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Volume 47, Issue 9
Displaying 1-13 of 13 articles from this issue
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Kiyoshi Terayama, Masao Ikeda1983 Volume 47 Issue 9 Pages 729-735
Published: 1983
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe effect of iron oxide on the reduction kinetics of MnO with carbon is investigated, in order to study the characteristics of pre-reduction of Mn ores, and Fe-Mn carbide formed in the reduction process of MnFe2O4 is identified by the effluent gas analysis method. Results obtained are as follows:
(1) The reduction of MnFe2O4 which yields the nonstoichiometric compound, MnO-FeO, occurs at 1163 K, and the reduction of this compound to MnO and metallic iron follows at 1273 K.
(2) At the earlier stage of reduction of MnO, Fe-Mn carbide is formed, and the activation energy of 205 kJ/mol nearly equal to that for the Boudouard’s reaction is obtained.
(3) When carbon is consumed entirely on the reduction process (C/MnFe2O4=4), the reaction between MnO and Fe-Mn carbide occurs and the activation energy of 245 kJ/mol is obtained.
(4) Fe-Mn carbide formed in the reduction process is identified to be (Fe, Mn)7C3 phase by the effluent gas analysis method using the He+O2 mixture. The examinations of EPMA and X-ray diffraction show the presence of this Fe-Mn carbide in the reduction products.View full abstractDownload PDF (1136K) -
Shu Yamaguchi, Atsuo Imai, Kazuhiro S. Goto1983 Volume 47 Issue 9 Pages 736-742
Published: 1983
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe chemical activity of sodium oxide in Na2O-SiO2 melt was determined by the EMF method, using beta-alumina as a solid electrolyte in the range from 0.2 to 0.6 mole fraction of sodium oxide at 1173 to 1673 K. The activity of sodium oxide in the reference melt of a fixed composition was measured in advance with a standard electrode of pure Na2CO3 melt under fixed partial pressures of oxygen and carbon dioxide.
The activity of sodium oxide measured showed an extremely large negative deviation from the Raoult’s law with the values of 10−10 to 10−3 depending upon temperature and composition.
Various thermodynamic properties of the Na2O-SiO2 binary solution have been determined from the activities of sodium oxide and silica.View full abstractDownload PDF (832K) -
Yoshio Ohta, Fumiyuki Shimizu, Kenji Morinaga, Tsutomu Yanagase1983 Volume 47 Issue 9 Pages 742-746
Published: 1983
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe improved four electrodes method has been used for measuring the electrical conductivity (σ) of Na3AlF6-Al2O3-additive fluoride melts. σ of these melts is increased with increasing contents of LiF and NaF and is decreased with increasing contents of AlF3 and CaF2. Iso-electrical conductivity lines were plotted to clarify the effects of the content of LiF, NaF, AlF3 and CaF2, respectively. Li+, Na+ and free F− ions seem to act as a charge carrier ion in these melts. Therefore, the distribution of AlO2−, AlOF2−, AlF4− and AlF63− was estimated from Laser Raman spectra of these melts and the literature about these studies to find out the content of free F− ion, and the parameter of σ was calculated in terms of the concentration and mobility of each carrier ion. A plot of observed σ values for the parameter has a linear relationship.View full abstractDownload PDF (597K) -
Yasutoshi Taniguchi, Michitaka Haruno, Kenji Morinaga, Tsutomu Yanagas ...1983 Volume 47 Issue 9 Pages 747-751
Published: 1983
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSDependence of the electrical conductivity (σ) of molten salts upon the current frequency (f) has been studied in the range of 0.1-200 MHz. A handmade apparatus and a new technique of measuring the dependence of σ were proposed. σ of molten salts was decreased with increasing f with the steps, the number of which seemed to be consistent with the number of charge carrier ions in the melts, that is, two steps for NaCl melts and three steps for NaCl0.5Br0.5 melts. The frequency at the decreasing point was the “cut-off frequency” for the electric transfer of charge carrier ions. In the Na2O-SiO2 system the two decreasing points were observed at the content of 50 mol%Na2O or more, so that a free oxygen ion O2−, as well as Na+, may be the charge carrier ion. The possibility of determining the charge carrier ionic species and the transport number in molten salts was discussed based on the results of σ vs f curve.View full abstractDownload PDF (614K) -
Masahiro Seo, Yuzi Sera, Norio Sato1983 Volume 47 Issue 9 Pages 752-759
Published: 1983
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe depth-composition profiles of Fe-30Cr alloy, a series of Fe-Ni alloys, SUS304 and 316 austenitic stainless steels anodically oxidized at room temperature in deaerated 10.7 mol·kg−1 NaOH solution were measured by simultaneous use of Auger electron spectroscopy and argon ion sputter-etching techniques. Chromium is enriched in the passive film formed on Fe-30Cr alloy. A rather thick film (9-28 nm) with a chromium-depletion zone extending to the substrate grows on Fe-30Cr alloy during short polarization time (5-15 min) in the transpassive region where chromium dissolves into solution. The effective thickness of chromium-depletion zone, δ (12-25 nm), in the substrate of Fe-30Cr alloy increases with increasing polarization time in the transpassive region. Assuming that the steady state of selective dissolution of chromium was established, the recession velocity, u (10−10−10−9 cm·s−1) of the film/substrate interface during transpassive dissolution was estimated, and further the interdiffusion coefficient, \ ildeD (10−15 cm2·s−1) of Fe-30Cr alloy, which was extremely large as a value at room temperature, was obtained from the approximate relation, δ\simeq\ ildeD⁄u.
