Journal of the Japan Institute of Metals and Materials
Online ISSN : 1880-6880
Print ISSN : 0021-4876
ISSN-L : 0021-4876
Volume 35 , Issue 8
Showing 1-16 articles out of 16 articles from the selected issue
  • Wataru Naruse, Masaharu Nojiri, Masafumi Tada
    1971 Volume 35 Issue 8 Pages 731-738
    Published: 1971
    Released: April 04, 2008
    Silicon nitride, Si3N4, has the two crystal phases, α and β, coexisting with different proportions depending on the nitridation conditions. The effect of nitridation condition on the formation of these two crystal phases and the differences of properties between them have been investigated.
    The results are summarized as follows:
    (1) The distribution of different crystal phases in a silicon nitride article obtained by nitridation of metalic silicon powder was such that α-Si3N4 was formed on the surface of the article and β-Si3N4 in the center of it. Also α-Si3N4 was formed in the initial stage of nitridation and β-Si3N4 in the later stage.
    (2) There existed a tendency that α-Si3N4 was formed at temperature below 1200°C and β-Si3N4 was formed over 1300°C. Further, the finer the granule and the lower the purity, the more α-Si3N4 was formed.
    (3) α-Si3N4 began to transform to β-Si3N4 at 1400°C by heating in nitrogen and transformed to β-Si3N4 completely at 1800°C.
    (4) The articles of α-Si3N4 powder and β-Si3N4 powder, which were pressed under the same conditions, were sintered in nitrogen at 1400°∼1800°C for 3 hr. Porosities and mechanical strength were measured in relation to sintering temperature and pressing pressure. The sintered articles of β-Si3N4 powder showed higher densities and lower porosities than those of α-Si3N4 powder. However, in mechanical strength no difference between them was observed.
    (5) Resistances to various gases of α-Si3N4 and β-Si3N4 at 1200°C have also been measured. β-Si3N4 was better in air, but α-Si3N4 was better in CO2,CO and NH3 gases. In vacuum α-Si3N4 was stable below 1300°C, and β-Si3N4 over 1400°C.
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  • Sennosuke Takahashi, Masataka Yoshioka
    1971 Volume 35 Issue 8 Pages 739-745
    Published: 1971
    Released: April 04, 2008
    The temperature dependencies of mechanical properties for dispersion strengthened Cu-Al2O3 alloys were investigated. The tension tests from liquid nitrogen temperature to 600°C, the creep tests in the temperature range of 400°∼600°C and the measurements of hardness were carried out on the Cu-Al2O3 alloys which were produced by mixing of powders, compacting, sintering and then extruding.
    The contribution of the difference in the thermal expansion and elastic constant owing to temperature dependencies to the strength of Cu-Al2O3 alloys was discussed.
    The activation energy of the steady-state creep at 450°∼600°C was calculated 52.1∼59.6 kcal/mol in consideration of the temperature dependencies of elastic modulus.
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  • Makoto Kassai, Masanori Okada, Tatsuji Sasaki, Zenzo Henmi
    1971 Volume 35 Issue 8 Pages 745-750
    Published: 1971
    Released: April 04, 2008
    The relationship between the crystalline texture and the magnetic anisotropy in the Co-12Fe-3Nb alloy cold-rolled by 96% reduction in area was investigated through the measurements of X-ray pole figures, hysteresis-loops, and magnetic torque curves. The results obtained are summarised as follows:
    (1) The magnetic anisotropy of this alloy is due to the magnetic crystal anisotropy (K1) and the induced magnetic anisotropy (Ku). The shape of hysteresis-loop depends on which anisotropy is prevailing; perminvar type for Ku>K1, constricted curve for Ku\fallingdotseqK1, and rectangular curve for Ku<K1.
    (2) In the cold-rolled and annealed states, the direction of major easy magnetization is along the transverse direction.
    (3) Upon annealing at temperatures above 700°C, the direction of hard magnetization changes to that of minor easy magnetization.
    (4) The cold-rolling texture of this alloy is the “brass type” one, that is, (110)[\={1}12]. This texture persists up to 900°C. The (111) peak intensity in the X-ray pole figure increases gradually as the annealing temperature rises. Consequently, the value of apparent crystal anisotropy constant increases gradually up to 750°C. When the annealing temperature is over 750°C, the apparent crystal anisotropy constant is −8.3×105 erg/cc.
