All issues
Volume 63, Issue 4
Displaying 1-22 of 22 articles from this issue
- |<
- <
- 1
- >
- >|
-
Kazutoshi Yamada, Hidenori Kohzuki, Teruo Takahashi, Muneyuki Motoyama1999 Volume 63 Issue 4 Pages 417-421
Published: 1999
Released on J-STAGE: April 24, 2008
JOURNAL FREE ACCESSWC powders were prepared by mechanical alloying (MA) or mechanical grinding (MG). C K X-ray spectra from WC (MA, MG, commercially available and single crystal) were measured using an electron probe microanalyzer (EPMA). The C K X-ray spectrum of WC powder mechanically alloyed for 360 ks was similar to that of WC powder mechanically ground for 360 ks. These spectra were approximately symmetrical. The C K X-ray spectra of commercially available WC powder or WC single crystal were different from that of WC prepared by MA or MG. The profile of C K X-ray spectra of WC single crystals were sensitive to observation angles. The C K X-ray spectrum of a WC single crystal observed at about 45 degrees to the basal plane was similar to that of WC prepared by MA or MG.View full abstractDownload PDF (441K) -
Yoshiaki Toda, Toshiyuki Koyama, Toru Miyazaki1999 Volume 63 Issue 4 Pages 422-428
Published: 1999
Released on J-STAGE: April 24, 2008
JOURNAL FREE ACCESSMicrostructural changes in Nb-20, 30, 40, 50 and 60 at%Zr alloys aged at 673∼973 K were mainly observed by means of transmission electron microscopy, and five time-temperature-transformation (TTT) diagrams of each composition and a coherent binodal line was obtained experimentally. The results obtained are as follows: (1) Sequences of the phase transformation in this alloy system are divided into four types. (2) An area of the coherent phase decomposition of the β phase is asymmetric and is located at about 400 K lower temperature than that of the chemical phase decomposition, which shows a strong elastic constraint on the phase decomposition in this alloy system. (3) The area of the coherent phase decomposition predicted based on the system free energy theory agrees well with the experimental one.View full abstractDownload PDF (1791K) -
Tatsuya Ohmi, Yoshiaki Kimura, Youichi Itoh, Kiyotaka Matsuura, Masayu ...1999 Volume 63 Issue 4 Pages 429-434
Published: 1999
Released on J-STAGE: April 24, 2008
JOURNAL FREE ACCESSCentrifugal Duplex Casting (CDC process) is applicable to produce an aluminum-cast pipe with an in-situ composite layer containing fine intermetallic crystals. In this process, two kinds of molten metal, i.e. molten aluminum (the first melt) and molten Al-Cr alloy with a higher liquidus temperature (the second melt), are cast in sequence at a given interval into the rotating mold of a centrifugal caster.
In the present paper, the solidification structure, hardness and wear resistance of Al-Cr alloy pipes produced by the CDC process were investigated. In the composite layer, there was a slightly graded hardness distribution: the hardness decreased gradually as the distance from the outer periphery of the pipe increases. The profile of hardness resembled that of the volume fraction of intermetallic crystals. The hardness and wear resistance of the outside surface of the CDC pipes increased as the chromium concentration of the second melt or the rotation speed of the mold increased.
The pipes with coarse intermetallic crystals, which were produced by the conventional centrifugal casting process, were fractured in the course of wear tests. On the other hand, the CDC pipes exhibited homogeneous-wear behavior because of the refinement of intermetallic crystals.View full abstractDownload PDF (766K) -
Shigeo Sugawara1999 Volume 63 Issue 4 Pages 435-439
Published: 1999
Released on J-STAGE: April 24, 2008
JOURNAL FREE ACCESSThe (111) wafers obtained from a Te-doped GaP crystal were etched at 60-80°C over a time period of 1.2×103 to 7.2×103 s with a solution composed of H2SO4+H2O2+H2O (5:1:1 in volume ratio) and the etch-figures were observed mainly by optical microscopy.
