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Volume 57, Issue 1
Displaying 1-18 of 18 articles from this issue
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Synchrotron Radiation Small-Angle X-ray Scattering Study on Reversion Process of Al-Li Binary AlloysMasanori Tanaka, Hiroshi Okuda, Kozo Osamura, Yoshiyuki Amemiya1993 Volume 57 Issue 1 Pages 1-6
Published: 1993
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe reversion process of δ′ pricipitates of an Al-7.94 mol%Li binary alloy has been investigated by means of in-situ synchrotron radiation small-angle scattering measurements. The Guinier radius and the integrated intensity decreased monotonically in this alloy, whereas the radius increased in the Al-Zn binary alloys.
Assuming that the origin of the difference in the time evolution of the Guinier radius is the difference in the rate-determining process, the kinetics of reversion has been analyzed in terms of the reaction rate controlled process at the precipitate interface. The kinetic equation for the integrated intensity agreed with the experimental results.View full abstractDownload PDF (650K) -
Katsuro Oda, Hiroshi Fujimura, Hiromitsu Ino1993 Volume 57 Issue 1 Pages 7-13
Published: 1993
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSMössbauer effect studies have been done for Fe-1.8 mass%C, Fe-6 mass%Al-2 mass%C, Fe-1.5 mass%Mn-1.8 mass%C, Fe-2.5 mass%Mn-1.8 mass%C and Fe-16 mass%Ni-1.4 mass%C γ-phase (austenite) in order to clarify the distribution of carbon atoms among the octahedral sites of fcc lattice in each alloy. From the obtained fractional intensity of each component of spectra for the Fe-C binary γ-phase, the local interaction energies between the first nearest and second nearest carbon atoms, J1 and J2, were quantitatively determined by means of Monte-Carlo simulation. The values of J1 and J2 were also determined for nitrogen atoms from the previously reported spectra for the Fe-N γ-phase. J1 and J2 were both strongly repulsive for carbon, while for nitrogen, J1 was strongly repulsive but J2 was very weak. From the fractional intensities obtained from the spectra for the ternary alloys, the local interaction energies between carbon and the first nearest or second nearest third element (Al, Mn and Ni), V1 and V2 were determined. V1 for Mn and V2 for Al were strongly attractive. The values of J and V were compared with the data obtained by thermodynamical activity measurements.View full abstractDownload PDF (752K) -
Koji Tanoue, Hiroshi Sakurai, Koji Fujii, Hidehiko Matsuda1993 Volume 57 Issue 1 Pages 14-20
Published: 1993
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSSome parameters characteristic of the configuration of secondary recrystallized grains grown in powder metallurgy tungsten wires are defined after making clear their contours three-dimensionally. The change in shape of the grains increases with an increase in heating rate and a decrease in annealing temperature, the trend of which is more clearly revealed in non-doped tungsten wire. The parameters reliably reflect such a change in the three-dimensional shape of various grains. It is then investigated through the parameters how the grain configuration influences the steady state creep rate. The effect of grain configuration to suppress creep rates can be confirmed only when the area of grain boundary is not largely changed.View full abstractDownload PDF (895K) -
Yasuo Kogo, Yutaka Kagawa, Hiroshi Hatta1993 Volume 57 Issue 1 Pages 21-28
Published: 1993
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe stress intensity factor calculated from far field stress and the shape of the specimen (K∞) and that at the crack-tip (Ktip) of CeO2 stabilized ZrO2 (CeO2-ZrO2) were measured using DCB (Double cantilever beam) test specimen. From observed K∞ and Ktip, contribution of transformation toughening (ΔK) was examined based on the relation
(This article is not displayable. Please see full text pdf.)
Compression splitting test method, compressing the top of the DCB specimen, was applied to achieve the slow crack growth of CeO2-ZrO2. The laser caustic method was also applied to observe the stress intensity factor at the crack-tip of the specimen.
The results showed that the K∞ was increased with increasing crack extension (R-curve behavior). Crack extension was started around K∞ of 3 MPa\sqrtm, and the K∞ was increased up to 7 MPa\sqrtm, where K∞ was saturated. On the other hand, the Ktip showed constant value in the rage of 2∼3 MPa\sqrtm during the crack extension. With these results, the shielding effect, which is the relaxation mechanism of stress intensity, was experimentally verified.View full abstractDownload PDF (1855K) -
Norio Furushiro, Yoshimasa Takayama, Tatsumi Tozawa, Hajime Kato, Kazu ...1993 Volume 57 Issue 1 Pages 29-35
Published: 1993
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSIn order to evaluate the basic characteristics of superplastic materials, an R-type specimen has been proposed, which has no ordinary gauge part of a uniform cross section.