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  • Katsutoshi Ono, Kiyoshi Yokogawa, Akio Yamaguchi, Joichiro Moriyama
    1971 Volume 35 Issue 8 Pages 750-756
    Published: 1971
    Released: April 04, 2008
    The isothermal sections of the iron-nickel-oxygen system at 757°, 900° and 1050°C were defined by determining the relationship between oxygen pressure, temperature and composition using thermogravimetry and X-ray techniques. The phase boundaries of the three-phase fields, wustite-alloy-spinel and spinel-nickel oxide-alloy were investigated in detail at 1050°C.
    Using available disorder model and oxygen pressure dependence of composition observed in this investigation, the disorder structures were discussed for nickel ferrite (NixFe3−xO4).
    The activity of iron in austenitic iron-nickel alloy was studied by means of the two-phase fields, ferrite-alloy and wustite-alloy. The solid solutions studied exhibit negative deviation from Raoult’s law nearly at the composition FeNi3.
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  • Katsutoshi Ono, Tadao Ueda, Tsuyoshi Ozaki, Yukitomi Ueda, Akio Yamagu ...
    1971 Volume 35 Issue 8 Pages 757-763
    Published: 1971
    Released: April 04, 2008
    The phase diagram of the Fe-Mn-O system was determined in the temperature range 800°∼1300°C and the range of oxygen partial pressure 10−18 atm≤PO2≤1 atm by means of thermogravimetry.
    The isobaric phase diagrams in air and helium and the isothermal section at 900°C were established for the Fe2O3-Mn2O3-Mn3O4-Fe3O4 system.
    For the Fe3O4-Mn3O4-Mn-Fe system, the equilibrium relationship between spinel and manganowustite, the phase boundaries of manganowustite and the isobars in the homogeneity range of FeO-MnO solid solution were determined by measuring the oxygen contents of the phases as a function of CO/CO2 ratio at 900°C. Moreover, the data obtained were used to derive activity-composition relations in FeO-MnO solid solution coexisting with Fe-Mn alloy.
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  • Kazuo Saito, Tokuzo Tsujimoto
    1971 Volume 35 Issue 8 Pages 764-769
    Published: 1971
    Released: April 04, 2008
    The change in resistivity during extension at 77°K was measured on a Cu-4%Ti alloy aged at 150°, 200°, 250°, 350° and 450°C. It was found that the resistivity of each aged specimen increased with straining at 77°K. The increment of resistivity for a strain of 5% became maximum for the specimen aged for a certain period of time at each temperature. The ageing time giving the maximum increase in resistivity of the specimen, tmax, tended to be shorter as the ageing temperature was raised. It was shown that the resistivity increase observed was due largely to the destruction of composition modulation or the modulated structure present in the aged specimen. It was suggested that the time tmax indicated a characteristic time ts at which the spinodal decomposition, i.e. the growth of amplitude of the composition modulation was over. The time tmax coincided well with ts which was determined from small-angle scattering experiments on this alloy. Based on Cahn’s spinodal theory, the dependence of ts on the ageing temperature T was found to be given by the relation:
    (This article is not displayable. Please see full text pdf.)
    where Ts was the coherent spinodal temperature and E the activation energy for the diffustion of Ti atoms in the alloy. Hence, with the observed values ts\simeqtmax, T and Ts\simeq350°C, we obtained E\simeq0.8 eV. The value of E thus obtained was reasonable for the diffusion of the solute atoms in the alloy during the early stages of ageing at relatively low temperatures.
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  • Masanobu Ohmori, Yoshitoyo Yoshinaga, Yoshihiko Sanemasu, Kazuya Sukeg ...
    1971 Volume 35 Issue 8 Pages 770-774
    Published: 1971
    Released: April 04, 2008
    Under hydrostatic pressures up to 3000 kg/cm2, the tension and torsion tests were performed at three different strain rates with a high purity cast zinc to examine the difference between the brittle-to-ductile transition pressures found in both tests.
    Main findings in the present study are summarized as follows:
    (1) A transition pressure found in the tension test was considerably higher than that in torsion at a given equivalent strain rate. As yet, however, any reasonable explanation has not been given to this observation. In addition, the transition pressures in both tests increased remarkably with strain rate.
    (2) Below the transition pressure, both tensile fracture stress and shear stress at fracture, each of which was measured under pressure, increased linearly with test pressure. The former stress was practically independent of strain rate, though the latter stress increased appreciably with the rate.
