Journal of the Japan Institute of Metals and Materials
Online ISSN : 1880-6880
Print ISSN : 0021-4876
ISSN-L : 0021-4876
Volume 45 , Issue 12
Showing 1-18 articles out of 18 articles from the selected issue
  • Shigenori Hori, Hideo Tai, Hiroaki Katayama
    1981 Volume 45 Issue 12 Pages 1223-1228
    Published: 1981
    Released: April 04, 2008
    JOURNALS FREE ACCESS
    Effects of certain solute elements on the recrystallization temperature of copper have been studied by X-ray, micro-hardness and electrical resistivity measurements. Specimens of copper alloys containing solute elements of 0.01–0.3 at% were melted and cast in vacuo, and cold rolled to 90% reduction. The recrystallization temperatures (the half softening temperatures) of these alloys were obtained from micro-hardness measurements after annealing for 7.2 ks at various temperatures.
    All solute elements raised the recrystallization temperature of copper with increase in their contents. The most pronounced influence on the recrystallization temperature was found to be associated with addition of elements which have the much larger linear size factor and the smaller maximum solid solubility. When the electrical resistivity change with cold rolling, ΔρW, was divided into the two parts of the decrement of resistivity during the recovery process. ΔρE, and the decrement during the recrystallization process, ΔρR, strong correlation between the recrystallization temperature and ΔρEΔρW was indicated. From these experimental results, the magnitude of the increase in the recrystallization temperature seems to be related to the binding energy of solute atoms with vacancy and dislocation.
    Download PDF (429K)
  • Ryuichi Ishizuka, Kazuo Akashi
    1981 Volume 45 Issue 12 Pages 1229-1235
    Published: 1981
    Released: April 04, 2008
    JOURNALS FREE ACCESS
    An attempt is made to apply an Ar-H2 (5–20 vol%) plasma arc to the selective smelting reduction of ilmenite. At the early stage in the melting operation, it was observed that molten fine iron particles (<φ1 mm) were dispersed in the product, due to the selective reduction of iron oxides contained in ilmenite. At the later stage, the fine particles grew to large spheres (φ8 mm), which may be caused by the cohesion process of the fine iron particles moving with a characteristic flow in the melt. The iron droplets were easily removed from a solidified product by hand dressing or magnetic separation. By this treatment, the iron content in the product decreased to less than 1%, while the titanium content increased to more than 60%, which was much higher than that of the initial sample (Ti: 33.4%, Fe: 29.6%).
    X-ray diffraction analysis revealed that the main component of the product was FeO·2TiO2-Ti3O5 type solid solution, and Ti2O3 solid solution including a very small amount of Ti3O5 was observed in the over-reduced products.
    In case of equivalent hydrogen added to the plasma, the percentage of hydrogen utilization in the smelting reduction was estimated to be about 62%.
    A rapid reduction of iron oxides, reduction of TiO2 to Ti2O3, and a high percentage of hydrogen utilization in this hydrogen plasma process, are attributed to a contribution of active hydrogen species to such reduction processes.
    Download PDF (838K)
  • Kozo Kitada, Fumiyoshi Miyashita, Giroku Miyatani, Toshio Miyake, Tuyo ...
    1981 Volume 45 Issue 12 Pages 1236-1243
    Published: 1981
    Released: April 04, 2008
    JOURNALS FREE ACCESS
    The reaction between chromium oxide and chromium carbide was caused in a high vacuum of 1.01–0.10 Pa at temperatures ranging from 1323 K to 1593 K. Mixture of 1 mol of Cr7C3 and 1 mol of Cr2O3 was prepared in a form of pellet and reduced under the above mentioned conditions. The results are as follows;
    (1) The reduction products of this reaction system were Cr23C6 and metallic chromium. At these experimental conditions, the reaction process producing Cr23C6 was assumed by considering possibility of uniform reaction model. However, the ensuing reaction process from the surface to the inside of the pellets formed metallic chromium. That means that the formed metallic chromium layer is considered to be caused by the topo-chemical reaction.
