Journal of the Japan Institute of Metals and Materials
Online ISSN : 1880-6880
Print ISSN : 0021-4876
ISSN-L : 0021-4876
Volume 41 , Issue 7
Showing 1-17 articles out of 17 articles from the selected issue
  • Itsuo Ishigami, Kyuhiko Yamanaka
    1977 Volume 41 Issue 7 Pages 639-646
    Published: 1977
    Released: April 04, 2008
    JOURNALS FREE ACCESS
    A white layer is formed on the vacuum oil-quenched high speed steel. The vacuum oil-quenched SKH-9 was rubbed against SUJ-2 in a dry condition by the use of an Ogoshi rapid wear testing machine to clarify the wear resistance of high speed steel on which the white layer was formed.
    The formation of the white layer tended to improve the wear resistance of the high speed steel at sliding speeds in excess of 2.0 m/s. As the thickness of the white layer increased, the wear loss decreased, in general. In improvement of the wear resistance, were three types as follows: In the case of the white layer that consists of a large amount of retained austenite and a small amount of M6C-type carbide as well as martensite, (1) Under light loads the white layer showed higher resistance to wear by itself. (2) Under heavy loads wear rates decreased rapidly as soon as the rotor reached the white layer-matrix boundary. It seemed that the white layer between the rotor and the matrix was effective as lubricant. The thinner layers were less effective. (3) In the case of the thicker layers, the carbide layers which perhaps consisted of M3C, M-C, and M2C-type carbide were formed. The carbide layers had high hardness as well as high resistance to decomposition on heating. Consequently, the carbide layers gave the improved resistance to wear all over the range of load tested.
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  • Kô Soeno, Masatoshi Tuchiya
    1977 Volume 41 Issue 7 Pages 647-650
    Published: 1977
    Released: April 04, 2008
    JOURNALS FREE ACCESS
    Precipitation in nickel maraging steels containing 10%Co and 5%Mo has been investigated as a function of nickel content by measuring the changes in electrical resistivity at liquid nitrogen temperature. The nickel content varied from 10 to 18%.
    The results are interpreted in terms of two precipitation stages. The precipitates formed in a low temperature region and in a high temperature region are named as phase-L and as phase-H, respectively. Arrhenius plots of the time to reach a constant resistivity decrease are constructed from isothermal aging curves, and it is found that the points in low aging temperatures where the phase-L is precipitated deviate from the high aging temperature line in the direction of shorter times. The phase-L is considerably reverted by heating up to temperatures where the precipitation of the phase-H proceeds rapidly. The line of demarcation between the precipitation of the phase-L and that of the phase-H is drawn as a function of nickel content. The upper temperature limit of the phase-L precipitation increases with increasing nickel content.
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  • Shigeo Matsushima
    1977 Volume 41 Issue 7 Pages 651-657
    Published: 1977
    Released: April 04, 2008
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    Tensile strength σB and the tensile fatigue strength (of the pulsating pull) for drawn Mo wire (sintered wire: JIS H-4781, VMW 1-D) and annealed Mo (annealed the wire at 2200°C for 10 min) are obtained by tensile and tensile fatigue tests at high temperatures of 800∼2300°C in a vacuum of 10−5 Torr. And the relations between these strengths are discussed. The results obtained are as follows:
    (1) For the annealed Mo, the relation between tensile strength and testing temperature T is approximately given by
    (This article is not displayable. Please see full text pdf.)
    \ oindentwhere A=22.3 kg·mm−2 and B=0.97×10−3 C−1.
    \ oindentThe relation among maxium stress σ0 (of cyclic tensile stress), cyclic number N (of the stress to fracture) and T is approximately given by
    (This article is not displayable. Please see full text pdf.)
    \ oindentwhere A0=1.86×1015 (kg·mm−2)−\barB and \barB=−10.
    (2) For the drawn Mo, the relation between σB and T is approximately given by
    (This article is not displayable. Please see full text pdf.)
    \ oindentAbove 1400°C, the relation among σB, N and T is approximately by
    (This article is not displayable. Please see full text pdf.)
    \ oindentwhere A0*=2.25×1018 (kg·mm−2)B*, B0*=1.37×10−2 C−1 and \barB*=−8.
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  • Hideyuki Toriumi, Seiji Terasawa, Osamu Izumi
    1977 Volume 41 Issue 7 Pages 657-663
    Published: 1977
    Released: April 04, 2008
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    Cu-Al eutectoid alloy has been transformed unidirectionally to produce aligned pearlitic structure in an electric resistance furnace under the temperature gradient of ∼150°C/cm and with the translation velocity from 0.28 to 5 mm/hr.