At temperatures above 70°C, spiral etch-pits developed on the (\bar1\bar1\bar1)P surface of the wafers in addition to the normal etch-pits. The spiral etch-pits increased in size with increasing etching temperature and etching time, while the size of normal etch pits remained constant. On the (111)Ga surface rather small spiral etch-pits were also formed at 80°C, but their size remained unchanged with increasing etching time. From the experiments of double etching with a H2SO4+H2O2+H2O solution and an RC etchant, it was concluded that the former etching produces normal pits at edge dislocations and spiral pits at screw dislocations, respectively, and that the latter etching forms dark pits at edge dislocations and S-pits at small lattice defects, respectively.View full abstractDownload PDF (1966K) -
Ken-ichiro Hara, Takao Endo1999 Volume 63 Issue 4 Pages 440-447
Published: 1999
Released on J-STAGE: April 24, 2008
JOURNAL FREE ACCESSBased on a solute atoms diffusion model, contribution from soluble nitrogen to the high-temperature strength was numerically examined for ferritic heat-resisting Fe-Cr-N and Fe-Mo-N alloys. The solute distribution around a moving dislocation was determined by simulating the jump process of interstitial and substitutional solute atoms under an elastic interaction between a dislocation and solute atoms. The Central Atoms Model was employed to evaluate the formation probability of interstitial and substitutional atom pairs (I-S pair) in a complex atmosphere consisting of interstitial and substitutional atoms. The steady-state dragging stress was calculated as a function of dislocation velocity. Calculations show that the existence of only a low concentration of I-S pairs (a few hundred ppm) suffice to give considerable improvement in high-temperature strength.View full abstractDownload PDF (738K) -
Satoshi Itoh, Atsushi Kikuchi1999 Volume 63 Issue 4 Pages 448-453
Published: 1999
Released on J-STAGE: April 24, 2008
JOURNAL FREE ACCESSIn order to determine the activities of components in the zinc-iron-sulfur ternary system, activity measurement of the iron-zinc binary system was carried out by employing an isopiestic method at temperatures of 1100 and 1200 K. Then the activities of components in the ternary system were calculated by applying the Gibbs-Duhem equations to the phase relation of metal-sulfide equilibrium. These data are of fundamental importance for discussing a new zinc distillation process with environmental consciousness proposed by the authors. In this process, zinc sulfide is directly reduced to zinc vapor with metallic iron, fixing sulfur as pyrrhotite. The results are summarized as follows:
(1) In the α-solid solution of the iron-zinc alloy, both the activities of iron and zinc exhibited considerable positive deviations from Raoult’s law. Both the activities of iron and zinc behave more ideal with increasing temperature. Activity coefficients were expressed by the following equations in the temperature range 1100 to 1200 K.
(This article is not displayable. Please see full text pdf.)
Raoultian activity coefficients of zinc at infinite dilution, γZn(l)0, were obtained as 8.3 and 7.0 at 1100 and 1200 K, respectively.
(2) Relation between the equilibrium sulfur partial pressure and the composition of the condensed phase was determined. Using the equilibrium sulfur partial pressure and the activity of iron, the activity of FeS was obtained from the equilibrium constant of FeS formation reaction. Then the activity of ZnS was calculated by the Gibbs-Duhem relation.
