Journal of the Japan Institute of Metals and Materials
Online ISSN : 1880-6880
Print ISSN : 0021-4876
ISSN-L : 0021-4876
Volume 59 , Issue 3
Showing 1-18 articles out of 18 articles from the selected issue
  • Kiyohiko Ito, Satoshi Yamaguchi, Hisashi Kuwano
    1995 Volume 59 Issue 3 Pages 237-243
    Published: 1995
    Released: April 04, 2008
    JOURNALS FREE ACCESS
    Hyperfine magnetic fields of 57Fe in ferritic Fe-Cr-5%Ni alloys have been measured in a concentration range from 0 to 60%Cr by Mössbauer spectroscopy at room temperature. The hyperfine magnetic field distributions are computed from the experimental Mössbauer spectra.
    The mean hyperfine magnetic field ⟨H⟩ depends linearly on Cr content xCr, as expressed by an empirical relation; ⟨H⟩⁄T=33.5−0.36 xCr (at%), whose slope being somewhat larger than that for Fe-Cr alloys. The full width at a half maximum of the hyperfine magnetic field distribution becomes constant in a concentration range from 25 to 50%Cr.
    The experimental hyperfine magnetic field distributions are numerically analyzed by considering the effect of Cr and Ni in the first and the second neighbor atomic shells on the hyperfine magnetic field of 57Fe. The resultant hyperfine magnetic field coefficients of Cr and Ni in the first neighbour atomic shell change from −3.9 to −2.4 T and 0.6 to −1.2 T, respectively, while the Cr content increases from 0 to 50%.
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  • Teruo Takahashi
    1995 Volume 59 Issue 3 Pages 244-250
    Published: 1995
    Released: April 04, 2008
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    Elemental titanium-amorphous boron and elemental titanium-titanium diboride (TiB2) mixed powders were mechanically alloyed to strengthen the conventional titanium-boron binary alloy by the dispersion of TiB. The mechanically alloyed (MA) powders obtained were heated in vacuum for degassing, and then consolidated by hot isostatic pressing (HIP) to investigate the microstructures and mechanical properties. The MA powders prepared from elemental titanium and amorphous boron could be converted into Ti-TiB composite powders by heating above 773 K for 3.6 ks, while the MA powders from elemental titanium-TiB2 needed the heating above 1073 K for 3.6 ks. The morphological feature of TiB as an in-situ reaction product was whisker or needle-like shape. Namely, TiB fiber-reinforced titanium can be prepared by the in-situ precipitation of TiB whisker or needle-like crystals. The maximum diameter of this reaction product was about 500 nm, while the maximum size of titanium matrix grains ranges from 3 to 5 μm. The crystal grains of the titanium matrix and the TiB crystals in this alloy system became smaller as the HIP’ping temperature decreased. The mechanical properties of Ti-TiB composites were significantly improved by the whisker or needle-like precipitation of TiB and the refining of titanium grains.
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  • Qi Cui, Goroh Itoh, Motohiro Kanno, Yoshihiro Tsuji, Kazunori Kobayash ...
    1995 Volume 59 Issue 3 Pages 251-257
    Published: 1995
    Released: April 04, 2008
    JOURNALS FREE ACCESS
    Age-hardening characteristics and precipitate structures have been examined in 2091 alloys (Al-2.15%Li-2.04%Cu-1.5%Mg-0.14%Zr) with and without 0.15%V or 0.19%Cr addition, with special attention to the relationship between S′-phase precipitation and the dispersoid particles which are formed during ingot homogenization. It was found that S′-phase precipitates mainly on dislocation loops around incoherent Zr-bearing and V-bearing dispersoid particles. In contrast, coherent Zr-bearing dispersoids and incoherent coarse Cr-bearing ones provided no nucleation site for S′-precipitate. The numerical density of S′-precipitates was not sufficient to contribute to hardening, corresponding to the low density of incoherent Zr-bearing and V-bearing dispersoids. The low density of V-bearing dispersoids was attributed to the low concentration of vanadium in solution before ingot homogenization, which was caused by the formation of a number of coarse V-bearing constituent particles during solidification. To avoid this, small 2091+V alloy ingots were prepared by chill-casting. The density of V-bearing dispersoids was significantly increased, leading to a finer distribution of S′-precipitates as well as a higher hardness level, which was comparable to that obtained in the 2091 alloy T8-treated.