    (3) Although, above the transition pressure, a tensile flow stress was almost constant at a given strain rate even when the intensity of hydrostatic pressure was varied, the stress increased linearly with the logarithm of strain rate.
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  • Hidehiko Matsuda, Hironori Kuroki, Tetsuo Eguchi
    1971 Volume 35 Issue 8 Pages 774-780
    Published: 1971
    Released: April 04, 2008
    Kinetic behaviors of ordered Fe-Co and β CuZn alloys have been investigated with basic equations derived on the basis of the Bragg and Williams theory which is extended to a binary alloy with CsCl structure involving vacancies. It is then assumed that atom movements occur in two mechanisms, a direct interchange of atoms and an interchange through vacancies. The dependence of vacancy concentration upon long-range order is also considered to follow the method of Girifalco. Both of the mechanisms assumed here for the interchange of atoms play an important role in the ordering process. The interchange through vacancies is dominant particularly in the ordering process for β CuZn alloy. The numerical calculations have been carried out by using the appropriate values estimated from the data of diffusion and of other experiments. On heating of ordered Fe-Co alloys, the order parameters at room temperature are retained to about 500°C. Beyond 500°C they begin to vary rapidly with the maximum rate at about 550°C and finally reach their equilibrium values. This result is in agreement with the interpretation by Yokoyama, Takezawa and Higashida. On the other hand, the temperature dependence of the order parameter in the ordered β CuZn alloy exhibits only a negligible anomaly near room temperature.
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  • Kenji Takeoka, Dietrich Oelschlägel, Osamu Izumi
    1971 Volume 35 Issue 8 Pages 780-787
    Published: 1971
    Released: April 04, 2008
    The influence of 0.02% and 0.1%Mg on the superplastic properties of the quenched Zn-22 wt%Al eutectoid alloy was investigated between room temperature and 250°C. Even small amounts of Mg raise the flow stress markedly and reduce the elongation to fracture. In the 0.1Mg alloy the decomposition process after quenching does not produce the usual fine structure but large Al grains containing finely dispersed Zn particles. This material is brittle up to 100°C, but shows superplastic properties at higher temperatures. It is observed that at such elevated temperatures the initial coarse grains are replaced by a finer structure during deformation. In all alloys it is demonstrated that on superplastic straining an initial short region of strong work hardening exists. From structure changes during deformation it is concluded that an extensive grain boundary movement occurs and that this is an essential factor for superplastic deformation. These results can best be explained by the assumption that the superplastic phenomenon is due to the continuous production of strain free grains by grain boundary migration.
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  • Koji Yuasa, Yoshito Murata
    1971 Volume 35 Issue 8 Pages 788-794
    Published: 1971
    Released: April 04, 2008
    Carbon steels for mechanical structural use, S 43 C(0.40∼0.46%C), have been extruded in the temperature range from 300° to 900°C and at the reduction in area from 20 to 80% to investigate the effects of working temperature and reduction in area on the mechanical properties of the products and microstructures of the products.
    The results obtained were as follows:
    (1) In case of the as-rolled materials with the reduction of 65% in area, the toughness of the extruded products remarkably increased for the temperature rise from 500° to 700°C. But this phenomenon was not observed for the spheroidized materials. For fully annealed materials, the increase toughness was not so high as in the case of the as-rolled materials.
    (2) As the reduction in area became higher, the toughness of the products increased and the range of the working temperature where a high toughness could be obtained became wider.
    (3) The impact value depended largely on the reduction in area, but not so much on other mechanical properties.
    (4) When the materials were extruded at the reduction of 80% in area and at 300∼600°C, the strength-toughness of the products were almost equal to that of quenched-tempered materials.
    (5) When the structures of materials composed of ferrite and pearlite become fibrous like fiber-reinforced composite materials by means of extrusion, the toughness of the products seems to become higher. On the contrary, when the structures composed of ferrite and spheroidized cementite do not become fibrous by means of extrusion, the toughness of the products do not seem to become higher.
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  • Takao Kusakabe, Shosuke Imoto
    1971 Volume 35 Issue 8 Pages 795-800
    Published: 1971
    Released: April 04, 2008
    Th3N4 and Th2N2O were prepared, and their crystal structures and compositions were determined by X-ray diffraction patterns and chemical analysis.
    The main results obtained were as follows:
    (1) Th3N4 was prepared by heating Th metal powder at 1200°C in a nitrogen atmosphere of 1 mmHg∼1 atm. N/Th ratio of Th3N4 thus obtained was 1.28∼1.36.
