All issues
Volume 38, Issue 8
Displaying 1-18 of 18 articles from this issue
- |<
- <
- 1
- >
- >|
-
Kenji Okazaki, Yoichi Eguchi, Kenji Senba, Koji Tanoue1974 Volume 38 Issue 8 Pages 675-682
Published: 1974
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSRecrystallization of sintered molybdenum and electron beam melted molybdenum occurred at the temperature where the maximum on the temperature derivative of the hardness was observed. The time law of grain growth can be written as
(This article is not displayable. Please see full text pdf.)
where the constant n for the sintered Mo is larger than that for the melted Mo. The apparent activation energy Q for grain growth is smaller in the longitudinal direction than in the transverse direction of the specimen in both materials. The grain growth rate in sintered Mo is smaller than that in the melted Mo, which is probably due to the influence of voids inherited from sintering powder in the former material. The relation between the hardness and flow stress at 8% strain is given by
(This article is not displayable. Please see full text pdf.)
Here the proportionality constant α for the sintered Mo is smaller than that for the melted Mo. This is presumably because that voids in the sintered Mo act as an obstacle to dislocation motion and thereby raise the work hardening rate.View full abstractDownload PDF (730K) -
Keiichi Iida, K\={o}ji Honma, Hideo Okazaki1974 Volume 38 Issue 8 Pages 682-688
Published: 1974
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSX-ray diffraction experiments of α-Ag2S1−xTex (x=0.2∼0.8) have been carried out at room temperature by the use of a step scanning method to study the distribution of cations in the so-called “averaged structure”. CuKα-radiation was used in the small region of s, defined as s=2sinθ⁄λ, and MoKα in the large one. The X-ray profiles show a remarkable oscillatory background together with Debye lines due to the regular arrangement of anions. On the assumption that Ag ions are randomly distributed, this oscillation can be separated into two partial interference functions, aAg-Ag(s) and aAg-anion(s), in a similar way to that for liquid binary alloys. Two partial radial distribution functions, gAg-Ag(r) and gAg-anion(r), were also obtained from the partial interference functions. From the above analysis, the following information has been obtained.
(1) Mean distance between Ag and anion is smaller than that between Ag and Ag. This is physically reasonable.
(2) gAg-Ag(r) shows a similar curve to that for liquid metals, indicating that Ag ions are randomly distributed. However, the sharp first peak observed in gAg-anion(r) shows that localization of Ag ions in a narrow region around the anion. The behavior of g(r) in the region of large r is close to that of liquid metals.
(3) Coordination number nAg-anion, estimated from 4πr2ρ0gAg-anion, is 8.0. This value seems to be reasonable in terms of the arrangement of anions occupying bcc sites. On the other hand, nAg-Ag shows some scatter by the method of calculation, as in the case of liquid metals.View full abstractDownload PDF (527K) -
Oxidation Kinetics and Scale Structures of Co-Ni Alloys in the Temperature Range from 1000 to 1200°CKeizo Nishida, Toshio Narita, Norio Ohya, Tadaharu Yamauchi1974 Volume 38 Issue 8 Pages 688-697
Published: 1974
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSCo-Ni alloys over the whole composition range were oxidized in the temperature range from 1000 to 1200°C under 1 atm of pure oxygen, and kinetics, internal oxidation, surface morphology, and concentration profiles in the cross-section were clarified by means of thermogravimetry, X-ray diffraction, optical microscopy, and electron probe microanalysis.
Results obtained are as follows:
(1) Oxidation was measured by batch-type measurements of weight gain and scale thickness. Both of the rate constants were exponentially changed with nickel contents in the alloy and the scale. Accordingly, the over-all oxidation rates seemed to be determined by cation diffusivities which decreased with increasing NiO content in the oxide.
(2) The grown oxide was mainly the solid solution of CoO and NiO, except for the precipitation of Co3O4 particles in high Co-Ni alloys.
(3) In all cases, NiO and CoO were found to concentrate in the alloy-scale and scale-gas interfaces, respectively.