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  • Yasuhide Shindo, Naoki Niwa, Hideaki Nozaki, Hassel M. Ledbetter
    1995 Volume 59 Issue 3 Pages 258-262
    Published: 1995
    Released: April 04, 2008
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    We calculate the defect-free elastic constants of high temperature ceramic superconductor YBa2Cu3Ox from measured elastic constants of bulk YBa2Cu3Ox which contains numerous microcracks and voids. Defect-free elastic constants represent long-wavelength acoustic phonons and relate to a variety of solid-state-phenomena such as Debye temperature, thermal expansivity and theoretical strength. By the use of the self-consistent method or the differential method, we eliminate the effect of random distribution of microcracks on the elastic constants of YBa2Cu3Ox. The scattered-plane-wave method is also used to eliminate the effect of voids and then obtain the defect-free elastic constants. Numerical calculations are carried out and the influence of the microcracks and the voids on the elastic constants of YBa2Cu3Ox is discussed in detail.
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  • Sadahiro Tsurekawa, Yuichi Hasegawa, Hideo Yoshinaga, Yuichi Ikuhara
    1995 Volume 59 Issue 3 Pages 263-270
    Published: 1995
    Released: April 04, 2008
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    In order to clarify the intrinsic nature of high temperature deformation of β-SiC without crack formation, pressureless sintered β-SiC with B+C additives as sintering aids has been deformed by compression at temperatures from 2070 to 2270 K and at strain rates from 6×10−6 to 7×10−5 s−1. Microstructures were also examined by scanning electron microscopy (SEM) and X-ray diffraction.
    It was found that the shape of stress-strain curves showed a regular oscillation. The oscillation depended markedly on strain rate; the period and the amplitude of the flow stress oscillation respectively tend to decrease and to increase with decreasing strain rate. A change in grain shape was observed from acicular grain, which is characteristic of pressureless sintered β-SiC, to almost equiaxed one after deformation. Furthermore, X-ray diffraction analysis revealed that there was no definite sign of structure change, that is, the β structure was maintained after deformation. The observed phenomena were discussed from the viewpoint of dynamic recrystallization.
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  • Nobuo Takahashi, Satoshi Asano
    1995 Volume 59 Issue 3 Pages 271-276
    Published: 1995
    Released: April 04, 2008
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    Solvent extraction of europium (II) was carried out by using 15-crown 5-ether, 18-crown 6-ether and dicyclohexyl 18-crown 6-ether in the presence of a reducing agent. In three types of the crown ethers, dicyclohexyl 18-crown 6-ether was the most effective extractant for extraction of europium (II).
    As a diluent of the crown ether, α,α,α-trifluoro toluene, and the mixture of bromoform and carbon tetrabromide were used, and it was found that α,α,α-trifluoro toluene was a suitable diluent for extraction of europium (II) under reducing environment.
    Lithium salts of trichloro acetic acid, trifluoro acetic acid and trifluoro methane sulphonic acid were added into the aqueous phase as counter ions for europium (II), and it was found that the trifluoro methane sulphonic acid was the most effective counter ion.
    Metallic zinc fine powder and low melting point liquid alloy of Ga-In-Zn were used as reducing agents for Eu (III) to Eu (II), and it was found that the liquid Ga-In-Zn alloy was suitable reductant in the presence of L-Ascorbic acid. Under the suitable condition, high distribution ratio of Eu (9.0×10) and high separation factor of Eu/Gd (7.0×105) were obtained.
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  • Yoshinori Wakamatsu, Masami Onishi, Toshitada Shimozaki
    1995 Volume 59 Issue 3 Pages 277-283
    Published: 1995
    Released: April 04, 2008
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    Fe specimens were annealed in molten Bi containing 1-20 mass%Zn at 553 to 673 K, in order to investigate the structures of Fe-Zn alloy layers formed by reactive diffusion between Fe and molten Bi-Zn. On surfaces of the specimens, seven kinds of alloy layers composed of the following Fe-Zn intermetallic phases were formed depending on the annealing condition: (1) Γ, (2) Γ and Γ1, (3) Γ, Γ1 and δ1, (4) Γ, Γ1, δ1 and ζ, (5) Γ, δ1 and ζ, (6) δ1 and ζ, and (7) ζ. The structure of the alloy layer changed in order of (1)→(2)→(3)→(4), (1)→(2)→(3)→(5) or (1)→(3)→(7) with increasing Zn content of molten Bi and in order of (7)→(6)→(5)→(4) with annealing time in molten Bi saturated with Zn. It seems that the Fe-Zn intermetallic phase having zinc activity approximately equal to that of molten Bi-Zn is formed at an outer surface of the alloy layer and that the lag in the appearance of δ1, Γ and Γ1 phase layers in the molten Bi saturated with Zn is caused by the formation of ζ phase layer having a non-equilibrium composition ranging from the δ1 to ζ phases.