First, the fundamental problems of a conventional evaluation method have been pointed out. Then, the superplastic characteristics of a Zn-Al eutectoid superplastic alloy have been examined to investigate the possibility of the new evaluation method using the R-type specimen.
As a result, it is found that the R-type specimen has the excellent possibility. In particular, the extremely high elongation can be estimated from a peak value of strain distribution after fracture. Moreover, true stress versus true strain rate relation and m-value in a wide range of strain rate can be derived from the results for a pair of R-type specimens.View full abstractDownload PDF (935K) -
Hideaki Miyagawa, Hideharu Nakashima, Hideo Yoshinaga1993 Volume 57 Issue 1 Pages 36-44
Published: 1993
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSFor clarification of the path dependence of flow stress in a solution- and dispersion hardened alloy at high temperatures, stress-strain curves were measured at 673 and 573 K for several different deformation paths using Al-3.1 at%Mg-1.3 vol%Be and Al-2.8 at%Mg-0.97 at%Mn alloys. A method for the theoretical prediction of flow stress along an arbitrary deformation path was proposed based on the deformation mechanism in a solution- and dispersion hardened alloy at high temperatures. The theoretical stress-strain and creep curves were compared with the experimental ones.
The results are summarized as follows.
(1) The flow stress strongly depends on the deformation path in the same manner as solution hardened alloys without dispersoid.
(2) The dispersion hardening component ‾σip depends on the flow stress σ as
(This article is not displayable. Please see full text pdf.)
\ oindentwhere ‾σid is the mean internal stress due to dislocation interaction, σv the void hardening stress, xc the maximum bowing-out distance of dislocation between the particles, and ‾ls the mean particle spacing on the slip plane.
(3) The predicted curves agree well with the experimental ones, as long as the solute atmosphere drag mechanism operates.View full abstractDownload PDF (957K) -
Sumiko Sanuki, Kazuhiro Takata, Noboru Homura, Koichi Arai, Akio Sugiy ...1993 Volume 57 Issue 1 Pages 45-53
Published: 1993
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSA novel method for preparing monosized ultrafine particles of gold utilizing a technique of the reductive stripping of Au(III)-loaded organics has been developed. Au(III)-loaded organics were prepared by extracting HAuCl4 dissolved in an aqueous HCl or HNO3 solution with MIBK, DBC or TBP, and an aqueous solution containing suitable reductive agents of Au(III), such as HCOOH, H2C2O4, CH3OH, etc., were used for stripping purpose.
Organic loaded with Au(III) loose their yellow color through photochemical reaction. Both yellow and colorless solutions of Au in MIBK or DBC can be reduced to a metallic state to form monosized ultrafine particulates at ambient temperature by stripping Au-loaded organics with an aqueous solution containing suitable reductant. The required amount of reductant is far less than that of equivalent molar ratio, indicating that water plays a role of the reductant of gold in organics. In the case of TBP, however, Na2SO3, Na2C2O4 and HCOONa, instead of their acid form, are a more effective reductant for Au. However, the yield of gold particulates from Au(III)-loaded TBP is low compared to those from the other organic even though the excess amount of Na salts was used. Gold particulates thus formed are smaller than 0.3 μm in diameter. When NaPP was used with H2C2O4, the particle size becomes finer.View full abstractDownload PDF (1470K) -
Seiji Yokoyama, Sadao Kokubo, Katsuyoshi Saito, Koin Ito, Masahiro Kaw ...1993 Volume 57 Issue 1 Pages 54-62
Published: 1993
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSAs a fundamental study of gas evaporation method for preparation of ultra fine particles, molten aluminum was evaporated in a cold gas stream of Ar, He and an Ar+He gas mixture with the levitation melting method. Effects of temperature, gas flow rate and He molar fraction, xHe, in Ar+He mixed gas on the evaporation rate (Production rate of condensed particle) and the particle diameter distribution were investigated. The experimental results were discussed analyzing the temperature distribution around the levitated specimen and using the homogeneous nucleation theory. In this experiment, the aluminum vapor condensed in the boundary layer of diffusion. The evaporation rate and particle diameter were affected by the condensing conditions.
The results obtained were summarized as follows:
(1) Evaporation rate
Evaporation rate increased with increasing temperature and gas flow rate. The evaporation rate in He was larger than that in Ar. The evaporation rate in the Ar+He gas mixture increased slightly with increasing xHe. The rate observed in He was similar to the theoretical one, while the evaporation rate observed in Ar was 0.56 times as small as the theoretical one.
