All issues
Volume 48, Issue 5
Displaying 1-17 of 17 articles from this issue
- |<
- <
- 1
- >
- >|
-
Kun-ichi Miyazawa, Du-bin Cheng, Hideo Saito, Minoru Mori, Yoichi Ishi ...1984 Volume 48 Issue 5 Pages 455-460
Published: 1984
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSBurgers vectors of twin boundary dislocations in annealed Cu-Ni alloys were analysed by the weak beam method using HVEM in such a way that the number of extinction contours terminating at the end of a dislocation on the surface of a thin foil specimen is counted. By this method the size and sign of the Burgers vector was determined.
The present method is applicable to general coincidence boundary dislocations, when electrons are diffracted simultaneously from two adjacent crystals.View full abstractDownload PDF (2504K) -
Tohru Takahashi, Ryo Horiuchi1984 Volume 48 Issue 5 Pages 461-467
Published: 1984
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSGrain boundary sliding behavior was investigated on high-purity Zn bicrystals with special geometry, in order to examine critically the validity of McLean’s model which presumed grain boundary sliding to be brought about by climb-glide motion of slip dislocations along the grain boundary. Geometrical calculation based on this model leads to grain boundary sliding in the opposite direction to that of the resolved shear stress on the grain boundary plane at an angle of π/4 to the tensile axis, if an active slip plane intersecting the grain boundary is inclined by an angle θ(π⁄4<θ<π⁄2) to the tensile axis. Experimental results revealed that this prediction did not come true. This discrepancy can be solved, if one assumes a slip dislocation supplied from grain interior to grain boundary to dissociate into DSC dislocations which can climb-glide independently in the grain boundary to produce grain boundary sliding. Quantitative evaluation making use of the DSC dislocation model has successfully illustrated the characteristics of the grain boundary sliding rates.View full abstractDownload PDF (1134K) -
Toshihiro Seo, Kazumitsu Shinohara, Takashi Naohara, Takashi Monde, Se ...1984 Volume 48 Issue 5 Pages 468-477
Published: 1984
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSSupersaturated Cu-In alloys were aged at various temperatures for various periods of time in order to study precipitation kinetics of the alloys. The results were interpreted mainly on the basis of Cahn’s model. The fact that the compositions of the matrices and the precipitated δ-phase which were reacting deviated from those of the stable phases was confirmed by the presence of the modulated structure, justifying one of the Cahn’s assumptions. The solubility limit of In into Cu was determined by X-rays, and it was found that the actual solubility was smaller at low temperatures than that reported elsewhere. The activation energy for δ-phase precipitation was found to be 145 kJ/mol, which was believed to correspond both to vacancy creation and its short range migration. The habit plane between the matrix and the precipitated δ-phase was found to be (001)α\varparallel(114)δ.View full abstractDownload PDF (3648K) -
Yoritoshi Minamino, Toshimi Yamane, Shuji Ueno, Mitsue Koizumi, Noriyu ...1984 Volume 48 Issue 5 Pages 478-481
Published: 1984
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSReaction-diffusion experiments of aluminium and silver have been done under high pressure up to 3 GPa at temperatures between 729 K and 873 K. The eutectic reaction temperature of 839 K rises with increasing pressure. The solubility of silver in aluminium decreases with pressure, but the concentration of ζ phase at the interface between ζ and α phases is independent of pressure. The excess enthalpy of mixing for α solid solution increases with pressure.View full abstractDownload PDF (479K) -
Ken-Ichi Arai, Hideki Tsutsumitake, Kenji Ohmori1984 Volume 48 Issue 5 Pages 482-488
Published: 1984
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSIt has been found that soft magnetic properties such as the coercive force and the permeability of 6.5 mass% silicon-iron ribbons prepared by a rapidly quenching roller method can be improved by annealing at 1373 K in a vacuum atmosphere. In the annealed ribbons, grains have the average size larger than 1 mm, and the ribbon surface is parallel to (100) plane. This paper reports results on the grain growth during annealing and texture formation in the 6.5 mass% silicon-iron ribbons.