    (2) At the earlier stage of the reaction, a rate equation for interfacial reaction control was applicable to the formation of metallic chromium from Cr23C6, and moreover it was presumed that the reaction rate was controlled by the interfacial reaction, from the proportionality of the rate constant to the reciprocal particle diammeter of Cr7C3, but at the later stage of reaction, the rate determining step was obserbed to be the diffusion reaction.
    (3) Judging from the isothermal TGA and the formed metallic layer of section of pellets, the apparent activation energy was estimated to be 247–277 kJ/mol, from the Arrhenius plot under the interfacial reaction.
    (4) It may be concluded from the experimental results of this investigation that the chain reaction was controlled by supply of CO2 and CO gases.
    Download PDF (766K)
  • Koichi Arai, Akira Furukawa, Sumiko Sanuki, Toshio Izaki
    1981 Volume 45 Issue 12 Pages 1244-1250
    Published: 1981
    Released: April 04, 2008
    JOURNALS FREE ACCESS
    The reductive leaching reaction of manganese oxides in acidic cuprous chloride solutions was studied from both thermodynamic and kinetic points of view, carrying out the determination of the leaching rates, the measurement of rest potentials and so on. A rotating disc technique was empolyed in this study.
    Experimental results obtained are as follows:
    (1) The reductive leaching reaction of manganese oxides in acidic cuprous chloride solutions is expressed as:
    (This article is not displayable. Please see full text pdf.)
    \ oindentThe leaching rates were of the first oder with respects to the concentration of aqueous cuprous chloride, while no distinct dependence was observed for the acid concentration.
    (2) The reductive leaching rates of manganese oxides were influenced greatly by the stoichiometry of the ores. Reaction with manganese dioxide proceeds faster than that with Mn2O3 or Mn3O4. This tendency is explained thermodynamically by a decrease in driving force of the leaching reaction.
    (3) The overall reaction of reductive leaching of manganese oxides in acidic cuprous chloride solutions is controlled by a mass transfer of cuprous ions through a boundary layer between the acid solution and the surface of the ore.
    (4) The rest potentials of the manganese oxides were influenced greatly by the chemical composition of the ore and the hydrogen ions.
    Download PDF (532K)
  • Katsutoshi Ono, Yukitomi Ueda, Joichiro Moriyama
    1981 Volume 45 Issue 12 Pages 1251-1256
    Published: 1981
    Released: April 04, 2008
    JOURNALS FREE ACCESS
    Possibilities and conditions for preparing homogeneous Nb-W alloys by the carbothermic reduction-electron beam melting combination method have been examined with regard to the following items: (1) Determination of the relationship among the CO-pressure, the temperature and the concentration of carbon and oxygen in the Nb-W-C-O solid solutions by the low-pressure gas equilibrium method at 2173 K. (2) Simultaneous reduction of the Nb-W alloys from mixtures of constituent metal oxides, Nb2O5 and WO3, by carbon in vacuum at about 2200 K. (3) Elimination of carbon and oxygen in the carbon-reduced Nb-W alloys by the electron beam melting.
    In this process alloying would proceed and be completed at the first reduction stage. Subsequent melting in an electron-beam furnace lowers the carbon and oxygen contents to a commercial grade and consolidates the alloys into ingot. The evaporation deoxidation as in volatile oxides of niobium and tungsten plays an important role in this process.
    The purity and homogeneity of the alloys thus prepared have been assured to be a sufficient degree.
    Download PDF (508K)
  • Katsuyoshi Naganuma
    1981 Volume 45 Issue 12 Pages 1257-1262
    Published: 1981
    Released: April 04, 2008
    JOURNALS FREE ACCESS
    Effects of manganese and lead added to Cu-Zn alloys on the intensities of CuI (391.41 nm) and ZnI (481.05 nm) lines, and determinations of large amounts of zinc and lead in copper-base alloys were studied by using a Grimm glow lamp with anode inner diameter of 4.5 mm.
