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Volume 38, Issue 6
Displaying 1-16 of 16 articles from this issue
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Masaharu Tokizane, Masakazu Shishido, Imao Tamura1974 Volume 38 Issue 6 Pages 475-481
Published: 1974
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe aging behavior of a ferritic Fe-2.5 at%Ni-7.5 at%Al alloy was investigated by means of electrical resistivity and specific heat measurements, electron microscopy and Mössbauer spectroscopy.
A different tendency in the resistivity change was observed by isothermal aging above and below 600°C. Electron microscopic examination and Mössbauer studies suggest that isothermal aging process of this alloy at a comparatively low temperature such as 550°C is a complex process consisting of two stages; the precipitation of an ordered aluminum rich zone (Al-ORZ) at the earlier stages, and the precipitation of a stable NiAl (CsCl-type) phase at the later stage. On the other hand, above 600°C, each isothermal aging run could be explained as a simple precipitation process of a stable NiAl phase. The Al-ORZ may be the (Fe, Ni)Al phase with the CsCl-type structure which was proposed by Hornbogen et al. as the α″-phase.
Reversion of the Al-ORZ was recognized by reaging at a higher temperature; the zone can be regarded as a metastable phase which can be distinguished from the stable NiAl phase. It seems likely, however, that this Al-ORZ act as nucleus for the precipitation of the stable NiAl phase.View full abstractDownload PDF (1022K) -
Noboru Komatsu, Mikio Obayashi, Junji Endo1974 Volume 38 Issue 6 Pages 481-486
Published: 1974
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe boronizing method using a ferroboron and alkali-metal carbonate mixture was reported in a previous paper. The disadvantage which entails this method was deformation caused by thermal strain due to the use of a high temperature above 900°C. In this paper, a pack boronizing method using a ferroboron and KBF4 powder mixture is studied to remove this defect by lowering the processing temperature.
The main results obtained can be summarized as follows:
(1) The optimum range of KBF4 content is 5∼20 wt% to obtain a thick and dense boride layer with the hardness of MHv 1300∼1800.
(2) The boride layer, thick enough for practical use, is obtained even at a temperature below 700°C.
(3) The boride layer formed on steel consists of FeB and Fe2B. Enrichment of Si and formation of an iron-borocarbide-like compound are observed at the interface zone of the substrate.View full abstractDownload PDF (1002K) -
Takehiko Itagaki, Renpei Yoda1974 Volume 38 Issue 6 Pages 486-492
Published: 1974
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe effect of palladium on the sintering and oxidation behavior of tungsten-chromium alloys has been investigated and compared with that of nickel which is an effective activator for the sintering of tungsten. The specimens contain 10∼20% chromium and 0.1∼2% palladium and 0.1∼2% nickel. Both palladium and nickel accelerated the sintering of tungsten-chromium as well as the sintering of tungsten. Palladium was more effective in activating the sintering than nickel.
Tungsten-chromium-palladium alloys when oxidized in 750 mmHg at 1000°C were covered by a protective oxide layer which consisted of only Cr2O3, whereas tungsten-chromium and tungsten-chromium-nickel alloys showed no oxidation resistance and their oxide layers consisted not only of Cr2O3 but also of many tungsten oxides.View full abstractDownload PDF (1175K) -
Masaaki Fukuchi, Katsuya Watanabe1974 Volume 38 Issue 6 Pages 492-498
Published: 1974
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSIt is known that the compositional defects and thermal defects play a significant role in the high temperature properties of an intermetallic compound which exists over a wide range of composition. The present investigation was undertaken to study the effects of these defects on properties of the γ-phase in the Cu-Al system. The lattice parameter, absolute thermoelectric power, electrical resistivity and hardness were measured at various temperatures as a function of the composition. The results are summarized as follows:
(1) When the aluminum content was increased, the type of compositional defect of the γ-phase appeared to undergo a change from a substitutional to a vacancy type.
