Journal of the Japan Institute of Metals and Materials
Online ISSN : 1880-6880
Print ISSN : 0021-4876
ISSN-L : 0021-4876
Volume 43 , Issue 12
Showing 1-20 articles out of 20 articles from the selected issue
  • Mizuo Edamura, Minoru Makimura, Takashi Kajikawa, K\={o}ichi Imai, Sat ...
    1979 Volume 43 Issue 12 Pages 1111-1114
    Published: 1979
    Released: April 04, 2008
    JOURNALS FREE ACCESS
    In our previous report, it is shown that the growth rate of the compound layer in the ion-softnitrided S15C steel follows the linear law during the first one-half hour and then it nearly follows the parabolic law. In this report, the thickness of the compound layer in the ion-softnitrided S15C steel was investigated by optical microscopy by varying the current density, voltage, nitriding temperature and nitriding time. The main results obtained were as follows.
    (1) Both the values of k and t0 were hardly affected by the current density but influenced by the voltage when the nitriding temperature and time were constant. Here k was the growth rate of the compound layer during the stage of the linear law, and t0 was the time when the stage changed from the linear law to the parabolic law. When the voltage was increased, the value of k was increased and the value of t0 was decreased.
    (2) During the stage of the parabolic law, the activation energy for diffusion of nitrogen in the compound layer showed a nearly almost constant value, which was hardly affected by the current density and voltage.
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  • Mizuo Edamura, Minoru Makimura, Takashi Kajikawa, K\={o}ichi Imai, Sat ...
    1979 Volume 43 Issue 12 Pages 1115-1120
    Published: 1979
    Released: April 04, 2008
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    The study on the ion-nitriding (or ion-softnitriding) in the atmosphere of N2-H2 mixing gas (or N2-H2-C3H8 mixing gas) was previously carried out. In this report, NH3 gas was added to the above-mentioned atmosphere, and the degree of dissociation of NH3 gas, the thickness and composition of the compound layer and the depth of the diffusion zone were investigated (nitriding temperature: 550°C, nitriding time: 6 h, total gas pressure: 400 Pa (3 Torr), current density: 11.5 A/m2). The main results were as follows.
    (1) The degrees of dissociation of NH3 gas as a function of its molar fraction in the introduced gases (NH3-N2-H2 and NH3-N2-H2-1%C3H8) were measured when the molar fraction ratio of N2 to H2 gases in the exhaust gases was kept constant as 1/3. Using the above measured degrees of dissociation of NH3 gas, the molar fractions of NH3, N2, H2 gases in the introduced gases (NH3-N2-H2 and NH3-N2-H2-1%C3H8) were well calculated to keep the molar fraction ratio of N2 to H2 gases in the exhaust gases as 2/1.
    (2) When the molar fraction of NH3 gas in the exhaust gases was increased, the voltage was increased and the thickness of the compound layer was also increased; however, the depth of the diffusion zone was almost constant.
    (3) The volume ratio of the ε-Fe2–3N phase to the sum of the ε-Fe2–3N and γ′-Fe4N phases in the compound layer, cε⁄(cε+cγ′), was almost constant when the molar fraction ratio of N2 to H2 gases in the exhaust gases and the C3H8 gas content were constant. Here cε and cγ′ were the volume fractions of the ε-Fe2–3N and γ′-Fe4N phases in the compound layer.
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  • Hideo Ike, Hirobumi Okabe
    1979 Volume 43 Issue 12 Pages 1120-1126
    Published: 1979
    Released: April 04, 2008
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    The oxidation of Fe-Cr-0.3%Al alloys containing 15∼28%Cr in atmospheric dry oxygen at 1173∼1473 K has been studied by thermogravimetric methods, metallography and scanning electron microscopy. Effects of Al on the oxidation resistance decrease with an increase in the Cr content of the alloys. Spallation of the oxide scales after cooling can be completely avoided by the addition of Al below 1273 K. Above 1373 K, however, the effect of Al decreases as the Cr content in the alloy increases. Uniform single-layered scales of (Fe,Cr)2O3 rich in Cr are produced. All of the alloys tested with Al additions form internal oxidation zones of α-Al2O3. A brief discussion has been given on the optimal amount of Al within a small range of addition. The apparent activation energies are within a range from 205 to 223 kJ/mol. The durations which obey the parabolic rate law are longer for the alloys without Al addition below 1273 K. Finally, the spalling behaviour of the scales has been discussed in some detail.
