit starts at about −0.1 V and the reaction rate increases with increasing concentration of Ag(S2O3)23− ions in the solution. The reaction rate is controlled by the rate of Ag(S2O3)23− ions from the bulk solution to the solid interface.
(3) Under the optimum electrolytic conditions, the cathodic current efficiency of the Ag deposit is more than 94%, and metallic silver of more than 99.8% purity can be recovered from the thiosulfate solution containing Ag(S2O3)23− ions.
(4) The electrochemical and other observations have proved the effectiveness of the above electrolytic silver recovery process from the oxidative leaching residue of Cu-anode slime.View full abstractDownload PDF (1119K) -
Chikabumi Yamauchi, Toshiharu Fujisawa, Shigeaki Goto, Hiroyuki Fukuya ...1989 Volume 53 Issue 4 Pages 407-414
Published: 1989
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe effect of partial pressure of CO2 in the gas phase on the distribution ratio of Sb(LSbS/Cu) between Na2CO3 slag and molten copper at 1523 K was investigated. The quantitative evaluation of the distribution ratio, which increases with decreasing partial pressure of CO2, may be made by the equation
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\ oindentwith the aid of the relation between aNaO0.5 in Na2O-CO2-Sb2O5 slag and PCO2 in the gas phase, where Q is a constant determined experimentally. The solubility of copper in Na2CO3 slag is also strongly affected by the partial pressure of CO2 in the gas phase and increases with decreasing partial pressure of CO2. This means that the activity coefficient of CuO0.5 in Na2CO3 slag is lowered towards unity with decreasing partial pressure of CO2 and the melt Na2CO3-Cu2O approaches an ideal solution.
Subsequently, the distribution ratio of Sb between Na2O-Sb2O5 slag with the value of N of 0.75 [N=nNa2O⁄(nNa2O+nSb2O5), n: number of moles] and molten copper was measured under the CO2 partial pressure of 0.09 MPa at 1523 K in order to determine thermodynamic quantities required to estimate the distribution ratio of Sb for the slag Na2O-CO2-Sb2O5 of any composition with the value of N between 0.75 and 1.0. From the results obtained, activity of SbO2.5 in the Na2O-Sb2O5 slag with the value of N of 0.75 and the standard free energy of formation of Na3SbO4 at 1523 K were calculated to be 1.42×10−6 and −752 kJ, respectively.View full abstractDownload PDF (1008K) -
Takuya Takahashi, Shiro Matsuda, Katsuhisa Sugimoto1989 Volume 53 Issue 4 Pages 415-421
Published: 1989
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSIn order to investigate the relationship between corrosion resistance and the nature of surface films on a Ti-Ni shape memory alloy in aqueous solutions, ellipsometric measurements have been performed in-situ on the alloy under anodic polarization in 0.5 kmol·m−3 H2SO4 and 3.0 mass%NaCl at 293 and 363 K. The chemical composition of these films was also analyzed by ESCA.
From the ellipsometric measurements, it was found that both the refractive index and the extinction coefficient of optical constant for the films formed in 0.5 kmol·m−3 H2SO4 at 363 K were smaller than those formed at 293 K, whereas the films formed at 363 K were considerably thicker than those formed at 293 K. In the case of 3.0 mass%NaCl, both the refractive index and the extinction coefficient of optical constant for the films formed at 363 K were also smaller than those formed at 293 K. The thickness of films was also larger at 363 K. After pitting corrosion occurred in the solution, the optical constant became smaller and the thickness increased abruptly.
The cationic fraction of Ni2+ of the films formed at 363 K in 0.5 kmol·m−3 H2SO4 was larger than that of films formed at 293 K at any potentials examined. The changes in the optical constant and the protective nature of the films with temperature were closely related to that in the cationic fraction of Ni2+ of the films.View full abstractDownload PDF (1018K) -
Yoshio Sakka, Tetsuo Uchikoshi, Eiichi Ozawa1989 Volume 53 Issue 4 Pages 422-428
Published: 1989
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSSintering characteristics and structure changes were examined for the oxidized (slow oxidation treated) Cu and fresh (not slow oxidation treated) Cu ultrafine powders.
Shrinkage of the compacts was observed at temperatures of 400-500 K, and it was considered to be the result of rearrangement of ultrafine powders accompanied by the extreme desorption of H2O and CO2 gases. The specific surface areas of the oxidized powders increased and took the maximum value at apploximately 420 K, which was also considered by the gas desorption.
