Journal of the Japan Institute of Metals and Materials
Online ISSN : 1880-6880
Print ISSN : 0021-4876
ISSN-L : 0021-4876
Volume 45 , Issue 6
Showing 1-17 articles out of 17 articles from the selected issue
  • Koichiro Inomata
    1981 Volume 45 Issue 6 Pages 547-550
    Published: 1981
    Released: April 04, 2008
    JOURNALS FREE ACCESS
    Through a NMR investigation, M substitution for Co in Y2(Co1−xMx)17 (M=Cu, Al) is pointed out to occur at random in M=Cu and with a site preference in M=Al. Al is found mainly to prefer a 6c dumb-bell site. Consequently, it is shown that the different magnetic anisotropy behaviour between Y2(Co1−xCux)17 and Y2(Co1−xAlx)17 arises from the difference in site preference between Cu and Al for Co.
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  • Yasuhiro Watanabe, Yuichiro Murakami, Sukeji Kachi
    1981 Volume 45 Issue 6 Pages 551-558
    Published: 1981
    Released: April 04, 2008
    JOURNALS FREE ACCESS
    Phase changes in Ni75−xCuxSn25 and Ni75−xMnxSn25 alloys were studied by X-ray diffraction, differential thermal analysis and optical microscopy. Four kinds of structures, i.e. DO19-type hexagonal (βm phase), β-Cu3Ti(2H)-type orthorhombic (γ1′ phase), DO3-type cubic (β1 phase) and Heusler (L21)-type cubic (β3 phase), were observed. Martensitic and massive transformations and ferromagnetism were observed. The results are summarized as follows:
    (1) In Ni-Cu-Sn alloy, βm, γ1′ and β1 phases appear successively with increase in Cu content at room temperature. In Ni-Mn-Sn alloy, βm, β1, β3 and β1 phases appear successively with increase in Mn content at room temperature.
    (2) The high temperature β1 phase undergoes a martensitic transformation to the 2H structure during quenching and a massive transformation to the DO19 structure during slow cooling in a region of Cu(or Mn) content below about 6.5 at% in both alloys. In Ni-Cu-Sn alloy, martensitic transformation is observed in the region of less than 19 at%Cu.
    (3) The β1 phase undergoes a martensitic transformation in the range of electron concentration (ea*) from about 10.7 to 11.2 in these alloys (ea* represents the average number of d+s+p electrons in the outer shell of an atom).
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  • Koji Tanoue, Hidehiko Matsuda
    1981 Volume 45 Issue 6 Pages 559-565
    Published: 1981
    Released: April 04, 2008
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    The activation volume V* and the dislocation velocity-stress exponent m* were obtained by stress relaxation tests at low temperatures in sintered pure molybdenum. The effect of grain size (30∼1500 μm) on these parameters was investigated over the temperature range of 300 to 500 K. The values of V* and m* remained constant independent of grain size at temperatures below 400 K within the experimental error. It is concluded, therefore, that the effective stress σ*(=2kBTm*V*) calculated using the parameters does not vary with grain size.
    Subsequently, the grain size dependence of the yield and flow stresses was discussed in relation to the internal stress σi and could be explained by the change in σi due to the grain size at low plastic strains. Namely, the Hall-Petch relationship which holds up to about 1% plastic strain can be expressed by the Ashby type equation of σi∝ε1⁄2d−1⁄2, which is not applicable above that strain.