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  • Yasuhiro Miura, Minoru Furukawa, Kenji Fujiyama, Hiroya Kaieda
    1979 Volume 43 Issue 12 Pages 1127-1131
    Published: 1979
    Released: April 04, 2008
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    Dislocations in aluminum sheets were observed at high temperatures and at room temperature by means of X-ray topography, and the annihilation process and the nature of dislocations were discussed.
    Approximately linear relation has been found between the reciprocal of dislocation density and the time of isothermal annealing, and the annealing process is explained in terms of the theory of dislocation network growth. The apparent activation energy of the process is estimated to be 1.8 eV.
    The majority of dislocations in well annealed sheets, observed at room temperature, had a strong edge component and did not lie on the exact {111} planes.
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  • Kenzaburo Kumada, Takashi Naohara, Tsuneo Fujiwara
    1979 Volume 43 Issue 12 Pages 1131-1137
    Published: 1979
    Released: April 04, 2008
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    In order to study the phase transformation of austenite, 25Cr-20Ni steels cold-rolled with 0∼60% reductions were aged at 1073 K for various times up to 3000 h. Subsequently, the ferrite precipitation was investigated by means of optical and electron microscopy, magnetic powder pattern, magnetic analysis and electron diffraction.
    The results obtained are as follows:
    (1) In 25Cr-20Ni steels, ferrite precipitates from austenite and possesses the following orientation relationship with the matrix.
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    (2) Cold working before aging accelerates the precipitation of needle-shaped ferrite which occurs only in the recrystallized regions.
    (3) By using a magnetic powder pattern method and a usual etching technique at the same time, optical microscope observation enables to discriminate ferrite from austenite and the sigma phase.
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  • Nobuya Iwamoto, Yoshiaki Tsunawaki, Makoto Miyago
    1979 Volume 43 Issue 12 Pages 1138-1144
    Published: 1979
    Released: April 04, 2008
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    Raman spectra of PbO-SiO2 slags have been measured. They are characterized by some peaks due to the Pb-O vibrational mode in a frequency region of less than 2×104 m−1 and also by a large broad band due to Si-O stretching in the frequency region of 8×104 to 12×104 m−1. By comparing with the infrared dielectric constant (ε″) obtained from the Kramers-Kronig analysis of reflectance of PbO-SiO2 slags, it is deduced that the band consists of five peaks near 8.9×104, 9.2×104, 9.6×104, 10.3×104 and 11.5×104 m−1. Furthermore, a comparison with the Raman and infrared absorption spectra of crystalline silicates suggests that these five peaks will arise from the SiO4 tetrahedron with four, three, two, one non-bridged oxygens and with four bridged oxygens, respectively. Accordingly, the distributions of three kinds of oxygens, i.e. bridged oxygen (O0), non-bridged oxygen (O) and free oxygen (O2−), have been caluculated from the analysis of area intensities of these five peaks. The results are in agreemet with the results of thermodynamical models.
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  • Toshiaki Yoneoka, Michio Yamawaki, Masayoshi Kanno
    1979 Volume 43 Issue 12 Pages 1144-1150
    Published: 1979
    Released: April 04, 2008
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    The oxidation behavior of 95Ni-5Nb and 90Ni-10Nb alloys was investigated at PO2=40 Pa and 1023 K by using the 16O ion backscattering analysis and they were compared with the preceding study of those obtained at the low pressure of PO2=6×10−2 Pa. The surface of each alloy was covered by either a thin smooth NiO layer or rough nodular NiO oxides. The thickness of the smooth oxide layer was measured by means of 16O ion backscattering. The formation of an internal oxidation zone was identified by the backscattering method and the X-ray diffraction analysis, etc. The thickness of this zone and the size of the internal oxide particle were determined and a considerable part of the weight gain was attributed to the internal oxidation. The internal oxide particles were identified to be mainly T-Nb2O5.