    Manganese and lead affect the intensities of CuI and ZnI lines; linear relations between the sputtering yield of copper and the intensity of CuI line for Cu-Zn-Mn and Cu-Zn-Pb alloys differ from that for Cu-Zn alloy, and the same are true for zinc. Furthermore, the addition of manganese to Cu-Zn alloy decreases the sputtering yield of the alloy. Zinc added to copper was determined over the concentration range 0 to 52 mass%Zn (Zn/Cu\fallingdotseq1.1) with a single working curve irrespective of the presence of manganese. The working curve of zinc for Cu-Zn-Pb alloys containing about 5 mass% of lead differs from that for Cu-Zn alloys. Lead was determined with a single working curve over the concentration range 0 to 14 mass%Pb (Pb/Cu\fallingdotseq0.2) in Cu-Zn-Pb alloys containing different concentrations of zinc. The concentration ratio of alloying element to copper must be taken as abscissa of the working curve when copper is used as an internal standard.
    Download PDF (854K)
  • Norihiko Fukatsu, Zensaku Kozuka
    1981 Volume 45 Issue 12 Pages 1263-1270
    Published: 1981
    Released: April 04, 2008
    JOURNALS FREE ACCESS
    The E.M.F. method using solid oxide electrolyte was applied to determine the sulfur activities for the Ag-S system. The oxygen partial pressures for the system equilibrated with the atmospheric pressure of SO2 were measured by the following galvanic cell:
    (This article is not displayable. Please see full text pdf.)
    The equilibrium sulfur pressures were calculated from the measured oxygen partial pressures using published data on the molar Gibbs energy of coexisting gas species.
    The activities of sulfur in the one-phase-melts or some two-condensed-phase equilibria were evaluated for the compositions up to 32 mol per cent S over the temperature range 867 to 1538 K.
    It was found that the sulfur activities for the equilibrium Ag (s)-Ag2S (s) were in good agreement with those reported by other investigators using the E.M.F. method with different electrolytes. The eutectic and the monotectic temperature estimated by the present activity measurements were found in good agreement with results of earlier works. The boundary of the miscibility gap in the liquid state, however, was found to extend a little wider in the low sulfur content region than that reported in the literature.
    The thermodynamic functions of liquid Ag-S solution were determined from the present results. These functions show that this solution behaves like a solution associated with the complex Ag2S.
    Download PDF (585K)
  • Hakaru Masumoto, Naoji Nakamura, Yuetsu Murakami
    1981 Volume 45 Issue 12 Pages 1271-1278
    Published: 1981
    Released: April 04, 2008
    JOURNALS FREE ACCESS
    The magnetic properties, the thermal expansion coefficient α, the electrical resistivity ρ and the hardness Hv have been studied for the Fe-<about 3 mass%Nb-20 mass%Co-<10 mass%W alloys and Fe-<about 5 mass%Ta-20 mass%Co-<10 mass%W alloys. All the alloys used in this study were water quenched from 1323 K, cold drawn by 97.2% reduction in area and subsequently reheated at 673-1273 K for the period less than 18 ks. The magnetic properties of the Fe-Nb-Co-W and Fe-Ta-Co-W alloys depend remarkably on the tungsten content, the reheating temperature and the reheating time. Among these properties, both BrBs and Hc increase particularly with increasing W content. The thermal expansion coefficient α shows a minimum at the composition of 3 mass%W in the former alloys and a maximum at 7 mass%W in the latter alloys, respectively, and these values are less than 10×10−6 K−1. With increasing W content in both of these alloy systems, ρ and Hv increase monotonically for the most part. When water quenched, cold drawn and subsequently reheated at 973 K for 18 ks, an Fe-about 2 mass%Nb-20 mass%Co-5 mass%W alloy exhibits the following values: B8=1.97T at 8 kA·m−1, Br=1.85T, BrB8=0.94, Hc=1.84 kA·m−1, \sqrt(BH)maxBrHc=0.94, α=9.8×10−6 K−1 at 273–313 K, ρ=0.263 μΩ·m and Hv=404. Also, an Fe-about 3 mass%Ta-20 mass%Co-5 mass%W alloy exhibits: B8=2.02T, Br=1.89T, BrB8=0.94, Hc=2.03 kA·m−1, \sqrt(BH)maxBrHc=0.94, α=9.3×10−6 K−1, ρ=0.234 μΩ·m and Hv=446.