    (2) X-ray diffraction powder pattern of Th3N4 showed a rhombohedral lattice structure with parameters of a0=9.405 Å and β=23.723°.
    (3) Hexagonal Th2N2O (a0=3.880 Å, c0=6.180 Å) was prepared by the reaction of 3Th+ThO2, 3ThN+ThO2 and Th3N4+ThO2 mixtures with 1 atm N2 at 1200°C.
    (4) According to X-ray lattice parameter data and the results of chemical analysis, the composition of the Th2N2O phase falls on a nearly stoichiometric range.
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  • Kôichi Arai, Toshio Izaki, Kouei Nakabayashi
    1971 Volume 35 Issue 8 Pages 801-807
    Published: 1971
    Released: April 04, 2008
    The electrochemical interaction of sulfide particles suspension of the cadmium sulfide-cupric sulfide system in dilute hydrochloric acid solutions are studied in order to obtain a data on acidic leaching. The test solutions used are dilute hydrochloric acid solutions containing sodium chloride with pH values 0.5∼2 and oxygen gas. The amounts of cadmium sulfide and cupric sulfide suspended in the solutions are 10−2∼10−1 M/L. The solutions are maintained at a constant temperature between 25° and 60°C, and stirred at 600 rpm.
    The experimental results obtained are as follows:
    (1) The dissolution reaction of cupric sulfide in the solution is of the S0 producing type. The reaction is small at first and increases with the lapse of time. The rate of dissolution is accelerated with increasing cupric sulfide suspended in the solution, elevating temperature, increasing chloride ion concentration and lowering pH values. The reaction is chemical reaction control.
    (2) The dissolution reaction of cadmium sulfide in the solution are a concurrent reaction of the S0 producing type and the hydrogen sulfide gas formation. The reaction is remarkable at the initial stage and then increases with the lapse of time. The dissolution concentration of cadmium ion is accelerated with increasing cadmium sulfide suspended in the solution, elevating temperature, lowering pH values and increasing concentration of chloride ion in the solution. The reaction is mass-transport control.
    (3) The dissolution of cadmium sulfide-cupric sulfide mixture ore is accelerated with elevating temperature, lowering pH values, and increasing concentration of cupric sulfide suspended and chloride ion in the solution. The acceleration of the S0 producing type reaction in the dissolution of the mixture ore is caused by the formation of galvanic couple of the CdS-CuS system.
    In this case, cadmium sulfide serves as the anode and cupric sulfide exists as the cathode for the reduction of aqueous oxygen in the solution.
    (4) Influences of effective factors on the galvanic reaction of the CdS-CuS system in the solution can be explained by the models of the local cell and the anodic-cathodic polarization diagram.
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  • Takayoshi Yoshimori, Shuiti Ishiwari, Yoshio Watanabe, Takashi Harada, ...
    1971 Volume 35 Issue 8 Pages 808-812
    Published: 1971
    Released: April 04, 2008
    Water absorbed on the surface of a sample was determined by the carrier gas extraction followed by the coulometric titration method (ref. 3, 4). The water was extracted from a heated sample into argon, and was transferred to NH3 with NaNH2. The NH3 was titrated with the electrolytically generated BrO ion.
    The absorbed water on the surfaces of steels differed depending on the roughness of the surfaces. The amounts of it on the filed and electropolished samples were 0.5∼0.7 μg/cm2 and 0.2∼0.3 μg/cm2 respectively. These results show that the disturbance of the surface water on the sample is almost negligible in the determination of hydrogen in steel. Fractional determination of the surface water and hydrogen in a stainless steel was also possible. The water was first determined by heating the sample at 100°∼120°C, hydrogen in the sample was extracted at 1100°C, and then determined after oxidation to water.
    Hydrogen in beryllium was extracted into argon by heating the sample at 1100°C and determined by the same method. A sample contained 4.8 ppm of hydrogen. The water evolved from the same metal was also determined, and a considerable amount of water (21∼23 ppm) was observed by heating the sample at 400° or 800°C.
    The water evolved from glasses by heating the sample at 300°C was determined by this method. A soft glass evolved 4∼7 μg/cm2 of water, and many hard glasses (Pyrex or others) evolved 0.2∼0.3 μg/cm2 of it. The water on the surface of quartz was only 0.05∼0.07 μg/cm2.
