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Volume 46, Issue 3
Displaying 1-17 of 17 articles from this issue
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Iwao Ishida, Takashi Takahashi, Hitoshi Nakae1982 Volume 46 Issue 3 Pages 237-244
Published: 1982
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSA saw-tooth domain pattern has been observed in a (001) Fe-3%Si single crystal using the magneto-optic Kerr effect by applying gradient field, and a charged wall has been investigated. A domain bounded by a straight 180° Bloch wall changes into a saw-tooth domain separated by a zig-zag charged wall with the gradient of field. The relation between the charged wall energy and the effective field gradient is obtained by considering the wall and the field energies in the gradient field.
A model of the charged wall is proposed to combine the 180° Bloch-like and Néel-like regions. The variation method is applied to the free energy of the Néel-like regions to obtain the minimum free energy, the configuration of magnetization and the distribution of pole density in these regions. Furthermore, by considering the wall energy of the inclining 180° Bloch wall to the minimum free energy of the Néel-like regions, the wall energy γ(θ) of the charged wall of tilt angle θ is obtained as follows:
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\ oindentThe estimated energy of the charged wall in the range |θ|≤12° is smaller than the maximum energy of the inclining 180° Bloch wall.View full abstractDownload PDF (901K) -
Takanobu Shiraishi1982 Volume 46 Issue 3 Pages 245-252
Published: 1982
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe ordering process during continuous heating in Cu-Pd alloys containing 34.74∼44.80 at%Pd was investigated by means of electrical resistivity measurements, X-ray diffraction, hardness test and transmission electron microscopy.
In all alloys, the electrical resistivity increased slightly in the early stage of ordering. This increase in resistivity was found to be due to the development of short range order in the disordered α phase. The activation energy for this stage was evaluated to be 83.7∼100.4 kJ/mol, being equal to the migration energy of quenched-in vacancies in α phase.
In alloys whose compositions are in the two phase region of (α1+β), ordering occurred through two processes (viz. stage I and II). In the stage I, the electrical resistivity decreased slightly and microdomains of short range order grew markedly. It is suggested that the vacancy-hydrogen atom complexes dissociate into a vacancy and a hydrogen atom in the stage I, and newly produced vacancies contribute to the marked growth of microdomains of short range order.
The hardening of the alloy was attained by the increase in volume fraction of the ordered β phase. The hardness of β phase decreased gradually with the growth of anti-phase domain size.View full abstractDownload PDF (649K) -
Hiroshi Narai, Shigeru Asano1982 Volume 46 Issue 3 Pages 253-257
Published: 1982
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSInternal friction in Cu-0.8 at%Al and Cu-1.8 at%Al alloy crystals was measured as a function of strain amplitude at around 800 Hz over the temperature range of 160-330 K. The data were analyzed by the phenomenological method and converted into typical mechanical responses, such as the microplastic strain and dislocation velocity expressed as a function of stress. Results obtained are summarized as follows. (1) Plastic flow in copper was remarkably suppressed by aluminum alloying in the microplastic region where plastic strain ranged from 10−9 to 10−8. This alloying effect was two orders of magnitude greater than the usual solid solution hardening in a macroplastic region. (2) The microplastic flow stress increased with decreasing temperature in alloy crystals containing more aluminium, as in the case of the usual solid solution hardening. (3) The dislocation velocity estimated from the amplitude dependence of internal friction agreed well with the etch-pit data so far reported in the literature. It was shown that the dislocation motion was impeded by solute atoms as much in the microplastic region as in a macroplastic region.View full abstractDownload PDF (415K) -
Koichiro Koyama, Yasuhiko Hashimoto, Shinichiro Omori, Sadao Onishi1982 Volume 46 Issue 3 Pages 258-265
Published: 1982
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe process of the carbothermic reduction of vanadium (III) oxide was investigated in the temperature range of 1373 to 1873 K by chemical analysis and X-ray diffraction analysis.