Nickel-enrichment ranging from the uppermost surface to the alloy substrate was always observed for a series of Fe-Ni alloys anodically oxidized in the passive, transpassive or secondary passive potential reigon of nickel. Particularly, nickel enrichment is significantly enhanced on the uppermost surface and at the film/substrate interface, which may be attributed to anodic deposition of nickel once dissolved and to selective dissolution of iron, respectively. The thickness (2-4 nm) of the anodic oxide film formed on a series of Fe-Ni alloys decreases with increasing buk nickel content, indicating the improvement of corrosion resistance due to nickel-enrichment. The effective thickness of nickel enrichment layer, δ (6-10 nm), in the substrate exhibits both the potential-and alloy composition-dependence, suggesting the importance of interdiffusion process in the vicinity of the alloy surface for anodic oxidation of a series of Fe-Ni alloys.
The addition of nickel suppresses the transpassive dissolution of chromium and contributes to improvement of the corrosion resistances of SUS304 and 316 austenitic stainless steels in concentrated NaOH solution.View full abstractDownload PDF (939K) -
Yutaka Kagawa, Eiichi Nakata, Susumu Yoshida1983 Volume 47 Issue 9 Pages 760-767
Published: 1983
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe fracture toughness of copper matrix composites reinforced with helical tungsten fibers has been investigated. Tungsten fibers 15 μm in diameter were formed into helices, whose helical radius and angle were 75 μm and 78.4°, respectively. They were embedded in a copper matrix by means of electrodeposition and vacuum hot-pressing techniques. The volume fraction of the fiber was 0.072. Single edge notched (SEN) type specimens with various notch depths were tensile tested, and their fracture behaviors were examined. The process of fracture, the appearance of fracture surface and the behavior of fiber-matrix interface were observed macroscopically as well as microscopically. The results were compared with those for the straight fiber reinforced composites.
When tensile tested, the helical fiber reinforced composites showed loss notch-sensitivity than the straight fiber reinforced composites. A much larger plastic deformation zone was observed in front of the notch root for the former type of composite than for the latter type. Thus, the difference in the notch sensitivity between the two types of composites was attributable to the difference in the work of fracture, that is, the difference between the work done in plastic deformation of the matrix and that in breaking the fibers during the process of crack propagation. As a trial, the difference in fracture toughness between the two types of composites was represented quantitatively by using the nonlinear energy fracture toughness \ ildeGc or \ ildeKc.View full abstractDownload PDF (2077K) -
Tetsuzi Maruno, Hitoshi Tsuji, Rikuro Otsuka1983 Volume 47 Issue 9 Pages 768-775
Published: 1983
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSTo clarify the correlation between the hydrogen embrittlement and the hydride (β-phase) formation in transition metals, Pd-Ag binary alloys have been investigated by means of electrolytic hydrogen charging and X-ray diffraction methods. The hydride formation was controlled by varying silver content and temperature. In both cases of the two factors, it was found that independent of the hydrogen content the hydrogen embrittlement occurred always only when the hydride was formed. Depending on the silver content, Pd-Ag binary alloys were hardened or softened by hydrogen charging. It was, however, found that the hardening and softening are not responsible for the hydrogen embrittlement directly. It is concluded that the hydrogen embrittlement is ascribed to the discontinuous expansion which accompanies the α-β transformation (hydride formation) caused by the absorption of hydrogen.View full abstractDownload PDF (1308K) -
Masanobu Obmori, Misao Itoh, Fusahito Yoshida1983 Volume 47 Issue 9 Pages 775-781
Published: 1983
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSIntermediate temperature embrittlement behaviors of a 99.5 wt% purity polycrystalline nickel were examined by tension tests in vacuum at temperatures up to 1273 K under eight deformation speeds from quasi-static to impact. Present findings are summarized as follows.