(2) The maximum of thermo-electromotive force was found to shift to the side of less aluminum content with increasing temperature. This shows that in the high temperature region the vacancy defect structure replaced the substitutional one at less aluminum content.
(3) The anomalies observed on the temperature dependence of lattice constant and resistivity took place owing to a clustering reaction of a large number of vacancies formed at elevated temperatures.
(4) The softening temperature of hardness was found to correspond well to the temperature of anomalies of resistivity and lattice constant in the compositional range studied.View full abstractDownload PDF (659K) -
Tatsuhiko Tanabe, Tadatsune Okubo, Isao Gokyu1974 Volume 38 Issue 6 Pages 499-504
Published: 1974
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSTaking the deformation mechanism and texture of titanium sheet into account, yield criteria and the stress-strain relationship were obtained. The results obtained by the tensile test in the plane of the sheet were analyzed using these criteria and relationship. The results were as follows.
(1) The planar anisotropy of yield stress ratio and strain ratio could be explained by the use of a yield criterion based on the prismatic slip for the specimen of large grain size.
(2) The planar anisotropy of the yield stress and strain ratios could be explained by the use of a yield criterion based on the {10\bar11} slip for the specimen of small grain size.
(3) It is not appropriate to apply the criteria proposed here to the case where the deformation parallel to the C axis is required. In this case a new criterion based on the other slip or twinning system should be proposed.View full abstractDownload PDF (410K) -
Tatsuhiko Tanabe, Tadatsune Okubo, Isao Gokyu1974 Volume 38 Issue 6 Pages 505-510
Published: 1974
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSPlanar anisotropy of the yield stress and the plastic strain ratio obtained by uniaxial tensile tests has been analyzed for titanium sheets with grain sizes ranging from 10 to 140 μ. The results obtained are as follows:
(1) Planar anisotropy of the yield stress and the plastic strain ratio of the titanium sheet under the uniaxial stress can be explained in terms of the yield criterion,
(This article is not displayable. Please see full text pdf.)
\ oindentwhere σX, σY and τXY, τXZ, τYZ ware referred to the principal axis of the anisotropy proposed by the authors.
(2) It can safely be said that the position of the Z-axis is located at an angle θ on the basal pole figure where the basal pole intensity was maximum. This position can also be predicted from the plastic strain ratio in the rolling direction.
(3) In the same material, the parameter q in the above equation decreases with an increase in grain size, but its dependence on grain size differs for the other materials.
(4) The q value was determined from the following equation when the position of Z-axis on the basal pole figure was determined:
(This article is not displayable. Please see full text pdf.)
(5) The yield criterion proposed here coincides with that of Hill when the plastic strain ratio r (in the rolling direction, the 45° direction and the 90° direction) has been measured precisely.View full abstractDownload PDF (434K) -
Tatsuhiko Tanabe, Tadatsune Okubo, Isao Gokyu1974 Volume 38 Issue 6 Pages 511-518
Published: 1974
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSFrom the results of tensile tests of titanium sheets which have an intensity maximum of the basal pole at an angle θ inclined from the sheet normal to the transverse direction, the equivalent stress-equivalent strain relation has been discussed. The results are as follows.
(1) When several slip systems and/or twin systems are activated simultaneously, the yield criterion for titanium sheet is given by
(This article is not displayable. Please see full text pdf.)
Here σX, σY…τYZ are related to the principal axes of anisotropy and the axis (Z-axis) can be assumed to be located at the maximum intensity of the basal pole on the basal pole figure.
(2) The above equation coincides with the criterion of Hill that is introduced when yielding occurs symmetric ally about the axis.
(3) When the parameters in the above equation vary without the rotation of the principal axis of anisotropy as deformation proceeds, the ratio of the contribution of each activated system to the deformation varies.