In the case of a mixture of V2O3 and C in the molar ratio of 1/3 under pressures between 0.67 and 20 Pa, the low oxygen VC-VO solid solution was formed at lower temperatures than 1373 K, while the medium oxygen VC-VO solid solution was formed at higher temperatures than 1373 K. The former changed to the medium oxygen VC-VO solid solution as the temperature was raised. From the medium oxygen VC-VO solid solution, the V2C phase and the high oxygen VC-VO solid solution, were formed, then the V4O phase was formed from the reaction of them, and finally the vanadium phase was formed by the reaction of the V4O phase and the V2C phase.
In the case of a mixture of V2O3 and C in the molar ratio of 1/4 under pressures between 0.67 and 20 Pa, the final product was the V2C phase which was formed from the medium oxygen VC-VO solid solution.
In the case of a molar ratio of 1/5, the final product, the VC phase, was formed by two different paths under pressures between 0.67 and 20 Pa, while it was formed by a single path under a pressure of 1330 Pa.View full abstractDownload PDF (593K) -
Kyoko Wasai, Kusuhiro Mukai1982 Volume 46 Issue 3 Pages 266-274
Published: 1982
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESS49 systems, which have reliable phase diagrams with intermetallic compounds and activity values in the whole range of concentration, are found out of all the binary liquid alloy systems with negative deviation of activities from Raoult’s law given by Hultgren et al. Thermodynamic properties, such as activity and heat of mixing, of these 49 systems were well described by an ideal associated solution model except the Cd-Na system. The following relation was found between standard free energies of formation of associated compounds calculated by the model, ΔGι°, and published data of intermetallic compounds, ΔGs°.
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\ oindentThis relation may be available for estimating unknown values of activities from the data of ΔGs°. ΔHm°, the enthalpy changes of fusion of associated compounds, were calculated by an approximation that differences between values of standard enthalpy of formation of associated compounds calculated by the model and those of intermetallic compounds were due to enthalpy changes of fusion. It was found that ΔHm° and the melting temperature Tm has a relation similar to Richards’ rule. For seven associated compounds, AuSn, AuZn, CdSb, FeSi, InSb, Mg2Pb, and NaTl, the differences between ΔGι° and ΔGs° were explained reasonably from published thermodynamic data and thermodynamic properties of fusion, ΔHm°, ΔGm° and ΔSm°, which were calculated by the model and published thermodynamic data.View full abstractDownload PDF (646K) -
K\={o}taro Kuroda, Masayasu Kawahara, Ken-ji Morinaga, Tsutomu Yanagas ...1982 Volume 46 Issue 3 Pages 275-280
Published: 1982
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe viscosity and the electrical conductivity have been measured to find out the behavior of CoO in CaO-SiO2 and Na2O-SiO2 melts. At the compositions of Na2O/SiO2 ranging between 1/1 and 3/7, the viscosity coefficient (η) decreased with increasing CoO content, while the electrical conductivity (κ) had a maximum at 10 mol%CoO.
At the compositions of CaO/SiO2 ranging between 1/1 and 2/3, η decreased and κ increased remarkably up to 30 mol%CoO. The strength of CoO as a basic oxide was higher than that of CaO at the compositions ranging between 5 and 20 mol%CoO in the CaO-SiO2-CoO system, but this strength of CoO decreased with increasing CoO content. Since the behavior of CoO is similar to that of NiO in these melts, then redox-equation of Co2+-Co3+ in silicate melts seemed to be of R-type, that is,
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Shigeo Sumita, Hironori Takano, Ken-ji Morinaga, Tsutomu Yanagase1982 Volume 46 Issue 3 Pages 280-285
Published: 1982
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSViscosity (η) and electrical conductivity (κ) have been measured to find out the behavior of ZnO in Na2O-SiO2 and CaO-SiO2 melts. Since ZnO is an amphoteric oxide like Fe2O3 and MgO, the oxygen co-ordination number of Zn2+ may be assumed to be 4 (Zn2+(4)) and 6 (Zn2+(6)).
The distribution of Zn2+(4) and Zn2+(6) in these systems are estimated, and the parameter of Kp is calculated for these systems from the following eq.