(4) Concentration profiles in the scale and an alloy substrate were shown by one master curve at a specified temperature when the concentration was plotted against x⁄\sqrtt. This result shows that the concentration profiles are determined by the diffusion process in both of the scale and the alloy.
(5) Internal oxidation and Co-depletion in the alloy substrate were found in the nickel-rich alloys, resulting in the enrichment of CoO in the scale. The growth rate of the Co-depletion zone depended not on the alloy composition but on the temperature, and its activation energy was about 72 kcal/mol which is close to those of oxygen- and inter-diffusivities in the Ni-Co alloys.
From the results of the present and other authors’ studies, the composition-temperature diagram of the oxidation behaviors was schematically shown.View full abstractDownload PDF (1235K) -
Kyoko Fujii, Toshio Katagiri, Shun Araki1974 Volume 38 Issue 8 Pages 698-702
Published: 1974
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSOxidation behaviors of FeB and Fe2B layers formed on pure iron by gas boronizing were studied in air at high temperatures by the measurements of weight gain, X-ray diffraction, infrared spectroscopic analysis and microscopic examinations.
Main results obtained are as follows.
The results of infrared spectroscopic analysis showed that the B2O3 phase was produced principally on the surface due to preferential oxidation of boron in the boronized layer in the temperatures range between 650 and 850°C. X-ray diffraction lines similar to the α-Fe were detected from the inner layer formed at the same temperatures.
At temperatures higher than 850°C the layer structures were not found, but Fe(BO2)2, Fe2O3, and Fe3O4 were observed as the oxide scale simultaneously with the formation of B2O3 and α-Fe.
It was observed from the determination of weight changes that the oxidation rate of boronized iron decreased in comparison with that of pure iron and an intermittent weight loss was caused by imperceptible effervescence of B2O3 formed on the surface. These data show that the oxidation resistance of the boride layer at high temperatures should not be persistent.View full abstractDownload PDF (686K) -
Toshiyuki Hirano, Masaharu Yamaguchi, Toshimi Yamane1974 Volume 38 Issue 8 Pages 703-708
Published: 1974
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSTensile tests of grain refined Fe-Ni and Fe-Cr alloys were carried out in the strain rate range 10−4 min−1∼10−1 min−1 in order to measure the strain rate sensitivity, m, in the α single phase, (α+γ) two-phase and γ single phase regions. The effect of the two-phase structure on the superplasticity was discussed.
The largest value of m was obtained at a strain rate lower than \dotε=10−3 min−1 and in the (α+γ) two-phase region. In the (α+γ) two-phase region m depends strongly on strain rate, grain size and in particular the volume fraction of the γ phase, Vγ. The m value reached its maximum at the temperature corresponding to Vγ=0.5. Them value was also found to have a strong dependence on the metallographical characteristics of grain boundary.View full abstractDownload PDF (848K) -
Koh Matsumura, Kazuo Tsuruoka1974 Volume 38 Issue 8 Pages 708-715
Published: 1974
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSIn order to evaluate the influence of precipitates on grain boundary migration quantitatively, the rate of normal grain growth of 3% silicon-iron containing aluminum nitrides was investigated.
The 3% silicon-iron ingots containing different amounts of aluminum and nitrogen were prepared by vacuum melting. These ingots were forged and hot-rolled to plates 2 mm in thickness, then the plates were cold-rolled to 0.5 mm in thickness. After decarburizing the specimens at 700°C in wet hydrogen, the rate of normal grain growth during isothermal annealing at 800, 850 and 900°C were measured.