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  • Shinji Hirai, Hiroshi G. Katayama, Kazuto Sasaki, Hideo Kanisawa
    1995 Volume 59 Issue 3 Pages 284-289
    Published: 1995
    Released: April 04, 2008
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    In order to improve the corrosion resistance to a chloride-containing aqueous solution of steel for concrete reinforcement, an attempt was made to form a low Al alloy layer on the steel surface by immersion into a molten Mg-Al alloy bath. The principle of this method is based on the fact that the solubility of Mg in solid iron is negligibly small and that Al can be distributed between the molten alloy bath and the surface of steel according to the distribution law. The higher the Al concentration of the bath, the higher the surface Al concentration of the alloy layer bacame. On the other hand, the surface Al concentration did not depend on the immersing time, but it decreased somewhat with the increase of temperature. The adhesion of the alloy bath to the specimen was prevented by adding the flux consisting of MgCl2 to the bath. However, the addition of an excessive amount of flux resulted in the decrease of the surface Al concentration due to the volatilization of Al as AlCl3 from the bath. The thickness of the alloy layer increased with immersing time according to the palabolic rate law and an apparent activation energy was calculated to be 198 kJ/mol. The anodic polarization tests showed a corrosion potential of −571 mV, a current density for maintaining the passive state of 12 μA·cm−2, and a pitting potential of +285 mV for the specimen having the surface Al concentration of 11.4 mass%. From the comparison with the test results for commercial corrosion-resistant steel for sea water, it was concluded that the above-mentioned specimen had very excellent corrosion resistance. When the surface Al concentration was further increased, the corrosion-resistant characteristic deteriorated.
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  • Takeshi Kobayashi, Kunikazu Ide, Shin-ichi Hasegawa, Ryosuke Hasegawa, ...
    1995 Volume 59 Issue 3 Pages 290-295
    Published: 1995
    Released: April 04, 2008
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    An analytical method has been established for the direct determination of trace amounts of sodium, potassium, manganese, nickel and lead in titanium and titanium alloys by graphite furnace atomic absorption spectrometry (GF-AAS). The titanium and titanium alloy were dissolved in a mixture of hydrofluoric acid and nitric acid. After the solution (20 mm3) was pipetted into a L’vov platform furnace, it was ashed and then atomized by using argon as a purge gas, and atomic absorption of each analyte was measured. The effect of diverse elements was suppressed by the use of peak area measurement. Synthetic calibration solutions were prepared by addition of standard solution of each analyte to titanium matrix solution. For sodium, potassium, manganese, nickel and lead, the limits of detection (3 σ of blank values) were 0.013, 0.009, 0.018, 0.075 and 0.056 ppm, respectively, when one gram of the specimen was used. The proposed method is able to be applied to many kinds of titanium alloys.
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  • Motohiro Kanno, Hiroshi Okada, Goroh Itoh
    1995 Volume 59 Issue 3 Pages 296-302
    Published: 1995
    Released: April 04, 2008
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    An equipment has been developed for detection of gasses evolved from metallic materials during deformation. It consists of a tensile-compression fatigue testing machine, a quadrupole mass spectrometer and an ultra high vacuum chamber which is evacuated to a vacuum of about 1.0×10−7 Pa with a tandem turbo molecular pump and a non-evaporable getter pump. Tensile tests have been carried out in the chamber for various metallic materials: an Al-5%Mg alloy, a 7005 aluminum alloy, an oxygen free copper, a Ti-6%Al-4%V alloy, a Cr-Mo steel, a Ti-48%Al alloy and some sintered materials and evolved gasses are analyzed by the quadrupole mass spectrometer connected to the chamber. Hydrogen gas has been evolved from all these materials during fracture even when impurity hydrogen is as low as a few ppm. This fact means that impurity hydrogen has been concentrated during deformation to the area where fracture will occur. In addition, other gasses were also detected during fracture, and the amounts of these gasses were lower than that of hydrogen.