Kp=[at%Na+ or Ca2+]+α[at%Zn2+(6)], where α=an equivalent value of Zn2+(6) for Na+ or Ca2+.
The dependence of Kp upon the composition is in agreement with that of κ. The distribution of Zn2+(4) and Zn2+(6) is closely correlated with the ZnO-content and basicity of melts.View full abstractDownload PDF (463K) -
Yoshiichi Sakamoto, Keizo Takao1982 Volume 46 Issue 3 Pages 285-290
Published: 1982
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe diffusivity and solubility of hydrogen in both annealed and as-cold-rolled copper were determined at room temperature by means of the electrochemical permeation method under the galvanostatic charging condition. Results obtained were as follows:
(1) The observed build-up transient of hydrogen permeation through Cu foil specimens coincided with the theoretical transient which is the boundary condition of constant hydrogen concentration directly beneath the cathodic surface. Furthermore, the specimen thickness dependence of the steady state permeation current density was examined and consequently, the diffusion of hydrogen through the Cu foil in the permeation process was the rate determining step.
(2) The diffusivity in the annealed Cu did not depend on the cathodic current densities in the range of ic=2.5 to 250 A·m−2, i.e., the hydrogen concentration in the cathodic surface, but in the case of as-cold-rolled Cu, it was slightly low, when the hydrogen was introduced at low ic values. While the solubility of hydrogen beneath the cathodic surface for each specimen increased with an increase of ic value, the difference of solubility between the annealed Cu specimen and the as-cold-rolled one was not remarkable at 315±1 K.
(3) The temperature dependences of the diffusivity (D) and solubility (C) of hydrogen in the annealed Cu determined at the temperature range of 292 to 339 K under ic=10 A·m−2 can be described as follows:
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\ oindentOn the other hand, compared with annealed Cu, the as-cold-rolled Cu had a lower diffusivity and slightly higher activation energy for diffusion, and the hydrogen absorption occurred by the exothermic reaction.View full abstractDownload PDF (480K) -
Hakaru Masumoto, Michio Kikuchi, Takafumi Nakayama1982 Volume 46 Issue 3 Pages 291-296
Published: 1982
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe thermal expansion, magnetic properties, electrical resistivity, lattice constant and hardness of Mn-Ge alloys cooled at various rates after homogenizing at 50 K below the melting point for 1.8-86.4 ks were investigated. It has been found that the alloys containing about 15-25 at%Ge consist of the mixture of a paramagnetic fcc γ-phase and a ferrimagnetic fct ε1-phase at room temperature.
The ε-phase is stable for all heat-treatments except the cooling rate less than 0.19×10−3 K/s, showing antiferromagnetism at room temperature. The Mn-Ge alloys consisting of ε-phase exhibit the Invar characteristics below the Néel temperature, and a representative linear thermal expansion coefficient at room temperature is 0.3×10−6 K−1 in the Mn-23.2 at%Ge alloy. The magnetization of the ε-phase alloys is 0.6×10−6 Wb·m/kg at the maximum, and their electrical resistivity shows a minimum at the Néel temperature.
The machinability of the ε-phase alloys is fairly good, but the hot-forging and swaging are not so easy because the hardness is remarkably high.View full abstractDownload PDF (464K) -
Yoshinori Sasaki, Yukio Iida1982 Volume 46 Issue 3 Pages 296-300
Published: 1982
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSA study was undertaken to provide information concerning the layer structure of phosphide films formed during the reaction of cobalt with phosphorus, the relationship between the products and reaction conditions, and the kinetics and the mechanism of the reaction. A cobalt sheet was phosphidized in phosphorus vapor of 1 to 100 kPa at 873-1073 K by means of a sealed-tube methed. The following conclusions were drawn:
(1) X-ray diffraction and x-ray microprobe analysis showed that all the phosphide layers in contact with the cobalt were Co2P, regardless of the reaction condition, and that the outer layers of phosphide films were composed of CoP at higher temperatures and pressures, whereas at both lower ones they were composed of mixtures of CoP and Co2P.