(4) In analyzing the equivalent stress-equivalent strain relation obtained from the above criterion by the same method as Hill did, a good agreement between the equivalent stress-equivalent strain curves, plotted for the tensile directions in the plane of the titanium sheet is observed in those in the 45, 67.5 and 90° directions; the curves in the 0 and 22.5° directions did not agree with each other nor did with those in the directions mentioned above. As this inconsistency is due to the difference of parameters in the above cditerion by the tensile directions, it can be said that the anisotropy of work hardening exists among those directions.View full abstractDownload PDF (628K) -
Mikio Obayashi1974 Volume 38 Issue 6 Pages 518-525
Published: 1974
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSLead oxide (PbO) is generally known to cause accelerated oxidation in heat-resisting alloys. To make clear this phenomenon, the oxidation behavior and the oxidation products were investigated for element metals such as iron, nickel, copper, and tungsten subjected to accelerated oxidation by PbO.
The results obtained are summarized as follows.
(1) At temperatures above the melting point of PbO, the accelerated oxidation of all the metals studied was observed to proceed by the same mechanism; oxidation of metals by molten PbO and subsequent dissolution of the oxides into the melt.
\ oindentAt temperatures below the melting point of PbO, however, the oxidation behavior was divided into the three types according to its characteristics of oxidation.
\ oindent(i)\phantomii Formation of low melting point eutectic oxide: Fe, W, Mo, Ti, Si, etc.
\ oindent(ii)\phantomi Dissolution and grain boundary attack of the metals by molten Pb: Ni.
\ oindent(iii) Complex reaction involving both types (i) and (ii): Cu.
(2) The starting temperature of the accelrated oxidation was found to be closely related with the temperature of formation of a molten phase between metal oxide and lead oxide. This suggests that the accelerated oxidation is caused mainly by molten PbO-base oxides.View full abstractDownload PDF (817K) -
Mikio Obayashi1974 Volume 38 Issue 6 Pages 525-532
Published: 1974
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe purpose of the present study is to make clear the mechanisms of the accelerated oxidation of pure metals by PbO through theoretical consideration of sequential steps in the process and some experiments, such as thermo-analysis of the oxidation of iron and nickel by molten PbO.
The results are summarized as follows.
(1) The rapid oxidation of iron and nickel by PbO caused a significant temperature rise in the reaction system (over 50°C), and strong convection of the melt was observed.
(2) The accelerated oxidation is considered to proceed through the following mechanisms. [(i)] Formation of low melting point eutectic oxide on the metal surface, resulting from the interaction between the metal oxide and solid PbO (T<m.p. of PbO). [(ii)] Temperature rise and convection of molten oxide due to the rapid exothermic oxidation of metal by molten PbO-base oxide accelerate the dissolution of the surface oxide and the diffusion of both oxidizing species and oxidation products, leading to a self-accelerating series of reactions.View full abstractDownload PDF (772K) -
Seiichi Ikeda, Goro Ito1974 Volume 38 Issue 6 Pages 533-538
Published: 1974
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe oxidation resistance of Fe-Al(7%)-Cr(10%)-Ti(0.5%) alloys containing 0∼0.59% of silicon, in carbon dioxide gas at the temperature of 600∼900°C under a pressure of 10 kg/cm2 were studied together with mechanical properties and workability.
The results obtained were summarized as follows:
(1) The oxidation of Fe-Al-Cr-Ti alloy in carbon dioxide gas decreased with increasing silicon content in the alloy. The addition of titanium to Fe-Al-Cr alloy for the purpose of improving the poor mechanical property of the alloy made the alloy less resistant to oxidation. The addition of silicon, together with titanium, brought about the recovery of good oxidation resistance of the Fe-Al-Cr alloy.
(2) Although the existance of silicon in the oxide film formed at 600°C was detected by X-ray microanalysis, SiO2 could not be found by electron diffraction analysis of the film. These result showed that SiO2 was existed in the layer as solid solution or in the film as amorphous state.