    At lower translation velocities, well-aligned pearlite paralell to the heat flow direction was produced. However, at higher velocities, a “zigzag” or “herringbone” structure was produced. The relationship between translation velocity (R) and interlamellar spacing (λ) was determined. At low velocities a growth law of Rλ3.7=const. existed. As the growth velocity increased, the exponent in the growth law continuously changed from 3.7 to 1.2. The change in R-λ relationship over a wide velocity range was consistent with the theoretical analysis by Carpay.
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  • Yoshinori Wakamatsu, Kotaro Samura, Masami Onishi
    1977 Volume 41 Issue 7 Pages 664-669
    Published: 1977
    Released: April 04, 2008
    JOURNALS FREE ACCESS
    The diffusion couples consisting of δ1 specimens with an equilibrium concentration on the zinc-rich side and electrodeposited iron were annealed in the temperature range of 468 to 525°C. In the diffusion zone, δ1, Γ1 and Γ phases appeared, while α solid solution of zinc in iron could not be detected in any couple examined. The δ1 phase is composed of two layers with different microstructures; the same structure layer as the palisade δ1 in hot dip galvanizing and the same granular structure layer as the δ1 couple half in this experiment. The Kirkendall markers exist at the interface between the two δ1 phase layers, where the intrinsic diffusion coefficient of zinc is far greater than that of iron. This probably means that the granular δ1 phase layer is formed as a result of the one-sided diffusion of zinc atoms from the δ1 couple half and the palisade δ1 phase layer is formed by the reaction of zinc atoms with iron atoms in the iron couple half.
    The interdiffusion coefficient of δ1 phase reaches a minimum value in the concentration range of 10.5 to 12.5 at%Fe where the concentration gradient in the penetration curve is very steep. The concentration gap between the compact and palisade δ1 phase layers formed in the hot dip galvanizing process ranges from 10 to 12 at%Fe, which approximately corresponds to the range of the steep concentration gradient mentioned above. The steep gradient has so far been presumably misunderstood as the concentration gap.
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  • Shinji Tsuji
    1977 Volume 41 Issue 7 Pages 670-678
    Published: 1977
    Released: April 04, 2008
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    A numerical method has been developed for exactly solving the equations describing binary multi-phase interdiffusion. The layer growth rate constants of the intermediate phases, formed in Cu-Zn and Fe-Ti couples for example, were numerically calculated from the interdiffusion coefficients, phase boundary compositions and partial molal volumes given in the literature. The resulting rate constants are in good agreement with literature values, in spite of some uncertainty of the numerical values for the calculation.
    No numerical solution satisfying the diffusion equations and the requirement that the growth rates of all the intermediate phases are positive, could be found in the case of an Fe-Ti couple. This result is essentially consistent with the experimental results by other investigators that all of the three intermediate phases predicted from the equilibrium diagram do not appear in the diffusion zone of Fe-Ti couples.
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  • Shinji Tsuji
    1977 Volume 41 Issue 7 Pages 678-685
    Published: 1977
    Released: April 04, 2008
    JOURNALS FREE ACCESS
    Two types of binary diffusion couples, γFe-βTi and αFe-βTi, were prepared and the layer growth of intermediate phases formed in these couples was examined at 1000°C. The layer growth rate constants of intermediate phases in diffusion couples of the Fe-Ti and Cu-Zn systems were numerically calculated by the previous method from data where one of the principal limiting factors, i.e., the diffusion coefficient, the concentration range of the solibility area and the adjoining two-phase area of a given phase, was changed into an arbitrarily assumed value.
    The results obtained experimentally and numerically have made it clear that the layer width of any intermediate phase formed in a couple is greater as the compositions of the two alloys, the constituents of the couple, are brought closer to that of the intermediate phase.
    The effect of the above limiting factors in an intermediate phase on the layer growth rate constants of its phase and the other phases formed in a couple have been disclosed by the numerical calculation. A simple approximate expression for the layer growth rate of any intermediate phase formed in a couple has been given by the interdiffusion coefficients and the solubility ranges of all the phases in the couple. The distinctive features have been discussed for the exceptional phase in a couple where its layer growth rate shows an abnormal deviation from this expression.