(2) All the phosphidations obeyed a parabolic rate law; hence, the rate-determining step was apparently a diffusion process. The parabolic rate constant was given as a function of the absolute temperature by the following expression:
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\ oindentThe pressure dependence of Kp resulted experimentally in the expression Kp∝P0.18±0.04 at 973 K.
(3) A marker experiment indicated that cobalt was the component which diffused. It was concluded that the rate-determining process was a diffusion of cation.View full abstractDownload PDF (404K) -
Masamichi Miki, Shigenori Hori1982 Volume 46 Issue 3 Pages 301-307
Published: 1982
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe characteristics of the grain boundary reaction in Cu-20 mass%Ni-20 mass%Mn and Cu-30 mass%Ni-30 mass%Mn alloys aged isothermally at temperatures of 523∼723 K after water quenching from 1173 K were investigated by optical and electron microscopic observations, hardness measurements and the X-ray diffraction method. Results obtained are as follows:
(1) The incubation periods were not observed in the nodule growth curves, namely the nodule began to grow along with the hardening of the matrix from the early stage of aging. At the temperature below 623 K, the nodule engulfed all over the matrix after a long time aging, but on aging at the temperature above 673 K, the nodule did not engulf the matrix entirely owing to the influence of the intragranular precipitation. Moreover at the temperature above 723 K the nodule grew scarecely.
(2) The microstructure in the nodule was not pearlitic. A light and shade structure with θ phases waved periodically was observed in the nodule at the early stage of aging and this structure grew with the progress of aging. Also the hardness of the nodule increased during aging, and decreased slowly after reaching its maximum value.
(3) The lattice parameters of the α phase and the θ phase [(Ni·Cu)Mn] in the nodule changed with progress of aging.
(4) The area fraction of the nodule, X, could be represented by Johnson-Mehl’s equation: X=1−exp(−btn), where t is the aging time and b and n are constants, and 0.7∼1.2 were obtained as the values of n.
(5) The value of apparent activation energy for nodule growth was about 80 kJ/mol in Cu-20 mass%Ni-20 mass%Mn alloy or about 110 kJ/mol in Cu-30 mass%Ni-30 mass%Mn alloy.View full abstractDownload PDF (740K) -
Masamichi Miki, Takuzo Sogabe, Shigenori Hori1982 Volume 46 Issue 3 Pages 307-312
Published: 1982
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe characteristics of the grain boundary reaction in a Cu-10 mass%Ni-8 mass%Sn alloy aged isothermally at 623 to 773 K after water quenching from 1123 K were investigated by optical and electron microscopic observations, hardness measurements and the X-ray diffraction methed. Results obtained are as follows:
(1) The incubation periods were observed in the nodule growth curves, namely the nodule began to grow after the hardness of the matrix nearly reached a maximum value, and then engulfed the matrix entirely.
(2) The pearlitic structure which consisted of the equilibrium α phase and the equilibrium γ phase [(Cu·Ni)3Sn] was observed in the nodule from the period of nodule formation, and the shape of the γ phase scarecely changed with progress of aging. The lattice parameter of the γ phase of an ordered fcc structure was 0.5940 nm.
(3) The secondary pearlitic nodule containing γ precipitates larger than those in the primary nodule was observed on the prolonged aging after the completion of the primary grain boundary reaction.
(4) The area fraction of the nodule, X, can be represented by Johnson-Mehl’s equation: X=1−exp(−btn), where t is the aging time and b and n are constants, and values 2.2∼2.6 were obtained as n.
(5) The value of apparent activation energy for nodule growth was about 120 kJ/mol.View full abstractDownload PDF (644K) -
Yutaka Kagawa, Hajime Okuhara, Eiichi Nakata, Susumu Yoshida1982 Volume 46 Issue 3 Pages 313-322
Published: 1982
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSA study on the deformation and fracture behaviors of composites consisting of copper matrix and helical tungsten fibers has been carried out experimentally. Specimens each containing a single tungsten fiber, whose helical angle is varied from 15° to 76°, have been tensile-tested, and the effect of the helical angle on the fracture mode has been studied.