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  • Kazuo Yamanaka, Masamichi Kowaka
    1979 Volume 43 Issue 12 Pages 1151-1157
    Published: 1979
    Released: April 04, 2008
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    The micro-structure and the analysis of the metallurgical factors contributing to the strength and the toughness of Fe-Mn alloys containing up to 8 wt%Mn have been studied. The results obtained are as follows:
    (1) Transformation products depended on the manganese contents and formed the equiaxed ferrite, massive ferrite and lath martensite in order with increasing manganese content.
    (2) Yield strength and impact transition temperature were strongly influenced by the transformation products.
    (3) The unit crack path gave experimentally good correlations with the ductile/brittle transition temperature.
    (4) The fracture modes in the brittle temperature range depended on the manganese content: low manganese alloys showed cleavage fracture, and the intergranular fracture increased with increasing manganese content.
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  • Yoshinari Kaieda, Atsushi Oguchi
    1979 Volume 43 Issue 12 Pages 1158-1163
    Published: 1979
    Released: April 04, 2008
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    Bending tests at atmospheric pressure and under high hydrostatic pressures up to 800 MPa have been carried out in the temperature range above room temperature to 1000 K in order to make clear the influence of hydrostatic pressure on the brittle to ductile transition phenomenon of a very brittle Cu-Zn alloy (γ-Brass). From the observations of bending load-deflection relation and fracture surface, the fracture modes in the pressure and temeprature ranges tested have been grouped into five classes, and the change in mode due to pressure and temperature has been discussed. As a result, it was observed that the transition temperature from the transgranular cleavage type fracture to the other more ductile types was hardly influenced by hydrostatic pressure. However, the modes of fracture at higher temperatures were affected remarkably by hydrostatic pressure, and the spesimens became to be deformed largely without occurence of cracks by the application of hydrostatic pressure of the same order of magnitude as the flow stress of the material.
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  • Takeo Oki, Yoshihiko Kunieda
    1979 Volume 43 Issue 12 Pages 1164-1168
    Published: 1979
    Released: April 04, 2008
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    The etching of silver by the graphite-suspension method based on an anodic electroxidation of graphite particles existing in the suspension state in 0.5M sulfuric acid solution was investigated. Silver which belongs to metals of the nobler electrode potential, is able to be etched excellently by the graphite-suspension method. The etching velocity of silver increases with making fine graphite particles, with increasing concentration of suspension graphite and furthermore with elevating temperature. The etching velocity within this experimental region of the suspension potential becomes faster with increasing total surface area of graphite particles striked against silver plate. The etching ability represented by the etching velocity divided by the apparent surface area of graphite in the unit volume of suspension increases with increasing concentration of graphite, but decreases with decreasing diameter of graphite particles. The etching silver takes place according to a local cell reaction consisting of Ag→Ag++e as anodic reaction and reductions of the products on the anodically oxidized graphite particles as cathodic reactions.
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  • Shinji Narishige, Mitsuo Sato
    1979 Volume 43 Issue 12 Pages 1168-1174
    Published: 1979
    Released: April 04, 2008
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    In wear tests of Permalloy and Sendust alloy for magnetic heads rubbing against magnetic tapes, it has been found that some lusterless substance is formed on the worn surface. The shape and chemical composition of the lusterless substance are examined by photographing optical bright field and differential interference contrast images and with an Auger electron emission spectroscope.
    The lusterless substance can be observed on the worn surfaces with an optical microscope. The surfaces where the substance is formed have larger wear resistance than the surfaces where it is not. The shape of the substance is spotty or spread over all the rubbing area. The substance is raised by about 30 nanometer from the alloy surface, but the number of the scratch lines on the surfaces of the substance is fewer than on the exposed parts of the alloy. Elements contained in the sample alloys and oxygen are detected from the substance.
    It is considered that burnishing and oxidation take place on the worn surfaces when magnetic tapes wear off the alloys and the oxides formed on the worn surfaces reduce wear.
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  • Mutsumi Touge, Kazuyoshi Kamachi
    1979 Volume 43 Issue 12 Pages 1175-1180
    Published: 1979
    Released: April 04, 2008
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    Anisotropic distributions of hydrogen induced lattice sitran in Fe-32.3%Ni single crystal were studied with the aid of the X-ray divergent beam method.