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  • Kunio Shiobara, Susumu Morioka
    1971 Volume 35 Issue 8 Pages 812-820
    Published: 1971
    Released: April 04, 2008
    In order to obtain a detailed knowledge of the mechanism of titanium crevice corrosion, investigations were made on the effect of temperature, the set potential, and the surface treatment of the specimens on the anodic behaviour of titanium in the crevice. In the anodic polarization measurement, the potential in the center of a crevice was measured together with the potential at the mouth of the crevice. In addition, X-ray diffraction, the measurement of changes in the anolyte pH, microscopic observation of the corroded specimen and the repolarization measurement were performed. The results obtained were summarized as follows.
    (1) Potential in the crevice was, at first, equal to that at the mouth of the crevice, but became progressively less noble as crevice corrosion proceeded. (2) Apparent activation energy obtained for the onset of the crevice corrosion was about 71.5 kcal/mol and that for the stationary crevice corrosion was about 5.1∼8.7 kcal/mol. (3) Corrosion product in the crevice was identified to be TiO2 (rutile) and Ti2O3. (4) In the stationary state of the crevice corrosion, the solution pH in the crevice was estimated less than about 0.7. (5) From the results mentioned above, it is considered that the crevice corrosion of titanium in hot concentrated chloride solution is of the pitting type in the initial stage and finally becomes of the active dissolution type as crevice corrosion proceeds to develop a lower pH value as a result of hydrolysis of corrosion product.
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  • Yoshikazu Matsumura, Yoshihiro Hisamatsu, Tuguyasu Yoshii
    1971 Volume 35 Issue 8 Pages 820-825
    Published: 1971
    Released: April 04, 2008
    Electrochemical study with a microelectrode of pitting corrosion of type 304 stainless steel in 1 N-H2SO4 containing 0.5 N-NaCl at 25°C has been carried out under a microscope.
    By using a microcapillary whose tip was 5 microns in outer diameter on a micromanipulator, the electrode potential distribution inside a single pit was measured. Potentials inside the shallow pit developed potentiostatically at 600 mV (SCE) are uniformly +450 mV and the protection potential of the pit was estimated as +250 mV from potentials outside and inside the pit.
    A single pit, which had grown potentiostatically to a predetermined size, was brought up by the galvanostatic method. The mouth periphery of the pit soon became repassivated and a deep pit could be obtained. During the galvanostatic growth the electrode potential difference between those determined from macrocapillary (outside) and microcapillary (near the pit bottom) was about 150 mV. Both potentials changed gradually to less noble values with time and then a sudden potential drop was observed. The potential at the bottom jumped from +150 to −150 mV. The latter is the potential corresponding to the current maximum in the active region on the polarization curves, determined using a microcapillary, of the activated steel in 1 N-H2SO4 containing NaCl of more than 3 N.
    The polarization curves show also the dissolution reaction at the surface inside the pit growing potentiostatically is the diffusion-controlled one in the passive potential region.
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  • Tadayuki Nakayama, Yoshiki Oshida
    1971 Volume 35 Issue 8 Pages 826-830
    Published: 1971
    Released: April 04, 2008
    Effects of absorbed hydrogen and surface polishing conditions on the structures of the initial oxide films formed on hydrogenated 18Cr, 18-8 and 18-18 stainless steels in high-temperature water at 300°C for 1 hr were investigated by means of electron microscopy, transmission electron diffraction and characteristic X-ray microanalysis.
    Main results obtained are as follows:
    (1) The corundum type oxide containing Fe and Cr was produced on the mechanically polished surface of 18-8 stainless steel; however, on the hydrogenated surface of this steel after mechanical polishing the spinel type oxide having Fe and Cr was formed.
    (2) The oxide film formed on hydrogenated 18-18 stainless steel was identical with the spinel type oxide consisting of Ni besides Fe and Cr.
    (3) The spinel type oxide containing Fe and Cr was produced on the hydrogenated surface of 18Cr stainless steel; on the other hand, the corundum type oxide was formed on the non-hydrogenated surface of this steel.
    (4) No effects of surface polishing conditions on structures of oxide films were noticed for the present steels.
    (5) From the above, surfaces of 18-18 and chemically polished 18-8 stainless steels showed the fcc phase and those of 18Cr and mechanically polished 18-8 stainless steels presented the bcc one; the latter was especially sensitive to the cathodic treatment, resulting in the formation of Fe++ ion which was necessary for forming of the spinel type oxides.
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