(3) At the testing temperatures higher than 700°C, silicon was not detected in any of the oxide films. The accelerated formation of Al2O3 on the surface of the alloy caused by alloying with silicon may be thought to have contributed to the increased oxidation resistance of the alloy.
(4) The tensile strength of the alloy at room temperature increased and the elongation decreased as its silicon content increased.
(5) The tensile strength and creep rupture strength of the alloys at high temperature increased with increasing content of silicon.View full abstractDownload PDF (581K) -
Mitsuji Kato, Eiichiro Kawai, Kensuke Mutsuzaki, Matsuo Miyagawa1974 Volume 38 Issue 6 Pages 539-545
Published: 1974
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSAging characteristics of Zn-22%Al alloy at room and elevated temperatures were measured by structure observations and thermal analysis. The relationship between microstructure and tensile properties were as follows:
(1) The TTT curve of this alloy showed a typical C-curve. Lamellar microstructure appeared above 100°C, granular microstructure below 50°C and a mixed microstructure between the two temperature ranges. In addition, a superplastic phenomenon was observed in the presence of the granular microstructure, and the superplastic behaviour disappeared rapidly with the appearance of the lamellar structure.
(2) The tensile properties of this alloy were influenced by the aging time at room temperature after solution-treatment. The dissolution into two phases lasted about 20 min after water quenching, but the superplasticity was not observed within 1 hr because of the smaller grain size, and after 2 months these specimens showed a remarkable total elongation.
(3) This aging phenomenon showed that grains were grown with aging time, and their grain size which showed the maximum elongation was related to the strain rate; the faster the strain rate, the smaller the grain size which showed the maximum elongation and the smaller the total elongation.
(4) After the dissolution into two phases, the aging time was shortened by elevating the temperature, and the grain size showing the maximum elongation was equal to that in the case of aging at room temperature.View full abstractDownload PDF (812K) -
Tsuneo Takahashi, Yo Kojima, Kazuhiro Mihama, Yoshinori Ando1974 Volume 38 Issue 6 Pages 545-552
Published: 1974
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe precipitation process during aging at 150°C in Al-4 wt%Cu alloy was investigated by measuring the changes of hardness, electrical resistivity and X-ray Laue photographs. To elucidate the growth process of pre-percipitates, the structures of G.P. zones and θ″-phase were examined by means of high-resolution electron microscopy including the lattice image technique.
In electron micrographs, G.P. zones were observed as single black lines and θ″-phases were observed as pairs of black lines aligned in parallel with a distance of about 6 or 8 Å.
The positions of lattice fringe in (200) lattice images were measured precisely to determine the coherent strain around the precipitates. Consequently, an asymmetric strain field was found to exist around the G.P. zones and θ″-phase. The existence of such asymmetric strain field may suggest that there exists an unknown transient stage of growth in the process from G.P. zones to θ″-phase.View full abstractDownload PDF (1905K) -
Asahi Kawashima, Koji Hashimoto, Saburo Shimodaira1974 Volume 38 Issue 6 Pages 553-559
Published: 1974
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSA kinetic study has been made of the reaction mechanism in which the hydrogen absorption of mild steel in acidic solution is promoted by the presence of hydrogen sulfide. HClO4-NaClO4 solutions (pH 1.1∼3.0) containing hydrogen sulfide, whose concentration was adjusted to 10−6∼10−2 mol/l by addition of Na2S, were used. Galvanostatic cathodic polarization curves were measured using an oscilloscope at a current density of 10−4∼10−1 A/cm2. From the experimental results and theoretical considereations, the hydrogen electrode reaction mechanism of mild steel in acidic solutions has been estimated as follows.