(2) Condensed particle
Both the mean particle diameter and the variance of particle diameter distribution were increased with increasing temperature and with decreasing gas flow rate. They obtained in Ar were larger than in He. They were unaffected by xHe. The mean diameter was estimable from the collision number of nuclei and the distance for particle growth after nucleation. The variance was also estimable from the growth distance.View full abstractDownload PDF (943K) -
Kiyoshi Nogi, Yukimasa Okada, Kazumi Ogino, Nobuya Iwamoto1993 Volume 57 Issue 1 Pages 63-67
Published: 1993
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe wettability of diamond by liquid pure Bi, Pb, Sn, Ag and Au was measured by the sessile drop method. The results can be summarized as follows:
(1) The wettability of diamond depended on its surface orientation.
(2) The wettability of diamond was significantly affectd by adsorption and desorption of hydrogen and graphitization on diamond surface.
(3) The interaction between liquid metals and diamond was not the chemical one but the physical one.
(4) The work of adhesion between liquid Bi and diamond which was measured at the lowest temperature in this work was qualitatively in good agreement with the result obtained by AFM (atomic force microscope).
(5) It might be possible to evaluate the surface structure change of diamond from the wettability measurement.View full abstractDownload PDF (449K) -
Tomoki Tomita, Yukinobu Hayashi1993 Volume 57 Issue 1 Pages 68-74
Published: 1993
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSIn order to develop a wear-resistant titanium alloy, TiC-dispersed overlay was formed on the surface of titanium substrate by the plasma powder welding process using a new composite powder made from fine TiC particles (1.4 μm) and titanium particles (<15 μm). For comparison, another TiC-dispersed overlay was also formed using coarse TiC powder (60∼150 μm), which mixed with titanium powder (<150 μm). Effects of plasma arc current on the dispersion of TiC particles and the hardness of these overlays were examined by mean of metallographic and X-ray diffraction measurements. The following results were obtained.
(1) In the case of the Ti-TiC mixed powder, TiC particles sank to the lower part of the overlay and dendritic TiC was in-situ formed at the upper part of the overlay. Although the hardness of the upper part was nearly constant (Hv240), that of the lower part increased from Hv260 to Hv460 as plasma arc current increased from 100 to 200 A.
(2) In the case of the Ti/TiC composite powder, TiC particles were completely dissolved into molten titanium. During the solidification process, TiCx (X=0.42∼0.46) particles having a diameter of 10∼50 μm were in-situ formed and were uniformly dispersed in high density. As plasma arc current increased from 100 A to 200 A, the hardness of this overlay decreased from Hv1000 to Hv600. However the hardness was much higher than that of the overlay made from the Ti-TiC mixed powder.View full abstractDownload PDF (2019K) -
Saburou Ohtani, Toshinori Takagi, Chihiro Yanagi1993 Volume 57 Issue 1 Pages 75-80
Published: 1993
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThis study deals with the data on the changes in the microstructure of SUS304 type austenitic stainless steel implanted with B+ ions. We first investigated the multi-energy implantation method to discuss the changes of the microstructure and the characteristics of metals with the implanted atom concentration, and achieved a homogeneous distribution of the implanted atoms. Using this method, SUS304 specimens were implanted with boron ions having energies of 2.89×109∼1.74×1010 J/mol (30∼180 keV). Then the microstructure of the specimens was analyzed with AES, grazing XRD, and TEM. The results revealed that at a B atomic concentration of about 12% produced by implantation at 3×1021 B+/m2, there was partial disordering of the lattice, and (Fe, M)2B and (Fe, M)B(M=Cr, Ni) were also observed. After implantation at the 6×1021 B+/m2, equivalent to about 19 at%B, the amorphous parts had increased although crystals measuring about ten nm also presented. After annealing at 500°C for 1 h, (Fe, M)2B measuring several tens of nm and small amounts of (Fe, M)B could be observed. An X-ray diffraction peak corresponding to the α′ martensite, which is reported in the austenitic stainless steel implanted with gas ions such as He+ and metal ions like Au+, was observed in the surface of SUS304 specimens implanted with B+ ions, and its height compared to that of γ peak tended to increase in the range of about 19 at%B.View full abstractDownload PDF (1233K) -
Haruyuki Nakanishi, Yoshiki Tsunekawa, Masahiro Okumiya, Naotake Mohri ...1993 Volume 57 Issue 1 Pages 81-87
Published: 1993