    Download PDF (912K)
  • Shuji Hanada, Sadao Watanabe, Takashi Sato, Osamu Izumi
    1981 Volume 45 Issue 12 Pages 1279-1284
    Published: 1981
    Released: April 04, 2008
    JOURNALS FREE ACCESS
    Magnetic heads made of Sendust alloy head cores (standard chemical composition: Fe-9.6 wt%Si-5.4 wt%Al) are known to have superior magnetic properties and wear resistance. The cores are usually made by mechanical working, such as slicing and grinding since the alloy is so hard and brittle that it has been believed to be difficult to make head cores by plastic deformation. In the present work, plastic deformability of the alloys was investigated by compressive tests on Sendust single crystals at temperatures between room temperature and 1173 K and various strain rates. Main results are summarized as follows.
    The operative slip systems are {110}⟨111⟩ and {112}⟨111⟩ depending on compressive axis. Therefore, the von Mises criterion for a polycrystalline material to deform plastically by slip within grains is satisfied, indicating that the brittleness of Sendust alloys cannot be explained by the number of independent slip modes available. At room temperature the stress-strain curve exhibits three stages in a similar manner to Fe3Al and Fe3Si with DO3 structure.
    Above the temperature where yield stress decreases abruptly, the steady state deformation takes place. Under the condition of the steady state deformation, the strain rate is represented by the relationship of \dotε=Bσnexp(−QkT), where n=4.6 and Q=540 kJ/mol. These results suggest that even a polycrystalline material of Sendust alloy may be deformable under the suitable conditions.
    Download PDF (908K)
  • Shuji Hanada, Takashi Sato, Sadao Watanabe, Osamu Izumi
    1981 Volume 45 Issue 12 Pages 1285-1292
    Published: 1981
    Released: April 04, 2008
    JOURNALS FREE ACCESS
    Based on the previous result that the steady state deformation is observed in the Sendust single crystals, deformation behaviors of Sendust polycrystals were investigated in compressive tests at various temperatures and strain rates.
    The steady state deformation occurs at high temperatures and low strain rates. Under the conditions, the strain rate is represented by the relationship of \dotε=Bσnexp(−QkT), where n=4.3 and Q=360 kJ/mol. Compared with the values obtained on Sendust single crystals, n is nearly equivalent but Q is considerably lower. Sendust polycrystals can be plastically compressed to high strain under the conditions where the steady state deformation occurs. After the deformation, fine recrystallized grains are formed at original grain boundaries, and sub-boundaries and dislocation networks are observed within original grains. The steady state deformation of Sendust polycrystals is controlled by grain boundary sliding, grain boundary migration and dynamic recrystallization. On the contrary, the steady state deformation of Sendust single crystals can be explained in terms of the recovery-controlled mechanism.
    Download PDF (1933K)
  • Shuji Hanada, Takashi Sato, Sadao Watanabe, Osamu Izumi
    1981 Volume 45 Issue 12 Pages 1293-1299
    Published: 1981
    Released: April 04, 2008
    JOURNALS FREE ACCESS
    It has been revealed in previous papers that under the conditions where the steady state deformation is observed, Sendust alloys can be plastically deformed to high strain without cracks in compressive tests. In this study, deformation behaviors of Sendust polycrystals were investigated by the experiments that tensile stress was predominantly applied, such as bending tests and tensile tests.
    In the diagram showing the relation between the logarithm of the cross head speed and the reciprocal of the absolute temperature in bending tests, a straight line is obtained as the critical conditions of the ductile-brittle transition of deformation.
    Below 800 K, cleavage fracture is dominant independent of the deformation conditions. Above 900 K, either cleavage fracture or grain boundary fracture is observed depending on the deformation conditions.