(3) It was found from these results that the activity of FeS in the pyrrhotite which will be formed in the new zinc distillation process, can be regarded as almost unity. Zinc content in the pyrrhotite is therefore expected to be negligibly small, and the pyrrhotite can be utilized as a source of sulfuric acid or fuel for smelting processes for metals such as copper, nickel.View full abstractDownload PDF (572K) -
Takashi Goto, Takuya Sasaki, Toshio Hirai1999 Volume 63 Issue 4 Pages 454-460
Published: 1999
Released on J-STAGE: April 24, 2008
JOURNAL FREE ACCESSHeat-resisting alloys of stainless 304 steel, Incoloy 825 and Inconel 625 alloys were coated with Pt and Ir films by metalorganic chemical vapor deposition (MOCVD). Corrosion behavior of these materials was investigated by thermogravimetry in a Br2-O2 atmosphere at 1073 K. By coating Pt films, the mass gain during the corrosion was significantly reduced, and almost no morphological change of the film surface was observed after the corrosion. Alloy elements (Ni, Cr, Fe) diffused into Pt films with forming pores at the Pt/alloy substrate interface. The corrosion resistance of Ir coating was slightly higher than that of Pt coating except that on stainless 304 steel. A difference of thermal expansion between Ir film and stainless 304 steel caused many cracks at the Ir/alloy substrate interface. No inter-diffusion between Ir and alloy elements were observed.View full abstractDownload PDF (1329K) -
Noriyuki Wada, Hajime Ishii, Kenji Morinaga1999 Volume 63 Issue 4 Pages 461-466
Published: 1999
Released on J-STAGE: April 24, 2008
JOURNAL FREE ACCESSThe heating treatment condition to make copper particle dispersed glass to control the dispersion and the particle size by melt quenching and heat treatment method, and the mechanism of growth of copper particles during heat treatment, were investigated. The phosphate glasses were suited for host glass to make copper particle dispersed glass by the method. In the phosphate glasses, time temperature copper dispersion diagrams (T-T-D diagrams) for the homogeneous dispersion of copper particles in the glass, were prepared. The particle size of copper increased linearly with the cube root of the heating time at temperatures less than the glass transition temperature (Tg). On the other hand, the particle size increased linearly with the heating time at temperatures higher than Tg. Dispersion and particle size of copper were controlled by heat treatment condition to prepare T-T-D diagrams and prove the mechanism of growth of copper particles in the glass.View full abstractDownload PDF (736K) -
Toshihide Sunada, Masahisa Otsuka, Hiroshi Yamagata, Masami Fujiwara1999 Volume 63 Issue 4 Pages 467-473
Published: 1999
Released on J-STAGE: April 24, 2008
JOURNAL FREE ACCESSConstant-compressive-load creep testing on polycrystalline (average grain size; 1.48 mm) and [110] single crystalline Sn was carried out at 393 K. Rapid increases in the creep rate (strain burst) were observed for polycrystalline Sn under stresses ranging from 3.5 to 5.5 MPa. The strain burst was also observed for a single crystalline Sn at 5 MPa. Microstructural observations revealed that the newly recrystallized grains contain subgrains and that the strain burst is caused by dynamic recrystallization. A constant-compression-speed testing was also performed at a strain rate of 1.67×10−3 s−1 and at 393 K. The stress-strain curve showed a multipeak stress-strain curve which is typical of dynamic recrystallization.View full abstractDownload PDF (1576K) -
Liang Haiying, Masatoshi Chikazawa, Tohru Watanabe1999 Volume 63 Issue 4 Pages 474-481
Published: 1999
Released on J-STAGE: April 24, 2008
JOURNAL FREE ACCESSThe crystallographic structure of an electroplated Cu-Sn alloy film was investigated in detail using an X-ray diffraction method and electron microscopy. This structure was then compared with the thermal equilibrium diagram of Cu-Sn alloy. The structure of the plated film does not always agree with its thermal equilibrium diagram but is cross related. In this alloy system some metastable phases have been discovered. In this investigation further four kinds of metastable phases were discovered. They are two kinds of tetragonal system crystals, one kind of orthorombic crystal, and one super-saturated solid solution. The lattice constants of these crystal were also identified.View full abstractDownload PDF (1043K) -
Tohru Watanabe, Isao Satoh, Masatoshi Chikazawa1999 Volume 63 Issue 4 Pages 482-488
Published: 1999
Released on J-STAGE: April 24, 2008