    Various phenomena such as hydrides formation, phase transformations and surface cracks were observed when hydrogen was charged cathodically into austenitic stainless steels and Fe-Ni alloys. One of the origins of these phenomena was considered to be the lattice strains induced by hydrogen charging in the steel and the alloy.
    The lattice strains of the single crystal of Fe-32.3%Ni alloy were obtained by measuring lattice spacing, d, precisely of more than six independent (hkl) lattice planes using the X-ray divergent beam method. Principal strains and compositions of strain tensor were then computed by the strain analysis method in various stages of hydrogen charging. A lattice strain of an optional lattice plane (HKL) was calculated numerically using this results, and strain distribution curves on various specific sections of the specimen are drawn on polar nets for every charging time.
    The strain distribution curves were anisotropic showing ellipsoidal shapes: this suggests the formation of platelet aggregations of hydrogen atoms or hydride phases. It was confirmed from an analysis of the stereographic projection that platelet aggregations were formed on {211} lattice planes along the axis of ⟨110⟩.
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  • Takashi Otowa, Mutsuhiro Kobayashi, Kazuhiro S. Goto, Mayumi Someno
    1979 Volume 43 Issue 12 Pages 1181-1185
    Published: 1979
    Released: April 04, 2008
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    In order to identify the electric charge carrier in an ion-conductive calcium sulfide, tracer diffusion coefficients of sulfur have been measured by IMA (Ion Micro-Analyzer). Stable isotope 34S diffused by a gas-solid reaction was analyzed in depth by continuous sputtering of the sample. The tracer diffusion coefficient determined from the in-depth profile of 34S was expressed for a temperature range from 1053 to 1483 K by;
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    Using the measured diffusion coefficient and the Nernst-Einstein relation, the electrical conductivity by S ion was estimated. The estimated conductivity was 10 to 100 times smaller than the reported measured value. The activation energy for sulfur tracer diffusion was 1.5 times greater than that for electrical conduction. These results confirm the deduction that the electric charge carrier in CaS is predominantly Ca2+.
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  • Takashi Sakaki, Kazutaka Sakiyama
    1979 Volume 43 Issue 12 Pages 1186-1190
    Published: 1979
    Released: April 04, 2008
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    Effects of NaClO3 and NaCl on the corrosion behaviour of iron-chromium alloys are studied by means of potentiodynamic polarization and immersion tests in 48%NaOH solutions at temperatures between 140 and 200°C, and the following results are obtained. With increasing chromium content in alloys, the passivation of iron-chromium alloys even takes place in caustic soda solutions containing small amount of NaClO3 and the dissolution at active state of the alloys containing more than 18%Cr disappears. Natural electrode potentials of alloys that is 24%Cr or less are about Eh=−0.9 V. But, when 0.1%NaClO3 is contained in solution, the corrosion potential of a 18%Cr-Fe alloy shows a high potential in the passive state. Therefore, we suppose that the effect of NaClO3 on the corrosion behaviours is caused by the oxidation power of ClO3 ion. On the other hand, the corrosion of Fe-Cr alloys is invariable in 48%NaOH solutions containing NaCl that is up to 1%. At temperatures more than 160°C, high chromium-iron alloys that have a excellent corrosion resistance at 140°C are corroded. Especially, these alloys are severely attacked in solutions containing NaClO3.
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  • Kiyoshi Aoki, Osamu Izumi
    1979 Volume 43 Issue 12 Pages 1190-1196
    Published: 1979
    Released: April 04, 2008
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    The room temperature ductility of the L12 type intermetallic compound Ni3Al which has been accepted to be brittle so far was improved considerably by a small addition of boron. Binary Ni3Al poly-crystals without boron did not exhibit any ductility at room temperature in agreement with previous reports, while those to which boron was added showed considerable ductility as determined from the bending, cold-rolling and tensile tests. Improvement of the room temperature ductility by boron addition did not bring about lowering of the yield strength of Ni3Al. Fracture mode changes trom the intergranular one which is typical for the alloy without boron to the transgranular type in the alloys containing a small amount of boron. Boron appeared to be the effective element which suppress the intergranular fracture. The mechanism of the improvement of the room temperature ductility was discussed based on impurity segregation to grain boundaries or the peculiarity of the grain boundary structure.