    By extrapolating the straight line of critical conditions of ductile deformation to a higher strain rate region, the optimum condition of hot rolling or forging can be determined.
    Download PDF (1390K)
  • Yoshitake Nishi, Kenji Suzuki, Tsuyoshi Masumoto
    1981 Volume 45 Issue 12 Pages 1300-1305
    Published: 1981
    Released: April 04, 2008
    JOURNALS FREE ACCESS
    The purpose of the present work is to evaluate the glass forming ability of iron-based alloys containing phosphorus, carbon and boron by measuring the critical cooling rate for glass formation. Measurments of the quenching rate from melt are made by using a modified piston-anvil type equipment. The cooling rate to obtain a perfectly amorphous phase is determined from the examination of the microstructure of a quenched sample by X-ray analysis. The degree of supercooling resulting from the measurements revealed that it is a practical quantitative indicator by which critical cooling rates can be estimated. The minimum critical cooling rate is obtained at about 20 at% metalloids for Fe-P and Fe-B alloys. The correlation of metalloids to the critical cooling rate of iron is obtained for Fe-20 at% metalloids alloys. Glass formation of iron-metalloids alloys is affected mainly by the liquidus temperature and the viscosity of supercooled liquid, using calculated TTT curves. Finaly the effect of metalloid elements on the glass forming ability of iron is discussed from the stand point of interaction of atoms in liquid.
    Download PDF (469K)
  • Teruo Kishi, Akira Nozue
    1981 Volume 45 Issue 12 Pages 1305-1309
    Published: 1981
    Released: April 04, 2008
    JOURNALS FREE ACCESS
    Fracture toughness test for AISI 4340 steel is carried out, and the fracture surfaces are analysed, of which patterns consist of ductile dimple patterns and brittle intergranular (IG) cracking induced by hydrogen. The purpose of this paper is to reveal the correlation between IG cracking unit during stable crack growth and acoustic emission (AE) characteristics. It would be concluded that the dominant sorce of AE is attributed to the microscopic IG fracture, from the significant experimental results that the AE event count is propotional to the number of the microscopic IG cracking, and that the AE energy is propotional to the area of the individual IG cracking.
    Download PDF (382K)
  • Michihiko Nagumo, Katsuyoshi Miyamoto
    1981 Volume 45 Issue 12 Pages 1309-1317
    Published: 1981
    Released: April 04, 2008
    JOURNALS FREE ACCESS
    The microscopic process of void formation and propagation has been investigated in hydrogen embrittlement of iron. Specimens of pure iron in bamboo structure as well as polycrystalline specimens were tested in tension under cathodic hydrogen charging in 3%NaCl aq. at a current density of 100 A/m2. Origins of fractographic features of hydrogen embrittlement were analyzed and interpreted by making correspondence to the structures developed within the specimens. Main results are as follows:
    (1) Initiation and propagation of voids take place along deformation bands of which orientations coincide with the traces of slip planes. Microvoids in array were observed within dislocation cell bands and along cell walls.
    (2) Units of fracture surface are areas bordered by deformation bands. Fine patterns on the fracture surface result from multiple slip band clusters.
    The above features have been discussed and a kinematic model has been proposed for hydrogen embrittlement of iron. It has been shown that hydrogen transported by dislocations can produce sufficient supersaturation at deformation bands, where glide of dislocations on primary slip planes is blocked, and can stabilize elastic microcracks which will successively extend plastically and link together.