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  • Yoshiro Kayahara, Katsutoshi Ono, Toshio Oishi, Joichiro Moriyama
    1977 Volume 41 Issue 7 Pages 686-690
    Published: 1977
    Released: April 04, 2008
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    Using the cell, Pt/Ni, NiO/ZrO2(+CaO)/Cu-Ni-O or Cu-Ni-O, NiO/Cr-cermet, Pt, the activities of unsaturated oxygen in the liquid Cu-3.5 wt%Ni alloy and the activities of oxygen and nickel in the liquid Cu-Ni alloys in equilibrium with NiO were measured in the temperature range 1200 to 1350°C. The samples were taken at 1300°C and analyzed for oxygen and nickel contents. The activities of oxygen in the liquid Cu-3.5 wt%Ni alloy followed Henry’s law and its activity coefficient was found to be 0.21. The activities of copper were evaluated by the Gibbs-Duhem integration at 1300°C. The activities of nickel and copper deviated positively from ideality. The solubility of oxygen in the liquid Cu-Ni alloys at 1300°C decreased rapidly with increasing nickel to about 0.1 mol nickel and then became nearly constant. The liquidus curve of the Cu-Ni diagram was obtained from the flection point on the emf-temperature curves. The valve of εONi at 1300°C evaluated by extraporation was −7.2.
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  • Hiroshi Kato, Takateru Umeda, Kazuyuki Hamachi
    1977 Volume 41 Issue 7 Pages 691-696
    Published: 1977
    Released: April 04, 2008
    JOURNALS FREE ACCESS
    The influence of solidification conditions on the secondary arm spacing (λs), the angle (θ) between the primary and the secondary arms and the initial position (λ0) of the branching of the secondary arms from a primary arm was investigated by quenching the unidirectionally solidifying Al-4.8 wt%Cu alloys. The spacing λs was approximately represented by the relation λs=const.×(the time spent from the passage of the solid-liquid interface prior to quench)n, and the constant n was approximately 1/3 in the range of experimental conditions used in the present work. The secondary arms initiated at an acute angle to the growth direction of the primary arms, and the variation of the angle θ may be an important factor for the coarsening process of the secondary arms. The initial position λ0 was the same order as the radius of curvature at the dendrite tip.
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  • Yoshiaki Shida, Kunihiko Yoshikawa, Taishi Moroishi
    1977 Volume 41 Issue 7 Pages 697-705
    Published: 1977
    Released: April 04, 2008
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    2\frac14Cr-1Mo steel is highly promising for construction materials of the LMFBR secondary system. The effect of carbides on the decarburization rate of 2\frac14Cr-1Mo steel in high-temperature sodium was studied.
    The effect was investigated by immersing specimens with different metallurgical structures and various kinds of carbides in static liquid sodium at temperatures from 550 to 700°C. The changes of carbides in the composition, phase and morphology were examined by the X-ray diffraction method, chemical analysis of carbides, electronmicroscopic observation by extraction replica and the electron diffraction method.
    The following results were obtained.
    (1) Decarburization rate of 2\frac14Cr-1Mo steel in sodium can be related to phase, morphology, transformation rate and the coagulation process of carbide precipitates. Carbides dissolve in the order of M3C>lamellar M23C6>granular M7C3\simeqgranular M23C6\simeqM2C>M6C.
    (2) Carbides dissolve so as to spheroidize themselves. Diffusion of Cr and Mo from carbide to the matrix seems to control the dissolution rate of comparatively stable carbide.
    (3) Carbides should be stabilized in order to minimize the rate of decarburization. It is most appropriate to make M6C a dominant carbide phase in steel.
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  • Hisashi Suzuki, Koji Hayashi, Wan Jae Lee
    1977 Volume 41 Issue 7 Pages 706-710
    Published: 1977
    Released: April 04, 2008
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    The relation between bending stress (σ) and rupture time (tr) in WC-10%Co alloy was investigated in the temperature range of 400∼900°C under the condition that tr was less than 2 h, and the ratio of σ to transverse-rupture strength was 0.4∼0.95. The tests were carried out in argon. The WC-10%Co high carbon two-phase alloy with a carbide grain size of 1.2 μm was vacuum-sintered at 1400°C for 1 h and used as specimens.