The size and distribution of aluminum nitrides in the specimens after annealing at 700 to 900°C depend on the concentration of solute nitrogen in the raw materials during heating before hot rolling. The rate of normal grain growth was controlled by the distribution of precipitates. When the precipitates were more dense, the rate of normal grain growth became slower. Values of activation energy Qg and activation free energy ΔFa for grain boundary migration were the same in all specimens, which were 65 and 34 kcal/mol respectively. The difference in the rate of normal grain growth could be explained in terms of the difference in the driving free energy ΔF which depended on the distribution of precipitates. In order to modify the Zener’s theory more quantitatively, a new equation was derived by considering the Ostwald growth of precipitates. The rate of normal grain growth measured coincided with the theoretical values calculated from the equation.View full abstractDownload PDF (748K) -
Yasunori Taga, Akio Isogai, Koichi Nakajima1974 Volume 38 Issue 8 Pages 716-719
Published: 1974
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSChanges in the composition and structure of Cu-5 wt%Sn alloy due to friction or heating were examined by means of Auger electron spectroscopy.
It was found that the intensities of Auger spectra of Sn in the surface layer increased rapidly by friction or heating in vacuum, and that after heating at 300°C for 30 min, their maximum was about 40% of that from pure Sn. Similar change was observed on the surface abraded in the atmosphere, resulting in the formation of a Sn-rich layer just below the surface.View full abstractDownload PDF (329K) -
Takeo Yokobori, Tamio Aizawa1974 Volume 38 Issue 8 Pages 720-724
Published: 1974
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSIn the present article, the influence of the temperature and the stress intensity factor upon both the striation spacing and the fatigue crack propagation rate, dC⁄dN, in the same materials has experimentally been studied, in order to get similarity and dissimilarity between them. The material used is 2024-T 3 Aluminum alloy. The results show that both dC⁄dN and the striation spacing are in good agreement with the Arrehenius type equation within the range of the temperature and stress intensity factor tested. It is to be noted that apparent activation energies are nearly equal between them at a higher level of stress intensity, although in this range dC⁄dN and striation spacing are not equal.View full abstractDownload PDF (591K) -
Nobuhiro Iguchi, Yoshiki Oka, Yasunori Saotome1974 Volume 38 Issue 8 Pages 725-730
Published: 1974
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSIn the present investigation the transformation superplasticity in a commercial grade pure-iron has been studied by using a specially designed apparatus.
The main results obtained are as follows:
(1) The transformation superplastic phenomenon in pure-iron was observed in the range of 910 to 1100°C under a rapid heating and cooling cycle.
(2) The strain rate (\dotγ) due to transformation superplasticity was detected to be variable in this temperature range. The maximum strain rate (\dotγmax) was observed just about 910°C which might be the temperature of initiation of phase transformation.
(3) The total strain per cycle was proportional to the flow stress in the lower stress range.
(4) The flow stress characterized by superplasticity in pure-iron was dependent on heating rate. This dependence on heating rate might be similar to that on grain size in the micro-grained superplasticity.
From these experental results, the mechanism of transformation and transformation superplasticity would be of great use for further studies on the interface behavior at the α⁄γ interface and for the approach based on the rapid heating transformation theory.View full abstractDownload PDF (497K) -
Kohji Kawahara1974 Volume 38 Issue 8 Pages 731-736
Published: 1974
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe relations between directions of cold rolling and the of hot rolling for the appearance of ridging have been studied, by using the pole figure method, microscopic observation, tensile deformation, and measurement of surface roughness. Hot rolled plates 4 mm in thick were cold-rolled to 90% reduction at different angle of 0°, 30°, 45°, 90° to the direction of hot rolling. The plates were then heat treated at 700°C for one min; this treatment imparted much softness and little changes to their rolling textures. These plates were finally subjected to 20% elongation.
It was found that the appearance and magnitude of ridging was governed as a function of the angles between the two rolling directions; with an increase of the angle, the ridging decreased and completely disappeared at 90°. It should also be noted that the ridging phenomena in this instance were independent of the rolling textures or the microscopic structures, because the textures or structures of the plates were essentially equivalent to one another at 90% reduction.