In the as-prepared ribbon, non-oriented columnar grains about 10 μm in diameter were observed, which grew from the surfaces to the inner part of the ribbon. When the annealing temperature was around 973 K, the primary recrystallization was formed near the middle part of the ribbon thickness, and the grain size increased with increasing annealing temperature. At the annealing temperature of 1223 K, the grain size became 30-40 μm. Around the annealing temperature, the motive force of the grain growth is the grain boundary energy. However, above 1223 K the surface energy plays an important role in the observed grain growth. When the ribbons were annealed at 1373 K, the grains whose (100) planes were parallel to the ribbon surface grew, and all ribbon surfaces were covered with these grains after 1 hour annealing. When the annealing temperature was kept above 1473 K, the grains with (110) planes parallel to the ribbon surface grew, and all ribbon surfaces became parallel to (110) plane.View full abstractDownload PDF (2508K) -
Kenki Hashimoto, Osamu Nakano, Haruo Doi, Tokuzou Tsujimoto1984 Volume 48 Issue 5 Pages 489-495
Published: 1984
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSMicrocracks about 0.1 \micron in width and 10-30 \micron in length were observed frequently on the surface of an intermetallic compound TiAl which was prepared for optical microscope observation. In this study the morphology and the formation mechanism of the microcracks have been examined in relation to the specimen preperation process. A method for eliminating them and effects of them on the mechanical property have been also studied. Results obtained are as follows:
(1) The microcracks were formed in plastically deformed regions which were induced during the specimen preperation process by cutting stress or polishing stress with emery paper. The morphology and the density of them depended strongly on the crystal orientation.
(2) The microcracks were observed in the TiAl phase containing 34-39 mass%Al, but not in that containing Al more than 40 mass%.
(3) The microcracks were formed by stress corrosion, when the surface was not masked by any oxide film.
(4) The plastic deformation region was cleaned out by electropolishing for 360 s or by annealing at 1473 K for the period over 7.2 ks under the vacuum of 2×10−6 Torr.
(5) The plastic deformation region decreased tension strength, when it was not taken away, but not compression strength.View full abstractDownload PDF (4501K) -
Kazumitsu Shinohara, Toshihiro Seo, Toshio Yoshioka1984 Volume 48 Issue 5 Pages 496-504
Published: 1984
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSFe-Cr base alloys to which minor percentages of Si or Ni were purposely added in order to accelerate the sigmatization reaction were cyclically heated between room temperature and an elevated temperature where the σ phase existed stably. The resistivity and acoustic emissions were simultaneously measured during the heating cycles. It was found that the resistivity made a closed loop during the cyclings for the specimen containing a small percentage of Si whereas it continued to increase for the specimen containing a minor percentage of Ni. The resistivity was divided into two contributions according to Matthiessen’s rule; the temperature dependent and temperature independent terms. The latter was correlated to an introduction of defects. The defects introduced were found by TEM examinations to be crackings and sequence faults. Furthermore, it was made clear that the faults were introduced after the transformation of the specimens from an initial phase of ferrite to a final phase of the sigma had been completed. This disagrees with the proposal made by Marcinkowskii and Miller that the introduction of the sequence faults occurs in the midst of the α→σ transformation.View full abstractDownload PDF (2000K) -
Keisuke Matsuura, Norio Matsuda1984 Volume 48 Issue 5 Pages 504-512
Published: 1984
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe stress and temperature dependences of steady state creep rate, \dotεs, have been investigated to examine the effects of grain size and dispersed particles on creep deformation in Al-Al2O3 and Al-Al2O3-1%Si alloys with different grain sizes.
Main results are as follows: The stress and grain size dependences of the temperature compensated creep rate, \dotεs⁄D, in a high stress range are different from those in a low stress range, where D is the lattice self diffusion coefficient of Al. In the high stress range, \dotεs⁄D becomes large and the stress exponent, n, increases from 14 to 21 with increasing grain size. In the low stress range, \dotεs⁄D decreases abruptly with lowering applied stress, showing the existence of threshold stress below which the creep rate approaches zero. In this range, \dotεs⁄D becomes large with decreasing grain size, so that the contribution of grain boundary sliding to creep rate becomes important. The threshold stress, (σ⁄E)th, for Al-Al2O3 alloy of coarse grains is estimated to be about 10−3.56 E, where E is Young’s modulus. The value is about one half of the yield stress at room temperature that is a measure of Orowan stress.
It is shown that the increased volume fraction of Al2O3 particles affects only the threshold stress but not the stress exponent n as far as the grain size is unchanged, and that the creep rate is generally expressed by the following empirical relation,
(This article is not displayable. Please see full text pdf.)
\ oindentwhere A is a constant independent of the volume fraction of particles and n=7-8 for Al-Al2O3 alloy of coarse grains.View full abstractDownload PDF (2488K) -
Shoji Goto, Shinji Yamashita, Toshio Mimura, Hideo Yoshinaga1984 Volume 48 Issue 5 Pages 513-521
Published: 1984
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSIn order to investigate the effect of microstructure on the high-temperature strength of lamellar composites, two kinds of eutectic Al-CuAl2 single crystals with different interlamellar spacings were made by unidirectional solidification. Their strengths were compared with each other by means of compression test at temperatures from 523 K to 673 K and at strain rates from 4×10−5 s−1 to 3×10−3 s−1.