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  • Tsuyoshi Yamamoto, Toshiyuki Takashima, Keizo Nishida
    1979 Volume 43 Issue 12 Pages 1196-1202
    Published: 1979
    Released: April 04, 2008
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    For the purpose of studying interdiffusion in an α-solid solution of the Ni-Zn system, nickel test pieces were diffusion-annealed in an evacuated capsule containing the powdered 45 wt%Zn-Ni alloy (α+β1 or α+β) or the powdered 40 wt%Zn-Ni alloy (α) as a Zn vapor source at 1073∼1323 K for 3.6∼705.6 ks.
    In the case of the diffusion-annealing with the former 45 wt%Zn-Ni alloy as a Zn vapor source, the surface concentration of Zn in the test piece at 1073 K coincided approximately with the solubility limit reported in the phase diagram of the Ni-Zn system, while a significant deviation toward the higher Zn concentration in the solubility limit was found at other temperatures.
    For the powdered 45 wt%Zn-Ni alloy as a vapor source, fine alumina markers placed on the surface of test pieces prior to diffusion still remained on the surface after annealing, so that it is considered that Zn atoms diffuse predominantly into the α-solid solution at the marker position. For the latter vapor source used at 1323 K, the markers were found inside the test pieces after annealing. In this case, the Zn concentration at the markers position was 36.3 at%Zn and the ratio of these intrinsic diffusion coefficients in this Zn concentration, (DZnDNi), was about 21.
    The interdiffusion coefficients (\Tilde{D}) were dependent upon Zn concentration and were evaluated to be the orders of 10−17∼10−13 m2/s in this experimental temperature range. Log \Tilde{D} increased linearly with increasing Zn concentration except the case annealed at 1073 K.
    The activation energies for interdiffusion (\Tilde{Q}) obtained from these data decreased linearly with increasing Zn concentration from 265 kJ/mol for 5 at%Zn to 208 kJ/mol for 30 at%Zn. The impurity diffusion coefficient (DZn*) at each temperature was obtained from extrapolating of \Tilde{D} to 0 at%Zn and the activation energy for the impurity diffusion of Zn in Ni (QZn*) obtained from the Arrhenius plot of DZn* was evaluated to be 276 kJ/mol.
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  • 1979 Volume 43 Issue 12 Pages 1202
    Published: 1979
    Released: April 04, 2008
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    Please see pdf. Wrong:Mössbauer Analysis on the Binding State of Tin in the Grain Boundary using 119mSn Segregated at the Grain Boundary Right:Mössbauer Analysis on the Binding State of Tin in the Grain Boundary using 119mSn Segregated at the Grain Boundary of Pure Iron
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  • Minoru Chiba, Tsutomu Ando
    1979 Volume 43 Issue 12 Pages 1203-1208
    Published: 1979
    Released: April 04, 2008
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    Oxygen in aluminum dust produced by the gas atomizing method was determined by means of 14 MeV neutron activation followed by nondestructive γ-ray counting. An external standard method was adopted to improve reproducibility and accuracy of the analytical results. The analytical process was simplified by using this method.
    The γ-rays of 16N was measured with the energy range of 4.5∼8.0 MeV. With this energy range, measurements were free from interferences due to simultaneously produced radioactive nuclides from matrix aluminum except 24Na. Satisfactory results were obtained by measuring 16N counts twice with an appropriate decay interval and subtracting the second counts as a back ground from the first counts to remove interference caused by 24Na. Increase of apparent 16N counts caused by contribution of 24Na was almost agreed with the calculated result.
    Oxygen concentration in aluminum dust larger than 270 mesh size was almost constant at 1700 weight ppm, increasing rapidly with the decrease of particle size, and reached about 3000 weight ppm for the fraction of 325∼400 mesh which occupied about 30% of the whole amount.
    Almost all of the oxygen in aluminum dust is thus supposed to be present as oxide because the oxygen content is much higher than that estimated from both solid soluble and surface adsorption.
    The time required for the analysis of one sample was 150 s.
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  • Shigeru Asano
    1979 Volume 43 Issue 12 Pages 1209-1210
    Published: 1979
    Released: April 04, 2008
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  • Naohiro Igata, Kazuya Miyahara, Hiroshi Asanuma
    1979 Volume 43 Issue 12 Pages 1211-1212
    Published: 1979
    Released: April 04, 2008
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