These results are significant for elucidating the mechanism of ridging, and other factors except the rolling textures should be required to account for the ridging phenomena.View full abstractDownload PDF (1026K) -
Kimitaka Sato1974 Volume 38 Issue 8 Pages 736-742
Published: 1974
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSAn investigation was made of the influence of minerals having water of crystallization on X-ray fluorescence analysis of iron ores using a briquetting technique. An electron microscope, a derivatograph, an infrared spectrometer and an X-ray diffractometer were used together with a fluorescent X-ray spectrometer in this investigation. The results obtained are summarized as follows: (1) The weight of iron ore reasonably decreases by grinding it for about 10 min. The weight loss gives a considerable influence on the fluorescent X-ray intensity of iron in iron ore. The analytical precision can be greatly improved by correcting the fluorescent X-ray intensity with the weight loss. (2) The minerals having water of crystallization like goethite (α-Fe2O3·H2O) and kaolinite (Al2O3·2SiO2·2H2O) are dehydrated by grinding iron ores for about 10 min. (3) Against the dehydration, cobalt (Co2O3) is fairly effective as an internal standard for the X-ray fluorescence analysis of iron in iron ores. The internal standard material (Co2O3) must be added into iron ores before grinding for its better performance.View full abstractDownload PDF (794K) -
Tadashi Takemoto, Shigenori Hori1974 Volume 38 Issue 8 Pages 743-748
Published: 1974
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSAging effects on the stress corrosion cracking of Cu-4%Ti alloy were investigated, where aging temperature was fixed at 450°C. Specimens were subjected to a uniaxial tensile load in aqueous ammonia containing cupric complex ions. We obtained the following results.
Stress corrosion lives were strongly dependent on the aging time and the minimum life was obtained in the specimen aged about 1 hr. From the microscopic observation only intergranular cracks were found in as-quenched specimens, but inter- and transgranular cracks were found in aged specimens. Stress corrosion lives, in all specimens, were predominantly controlled by propagation of intergranular cracks.
For the dislocation structures after tensile deformation, planar arrays were not observed in the as-quenched specimen, but in the aged specimens. These planar arrays of dislocations could be assigned to the high susceptibility of the aged specimens, but they could not account for the differences of stress corrosion lives with aging time. Therefore, the high stress corrosion susceptibility of this alloy seems to be related to the modulated structure formed during the aging process.
Discontinuous pricipitates in the aged specimens acted as arresters against the propagation of stress corrosion cracks.View full abstractDownload PDF (882K) -
Hakaru Masumoto, Showhachi Sawaya, Michio Kikuchi1974 Volume 38 Issue 8 Pages 749-752
Published: 1974
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSYoung’s modulus, thermal expansion, magnetic susceptibility and electric resistivity at −150∼400°C, and hardness at room temperature have been measured for annealed Mn-Ge alloys. It has been found that Mn-5.0∼28.9%Ge alloys slow-cooled after heating at temperatures 100°C lower than the solidus have distinct anomalies corresponding to antiferromagnetic Néel points on the Young’s modulus vs temperature curves. The curve of temperature coefficient of Young’s modulus at room temperature vs composition exhibits a minor positive maximum at the concentration of 20.0%Ge, thus showing the Elinvar property in this alloy system.View full abstractDownload PDF (265K) -
Y\={o}ichi Ono, Sh\={u}ji Matsumoto1974 Volume 38 Issue 8 Pages 752-757
Published: 1974
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSDiffusion coefficients of chromium, manganese, and nickel in molten iron have been measured by the diffusion-couple technique at 1550 and 1600°C in the composition range of up to about 5 per cent.
(1) Experimental diffusion coefficients of Cr, Mn, and Ni in molten iron are as follows:
(This article is not displayable. Please see full text pdf.)
(2) A correlation has been found between the diffusivity Dj and the standard free energy of solution ΔFj0 for the elements dissolved in molten iron, i.e., the diffusivity Dj increases with an increase of ΔFj0.