Expansion of the compacts was obsereved for the oxidized powders at temperatures of 473-673 K, while densification occurred for the fresh ultrafine powders at temperatures above 573 K. These different characteristics were explained by the difference in amount of the produced Cu2O.
Grain growth of the oxidized ultrafine powders was not observed at temperatures below 673 K, while large grain growth was observed at 623 K for the fresh powders. These results showed that the oxide phase depressed the grain growth of ultrafine powders.
The desorption occurred significantly at temperatures above 400 K especially for the oxidized powders. The desorbed gases were mainly carbon dioxide and water. The oxidation reaction was considered to be due to the adsorbed oxygen and water.View full abstractDownload PDF (2402K) -
Jian-Yih Wang, Tadatomo Suga, Yoichi Ishida1989 Volume 53 Issue 4 Pages 429-438
Published: 1989
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSAtomic structure in the diffusion-bonded alumina/niobium was observed by high resolution electron microscopy. A minor impurity calcium was contained in the surface layer of niobium in the form of inclusion particles, which resulted in the formation of hibonite (CaO·6Al2O3) about 0.15 μm thick when the joining was performed without removing the surface layer. The hibonite layer served not only as warning to control the minor element but also as a useful marker of the original interface and allowed us to assess the amount of alumina back-precipitated from niobium during cooling of the joined specimen. The back-precipitation is consided responsible for the observed ordering in the structure of the bonded interface. It must be a useful mechanism to relax the thermal stresses which develop at the ceramic/metal interface during the cooling of the joined specimen.View full abstractDownload PDF (2677K) -
Masaru Yokota, Naohisa Fukuda, Hiroshi Nagai, Keiichiro Shoji1989 Volume 53 Issue 4 Pages 439-444
Published: 1989
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSWettability of Sn-Ti binary alloys containing up to 5 mass%Ti to sintered alumina plates was studied by measuring wetting angles and surface tensions at a temperature of 1373 K in various O2 partial pressures. The interface energy and work of adhesion between them were also calculated for references. The results obtained are summarized as follows:
(1) Wetting angle of Sn-Ti alloys against sintered Al2O3 plates decreased abruptly with the increase of Ti content in Sn at any O2 partial pressure in ambient atmosphere, especially at a lower PO2 of 2.8×10−4 Pa. The minimal wetting angle was obtained for the Sn-Ti alloy containing about 1 mass% Ti and 3 mass% Ti at PO2=2.8×10−4 and 2.8×10−2 Pa, respectively.
(2) Surface tension (σLA) of Sn-Ti alloys showed almost no dependence on both Ti content in Sn and O2 partial pressure in ambient atmosphere; σLA of Sn-Ti alloys containing up to 5 mass% Ti was almost constant of 4×10−1 N/m.
(3) Wettability of Sn-Ti alloys against sintered Al2O3 plates could be improved by the adsorption or oxygen on the interface of liquid and solid, where the adsorption layer or the reaction layer containing Ti was not found to form on the interface between the alloys and sintered Al2O3 plates.View full abstractDownload PDF (1456K) -
Kazunori Sasaki, Katsuhiko Motoie, Tadashi Kawasaki, Tsuyoshi Miura1989 Volume 53 Issue 4 Pages 445-451
Published: 1989
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe effect of alternating stress, which was superimposed on the bonding pressure, on the bonding strength of alumina-copper joint was investigated. Alumina-copper joint with a thin aluminum interlayer deposited in the vacuum was performed at temperatures above 773 K in argon gas at a pressure of 0.4 MPa under the alternating stress.
The main results obtained are as follows:
(1) At each bonding temperature, the strength of joint increased with increasing time and reached a peak strength and then decreased with increasing time.
(2) The addition of alternating stress on the bonding pressure has the effect to increase the peak strength and to promote the bonding process.
(3) Apparrent activation energy for the bonding process is calculated to be about 49 kJ/mol.
(4) A reasonable explanation for improving the bonding strength due to the alternating stressing can be made on basis of the reduction in thermal stress due to local fatigue deformation.