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  • Koji Tanoue, Osamu Nakano, Hidehiko Matsuda
    1981 Volume 45 Issue 6 Pages 566-574
    Published: 1981
    Released: April 04, 2008
    JOURNALS FREE ACCESS
    It is experimentally ascertained that any stress relaxation curve, obtained from stress relaxation tests by a monotonic loading mode and plotted as logσ vs log\dotε, can be translated (scaled) in a particular direction so that it will coincide with the overlapping segment of any other stress relaxation curve, and that a linear relationship holds for scaling. The effects of (1) cyclic loading, (2) imposed strain rates, (3) impurities and (4) grain sizes as various factors on the shape of stress relaxation curves and the scaling parameter, m{=(δln\dotε⁄δlnσ)λ} obtained as a reciprocal of the slope on scaling are investigated. Any stress relaxation curve is concave upward and the linear relationship holds for scaling with the exception of fatigue tests and single crystals. The measured values of m depend on impurities and temperature, but are independent of the other factors. Then, the physical meaning of the scaling locus is discussed referring to the seexperimental results. It is shown that the locus of translation can be attributed to the relation between the pre-exponential term \dotε0 and the maximum internal stress σi0, and that the mechanical equation of state, f{\dotε,σ,(\dotε0i0),T}=0 holds for the arbitrary value of (\dotε,σ,T) under the present conditions of measurements, provided the scaling is possible.
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  • Hiroshi Fukutomi, Ryo Horiuchi
    1981 Volume 45 Issue 6 Pages 574-580
    Published: 1981
    Released: April 04, 2008
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    Stress induced migration behavior of three types of tilt boundaries which are described as vertical arrays of a⁄2[1\bar10](001) a⁄2[11\bar2](111), and a[001](010) dislocations for [110], [1\bar10], and [100] tilt boundaries respectively, was investigated by the use of aluminum bicrystals. These three types of boundaries whose misorientation angles were smaller than 10° migrated under the stress and produced plastic strain at elevated temperatures. The migration velocity (v) varied with stress (σ) and temperature (T) according to the following equation:
    (This article is not displayable. Please see full text pdf.)
    \ oindentwhere A(θ,ξ) is a numerical factor depending on the misorientation angle (θ) and type of grain boundary (ξ), n\fallingdotseq1 and Q=80±5 kJ/mol.
    Grain boundary sliding occurred at misorientations larger than 10°.
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  • Rokuro Nishimura, Kiyokatsu Kudo, Norio Sato
    1981 Volume 45 Issue 6 Pages 581-587
    Published: 1981
    Released: April 04, 2008
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    The passive films formed on iron in neutral, alkaline phosphate and alkaline borate solutions were investigated by using electrochemical and ellipsometric techniques. Chemical analyses of iron ion dissolved from the film and ellipsometric measurements of δPA curve during galvanostatic cathodic film reduction have shown that the passive films formed in these solutions consist of a deposit layer next to the solution and a barrier layer in contact with the metal. The oxidation state of iron ion in the deposit layer is in the iron (III) state and is scarcely affected by pH and anions in the solution. The barrier layer composition, however, depends on pH and anion species. In borate solutions, the barrier layer composition changes from ferric oxide (pH 8.42) to magnetite-like oxide (pH 11.50) with increase of solution pH. On the other hand, its composition in phosphate solutions contains iron (II) ions giving rise to the mean oxidation valency, ZFe=2.33 in the pH range of 8.42 to 12.60. It has been found that depletion or enrichment of iron ions occurs at the deposit/barrier layers interface in borate solutions of pH 8.42 and 11.50 with the degree of depletion or enrichment being dependent on pH. No iron depletion or enrichment, however, is found in the passive films formed in phosphate solutions. The results are explained in terms of the ion permselective property of the passive films formed in phosphate and borate solutions.
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  • Risaburo Yoshida, Keisuke Kaiho, Usaku Ide
    1981 Volume 45 Issue 6 Pages 588-592
    Published: 1981
    Released: April 04, 2008
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    In order to produce iron carbide industrially, heat decomposed products of prussian blue were investigated by means of X-ray diffraction and chemical analysis.
    The decomposition was performed at 973∼1173 K under the three kinds of atomsphere of nitrogen, carbon dioxide and their mixture in the experimental apparatus. Fe3C could be produced by the decomposition of the industrial grade of prussian blue in N2 atmosphere at higher temperature. The yield of Fe3C increased with increasing temperature, especially above 1073 K duration of the decomposition.
    The lattice constans of Fe3C formed at 1073 K for 1.8 ks decomposition were a=0.45211 nm, b=0.50902 nm, c=0.67439 nm.
    Prussian blue decomposed to Fe3C or mixture of Fe3C, Fe and FeO in CO2 atmosphere.