(1) The elementary reactions are the proton discharge and a recombination of adsorbed hydrogen atoms; the backward rate of both elementary reactions can be disregarded. The rate determining reaction is the proton discharge and the surface coverage of adsorbed hydrogen θ is much less than one (θ<<1). (2) The cathodic reaction mechanism does not change with the addition of hydrogen sulfide. The undissociated molecular H2S adsorbed on the iron electrode acts as a bridge-forming ligand for the proton discharge, thereby accelerating the discharge reaction and hydrogen entry into iron.View full abstractDownload PDF (543K) -
Atsushi Oguchi, Susumu Yoshida, Minoru Otaguchi1974 Volume 38 Issue 6 Pages 559-566
Published: 1974
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSFe-Mn alloys containing 15(A), 24(B) and 30%(C) Mn were deformed in tension under hydrostatic pressure at room temperature and the influence of hydrostatic pressure on their stress-strain relation was examined. The results obtained are as follows: (1) After pressurizing at 12000 kg/cm2 the stress-strain relation at atmospheric pressure for the materials A and B shows no changes. For C an increase in flow stress and a decrease in elongation at fracture due to the pressure-induced ε-martensite are observed. The ε-martensite transforms to austenite in the process of deformation at atmospheric pressure. (2) By deformation under high hydrostatic pressure, the ε-martensite is actively induced and it accelerates work-hardening. For the material A at large strains, however, the work-hardening due to the formation of α-martensite at atmospheric pressure exceeds that due to the ε-martensite under hydrostatic pressure. (3) After the specimen is deformed under high hydrostatic pressure and a large amount of ε-martensite is induced, the materials B and C are strengthened at atmospheric pressure. The flow stress in the material C increases by about 60%. For the material A, the ε→α transformation occurs under a very low external stress on reloading at atmospheric pressure and results in a large decrease in the flow stress. (4) For the material C in the range of small strains, the flow stress at atmospheric pressure of the pressurized specimen is significantly higher than that under hydrostatic pressure and the flow stress increases when the ambient pressure is released to atmospheric pressure in the course of deformation.View full abstractDownload PDF (993K) -
Katsuhiko Serata, Masanori Tokuda, Masayasu Ohtani1974 Volume 38 Issue 6 Pages 566-573
Published: 1974
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSSeveral attempts have been made to interprete the mechanism of slag-metal reactions in terms of electrochemistry. Because of many unsolved problems in the application of electrochemical methods to the kinetic study of slag-metal reactions, such an attempt has not met with sufficient success. In this paper, current-voltage curves for the platinum electrode and the CaO-SiO2-Al2O3 slag system are investigated in relation to slag composition, temperature, oxygen partial pressure in atmosphere and sweep rate. The results show that the electrode reaction on the cathode side in the reaction of silicon ion to the metallic silicon; on the anode side it is the evolution of oxygen gas. The residual current is much higher than that observed in aqueous solution and the Faradayic current of the reaction, {(O)+2e→O2−}, may make a considerable contribution to the residual current.View full abstractDownload PDF (753K) -
Yoshiaki Umehara, Shigeyasu Koda1974 Volume 38 Issue 6 Pages 574-579
Published: 1974
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSA Series of off-eutectic alloys have been directionally solidified under various conditions in order to investigate the controlled structure change and the solute redistribution along the solidified direction. The results obtained are as follows:
(1) For InSb-NiSb hyper-eutectic alloys, rod eutectic structures with NiSb dendrites were obtained in an early stage of crystal growth; in the advanced solidification, the NiSb dendrite phase decreased. And in the part of rod eutectic structure, the λ∝R−1⁄2 relationship based on Jackson’s model remained valid even for hyper-eutectic composition alloys.
(2) For InSb-NiSb hypo-eutectic alloys, the solute concentration increased along the solidified direction and approached the value for the eutectic composition, and also the rod spacing enlarged with progress of solidification. The value of λ2R was shown to be 2.5×10−10 cm3/sec in the central part of the ingot.
(3) The relative resistance RB⁄R0 of field plates made of the alloys was measured as a function of the magnetic induction, its value being lower than that of eutectic composition. For lower solidification rates, the value RB⁄R0 tended to be higher than that for higher solidification rates.View full abstractDownload PDF (1290K)
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