(5) Bonding reaction proceeding during heating up has no significant effect on the experimental results.View full abstractDownload PDF (739K) -
Seigi Aoyama, Mituaki Onuki, Yasuhiko Miyake, Ryoichi Urao1989 Volume 53 Issue 4 Pages 452-457
Published: 1989
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe spring elongation number (SEN) indicates a softening state with high sensitivity, and the windability of the annealed pure copper wires can be evaluated by the SEN. The SEN characteristics of the copper wires were studied in relation to the electrical conductivity and metallurgical structure of the wire rods. The hot-rolled copper (tough pitch copper) wire rods were heat-treated at 673-1073 K in 1.33×10−3 Pa within 86.4 ks, and they were cold drawn to about 89.8% and finally annealed at temperatures up to 673 K. The annealed copper wires were subjected to the SEN test, tesile test, electrical conductivity measurement and structural observation.
When the wires are annealed after heat-treatment at 873 K, the copper wires increase in SEN from the lowest annealing temperature. Completely softened copper wires have high electrical conductivity when the half-softening temperatures were low. The size of Cu2O particles in the copper wire rod increases with rise of heat-treatment temperature.
It is concluded from these results that the decrease in half-softening temperature of the cold-drawn copper wire after the heat-treatment at 873 K is due to the precipitation of impurities in the copper matrix and the growth of Cu2O particles.View full abstractDownload PDF (1456K) -
Sakae Saito, Senri Ikeda, Keisuke Ikeda, Shuji Hanada1989 Volume 53 Issue 4 Pages 458-463
Published: 1989
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSA new fabrication technique of Nb3Al wires, called the clad-chip extrusion (CCE) method, is proposed in this study. It is characterized by chipping and extruding Nb-Al clad sheets. The shear deformation stratifies Nb-Al clad chips in the extrusion process, and fine-multilayer Nb-Al wires are finally obtained by subsequent conventional drawing. An extruded Nb-Al composite bar shows excellent deformability in cold-working up to high reductions and Nb-Al composite wires with fine structure are easily fabricated because Nb plates containing low level oxygen are used as a starting material in this method.
Heat-treated Nb3Al wires show the superconducting transition temperature of 17 K, the critical current density of 108 A/m2 in the field up to 15 T at 4.2 K and the critical field of 23.3 T is extrapolated from the Kramer plots.View full abstractDownload PDF (1823K) -
Wei Zhang, Shojiro Ochiai, Kozo Osamura1989 Volume 53 Issue 4 Pages 464-470
Published: 1989
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe multiple fracture phenomenon of the Nb3Sn layer in multifilamentary Nb3Sn superconducting composite wires prepared by the bronze method was studied theoretically and experimentally. The results of the present work can be summarized as follows. (1) The stress distribution of Nb3Sn segment varies with the length of the Nb3Sn segment. When the Nb3Sn segment is long, the tensile stress distribution as a function of distance is trapezoidal and when it is short, it becomes triangle. (2) The smaller the volume fraction of Nb3Sn layer, the higher becomes the tensile stress exserted on the Nb3Sn layer, resulting in shorter segments. (3) When the multifilamentary composite is loaded, the Nb3Sn layer is not broken before the apparent yield point in the stress-strain curve, but it shows multiple fracture beyond this point. (4) The length of the broken Nb3Sn segment descreases rapidly in the early stage of multiple fracture, but it remains nearly constant for high applied strain.View full abstractDownload PDF (1149K) -
Tohru Takahashi, Hashiru Nagai, Hiroshi Oikawa1989 Volume 53 Issue 4 Pages 471-476
Published: 1989
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSCompression creep behavior was investigated on a Ti-53.4 mol%Al intermetallic compound which was prepared by ingot casting. The material was made into a single gamma (TiAl) phase by vacuum annealing, though it still retained a columnar structure whose dimensions were about 100 μm in diameter and about 1 mm long. Constant true stress compression creep tests were performed under 80∼400 MPa at 1000∼1150 K in an argon atmosphere.
Normal creep curves were obtained at the higher stress, but the shape of the creep curves gradually changed into sigmoidal-like one with decreasing stress. Stress- and temperature-dependence of the creep rate was evaluated by comparing the creep rates at a fixed true strain. Both the stress exponent and the apparent activation energy decreased with straining and reached constant values, n\fallingdotseq4.3, Q\fallingdotseq330 kJ/mol at around 0.3∼0.5 strain. Minimum creep rates were close to those reported on equi-axed samples and were characterized by nm\fallingdotseq5 and Qm\fallingdotseq380 kJ/mol in the high stress region.View full abstractDownload PDF (1127K) -
Yutaka Takahashi, Minoru Mori, Yoichi Ishida1989 Volume 53 Issue 4 Pages 477-478
Published: 1989
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSDownload PDF (364K)
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