    The composition of the products chiefly depended on the decomposing conditions and the flow rate of CO2.
    Cabon dioxide in the mixed atmosphere had less influence on the oxidation to prussian blue than that of the oxidation in CO2.
    This fact is caused by the lower partial pressure of CO2 in the mixed atmosphere than that in CO2.
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  • Kyoko Wasai, Kusuhiro Mukai
    1981 Volume 45 Issue 6 Pages 593-602
    Published: 1981
    Released: April 04, 2008
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    Activities, enthalpies of mixing and the other thermodynamic properties for different binary liquid alloys were calculated from the ideal associated solution model, assuming the formation of several species of associated compounds whose stoichiometric compositions correspond for the most part to those of the intermetallic compounds or intermediate phases in the solid state. The calculated results were in good agreement with the values of Hultgren et al. for the following typical A-B binary systems; (1) three systems (Sb-Sn, Mg-Pb, Bi-Mg) with only one compound in the solid state (AB, A2B, A2B3 respectively), (2) the Ag-In system in which the activity curve of In shows the change of deviation from negative to positive from Raoult’s law, (3) the Au-Cu, Cd-Hg, and Al-Au systems with several species of compounds in the solid state.
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  • Seiichi Iwata, Akitoshi Ishizaka, Hiroshi Yamamoto
    1981 Volume 45 Issue 6 Pages 603-609
    Published: 1981
    Released: April 04, 2008
    JOURNALS FREE ACCESS
    This study is concerned with the influence of Al surface condition on the thermocompression bondability of Au wires to Al electrode on IC’s. Au wires were connected to Al electrodes on IC’s by “nail-head bonding” after various Al surface treatments. The bondability was evaluated by measuring the wire pull strength and the fraction P of the number of failures at Au-Al bonds to the total number of failures. The dependence of P on applied load W was derived theoretically with a parameter named “critical load W0” to take into consideration the difference in Al surface conditions as follows:
    (This article is not displayable. Please see full text pdf.)
    \ oindentwhere K and E2 are constants. This relationship was also found to hold experimentally with different values of W0 for various surface treatments. The characterization of Al surface was carried out by using ESCA. W0 was found to depend on the intensity ratio of the metal Al to the oxidized Al peak, this ratio being determined mainly by the Al oxide film thickness.
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  • Atsushi Nishikata, Hiroh Numata, Shiro Haruyama
    1981 Volume 45 Issue 6 Pages 610-613
    Published: 1981
    Released: April 04, 2008
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    The spontaneous passivation behaviour of nickel and its alloys has been investigated in molten NaNO3-KNO3 eutectic at 533 K by using potentiostatic polarization and polarization resistance methods. The corrosion potentials of nickel and its alloys in the molten salt changed gradually toward a more positive value and finally reached passivation potentials. The corrosion rates of nickel and its alloys estimated from polarization resistance method were less than 10−2 A/m2 and decreased with time in accordance with parabolic rate law. It was confirmed by atomic absorption method that nickel ions did not dissolved in the melt. Therefore, it is likely that the corrosion rate estimated by polarization resistance corresponds to the growth rate of oxide film. In the presence of chloride ions, howevere, the passive film was locally destroyed and the corrosion potential shifted to noble direction, accompanied by the increase in corrosion rate.
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  • Kazuo Kameda, Yoshio Yoshida, Senzi Sakairi
    1981 Volume 45 Issue 6 Pages 614-620
    Published: 1981
    Released: April 04, 2008
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    The E.M.F. of the galvanic cells involving zirconia solid and fused salt electrolytes have been measured in order to obtain the standard free energy of formation of In2O3 in the temperature range 835 to 1272 K and the thermodynamic data of the liquid Ag-In system, for NIn=0.20∼0.85 and NIn=0.25∼0.85, in the temperature ranges 925 to 1296 K and 975 to 1223 K, respectively.
    The standard free energy of formation of In2O3 was determined as the following equation:
    (This article is not displayable. Please see full text pdf.)