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  • Ken’ichi Miura, Itsuo Ishigami, Masato Kuno, Hiroyuki Kaneda
    1995 Volume 59 Issue 3 Pages 303-311
    Published: 1995
    Released: April 04, 2008
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    Experiment has been made to gain an overall picture for an variation in hardness of TiN films deposited by reactive hollow cathode discharge ion plating with process parameters: deposition temperature, deposition time, electron beam current, substrate bias voltage, gas pressure, mixture ratio of nitrogen to argon, distance from an evaporation source to a substrate, and tilt angle of a substrate axis. Furthermore, an attempt has been made to find out factors controlling the hardness and reveal the relationship between a factor and hardness. The films of single phase TiN were deposited onto a substrate of high speed tool steel, SKH51. Line broadening of X-ray diffraction was utilized to determine the grain size of the films. Substrate temperature plays an important role in a variation in hardness. An increase in deposition temperature, deposition time and electron beam current brings about a higher substrate temperature and thereby gives the films of larger grains and lower hardness. On the contrary, an increase in distance from an evaporation source to a substrate and in tilt angle of a substrate axis leads to a lower substrate temperature, which results in finer grains and higher hardness. Increasing the substrate bias voltage gives rise to higher hardness mainly because of the grain size reduction which is presumably due to renucleation; however, an excess increase in the bias raises the substrate temperature and thus slightly lowers the hardness. The hardness values varies linearly with the inverse square root of the grain diameter, according to the Hall-Petch relationship.
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  • Joon-Pyou Park, Kensuke Sassa, Shigeo Asai
    1995 Volume 59 Issue 3 Pages 312-318
    Published: 1995
    Released: April 04, 2008
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    From the viewpoint of the protection of the earth environment, a crucial technical subject in recycling of scraps is how to develop an elimination method of tramp elements, which are harmful to the mechanical properties of its products and the elimination of which is difficult. The solution has been strongly desired these days. On aluminum scraps notorious tramp elements are iron, magnesium and zinc. Especially, in the molten aluminum alloys dissolving iron, an intermetallic compound of Al5FeSi easily precipitates during solidification in a needle-like morphology, in which the length of the precipitate sometime extends up to several millimeters, and provides inferior mechanical properties.
    In this paper, we propose a useful method for eliminating the tramp elements using EMF (electromagnetic force) which is induced by imposing a direct electric current and a steady magnetic field in a molten metal. The principle of this method is that as the EMF induced in the metal scarcely acts on non-metallic inclusions due to a low electric conductivity of them, the non-metallic inclusions are moved to the direction opposite to that of the EMF as the reaction of the force and are eliminated out of the bulk metal. The usefulness of the method was demonstrated in experimental works, in which at first the component of iron dissolved in aluminum alloys was precipitated as intermetallic compounds and then the compounds were eliminated by use of the EMF. The continuous operation of the method was studied through the visualization of the movement of polystyrene particles in a NaCl aqueous solution.
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  • Osamu Ohashi, Susumu Meguro, Toshihiro Yamagata
    1995 Volume 59 Issue 3 Pages 319-324
    Published: 1995
    Released: April 04, 2008
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    The aim of this study is first to find suitable bonding conditions for joining single crystal Ni-base superalloy TMS-26 without the formation of a recrystallized zone at bond-line, and secondary to investigate the relationship between misorientation angle at bonding interface and joint strength. Joints were made using samples prepared with a {100} crystal plane at the bonding surface. All the samples were joined in a vacuum of 4×10−3 Pa using radio frequency heating.
    Single crystal TMS-26 can be bonded without the formation of voids and recrystallized zone at the bond-line. The quality of creep rupture of joints deteriorates due to formation of precipitates at the bond-line. There are a few inclusions at the bond-line when the twist angles of 0° up to 3° are used. Creep rupture life of the joints is long. When twist angles greater than 3° are used, many inclusions are formed at bond-line and joint strengths are very low. The precipitates at the bond-line consist of oxides due to surface film and α tungsten phase.
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  • Tsuyoshi Mihara, Toyohiko Sato, Ryuzo Watanabe, Akira Kawasaki, Noriyo ...
    1995 Volume 59 Issue 3 Pages 325-330
    Published: 1995
    Released: April 04, 2008
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    Elastic constant of functionally gradient materials (FGM) is one of the most important material properties. The authors have developed new measurement procedures for local elastic constants for some uniform industrial materials by using a LFB acoustic microscope. The purpose of this paper is to verify the versatility of the LFB acoustic microscope in the measurement of the elastic constant distribution of FGM. Partially stabilized zirconia/stainless steel FGM specimens from four various fabrication routes were used for the measurement by the LFB acoustic microscope to estimate the elastic constant distribution in the graded samples. It has been shown that the present method is sufficiently applicable to the accurate determination of the local elastic constant in FGM.
