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Volume 38, Issue 1
Displaying 1-16 of 16 articles from this issue
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Masataka Sugiyama, Takateru Umeda, Hiroshi Kato1974 Volume 38 Issue 1 Pages 1-8
Published: 1974
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSIn this paper, the morphology of solid-liquid interfaces and the solute distributions at the interfaces were observed under various solidification conditions by quenching unidirectionally solidifying Al-4.5 wt%Cu alloy melts.
It is found that Gm⁄RZn values (G is the liquidus temperature gradient, RL is the solidification rate), which represent the critical growth conditions for the transition of interface structure, rule the morphology of macro- and micro-interfaces; though the optimum values of m and n are not decided in this paper, the experimental results using m=1 and n=0.5∼1 are shown.
By analyzing the solute profiles at the solid-liquid interfaces, it is confirmed that the long range solute pile-up exists at planar and cellular interfaces and is made clear the diffusion layer exists at the cellular dendritic interfaces (the intermediate stage between the simple cellular interface and the dendritic interface). The diffusion layer is not observed at the dendritic interfaces. It seems that this is caused not by the absence of the diffusion layer at the dendritic interfaces but by the narrowed width of the diffusion layer.
The diffusion coefficient of copper in the melt DL=2.5∼2.7×10−5 cm2/sec is obtained by analyzing the solute profiles at the interfaces with the assumption of mixing by diffusion only.View full abstractDownload PDF (926K) -
Hironori Kuroki, Hidehiko Matsuda, Tetsuo Eguchi1974 Volume 38 Issue 1 Pages 8-14
Published: 1974
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSKinetic behaviors of the 550°C-change in ordered FeCo alloy have been investigated with the measurement of specific heat CP and temperature derivative of electrical resistivity αR. Since αR has been found to be nearly proportional to CP in FeCo just as in β-CuZn alloy, αR has been compared with the corresponding theoretical value calculated with the kinetic equation of ordering which was derived in our previous paper on the basis of the Bragg-Williams approximation. The measured values for αR and the calculated ones as functions of temperature are in good agreement with each other in regard to the shape of the curves and the dependence of the temperature of the change on the rate of increasing temperature. This fact shows the validity of the kinetic interpretation of the 550°C-change in FeCo alloy.View full abstractDownload PDF (552K) -
Yoshinori Fujimura, Katsutoshi Kondo, Masataka Oishi1974 Volume 38 Issue 1 Pages 15-21
Published: 1974
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSTo obtain a better understanding of high temperature creep deformation in high Cr-high Ni austenitic steels, short time creep tests have been done in vacuum (∼10−5 mmHg) at 900 and 700°C on low carbon 20%Cr-30%Ni steel with different grain diameters of 0.30, 0.17 and 0.06 mm. Microstructural change during the deformation was also investigated and the following conclusions were obtained. (1) Stress dependences of the period of transient creep as well as that of steady state creep and of steady state creep rate showed remarkable changes at a stress level of 3∼4 kg/mm2 in 900°C and 7∼9 kg/mm2 in 700°C, irrespective of grain sizes. (2) At 900°C, the grain size dependence of the above-mentioned periods and of the creep rate changed at the stress level of 3∼4 kg/mm2. On the other hand, at 700°C the above-mentioned periods were greatly affected by grain sizes at any stress level except for the case of 0.06 mm grain diameter specimens stressed below 6 kg/mm2. That is, the smaller the grain diameter the longer were the periods. Besides, the finer the grain the slower was the creep rate at any stress level. (3) Coarse slip bands were observed as the stress exceeded 3∼4 kg/mm2 at 900°C and 7∼9 kg/mm2 at 700°C, respectively. (4) In a low stress region at 900°C where stress was below 3∼4 kg/mm2, subgrains were formed during a transient stage and their sizes were depended largely on stress. Furthermore their shapes did not change during the steady state stage. While at 700°C, except for the case of 0.06 mm grain diameter specimens stressed below 6 kg/mm2, the formation of subgrains was not observed at any stress level. (5) Andrade coefficient β increased remarkably at 900°C with increasing stress. Moreover its value at 900°C for the same creep rate was almost the same irrespective of grain sizes. (6) Creep properties under the conditions where subgrain formations occurred seem to be reasonably interpreted in terms of subgrain size.View full abstractDownload PDF (1113K) -
Masaji Mito, Hideo Sugawara1974 Volume 38 Issue 1 Pages 22-28
Published: 1974
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSPotentiodynamic polarization experiment was performed on a number of Fe-Cr binary alloys in N-H2SO4 solution with prolonged 475°C embrittlement. The curves for the Fe-Cr coupling electrode in which a high Cr alloy and a low Cr alloy were placed in a single mount were also studied. The second anodic current maximum in the active region was observed on embrittled (475°C×1000 hr) 26%Cr alloy and 31%Cr alloy. Pronounced first peak and second peak potentials accorded with the passivation potentials for unembrittled 50%Cr, 15%Cr alloy, respectively. Behaviour of the Fe-Cr coupling electrode resembled embrittled Fe-Cr alloys. The polarization curve can be explained without contradiction by assuming the existence of separated two phases.View full abstractDownload PDF (895K) -
Sakae Takeuchi, Katsuhiko Murakami1974 Volume 38 Issue 1 Pages 29-36
Published: 1974
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSHall coefficients of liquid copper alloys Cu-Bi, Cu-Sb, Cu-Sn and Cu-In were measured by means of the two-alternating current method in a wide temperature range from 500 to 950°C.