(3) Comparison of the above-mentioned finding with the previous results on the diffusion in molten carbon-saturated iron has revealed that the same functional relationship may be assumed between the diffusivity and the standard free energy of solution, irrespective of whether or not carbon is contained.View full abstractDownload PDF (481K) -
Kunihiko Mimura, Osamu Okuno, Ishi Miura1974 Volume 38 Issue 8 Pages 757-761
Published: 1974
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSCarbon fiber/Al composites were fabricated by vacuum hot pressing and their mechanical properties were measured. In order to improve bonding and wetting in the carbon fiber/Al interface and to avoid the formation of aluminium carbide, chemical deposition of copper was applied to carbon fiber surfaces. Moreover, to align carbon fibers in Al matrix, pre-preg sheets of plasma sprayed monolayer carbon fiber/Al foils were used. The results were as follows:
(1) The tensile strength of composites containing 10∼15 vol% carbon fiber was close to the theoretical values (23∼32 kg/mm2), but that for 20∼40 vol% carbon fiber was 50∼70% of these values (35∼48 kg/mm2).
(2) Damage of carbon fibers seems not to be observed by electron probe microanalysis, microscopic examination and scanning electron microscopic examination.View full abstractDownload PDF (749K) -
Tatsuhiko Ejima, Kazuyoshi Shimakage, Tatsuya Muto, Tadahito Sudo1974 Volume 38 Issue 8 Pages 761-770
Published: 1974
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe behaviors of some addition agents on the zinc electrodeposition were investigated with the aid of the cathodic polarization measurements by the galvanostatic method and microscopic observations of the deposit on the zinc surface. Gelatin, peptone, glycine, glycylglycine, m-cresol and β-naphtol were used as the organic addition agents. The experimental results obtained are surmmarized as follows:
(1) Gelatin and peptone in an electrolyte containing cobalt of 1 mg/l reduced the critical current density and refine the grain size of the zinc deposited. The crystal growth of zinc electrodeposition is modified by the addition of these agents due to the adsorption of colloidal molecules at the growth sites on the cathode surface.
(2) Glycine and glycylglycine show only a small effect on the cathodic polarization curves for the zinc electrodeposition.
(3) The behavior of m-cresol in the zinc electrodeposition is similar to that of β-naphtol by the addition of these agents and the critical current density decreases with increasing concentration. The effect may be attributed to the adsorption on the cathode surface with the formation of complex ions. Zinc particles deposited by the addition of m-cresol show pyramidal crystal growth.
(4) The role of the organic addition agents in an electrolyte varies effectively with the existence of impurity ions such as cobalt ions.View full abstractDownload PDF (1570K) -
Hitoshi Tobe, Nobuyuki Morito, Kiyoshi Monma, Wataru Suëtaka1974 Volume 38 Issue 8 Pages 770-776
Published: 1974
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe corrosion inhibition of copper by benzimidazole (Bzd) was investigated by means of infrared and visible absorption spectroscopy and polarization measurement. The polarization curve of copper electrode in 3% NaCl aqueous solutions with or without Bzd indicated that in neutral solutions Bzd acted as an effective corrosion inhibitor for copper. The infrared spectra of the surface film formed on copper surface in neutral solutions showed that the film consisted of bis(benzimidazolato)copper(II) polymer. The use of polarized beam revealed that the film was compact and adherent to the metal surface, suggesting that the inhibition is due mainly to the formation of a protective polymer film.
The film formed on the copper surface in slightly acidic (pH: 5.0) solutions was porous and not adherent to the metal surface, yielding poor inhibition of corrosion. The spectra of the porous film showed that the film did not consist of bis(benzimidazolato)copper(II) polymer, but contained copper(II) ions having neutral Bzd molecules as ligands.
Benzotriazole is an effective corrosion inhibitor for copper also in weakly acidic solutions in which Bzd plays as a poor inhibitor. The superiority of benzotriazole as inhibitor over Bzd can probably be ascribed to the acidity of the former which is stronger than that of the latter. Benzotriazole, owing to its stronger acidity, produces a protective film of a copper complex polymer also in acidic solutions where Bzd dose not.View full abstractDownload PDF (526K) -
Takeo Yokobori, Hashime Shimura1974 Volume 38 Issue 8 Pages 777-778
Published: 1974
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSDownload PDF (376K)
- |<
- <
- 1
- >
- >|