JOURNAL FREE ACCESSThe crystallographic structure of an electroplated In-Sn alloy film has been investigated in detail by using the X-ray diffraction method and differential thermal calorimetry. This structure is then compared with the In-Sn alloys thermal equilibrium diagram. The structure of the plated film is controlled by over-voltage during plating. However, the structure of In-Sn electroplated alloy film is not dependent upon the current density and bath concentration, and depends upon the concentration of the plated film, while the structure of the plated film is always in agreement with the thermal equilibrium diagram. This indicates that the plated film is a complete metallic material.View full abstractDownload PDF (1020K) -
Tohru Watanabe, Kazuyoshi Arai, Takeshi Hirose, Masatoshi Chikazawa1999 Volume 63 Issue 4 Pages 489-495
Published: 1999
Released on J-STAGE: April 24, 2008
JOURNAL FREE ACCESSThe physical properties of a plated film are directly related to its crystallographic structure. If the crystallographic structure of the film can be controlled, the physical properties can be controlled. From this reason, investigation of the crystallographic structure of the plated film are very important. In this investigation, the crystallographic structure of electroplated Ni-Sn film is studied in detail and compared with the thermal equilibrium diagram of its alloy. The structure of the plated film is seen to be closely related to the thermal equilibrium diagram. However, in the plated film a β and a γ phase which show in the thermal equilibrium diagram are not formed, and two kinds of metstable phases and a super-saturated solid solution are formed.View full abstractDownload PDF (965K) -
Tohru Watanabe, Takeshi Hirose, Kazuyoshi Arai, Masatoshi Chikazawa1999 Volume 63 Issue 4 Pages 496-501
Published: 1999
Released on J-STAGE: April 24, 2008
JOURNAL FREE ACCESSWe offen encounter with cases in which an amorphous or a phases which is not described in a thermal equilibrium diagram appears in an electroplated alloy film and also X-ray diffraction peaks which are not maintained in JCPDS appear in the X-ray diffraction pattern. All of theses are due to the existence of the metastable phase in the plated film. In this paper by investigating the transformation process of two kinds of metastable phases which appear in an electroplated Ni-Sn alloy film as a thermal equilibrium phase by heat treatment, the crystallographic structures of these metastable phases were characterized.View full abstractDownload PDF (890K) -
Takao Yamaguchi, Yasuoka Kobayashi, Imao Nagasaka, Naoyuki Ohnishi, Ry ...1999 Volume 63 Issue 4 Pages 502-507
Published: 1999
Released on J-STAGE: April 24, 2008
JOURNAL FREE ACCESSThe behavior of materials under impact loading tests are important in both research and practice, and practical testers are, in a narrow sense, only Charpy and Izod. However in many cases, this data cannot directly lead to the impact strength; the evaluation method for tensile impact property of materials is not always established. In particular, with toughness neither the definition nor the measurement technique has been well-defined.
In this study, a weight-dropping impact-tester is manufactured, with which the relationship between time and load is measured, then the impact-strength is determined from the maximum load. Also, the “Impulsivity” —the ratio between the standard impulse calculated by means of the maximum load and the impulse of the material taking no account of the strain and the reduction— is defined, and based on the relationship between the impact strength and this “Impulsivity”, a method to evaluate the materials’ toughness is proposed.View full abstractDownload PDF (558K) -
Tetsuya Watanabe, Masayuki Hasaka1999 Volume 63 Issue 4 Pages 508-514
Published: 1999
Released on J-STAGE: April 24, 2008
JOURNAL FREE ACCESSAg was added to FeSi2-1 at%M (M=Mn, Co) for fabricating a thermoelectric semiconductor with high-generating power by the means of lowering resistivity. Samples were produced in the following procedure. FeSi2-1 at%M (M=Mn, Co) ingots were fabricated by high-frequency melting method in a vacuum. These were ground into powders and then, these powders were dipped into AgNO3 solution. Through the process, Ag adhered to these powders. After the powders were made into tablets, they were sintered at 1373 K for 18 ks in a vacuum. Then the sintered samples were heat treated to make semiconductor at 1063 K for 360 ks. Thermoelectromotive forces and resistivities of the samples were examined. It turned out that while thermoelectromotive forces hardly changed, the level of resistivities was reduced. As a result, the power factor of the FeSi2-1 at%Co containing 3 at%Ag was six times larger than that of FeSi2-1 at%Co, at 573 K.View full abstractDownload PDF (892K) -
Takashi Ishiyama, Tatsuhiko Tanaka1999 Volume 63 Issue 4 Pages 515-519
Published: 1999
Released on J-STAGE: April 24, 2008