The dependence of the yield strength (σ0.2) on the interlamellar spacing was not detected at all test conditions. The strength was also independent of the lamellar orientation, that is, the strength was isotropic.
These experimental results were discussed in terms of the “rule of mixtures” and the constraint effect of hard CuAl2 lamellar on the plastic deformation of soft Al phase.View full abstractDownload PDF (1725K) -
Hiroshi Mabuchi, Osamu Imai, Koichi Okashita, Yutaka Nakayama1984 Volume 48 Issue 5 Pages 522-528
Published: 1984
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSIn order to investigate fatigue mechanisms at elevated temperatures, Al-5 mass%Mg alloy polycrystals were tested in axial fatigue (tension-compression mode) at a strain rate of 8.3×10−4 s−1 and a strain amplitude of 1% in the temperature range from 293 to 773 K. Development of an “orthogonal” or “squared-up” grain structure by grain boundary migration during fatigue was studied by optical and electron microscopy. Results obtained are summarized as follows.
(1) Grain boundary sliding and grain boundary migration occurred during cyclic tension-compression tests, and grain boundaries tilted gradually toward 45° to the stress axis. A well-developed squared-up grain structure was observed after about 20 cycles in this alloy.
(2) The grain boundary migration was mainly observed at triple points. This grain boundary migration was closely related with release of the strain in folds at triple points induced by the repeated grain boundary sliding.
(3) The above phenomena are sensitive to the testing temperature, and the most well-developed squared-up grain structure was obtained at 673 K in this study.View full abstractDownload PDF (3878K) -
Masanobu Ohmori, Shigeru Tanaka1984 Volume 48 Issue 5 Pages 529-533
Published: 1984
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSEffects of carbon content and morphology of pearlite on the decrease of yield stress caused by a pressurization under hydrostatic pressure of 980 MPa were experimentally examined using two carbon steels, S15C with 0.14%C and S45C with 0.44%C. In addition to the above, an effect of the pressurization on ductile-to-brittle transition behaviors observed in Charpy impact test was also described. The present findings are summarized as follows.
(1) The initial yield stress of S15C was decreased by the pressurization, while the stress of S45C was never affected. The decrease of the yield stress found in the former steel was 29 MPa in both cases of lammelar pearlite and spheroidal one.
(2) The transition temperature of S15C subjected to the pressurization became lower by 7 to 10 K, being about 0.3 K/MPa in reduction of the temperature per unit decrease of the yield stress. On the contrary, the transition temperature of S45C was not affected even after pressurized, since its yield stress was not changed.
(3) By spheroidization of pearlite, the transition temperature was lowered remarkably in S15C, but it was not varied in the other steel.View full abstractDownload PDF (729K) -
Satoru Kaneko, Akihito Kurimoto, Kazuo Arai, Yoshikazu Satoh, Seiichi ...1984 Volume 48 Issue 5 Pages 534-541
Published: 1984
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSIn order to understand the mechanism of micrographical preferential dissolution of phase in austenite-ferrite duplex stainless steel, effects of chemical composition, heat treatment and environmental condition on the preferential attack for 22Cr-Ni(0-15%) and 24Cr-Ni(0-17%)-2Mo-N(0.02-0.2%) were investigated with the potentiostatic method. Chemical compositions of austenite and ferrite phases were determined by the EPMA analysis technique. Electrochemical experiments were conducted in 1%H2SO4-NaCl for 22Cr-Ni and in 5%H2SO4-NaCl for 24Cr-Ni-2Mo-N at the boiling point.
Chromium and molybdenum are enriched in the ferrite phase, and nickel and nitrogen are enriched in the austenite phase. The degree of this enrichment of alloying elements relates to the phase ratio (γ%) . The duplex phase steel of 22Cr-Ni has a tendency that the ferrite phase preferentially dissolves in sulfric acid solution at −0.3 VSCE. On the other hand, the duplex phase steel of 24Cr-Ni-2Mo-N has a tendency that the austenite phase preferentially dissolves in sulfuric acid solution −0.3 VSCE. An addition of chloride ion tends to inverse the phenomena explained above. It is concluded that these micrographical preferential dissolution phenomena of duplex phase stainless steel depend on the environmental condition and chemical composition in phases.View full abstractDownload PDF (1734K) -
Takeshi Kobayashi, Osamu Kujirai, Fumio Hirose, Haruno Okochi1984 Volume 48 Issue 5 Pages 542-548
Published: 1984
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSTraces of antimony in nickel-base heat-resisting alloy were determined by graphite-furnace atomic-absorption spectrometry.