No temperature dependence of the Hall coefficient was observed in the liquid state of these alloys. The observed composition dependence of the Hall coefficient for the liquid Cu-Bi alloy was in good agreement with that calculated under the assumption of random mixing of Cu+1 and Bi+5 ions and of free electron approximation. In the other copper alloys, however, deviations from the free electron values R0 calculated under the above simple situation were observed. It is considered that some of the constituent atoms are randomly distributed and others are associated into clusters consisting of several atoms in the liquid states of Cu-In, Cu-Sn and Cu-Sb alloys. Such a cluster is referred to as a pseudo-molecule. A theoretical formula for the Hall coefficients of these liquid alloys was derived as a function of concentration of the pseudo-molecules nR⁄N, the number of localized electrons contributing to the bonding of the pseudo-molecule 2p and an effective volume of pseudo-molecule seen by conduction electrons αΩ0. Using the values of nR⁄N, 2p and αΩ0 obtained from the observations of other physical properties such as heat of mixing, magnetic susceptibility and electric resistivity, the calculated composition dependences of the Hall coefficients of the liquid Cu-In and Cu-Sn alloys were in good agreement with the observed ones. It was shown experimentally that the temperature dependence of the Hall coefficients estimated from the above formula was negligibly small.View full abstractDownload PDF (559K) -
Akihiko Kitada, Tadayuki Nakayama1974 Volume 38 Issue 1 Pages 37-41
Published: 1974
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSEffects of cold working on the structures and chemical compositions of oxide films of 18Cr stainless steel in water at 300°C were investigated.
Main results obtained are as follows:
After the non-deformed sample had been heated in water at 300°C for 1 hr, oxide films composed of corundum type oxide containing Fe and Cr were formed on the surface of the sample. When the sample deformed 5% or 15% by tension was heated under the same oxidizing condition, oxide films consisting of not only the corundum type but also the spinel type oxides were produced on the surface of the sample and the spinel type oxide in the films increased with increasing tensile strain.
The oxide films formed in water at 300°C on the sample which had been deformed 15% by tension and annealed to relieve the stress, were composed of the corundum type oxide only.
In the initial stage of the oxidation in high temperature water (150°C), the surface of the sample was covered with oxide films consisting of the corundum type oxide containing Fe and Cr, regardless of whether the sample was deformed by tension or not.View full abstractDownload PDF (693K) -
Yoshiaki Umehara, Shigeyasu Koda1974 Volume 38 Issue 1 Pages 42-46
Published: 1974
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSEutectic alloys of InSb-FeSb and InSb-CrSb have been directionally solidified at various rates of solidification in order to investigate the structure change due to the solidification condition.
The results obtained are as follows:
(1) The spacing λ between the MeSb rods showed a linear relationship with the rate of solidification R−1⁄2 and λ2R was shown to be 8.36×10−10 cm3/sec for FeSb rods and 8.38×10−9 cm3/sec for CrSb rods.
(2) The crystallographic orientation relationships between the InSb and MeSb phases was determined by X-ray diffraction. A preferred relationship observed can be stated approximately:
Growth direction: ⟨110⟩InSb\varparallel⟨0001⟩MeSb,
Coherent interface: {110}InSb\varparallel{11\bar20}MeSb.