Results obtained show that two types of fracture mode are observed; (I) the fracture ocures in the matrix prior to that at the fiber for the composites reinforced with the helical angles less than 45°, or (II) vice versa for those with the helical angles larger than 53°. The ultimate tensile stress or the fracture stress and the strain at that stress are larger for Type II composites than for Type I composites. Deformation of tungsten fibers in the matrix for Type I composite is elastic, but that for Type II is considerably plastic. When the helical angle is very large, multiple necking and multiple fracture are also observed.View full abstractDownload PDF (1067K) -
Tetsuichi Motegi, Atsumi Ohno1982 Volume 46 Issue 3 Pages 323-329
Published: 1982
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSSeveral experiments were carried out to study the formation mechanism of inverse segregation in Al-Cu alloy ingots.
Al-4 mass%Cu alloy ingots solidified horizontally in a stainless steel mold showed only a columnar zone and inverse segregation. However, an Al-14 mass%Cu alloy exhibited either only equiaxed crystals or a columnar-equiaxed transition structure depending on the cooling temperature. No clear inverse segregation occurred in these ingots. It is considered that equiaxed crystals moved with the flow of the melt, and these crystals were irregularly distributed when it solidified.
All ingots solidified from the bottom or from the molten surface in a stainless steel mold or a graphite mold showed inverse segregation. In particular, an equiaxed zone in the Al-14 mass%Cu alloy solidified from the molten surface in the graphite mold had extremely low Cu concentration.
On a chill face of ingots decanted during unidirectional solidification, the Cu concentration was always higher than the mean concentration of the alloy. This suggests that the solute Cu was already concentrated near the chill face at the initial stage of solidification. It is considered that the solute was trapped among the crystals of the stable solid shell formed on the mold wall.View full abstractDownload PDF (816K) -
Kiyoaki Akechi, Wolfgang A. Kaysser, Günter Petzow1982 Volume 46 Issue 3 Pages 330-335
Published: 1982
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe variation of graphite morphology was investigated in Ni-C compacts (0, 0.5, 1.0 and 2.0 mass%C) after sintering at 1553 K under dry hydrogen flow.
When C content is 0.5% which is less than the solubility limit of C into the Ni-phase at 1553 K, nodular graphite can be obtained after long time sintering. This result suggests the following mechanism; all graphite dissolves into the Ni-phase during heating, pores are spheroidized during sintering, and the supersaturated C precipitates as graphite to the spherical pores during cooling.
When C contents are 1.0% and 2.0% which are more than the solubility limit of C into the Ni-phase, no nodular graphite can be obtained, because of undissolved residual graphite in the pores.View full abstractDownload PDF (542K) -
Kiyoaki Akechi, Wolfgang A. Kaysser, Günter Petzow1982 Volume 46 Issue 3 Pages 336-340
Published: 1982
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThis paper describes, at first, graphite mophologies in Ni-0.5∼2.0 mass%C mixed powder compacts which are melted at 1723 K and solidified in hydrogen atmosphere. Short holding time at 1723 K provides nodular graphite because many micro-bubbles remain in the molten Ni. On the contrary, long holding time at 1723 K provides only lamellar and eutectic graphite because no bubble exists in the molten Ni.
Ni-C compacts were also “semi-liquid-sintered”: the specimens which were pre-sintered at 1553 K for 7.2 ks (2 h) were heated at the rate of 2 Ks−1 up to 1623 K over the eutectic temperature without holding at 1623 K and cooled at the rate of 4 Ks−1. The microstructures consisting of nodular graphite and lamellar one are obtained. The former is solidified in the residual bubbles in the liquid or precipitated in the pores in the solid, and latter takes place in the bubble-free and pore-free portions.View full abstractDownload PDF (504K) -
Mutsumi Touge, Toshikatsu Miki, Motoji Ikeya, Kazuyoshi Kamachi1982 Volume 46 Issue 3 Pages 341-342
Published: 1982
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSDownload PDF (123K)
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