    The results obtained were as follows: (1) The values of tr showed large scatter at low temperatures below 600°C; no such scatter was observed at high temperatures above 700°C. As a whole, a linear relation held between σ and logtr at each temperature, i.e., logtr decreased linearly with increasing σ and the slope decreased with rising temperature. (2) The creep rupture occurred through the following processes: (i) after a certain time of loading, microcracks formed mainly along the WC/WC or WC/binder interface; (ii) these microcracks connected with each other and the interconnected crack grew stably, absorbing microcracks formed ahead of the interconnected crack; and (iii) the stable crack led to rupturing of the specimen, when its length reached a critical value which is a function of temperature and σ. (3) The scattering of tr at lower temperatures was considered to be due to the fact that the stable crack often formed around microstructural defects and the time needed for the crack extension towards the critical one varied with the defect dimensions.
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  • Yoshio Hasegawa, Shinsaku Hanasaki, Masanori Yasutomi, Kenji Kinoshita
    1977 Volume 41 Issue 7 Pages 711-717
    Published: 1977
    Released: April 04, 2008
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    This paper describes the cutting mechanism of directionally solidified Ag-Cu eutectic alloy. The eutectic alloy has two prefered orientations, i.e. (113)[1\bar10] and (111)[1\bar10]. {113} and {111} planes are parallel with the side plane of the workpiece and a ⟨110⟩ axis is parallel with the direction of solidification. The experiment is conducted under orthogonal cutting. The inside of chip and the shear zone which are considered approximataly to be the plane-strain condition are observed by optical microscope and SEM, and also the relation between the texture and the cutting mechanism is investigated.
    The main results obtained are as follows.
    (1) In applying the tool rake angle of 40 deg., the cutting process is stable and a continuous ribon-like chip is formed. However, the shear angle shows the periodic change slightly. Consequently the streamline makes chevron-type markings and the free surface of chip is uneven.
    (2) In applying the tool rake angle of 30 deg., chevrons of streamlines become acute. In this case the cutting mechanism transforms from the shear plane to the shear zone model. Reducing the tool rake angle to 20 or 10 deg., shear deformation becomes discontinuous and the cutting mechanism tends to become the shear type model.
    (3) In cutting the workpiece having the texture with the rake angle of 40 deg., the cutting process is stable, and there is good agreement between the observed shear angle and the estimated one based on the assumption that shear deformation occurs in the slip system {111}⟨110⟩.
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  • Keikichi Nakamura
    1977 Volume 41 Issue 7 Pages 717-723
    Published: 1977
    Released: April 04, 2008
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    The deuteron magnetic resonance of tantalum deuterides exhibits the spectra of unexpectedly large asymmetry parameter, which suggests the presence of atomic displacements of tantalum. The asymmetry parameter is maximum at a stoichiometric composition, Ta2D, and decreases asymptotically as x in Ta2D1+x increases. This implies that the difference in the deuterium population between 2a(\frac14, \frac14, \frac14) and 2d(\frac34, \frac14, \frac14) interstices, which is the origin of the atomic displacements, becomes smaller. The relation between the atomic displacement, Δ, and asymmetry parameter, η, is calculated by using a simple electrostatic model and under a condition that deuterium atoms jump rapidly between 2a and 2d positions. Comparision of the calculated and the observed concentration dependency of η shows that the β type hydride, in which 1 deuterium is in 2a and x deuterium in 2d, is stable at least up to x=0.6.
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  • Keikichi Nakamura
    1977 Volume 41 Issue 7 Pages 723-729
    Published: 1977
    Released: April 04, 2008
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    First, the free energy of Ta2D1+x is represented as a function of the long-range order parameter z. z=1 corresponds to the β type deuteride based on the Ta2D superstructure; z=0 represents the δ type deuteride which is a nonstoichiometric form of the TaD superstructure. At the composition of Ta2D1+x, z and temperature are shown to have the following relationship:
    (This article is not displayable. Please see full text pdf.)
    \ oindentTc0 represents the β→δ phase transition temperature at x=0. Analysis of the above equation shows that Tcx decreases according to Tc0(1−x2). At x=0.6, Tcx calculated from the observed Cp data by Asano et al. is very close to room temperature, which is consistent with the observed β⁄δ phase boundary of the Ta-D phase diagram.