The phase interface energy between the InSb and MeSb phases was determined from a dislocation model considering the mismatch at the interface; the 930 erg/cm2 for the InSb-FeSb phase and 1020 erg/cm2 for the InSb-CrSb phase.
(3) The relative resistance RB⁄R0 of field plates made of InSb-FeSb and InSb-CrSb alloys was mesured as a function of the magnetic induction. The resistance increased by a factor of 4 for InSb-FeSb alloy and 6 for InSb-CrSb alloy in a field of 10 kG.View full abstractDownload PDF (1384K) -
Mitsuhiro Hasebe, Taiji Nishizawa1974 Volume 38 Issue 1 Pages 46-54
Published: 1974
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSAnalysis and synthesis of phase diagrams of alloys by means of computer calculation combined with a thermodynamic study have been realized fruitful results in recent years. This work has been done on the same lines to clarify the phase equilibria in the ternary Fe-C-B system.
The phase equilibria between γ and Fe3(C, B), and γ and Fe23(B, C)6 at 800∼1000°C were studied experimentally and analyzed thermodynamically according to the regular solution approximation. Thus the free energies of formation of metastable compounds Fe23C6, Fe23B6, Fe3B, etc. and the interaction parameters in the individual phases were evaluated. On the basis of these thermodynamic parameters, the Fe-C-B phase diagrams at low and high temperatures, 427 and 1100°C, were given together with the ones at the experimental temperatures.View full abstractDownload PDF (672K) -
Katsuhisa Sugimoto, Kosaku Kishi, Shigero Ikeda, Yoshinobu Sawada1974 Volume 38 Issue 1 Pages 54-62
Published: 1974
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSSurface films of 18 Cr-8 Ni stainless steels passivated in 1 M-Na2SO4 (pH 2.0) at various potentials have been studied by means of X-ray photoelectron spectroscopy. Photoelectron spectra of the 2p3⁄2 levels for iron, chromium and nickel, and 1s level for oxygen were measured. Three imporant conclusions are drawn on the basis of the binding energies and the intensities of the peaks observed in the photoelectron spectra.
(1) Iron, chromium and nickel in passive films exist in the form of Fe(III), Cr(III) and Ni(II), respectively. However, there is the possibility that a part of iron and nickel is still present in the metallic state.
(2) Two types of oxygen with different binding energies of 532.4 eV and 530.7 eV, which correspond to the binding energies of oxygen in hydroxides and oxides respectively, are observed in the photoelectron spectra of O 1s of passive films. The peak intensities of the two peaks depend on the potential. The intensity of the peak with the lower binding energy increases and that with the higher binding energy decreases with incresing potential in the passive region. It is thought that the passive film of the steel contains two types of chemical bonds between metal and oxygen, such as M-OH and M-O, and the relative content of the M-O bond in the films becomes larger with increasing potential in the range of passivity.
(3) The peak intensity ratios of Fe 2p3⁄2 and Cr 2p3⁄2 depend on the potential. The rates of the Cr 2p3⁄2 peak are higher than those of the Fe 2p3⁄2 peak for the films formed in the passive region, and the inverse relations are observed in the films formed in the transpassive region. It is evident, therefore, that the concentratoin of chromium occurs in the films formed in the passive region.View full abstractDownload PDF (779K) -
Naomi Kotani, Takeshi Goto, Tetsuo Matsumura, Kiichi Narita1974 Volume 38 Issue 1 Pages 63-69
Published: 1974
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe application of X-ray fluorescence spectroscopy to the analysis of aluminium and its alloy was undertaken to provide a rapid and accurate method for the determination of chromium, copper, iron, manganese, ncikel, silicon, titanium and zinc.
Sample surface was finished with a lathe because titanium contamination from emery abrasive paper was found and X-ray intensity of silicon Kα varied depending on the way to set emery lines to the axis of the spectrometer. Several samples were prepared on the laboratory scale of melting for the preparation of binary alloys, the remelting of differently shaped samples and the examination of the effects of metallurgical structure on analytical results. The remelt samples proved to be satisfactory for the determination of alloying elements. Only in the determination of silicon, the effect of the metallurgical structure was observed. The intensity of silicon Kα varied due to the absorption of the matrix aluminium and the morphology of silicon precipitation. Since the effect of coexisting elements was observed in the determination of copper and zinc, corrections were made using an equation derived from a modified Beatties’ equation, and the coefficient of mass absorption.