    Activities of indium show both positive and negative deviations from Raoult’s law, depend on the concentration of indium and they agree well with the data measured by Mycielska et al. and the others but differ from that of Nozaki et al. Activities of silver exhibit negative deviations from Raoult’s law over the whole concentration range.
    The properties of liquid alloys composed of IB (Cu, Ag, Au, noble metals) and indium have been investigated from the standpoint of the alloy solution theory of Engle.
    It is shown phenomenologically that the activities and ξ functions in liquid IB metals-indium alloys are better accounted for if the filling of the d shell is placed between IB metals and indium leaving copper, silver and gold as transition metals.
    The activities of liquid Cu-In and Ag-In alloys are quite different from those of the liquid Au-In system, in which activities show considerably negative deviations in the whole concentration range, owing to the larger electronegativity factor in the gold alloys.
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  • Minoru Otaguchi, Atsushi Oguchi
    1981 Volume 45 Issue 6 Pages 620-623
    Published: 1981
    Released: April 04, 2008
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    Investigations of the α-σ isothermal transformation of an Fe-Cr alloy containing about 45 at%Cr were carried out at various hydrostatic pressures up to 900 MPa, and the rate of the transformation and the behaviour of crack formation in σ-phase were examined. The rate of the transformation was accelerated under high hydrostatic pressures and was suggested not to be controlled by diffusion. The time necessary to obtain a given amount of the σ phase at 900 MPa was 1/2 to 1/1.5 times shorter than that at atmospheric pressure. The formation of the crack in the σ phase was inclined to be suppressed under high hydrostatic pressures. A good number of specimens made of the σ phase having few cracks were obtained at 900 MPa. Elastic constants measured with such σ phase specimens are as follows: Young’s modulus=209 GPa, shear modulus=79.8 GPa, bulk modulus=186 GPa and Poisson’s ratio=0.31.
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  • Masahiro Sakai, Katsuya Watanabe
    1981 Volume 45 Issue 6 Pages 624-630
    Published: 1981
    Released: April 04, 2008
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    Monofilament composites were prepared by coating Ni on the commercial SiC fibers obtained from the precursor of polycarbosilane. The compatibility between Ni and SiC was studied by SEM observations on the cross sections of the composites.
    Peculiar structures which were produced by the reaction between Ni and the fiber were observed. The temperature at which the reaction initiates extended from 873 K to 1273 K depending on the pre-treatment of the fibers and the methods of Ni coating. The reaction was suppressed to some extent by heating the fibers in the air prior to the Ni coating. The results obtained could be explained in terms of the oxide layer on the surface of the fiber.
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  • Hakaru Masumoto, Showhachi Sawaya, Masakatsu Hinai
    1981 Volume 45 Issue 6 Pages 631-636
    Published: 1981
    Released: April 04, 2008
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    The relations of internal friction Q−1 with coercive force Hc, hysteresis loss Wh and magnetostriction λ for Fe-Mo alloys were studied by varying the heating temperature and cooling rate. Measurement of Q−1 was carried out by the inverted torsion pendulum method at a maximum shear strain amplitude of 1∼270×10−6 at a frequency of about 1 Hz. Both Hc and Wh were measured using the automatic recording fluxmeter, and λ by the optical roller method.
    The Q−1 value of Fe-Mo alloys became higher with increasing heating temperature. For the alloys with 0∼2%Mo, the Q−1 value was generally low, and in the furnace-cooled state Q−1 was higher than that in the rapidly cooled state. By contrast, for the alloys with 4∼8%Mo, Q−1 was generally high and showed a slight variation with cooling rate. Among the alloys the Fe-6%Mo alloy showed a maximum value of Q−1. For the alloys with 10∼16%Mo, Q−1 became higher by rapid cooling from high temperatures, suggesting that the precipitation of the non-ferromagnetic β phase in the matrix of ferromagnetic α phase was substantially reduced by quenching.