A remarkable embrittlement accompanied with grain boundary crackings was observed around 1123 K in the specimen tested in a quasi-static manner. The embrittlement faded away gradually, however, with increasing tensile speed and disappeared completely beyond the speed of 1.67 mm·s−1 which is 8.4×10−2 s−1 in strain rate. The fact that the ductility minimum temperature of 1123 K remained unchanged even when the deformation speed was widely varied suggests that the present embrittlement is not diffusion controlled but deformation controlled. The embrittlement of the present nickel was caused by the process that fine voids formed on the grain boundaries at early stage of deformation grew and coalesced into the grain boundary crackings with increasing deformation. Since no grain boundary sliding occurred prior to appearance of the voids, they seemed to be originated from the vacant sites formed on the boundaries as a result of pile-ups of dislocations moving through the crystal grains.View full abstractDownload PDF (2761K) -
Hajime Kitagawa, Kiyoshi Tamura1983 Volume 47 Issue 9 Pages 781-788
Published: 1983
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSFor estimating the anisotropy of the physical properties of a polycrystal by the texture represented by ODF, there are two possible methods; One is a conventional method and the other is a new method proposed by us. In the newly proposed method, the correspondence between an anisotropy of the physical properties of a single crystal and that of the polycrystal becomes more clear.
In the present study of the magnetic anisotropy, the relation between the magnetic torque curves for aluminium killed, rimmed, and non-oriented silicon steel sheets and the texture ODF has been obtained by the new method. In this case, the magnetic anisotropy energy and the magnetic torque in an alpha-iron single crystal has been calculated as a function of the Eulerian angle. Magnetic torque values were measured using a torsion-wire magnetometer and compared with the calculated ones. The calculated value was also compared with that obtained by the conventional method. Although the recrystallized texture of the materials used is fairly widely disparsed, the torque curves agree with those calculated by the new method, with results better than by the conventional method.
In addition, some investigations are made on the pole-figure. To examine the symmetry of texture around RD and TD, four quadrants of the pole figure, which correspond to four oblique surfaces of each sample, were measured according to the method proposed by Lopata et al. It has been found that the textures of all samples used are symmetrical.View full abstractDownload PDF (892K) -
Setsuo Takaki, Hiroshi Morikawa, Youichi Tokunaga1983 Volume 47 Issue 9 Pages 788-794
Published: 1983
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe effect of Co addition to an Fe-13%Cr-5%Mo-10.5%Ni alloy on the strain-induced transformation was studied. All the alloys used have meta-stable austenitic structure after air cooling from a solution treatment temperature 1223 K, and transform to martensite during deformation at room temperature. By the addition of Co, Md temperature decreases by 8.4 K per 1%Co, and also the martensite morphology changes from lath to platelet.
The TRIP phenomenon of Fe-13%Cr-5%Mo-Ni-Co alloys with the mixed structure of age-hardened martensite (α′) and meta-stable austenite (γ) was also studied. The α′/γ ratio was controled by cold rolling after the solution treatment, and then the induced α′ was hardened by the succeeding aging of 773 K-18 ks. Therefore, the strength increment by the aging of this steels is in proportion to the martensite content. On the other hand, the elongation keeps a high value because of the TRIP of meta-stable γ. The TRIP, however, do not occur over a critical α′/γ ratio, resulting in the abrupt decrease in elongation. The critical value shifts to the lower side of α′/γ ratio with increasing stability of γ.View full abstractDownload PDF (1022K) -
Hisashi Suzuki, Motohiro Kanno, Takao Maeda1983 Volume 47 Issue 9 Pages 794-801
Published: 1983
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe half-softening temperature (TH) and the electrical resistivity of cold-rolled pure copper were studied in relation to the amount (\lesssim600 mol ppm) and the sorts of additive elements belonging to IIIb-VIb group in the periodic table. It was found that the additive such as In, Pb, Sn or Sb was effective for the sharp increase of TH even in the additional amount as small as 100 mol ppm. For the marked increase of TH, the additives with larger atomic radii compared with that of copper and with lower diffusion coefficients in copper matrix would generally be needed, because TH was suggested to be controlled by the migration rate of recrystallized grain boundaries, not by the recovery rate. It was noted that Linde’s rule is also applicable to cold-worked copper containing additives. As a result, highly heat-resisting and high conductivity copper (TH>550 K, and over 95% IACS) was found to be obtainable by the addition of In, Pb, Sn or Sb up to 200 mol ppm at most.View full abstractDownload PDF (1144K) -
Kiyoshi Sato, Takeo Yokobori, Hiroshi Igarashi, Shin-ichi Nishida, Hir ...1983 Volume 47 Issue 9 Pages 801-805
Published: 1983
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSFatigue properties (fatigue crack propagation behaviour, fatigue fracture toughness etc.) of weldments and the base metal in 5.5%Ni steel developed for low-temperature use were studied in the temperature range from 98 K to room temperature. The results obtained were compared with those in 780 MPa grade high strength tempered martensitic steel previously reported, and the influence of composition on fatigue properties at low temperature was discussed. Fatigue properties in 5.5%Ni steel weldments at low temperature are remarkably different from those in high strength steel. Fatigue properties at low temperature seem to be more material- and temperature-sensitive than static mechanical ones.View full abstractDownload PDF (542K) -
1983 Volume 47 Issue 9 Pages 806
Published: 1983
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSPlease see pdf. Wrong:[in Japanese], at% Right:[in Japanese], mass%View full abstractDownload PDF (16K)
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