    Secondly, Khachaturyan’s method of static concentration, waves and the theory of stress-induced interaction are discussed in relation to our treatment for the β−δ tantalum deuteride system. The following points are presented: (1) In the completely disordered state where n(p, R)=\barn, the partial molar configurational entropy in the Khachaturyan’s theory has the form, −K[ln\barn⁄(1−\barn)]. This, however, contradicts the generally supported blocking models, and is not consistent with the observed entropy in the α phase. (2) In Khachaturyan’s method, the relation, n(3, R)=n(\bar3, R), always holds, whereas n(3, R)\leavevmode\hboxto0pt=\llap\n(\bar3, R) in the actual Ta2D1+x superstructure. (3) The internal energy of β type Ta2D calculated by the Khachaturyan’s theory is in good agreement with that derived from the observed Cp data and the β⁄δ phase boundary.
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  • Tsuyoshi Masumoto, Akihisa Inoue, Hisamichi Kimura
    1977 Volume 41 Issue 7 Pages 730-737
    Published: 1977
    Released: April 04, 2008
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    Structural changes during heating or aging in a wide temperature range were examined with three amorphous alloys of Fe78Si10B12, Ni75Si8B17 and Co75Si15B10 by measurements of electrical resistance, differential scanning calorie and Vickers hardness and also by transmission electron microscopy and X-ray diffraction.
    The results obtained are summarized as follows:
    (1) The crystallization process of three amorphous alloys is divided into four stages: (a) the incipient stage of crystallization where a certain short range ordering of atoms occurs, (b) the formation of primary metastable phases (MS-I), (c) the formation of secondary metastable phase (MS-II) with complex single structures, and (d) the formation of a stable phase consisting of a mixture of each equilibrium phase. The MS-I phase appears in the amorphous matrix in a manner of homogeneous nucleation and gradual growth, while the MS-II phase grows rapidly from a few nuclei and completely spreads over the amorphous matrix containing the MS-I phases. At higher temperatures, these MS-II phases transform finally to stable phases.
    (2) The temperature-time-transformation diagrams of three alloys were constructed. In these diagrams, distinct differences in the transformation sequence and the mode are observable in the upper and lower ranges of the critical temperature (Tx′). Above this boundary, crystallization by way of nucleation and growth proceeds through two metastable phases and finally to a stable phase. Below that temperature, on the other hand, progressive aging gradually changes the amorphous structure to the assembly of fine grains (about 100∼200Å) with a simple structure such as bcc, fcc, or hcp.
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  • Yasunori Tanji, Hiroshi Moriya, Yasuaki Nakagawa
    1977 Volume 41 Issue 7 Pages 737-741
    Published: 1977
    Released: April 04, 2008
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    Flexural resonance frequencies of a composite vibrator may approximately be calculated by a simple assumption that the flexural rigidity of the composite vibrator is given by a sum of the flexural rigidities of the components. This can be applied to the measurement of Young’s modulus of a thin plate or a thin film, which cannot be tested by the flexural resonance technique unless pasted or deposited on a thicker substrate. Some experiments are made to justify the above assumption. In general, the effect of a layer of paste is found to be appreciable. Even if the flexural rigidity of the paste is negligibly small, the spacing due to the paste causes appreciable changes in the fluxural rigidities of the specimen plate and the substrate. As an example, Young’s modulus of a nickel plate 40 μm in thickness is determined by the composite vibrator method with an error of less than 3%.
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  • Tatsuhiko Ejima, Tsutomu Yamamura, Hiroshi Hisamoto
    1977 Volume 41 Issue 7 Pages 742-749
    Published: 1977
    Released: April 04, 2008
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    The diffusion coefficients of alkali metal ions in molten CsCl, KCl and NaCl were determined using the capillary reservoir method from the melting points of the solvent salts to temperature 200°C higher than them. The results obtained are summarized as follows:
    (1) In the same solvent, the diffusion coefficient decreases with increasing cationic radius of the solute except lithium ion. On the other hand, the diffusion coefficient decreases as the cationic radius of the solvent increases. The difference among the diffusion coefficients of solute cations becomes more pronounced when the cationic radius of the solvent is smaller.
    (2) There was a close correlation between the apparent activation energy for solute diffusion and the heat of mixing of solute and solvent salts at infinite dilution. There was also a close correlation between the apparent activation energy and the size parameter [(α1−λ2)⁄λ1λ2]2 of solute and solvent cations.
    (3) For the solvents with a smaller cationic size, the apparent activation energy for solute diffusion is mainly affected by the energy required for the formation of a hole large enough for diffusive displacement at the position adjacent to the cation. In the case of molten salt containing holes of a larger mean size than the size of diffusing solute cation, however, the apparent activation energy is affected both by the hole formation energy and by the short ranged interaction energy such as the polarization energy of anion.
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