    The Hc value of the alloys with high Q−1 value was as small as about 0.05 kA/m, and consequently the magnetic rearrangement was readily caused by a small amplitude of strain when the vibrational stress applied. The Q−1 values of all the Fe-Mo alloys decrease with increasing magnetic field H. Further, the values of dWhdH and dλ⁄dH, which are the slopes of the lines which connect the origin and each point on the Wh and λ vs Hc urves respectively, increase gradually with H, and then decrease after attaining the maxima. The strength of H for the most remarkable decrease in Q−1 with H is almost consistent with those for the maximum values of dWhdH and dλ⁄dH. These gradients in weak magnetic fields are in proportion to the values of Q−1. The results indicate that the high damping capacity of Fe-Mo alloys is due largely to irreversible magnetization, and then is casued by the resultant large magnetic energy loss per cycle when the small vibrational energy applied.
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  • Naotake Niwa
    1981 Volume 45 Issue 6 Pages 636-641
    Published: 1981
    Released: April 04, 2008
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    The present study deals with the effect of prestrain on strain and stress paths to fracture in the ductile fracture processes of tough-pitch copper, copper-chromium alloy, vacuum melted copper and pure aluminum round bar specimens pulled in tension. The neck shape change with development of necking was examined through measurements of the radius and curvature ratio of the neck contour. In addition the true flow stress in the neck was presumed by using the correction factor proposed by Davidenkov et al..
    Differences in fracture strain resulting from prestrain were almost invariably due to those in strain up to maximum load for each material. The post-instability strain to fracture was almost the same for each material and independent of prestrain. The prestrain had little effect on the change of neck shape with the development of necking. Although prestrain brought about slightly higher level of the apparent and true flow stresses at the same post-instability strain, it had little effect on a relative change of the both stresses (i.e., shape of stress-strain curve) with development of necking after the maximum load.
    Therefore, within the range of prestrain and materials used in this study, the post-instability strain to fracture was almost the same for each material but apparent and true flow stresses at fracture were slightly different and dependent on the prestrain.
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  • Hajime Suto, Zhong da Yin
    1981 Volume 45 Issue 6 Pages 641-647
    Published: 1981
    Released: April 04, 2008
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    In order to obtain 3.5 GPa grade maraging steels, the chemical composition and the effect of thermo-mechanical treatments (TMT) including cold rolling have been investigated. From age-hardening experiments of various Mo-Co-Ni-Fe alloys, 14%Mo-(18 and 20)%Co-6%Ni alloys having superior hardness were selected. Tensile tests of these alloys bearing Ti and Al subjected to various TMT were carried out and the results were discussed observing the microstructures. Finally the materials having the hardness higher than Hv 950 (max. Hv 965) and tensile strength higher than 3.5 GPa (max. 3.70 GPa) were obtained by performing double direct quenchings after hot rolling from 1350°C inserted solution treatment at 1000°C for grain refinement, with subsequent cold rolling and aging.
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  • Kojiro Kobayashi, Yasuji Seko, P. Hideo Shingu
    1981 Volume 45 Issue 6 Pages 647-651
    Published: 1981
    Released: April 04, 2008
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    Direct in situ microscopic observations of succinonitrile-6 mass% camphor during solidification show that the morphology of dendrite and its spacing are dependent on conditions of growth. The results are summarized as follows:
    (1) Secondary arm spacing, d(m), after the complete solidification is related to the growth rate, R(m·s−1), as
    (This article is not displayable. Please see full text pdf.)
    (2) Secondary arm spacing, d(m), in solid-liquid co-existing region coarsens during isothermal holding, t(s), according to the following relationship,
    (This article is not displayable. Please see full text pdf.)
    (3) Secondary arms migrate to the high temperature side during isothermal holding in a temperature gradient. The relationship between migration distance, X(m), and holding time, t(s), can be expressed by the following equation:
    (This article is not displayable. Please see full text pdf.)
    (4) An approximate value of the diffusion coefficient for camphor in succinonitrile-6 mass% camphor melts at liquidus temperature is 3×10−10 m2·s−1.
    (5) Secondary arms develop at an acute angle to the growth direction of primary arms and approaches to the right angle as solidification proceeds. Dendrite shape, including the change in the angle between primary and secondary arms, is found to be identical regardless of the crystal growth rate when the dendrite size is normarized with secondary arm spacing.
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