Precision of the method was less than 0.5% of the coefficient of variation and the results obtained were in good agreement with those from chemical analysis. However, accurate determination of silicon was affected by lower sensitivity of the method at low concentration of light elements and the metallurgical structure of precipitation in aluminium at higher concentration of silicon.View full abstractDownload PDF (632K) -
Tôru Miyazaki, Masatoshi Nakagaki, Etsujirô Yajima1974 Volume 38 Issue 1 Pages 70-77
Published: 1974
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSPhase decomposition and its influence on the 475°C embrittlement for Fe-30%Cr, Fe-45%Cr and Fe-45%Cr-5%Co alloys were investigated. The results obtained are as follows.
The modulated structure is thought to be formed by spinodal decomposition in these alloys. The wave length of the structure, about 90 Å, does not change by aging, while the amplitudes increase with the progress of aging. With the increment of the Cr content in the periodic zone (modulated structure), hardness and yield stress increase. The age-hardening is considered to be not due to lattice strain caused by the lattice misfit between the zone and the matrix but due to the increment of the strength of the zone itself. The alloys are deformed by mechanical twinning and become embrittle, when the Cr content in the zone reaches 60∼75%Cr. The twinning may be caused by the stress concentration by piled-up edge dislocations which preferntially move because of the large Peiels force of screw dislocations in the Cr rich zones.View full abstractDownload PDF (1206K) -
Yasutoshi Saito, Yoshihiko Iwano1974 Volume 38 Issue 1 Pages 78-86
Published: 1974
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThermodynamic properties of uranium oxides with O/U atomic ratios between 2.04 and 2.34, principally in the nonstoichiometric UO2+x range, were obtained by the electromotive force measurement of solid state galvanic cells of the type:
(This article is not displayable. Please see full text pdf.)
at temperatures from 500 to 1100°C.
The relative partial molar free energies and equilibrium pressures of oxygen for the single-phase region UO2+x and the two-phase coexisting regions UO2+x-U4O9−y and U4O9-U3O8−x were determined from the electromotive force values with sufficient precision.
The variation of the relative partial molar entropy of oxygen with the composition in the nonstoichiometric UO2+x phase was derived on the basis of the 2:2:2 defect complex model proposed from the neutron diffraction study by Willis. The entropies were computed to fit the experimental data on the assumption that the excess oxygen ions entered in pairs into the fluorite structure, and that available sites for such oxygen pairs and U5+ ions were partially restricted.View full abstractDownload PDF (760K) -
Hiroo Nagano1974 Volume 38 Issue 1 Pages 87-94
Published: 1974
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSAlthough copper steels are known to have excellent corrosion resistance to sulfuric acids, it has been found that in some cases they are attacked severely in dilute sulfuric acids with corrosion rates much higher than those in plain carbon steels. This phenomenon is termed as accelerated corrosion.
Immersion tests and measurements of polarization curves of 0.3%Cu steels in 1N sulfuric acid have been undertaken in regard to this accelerated corrosion. The results of the study are shown as follows:
(1) Copper steels with above 0.007%S has good corrosion resistance to sulfuric acids. However, the corrosion rates of copper steels with sulfur contents of below 0.007% and C/S ratios of above 20 in 1N sulfuric acid are several times higher than those of plain carbon steels.
(2) The rates of accelerated corrosion for low sulphur-bearing copper steels are improved appreciably by heat treatments for producing the spheroidized Fe3C phase. The corrosion rates are also decreased with increasing hydrogen sulfide in sulfuric acids.
(3) The corrosion rates of low sulphur-bearing copper steels increase exceedingly with time, corresponding to the increase in exchange curret densities of the cathodic reaction. Increase in cathodic exchange current densities are observed in copper-precipitated steels as well.
(4) Good corrosion resistance of copper steels containing more than 0.007% sulfur seems to be due to the formation of a protective Cu2S film which is effective for retardation of the cathodic reaction.
On the other hand, in low sulphur-bearing copper steels susceptible to accelerated corrosion, the copper in steel is retained or reprecipitated after dissolution on the metal surface instead of forming the Cu2S film, and increases active cathodic sites as in the case of the Fe3C phase. The resulting increase in active cathodic area with time appears to be the main cause for the accelerated corrosion.