JOURNAL FREE ACCESSCathodic stripping voltammetry at a silver disk electrode based on non-electrolytic preconcentration steps is developed for the determination of trace amounts of tellurium in steel and lead. Tellurium(IV) ions were accumulated on a rotating silver disk electrode surface as silver telluride in 4 mL of acidic solutions (pH 0.7∼0.9) containing sodium bromide and L(+)-ascorbic acid for 30 min with open circuit. A differential pulse cathodic stripping voltammogram for the deposits was then recorded in another cell with a 2 mol·L−1 sodium hydroxide solution in the potential range −0.45 to −1.5 V vs. Ag/AgCl at a scan rate of 50 mV· s−1. The presence of bromide ions allowed the non-electrolytic preconcentration of silver telluride and resulted in a single distinct peak. Maximum permissible concentrations of iron(II) and lead(II) in the determination of 100 μg·L−1 of tellurium(IV) were 1000 and 4000 mg·L−1, respectively. Iron(III) was reduced to iron(II) with L(+)-ascorbic acid. Calibration curve was linear over the 7.8×10−8 to 2.4×10−6 mol·L−1 concentration range and passed through the origin. The detection limit (3σ) calculated from repeated determinations of 3 μg·L−1 of tellurium(IV) was 0.31 μgTe·L−1. The advantages of the proposed method include simple and rapid operations and lessening contamination hazards. The method was successfully applied to the determination of tellurium at the 10 mass ppm level in 1-g samples of alloy steel and battery lead without any troublesome separation of the matrix element using harmful chemicals. The relative standard deviations were 3 to 5% for five determinations, and the time required for an analysis was less than 1 h.View full abstractDownload PDF (413K) -
Nagahiro Saito, Mitsuhito Hirota, Takahiro Ishizaki, Akio Fuwa1999 Volume 63 Issue 4 Pages 520-526
Published: 1999
Released on J-STAGE: April 24, 2008
JOURNAL FREE ACCESSThe pressure dependent rate constant for the reaction, SiH4(g)→SiH3(g)+H, has been unknown from the standpoints of both experiment and calculation. It is the basic data of the reaction path analysis for RPT (Reduced Pressure Thermal)-CVD from silane, and hence it is a valuable piece of information in science and technology in view of the reaction control. In this study, the pressure dependent rate constant was predicted using the RRKM theory aided by Ab-initio MO. It was calculated under conditions in which the temperatures were from 600 to 1500 K at intervals of 100 K, the pressures were 133.32×1010, 133.32×108, 133.32×106, 133.32×104, 101.32×103, 133.32×102, 133.32×101, 133.32×100, 133.32×10−1, 133.32×10−2 and 133.32×10−3(Pa), and the third body was argon gas. The Arrhenius type rate expression was shown as follows:
(This article is not displayable. Please see full text pdf.)
\ oindentHere, the subscript of k stands for the pressure.View full abstractDownload PDF (518K) -
Kazuhiro Nishizono, Fuminori Shinsei, Nobuyuki Mori, Keisaku Ogi1999 Volume 63 Issue 4 Pages 527-534
Published: 1999
Released on J-STAGE: April 24, 2008
JOURNAL FREE ACCESSFinely and uniformly dispersed non-superconducting particles, Ag particles and Y211(Y2BaCuO5) particles in the single crystal Y123(YBa2Cu3O7−x) matrix can improve the critical current density(Jc) and mechanical properties. In this paper, the effect of solidification factors on the microstructure (size and distribution of Y211, Ag particle) was investigated. Mixed and pressed Y123+Y211(0, 10, 40 mol%)+Ag(10, 15 mass%)+Pt(0∼1.0 mass%) powders were melted and solidified unidirectionally under the thermal condition that promoted Y123 columnar crystal growth. Comparing with Ag-free YBCO, more Pt was required to refine Y211 particles in Ag added YBCO. Less than 0.8 mass%Pt addition was insufficient to refine Y211 particles. Though 1.0 mass%Pt addition completely refines Y211 particles, excess Pt formed Ba-Y-Cu-Pt-O compound. Liquid Ag droplets, formed by peritecto-monotectic reaction LI+Y211→Y123+Ag(LII), were pushed forward by the faceted freezing front and grew to capsule-like particles with a critical radius at a distance L0 before they were trapped into Y123. In the 15 mass%Ag added sample, the mean radius, r0(μm), the mean spacing, λ(μm), and the pushing distance, L0(μm) of Ag particles dispersed in Y123 depended on the growth rate, Ri(μm/s), and the relations were expressed by r0=0.52·Ri−1, λ=3.5·Ri−1 and L0=6.8·Ri−1, respectively. The distribution of Ag particles in Y123 was quantitatively estimated based on the BCT (Body-Centered Tetragonal) array model.View full abstractDownload PDF (853K) -
Keisuke Matsuura, Norio Matsuda1999 Volume 63 Issue 4 Pages 535-541
Published: 1999
Released on J-STAGE: April 24, 2008
JOURNAL FREE ACCESSCreep tests were carried out on aluminum matrix composites reinforced with alumina short fibers to examine the effects of short fiber reinforcement on creep properties, such as creep rate, creep curve shape and creep damages.