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  • Isao Tsuchitori, Norichika Morinaga, Hideharu Fukunaga
    1995 Volume 59 Issue 3 Pages 331-338
    Published: 1995
    Released: April 04, 2008
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    The TiO2/Al composites are gradually hardened by the reaction between the reinforcement and matrix alloy during heat treatment at temperatures below the solidus line. In employing the practical aluminum alloy as the matrix, it is expected that the alloying elements affect the hardening behaviour of the composites during heat treatment. Experimental work was made to study the effect of the addition of Mg and Si to aluminum on the hardnability of TiO2/Al composites manufactured by squeeze casting. The results are surmmarized as follows: Mg in aluminium was segregated near the infiltrated surface of composites. The segregated Mg caused the formation of MgTiO3 near the surface of the composites after heat treatment, and then the soft layer are formed on surface of the composites. The addition of Si in aluminum caused no segregation, but a homogeneous distribution of Si itself in the composites. A large amount of Si addition produced a spotty distribution of relatively soft Ti7Al15Si12 compound after heat treatment, leading to the reduced rate of reaction hardening of the composites. By employing the practical AC4C alloy for the matrix of the composites, no large difference was observed in the time to the saturation of the reaction hardening, but a considrable decrease in the saturation hardness.
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  • Fumiaki Matsumoto, Yoshiaki Tanaka, Tomoyuki Yanagiya, Masayuki Ishizu ...
    1995 Volume 59 Issue 3 Pages 339-346
    Published: 1995
    Released: April 04, 2008
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    Ag- and AgCu alloy-sheathed Bi2Sr2CaCu2Ox (Bi 2212 phase) tapes have been fabricated by the powder-in-tube technique. Detailed microstructural observations during the fabrication process revealed the following factors which deteriorate critical current density due to the decrease in the Bi 2212 crystal texture: 1) swelling of the Ag sheath; 2) rough interface between the Ag sheath and the oxide core; 3) crack in the oxide core; 4) precipitates such as SrCaCuO; 5) radially grown crystal; 6) irregular deformation in the tape cross section during heat-treatment. The swelling was caused by the dissociation of H2O, CO2 and O2 gasses during heat-treatment. Calcination of the powder in low O2 partial pressure, gradual heating up the tape samples, and high tensile AgCu alloy-sheath reduced the swelling. Crack formation in the oxide core was prevented by the proper rolling process with the Vickers hardness below about 150. This resulted in smooth interface between the Ag sheath and oxide core and thus improved the reproducibility of high critical current density.
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  • Yukio Inokuti
    1995 Volume 59 Issue 3 Pages 347-355
    Published: 1995
    Released: April 04, 2008
    JOURNALS FREE ACCESS
    In order to clarify the mechanism responsible for the ultra-low iron loss in TiN-coated grain oriented silicon steel sheet, direct observations were made of the domain structure obtained by coating a thin TiN film, which had been produced by ion plating on polished silicon steel sheets.
    The results obtained are summarized as follows.
    (1) After making distinct chemically polished and TiN-coated areas inside a single giant secondary Goss grain of a silicon steel sheet, the domain structure of the chemically polished area showed an original main domain with large black and white 180° domain wall spacings elongated in the rolling direction, while that of the TiN-coated area showed marked domain refinement due to the induced strong tensile stress by the TiN film.
    (2) At the borderline between the chemically polished area and the TiN-coated area, the domain wall spacings changed drastically, showing four to six narrow wall spacings in the coated area for each wall spacing in the polished area, and lens-like refined-domains also formed at the beginning of the TiN coating area from the large black and white 180° main domains.
    (3) In the chemically polished side of these line between the two areas, longitudinally striped domains formed distinctively within regions about ±45° to the rolling direction due to local strain arising from the strong surface tension in the TiN film.
    (4) By causing a slight deviation in the orientation of the secondary Goss grains in the silicon steel sheet, both the main domain and its refined domain in the chemically polished and TiN-coated area became less pronounced.
    (5) It is considered that the ultra-low iron loss in TiN-coated silicon steel sheet was obtained due to the reduced eddy current loss arising from the strong surface tension of the TiN coating on the silicon steel sheet, which induced radical domain refinement.
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  • Kazuyoshi Sekine, Jing Huan Zheng
    1995 Volume 59 Issue 3 Pages 356-357
    Published: 1995
    Released: April 04, 2008
    JOURNALS FREE ACCESS
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