This theory might be applicable not only to the corrosion in sulfuric acids but also in both phosphoric and acetic acids.View full abstractDownload PDF (728K) -
Hiroo Nagano1974 Volume 38 Issue 1 Pages 95-104
Published: 1974
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSAs an extended study of the accelerated corrosion of copper steels in dilute sulfuric acids, experiments have been undertaken to clarify the mechanism of accelerated corrosion caused by several alloying elements. The results obtained are shown as follows:
(1) Small additions of the following elements to copper steels increase remarkably their corrosion rates in sulfuric acids in the order of Y, Zr, Ti>W, Mo>V. This enhanced corrosion might be caused by the increase in cathodic exchange current densities, as has been observed for low sulphur-bearing copper steels.
(2) Extra low carbon or high sulfur content (about 0.2%) prevents the accelerated corrosion of copper steels containing V, Mo and W, but this is not the case with the steels alloyed with Ti, perhaps with Y and Zr.
(3) MoO42− or WO42− in sulfuric acid increases exceedingly the corrosion rate of copper steel. VO3− has also the same action, but its effect is less than MoO42− and WO42−.
(4) The formation of MoO42−, WO42− or VO3− might be the main cause for the accelerated corrosion of copper steels containing Mo, W or V.
On the other hand, the corrosion accelerating action by Y, Zr, Ti might come from the very low solubility of their sulfides, i.e. YS, Mn(Zr)S and Ti2S, retarding the formation of Cu2S.View full abstractDownload PDF (1596K) -
Toranosuke Kawaguchi, W. S. Tseng, Koichi Ogawa1974 Volume 38 Issue 1 Pages 104-111
Published: 1974
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSBoth Fe-Cu and Co-Cu alloys are practically immiscible. As changes in 4πIs of Fe-Co-Cu ternary alloys are almost the same as those of Fe-Co binary alloys, ferromagnetic particles of Fe-Co binary alloys are distributed in the Cu matrix. Vanadium additions of less than a few percent improve workability of Fe-Co-Cu alloys extremely without changing their magnetic properties. Images of X-ray microanalysis show that Fe-Co-V ternary system particles are spaced in the Cu matrix. The characteristics of remanence, coercivity and squareness of Fe-Co-Cu-V alloys are improved by the process of heating after cold-reduction. The 16.3%Co-20.9%Cu-0.9%V-bal. Fe alloy shows the remanence of 17∼17.5 kG, the coercivity of 35∼40 Oe and the squareness (\sqrt(BH)max⁄Br·Hc) of 0.9∼0.93, when heated at 400∼500°C after 90% cold reduction in area. The 63.8%Co-19.4%Cu-1.7%V-bal. Fe alloy exhibits almost the same magnetic properties as those in the above alloy, except for a lower remanence. However, the properties are very stable against reheating at a higher temperature.
Little deterioration is observed in the magnetic properties of the preheated 16.3%Co-20.9%Cu-0.9%V-bal. Fe alloy which was previously cold-worked, and when heated again at temperatures lower than 900°C for a short time. The thermal expansion coefficient of the alloy is 105×10−7/°C. The Fe-Co-Cu-V system alloy is suited for use as a semi-hard magnetic material.View full abstractDownload PDF (834K) -
Toranosuke Kawaguchi, W. S. Tseng, Koichi Ogawa1974 Volume 38 Issue 1 Pages 112-116
Published: 1974
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSBehavior of magnetic properties of heated Fe-Co-Cu-V alloys after cold-reduction was analyzed by means of measurements of electric resistivity, micro-Vicker’s hardness and minor-loop susceptibility. The behavior of electric resistivity shows that the internal stress is increased by the formation of the G.P.zone and the precipitation of copper-rich nucleus in ferromagnetic Fe-Co particles. The minor-loop susceptibility is very sensitive to internal structural changes of Fe-Co-Cu-V alloys, and it is shown that there are four different stages when the alloy is heated at 200∼1100°C. The coercivity is increased at the 2nd stage and its increase occurs when the precipitates are coagulated and grown large enough to disturb the domain wall displacement. At the 3rd stage of 500∼900°C, the coercivity and internal stress through transformation decreases linearly with heating temperature and decreases by the logarithmic low with heating time. Also, the drop in remanence at this stage may be due to the disappearance of fiber structures in the alloys.View full abstractDownload PDF (593K)
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