At low stresses, a large part of the creep curve was mainly dominated by the tertiary stage. As the stress increased, the relative extent of the primary stage became larger.
The creep strength increased with increasing volume fraction of short fibers from 5 to 10 vol%, though it was nearly the same between 10 and 18 vol% alumina fibers in the range except for a high temperature (773 K) and a low stress. On the other hand, the increase of the creep strength when increasing volume fraction from 10 to 18 vol% was recognized in the range of high temperatures and low stresses.
The occurrence of the tertiary stage was associated with the detachment of alumina fibers from the matrix and the extension of voids at grain boundaries. It was shown that the θ-projection concept was useful in describing quantitatively the creep curve shape and the variation of θ parameters with stress and temperature was studied.View full abstractDownload PDF (1045K) -
Jun-Mo Yang, Daisuke Shindo, Masaki Takeguchi, Masahiro Kawasaki, Tets ...1999 Volume 63 Issue 4 Pages 542-548
Published: 1999
Released on J-STAGE: April 24, 2008
JOURNAL FREE ACCESSMicrostructure and magnetic domain structure of Sm(Co0.653Fe0.257Cu0.066Zr0.024)7.3-permanent magnets were investigated by advanced transmission electron microscopy (TEM), using techniques such as high-resolution electron microscopy (HREM) and Lorentz electron microscopy with a high-voltage electron microscope, and an elemental mapping method utilizing a small electron probe with a field-emission electron gun. As a result, the crystallographic arrangement of cellular microstructures including the Z phase and the composition distribution in the cell boundary phase were accurately evaluated. Also, the magnetic domain wall width was precisely measured from the intensity distribution of Lorentz electron microscope images recorded with the imaging plate. Furthermore, the magnetic field in both the inside and the outside of this material was observed by an electron holography technique for the first time.View full abstractDownload PDF (1743K) -
Masahiko Kato, Hisaoki Sasano, Toshiyuki Suzuki1999 Volume 63 Issue 4 Pages 549-550
Published: 1999
Released on J-STAGE: April 24, 2008
JOURNAL FREE ACCESSAuthors previously reported that the interdiffusion coefficients of NiAl phase are extremely small near the stoichiometric composition below 1123 K, and that it is highly possible to induce phase separation. In this study, the microstructures of Ni-50 at%Al and Ni-48 at%Al alloys annealed at 1073 K for 8 h after slow cooling from 1623 K have been investigated by electron microscopy. The banded structure, which have major axis at right angles to ⟨\bar110⟩ direction, was observed firstly in both alloys of Ni-50 at%Al and Ni-48 at%Al near the stoichiometry. The banded structure implies the structural change in the plane parallel to the {110}. This suggests occurrence of phase separation in NiAl phase.View full abstractDownload PDF (435K) -
Tohru Awane1999 Volume 63 Issue 4 Pages 551-552
Published: 1999
Released on J-STAGE: April 24, 2008
JOURNAL FREE ACCESSA new convenient method has been developed to remove adhesive organic compounds with high chemical resistance (e.g. epoxy resin) from metallographic surfaces without damaging the surfaces.
Epoxy resin has been found to be readily removed in the following process: 1) rapid cooling in liquid nitrogen and mechanical crushing of bulk resin, 2) swelling the residual resin in an organic solvent, 3) decomposition of the resin in cold concentrated sulfuric acid, 4) washed with saturated aqueous solution of sodium bicarbonate, and 5) blank replica.
This method has been found effective for metals with moderate corrosion resistance.View full abstractDownload PDF (336K)
- |<
- <
- 1
- >
- >|