    Download PDF (1778K)
  • Itsuo Ishigami, Eiji Tsunasawa, Kyuhiko Yamanaka
    1981 Volume 45 Issue 12 Pages 1318-1326
    Published: 1981
    Released: April 04, 2008
    JOURNALS FREE ACCESS
    Austenitic stainless steels (SUS 304 and 316) and a martensitic stainless steel (SUS 440C) were heated at temperatures from 900 to 1250°C (1173–1523 K) for the period of time up 300 min (0–18 ks) in a vacuum of 5.33 Pa. The steels heated were die cooled in the vacuum to prevent their surfaces from being stained with quenchants. Surface brightness was measured by use of an optical microscope equipped with a silicon photocell. Excess increases in temperature and/or time give rise to a deterioration in the brightness. A comparison of the surface appearance with the corresponding brightness shows that the deterioration results from occurrence of the following surface roughening: (1) relief formed by martensitic product on SUS 304 and 440C; (2) boundary groove on all the steels; (3) twin groove on SUS 304 and 316; (4) crevice at carbide-matrix interface and void brought about by disappearance of carbide due to growth of crevice on SUS 440C. Above all, the relief formed by martensitic products markedly deteriorates the brightness. In the case of the metastable austenitic stainless steels, SUS 304, evaporation of Cr and Mn induces the martensitic transformation in its surface layer. On the contrary, in the case of SUS 316, the transformation did not occur in spite of the evaporation at least under the present heating conditions. This is attributed to the natural stability of its austenite. No evaporation serves the obstruction or the suppression of all the above surface roughening and hence offers the excellent brightness to the stainless steels.
    Download PDF (1284K)
  • Tomei Hatayama, Osamu Izumi
    1981 Volume 45 Issue 12 Pages 1326-1332
    Published: 1981
    Released: April 04, 2008
    JOURNALS FREE ACCESS
    Tensile tests were carried out to investigate deformation behaviours of specimens with various shapes of pre-existing non-uniformities. The results are summarized as follows: (1) The deformation behaviours of the specimens depend not only on the initial ratio of minimum/maximum cross-sectional area (initial inhomogeneity factor α0) but also on the initial length of non-uniform region (l0). The reduction of the inhomogeneity factor with strain increases with increasing l0. (2) It is observed that the area-reduction rates of non-uniform region to that of uniform region (\Dot{A}n⁄\Dot{A}u) is less than 1 even if m<1, which is contrary to the expectation from the Backofen’s or the Hart’s analysis where \Dot{A}n⁄\Dot{A}u>1 for m<1. (3) It is shown that ΔA (the difference in cross-sectional area between uniform and non-uniform region) and Δ\Dot{A} cannot be connected directly with the uniformity of deformation. Therefore, it is not reasonable to use the Hart’s parameters for the evaluation of uniformity of deformation. (4) The boundary between non-uniform and uniform regions moves like Lüder’s front during deformation, which suggests strong force to act on the boundary. (5) It is pointed out that the fracture strain is controlled by the final value of α, the fracture diameter Df and the length of necking l0, so that the importnat is to find out the effects of m-value on α, Df and l0.
    Download PDF (599K)
  • Tomei Hatayama, Osamu Izumi
    1981 Volume 45 Issue 12 Pages 1332-1337
    Published: 1981
    Released: April 04, 2008
    JOURNALS FREE ACCESS
    A plastic instability (necking) occurs due to a local deviation of strain rate from a given strain rate. Energy barrier for the deviation was investigated, and was related to the strain rate sensitivity index m. The results are as follows: (1) The value of M*(=m2) shows the normalized energy barrier by the driving energy for a local necking. The uniform strain increases with increasing m-value. (2) m-value shows the normalized interaction force between Si and Q, by the driving force for the local necking where Si is the element of a local necking and Q is the outside of it. (3) The dependence of flow stress on strain is closely related to the distribution curve of m-value to strain rate. When J=∂m⁄∂ln\dotε>0, the stress-strain curve shows strain-hardening, when J<0, it shows strain-softening and when J=0, it shows constant flow stress. (4) Fracture occurs at the strain rate where the energy barrier for the local necking does not exist, that is, when the local strain rate reaches the strain rate of m=0 in the higher strain rate side.
    Download PDF (466K)
  • Yoshiaki Iijima, Kazutomo Hoshino, Ken-ichi Hirano
    1981 Volume 45 Issue 12 Pages 1338-1339
    Published: 1981
    Released: April 04, 2008
    JOURNALS FREE ACCESS
    Download PDF (190K)
feedback
Top