The alloy was dissolved in hydrofluoric acid and nitric acid. Solution (10 mm3) was pipetted into L’vov platform furnace, and then aluminium sulfate solution (10 mm3) was added into the furnace to suppress interferences. After the drying and ashing (1173 K; ramp 30 s, hold 20 s) steps, antimony was atomized (2473 K; ramp 0 s, hold 4 s) by using argon as a purge gas. Atomic absorption of antimony was measured at 217.6 nm.
Calibration solutions were prepared by adding antimony solutions to the matrix solutions composed of nickel and cobalt (1:1).
The relative standard deviation of the proposed method was within 3% at 10 ppm of antimony in nickel-base heat-resisting alloy. The detection limit was 0.5 ppm of antimony, when one gram of the specimen was used.View full abstractDownload PDF (1153K) -
Toshio Oishi, Yoichi Tobiyama, Kenji Tanabe, Katsutoshi Ono1984 Volume 48 Issue 5 Pages 549-553
Published: 1984
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe equilibrium of solid Co-Ni alloys and CoO-NiO solid solutions was studied by means of steam-hydrogen-argon mixtures.
By using the equilibrium compositions of three or four samples of different Co/Ni ratios at a fixed oxygen potential, the conjugation lines between the alloy and oxide phases were determined, and applying the Gibbs-Duhem relations to both phases, the activities of Co and Ni in the alloys as well as the activities of CoO and NiO in the oxide solid solutions were obtained.
The activities of Co and Ni in the Co-Ni alloys showed slight positive deviations from Raoult’s law except the activity of Ni at Ni-rich alloys which exhibited a slight negative deviation. Both the activities of CoO and NiO in the oxide solution showed slight negative deviations.View full abstractDownload PDF (592K) -
Ken Tohma, Hajime Kudo, Yo Takeuchi1984 Volume 48 Issue 5 Pages 553-559
Published: 1984
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSEffects of addition of a small amount of Fe, Si, Cu, Mn or Mg on the electrochemical property and the corrosion resistance of an Al-0.1 mass%Sn alloy were examined. The corrosion potential of the alloy was remarkably less noble, when it was water-quenched after the solution treatment, while it became noble when furnace-cooled, because of the precipitation of Sn. The addition of Cu, Si or Mn made the corrosion potential of quenched alloy noble, while that of Mg or Fe gave little effect. The additional elements had essentially no effect on the precipitation of Sn of the alloy. These suggest the effect of Cu, Si or Mn in the solid solution is greater than that of Sn on the electrochemical property of aluminum.
Corrosion rates of less noble alloys in an acidified chloride solution which simulated the solution of anodic area were unusually high, but those of noble ones were sufficiently low. The anodic efficiency in galvanostatic dissolution was lower in the less noble ones, but much higher in the noble ones. These results show that the anodic efficiency is controlled by the corrosion rate of anodic area which is closely related with the electrochemical property of the alloys and that an alloy with both a higher efficiency and an excellent sacrificial anode effect can be hardly obtained in these ternary alloys examined.View full abstractDownload PDF (2082K) -
Mototaro Sato, Takao Yamazaki1984 Volume 48 Issue 5 Pages 560-565
Published: 1984
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThis paper describes the effects of the crystal orientation upon the cutting mechanism and the theoretical analysis of the experimental results by the distortion method. The experiment was performed by the orthogonal cutting of an aluminum single crystal having the (001) plane and (110) plane. The single crystal was produced by the Bridgman method, and the crystal orientation was determined by the Laue X-ray back reflection method.
Main results obtained are as follows:
(1) The experimental results showed that the effects of the orientation appeared clearly on the cutting phenomenon. That is, the cutting force Ks, the shearing angle and the finished suface vary with the change in the cutting direction.
(2) It is clarified that the mechanism of the formation in the shear zone can be explained reasonably by the distortion method based on the slip system of the crystal.View full abstractDownload PDF (1127K) -
Hisashi Ando, Yoshiaki Kita, Hiroshi Sakamoto1984 Volume 48 Issue 5 Pages 566-570
Published: 1984
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe electrical resistivity, microstructure and oxidation behavior of Ta-N-O resistive Films have been investigated. These films were deposited by a dc-diode reactive sputtering in a mixture gas of Ar, N2 and O2. There exists a region where the specific resistivity of the films are insensitive to the partical pressure of O2. The specific resistivity of the films in the region is about 7 μΩ·m. The crystal structure of the films is identified to be by X-ray diffraction hcp structure similar to that of Ta2N compound. With the cyclic heating up to 823 K, the relative electrical resistivity changes reversibly in vacuum, while it increases in air. This increase may be caused by the decrease of the effective film thickness for electric conduction due to surface oxidation with the heating in air.View full abstractDownload PDF (785K)
- |<
- <
- 1
- >
- >|