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThis study was aimed to realize full incorporation with low applied pressure by means of ultrasonic infiltration accompanying an exothermic reaction between titanium powder and molten aluminum in a non-wetted Al2O3 particle/molten aluminum system as a model composite. Ultrasonic infiltration (resonant frequency=20.5 kHz) was performed with its power of 500 kW/m2 mainly at 1023 K, so as to evaluate the effects of ultrasonic vibration on the threshold infiltration pressure (Pc), non-infiltrated defects and synthetic reaction of titanium aluminides. The Pc of 10.8 kPa obtained in pressure infiltration to 5.3 mass% titanium powder premixed Al2O3 particle preforms with an average diameter of 302 μm, becomes zero in ultrasonic infiltration. The high Pc of 83.5 kPa owing to a small average diameter of 47 μm of Al2O3 particles also becomes zero with ultrasonic vibration, that is, molten aluminum can initiate infiltration into the preform without applied pressure like a wetting composite system. Ultrasonic vibration makes the titanium powder premixed Al2O3 particle preforms infiltrated fully with the applied pressure of 25 kPa for 10 s, although there can be seen non-infiltrated area in pressure infiltration with 25 kPa for 300 s. Non-infiltrated defects appear at the contact points of particles in pressure infiltration, but they disappear with ultrasonic vibration. Exothermic reaction of intermetallic TiAl3 formed around titanium powders is accelerated by ultrasonic vibration, then the molten aluminum temperature increases locally at an infiltration front. The composite systems are changed from non-wetting to wetting apparently by ultrasonic vibration, which arises principally from the hysteresis of contact angles due to molten metal vibration and the generation of ultrasonic pressure in front of a step horn. Hence, the ultrasonic infiltration is extremely useful as a liquid processing for non-wetted hybrid in-situ composite materials without any non-infiltrated defects.View full abstractDownload PDF (1557K) -
Setsuo Aso, Tatsumi Shida, Michihiro Tagami, Shoji Goto1993 Volume 57 Issue 1 Pages 88-95
Published: 1993
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe sand-erosion mechanism of wear-resistant materials having a composite structure was investigated on lamellar-eutectic Al-CuAl2 composites with different interlamellar spacings, prepared by unidirectional and metal-mold solidification methods. The interlamellar spacing was controlled from 0.5 to 2.1 μm. The single α phase and the single θ phase materials were also prepared. Sand-erosion test was carried out in a mixture of sand and water.
It was found that the erosion rate of the lamellar-eutectic composites rapidly decreased with decreasing interlamellar spacing in the smaller interlamellar spacing region, while the dependence of erosion rate on the interlamellar spacing was not detected in the larger interlamellar spaing region. Such a tendency was pronounced in the metal-mold solidification composites having fine structures. The erosion rate of lamellar-eutectic composites was always lower than that estimated from “the rule of mixtures”. These facts were discussed in term of shielding effect of hard θ lamellae from the attack of soft α phase.View full abstractDownload PDF (1350K) -
Setsuo Aso, Tsutomu Sugawara, Michihiro Tagami, Shoji Goto1993 Volume 57 Issue 1 Pages 96-102
Published: 1993
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe aim of this work is to investigate the effect of temperature on the sand-erosion behavior of high-chromium white cast irons. A 15%Cr pearlite-matrix white cast iron and a 15%Cr-3%Ni austenite-matrix white cast iron were prepared by unidirectional solidification method. The sand-erosion test was carried out under a constant slurry rate of 7.7 m/s at various temperatures of 277, 298, 313, 328 and 343 K.
It was found that erosion loss of each white cast iron linearly increased with increasing testing time and exponentially increased with increasing slurry temperature. The erosion rate of 15%Cr white cast iron was always larger than that of 15%Cr-3%Ni white cast iron. Many crater-like damages were observed on the eroded surface of both specimens. Formation of the crater-like damages was pronounced at higher temperature and especially in the pearlite-matrix white cast iron. That is, the pearlite-matrix means to have a weaker resistance for sand-erosion than the austenite-matrix. The temperature dependence of erosion rate well corresponded to that of anodic polarization curve in both the specimens, so that the temperature dependence of erosion rate was presumed to be strongly affected by corrosion-reaction during the erosion.View full abstractDownload PDF (2395K) -
Masatsugu Kaise, Kazuo Saito1993 Volume 57 Issue 1 Pages 103-107
Published: 1993
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSSuperconducting BiSrCaCuO ultra thin films with a thickness of 30 nm were grown epitaxially on (100)MgO substrates by using modified single-target sputtering and by optimizing the heat-treatment. The value of the superconducting transition temperature Tc,0 obtained was as high as 102 K, which is the highest level at this thickness of the Bi system. The target used in this study was modified to a concave-surface shape by heaping up the oxide powders in the sputter-erosion areas so that sputtered particles are continuously directed toward the central part of the substrate holder. The optimum heat-treatment consisted of the multistep annealing at 1148 K for 2 min, down to 1144 K and to 1123 K at the elaborately controlled rates of cooling, respectively, followed by final cooling to room temperature. Particularly, the short term annealing was necessary to suppress undesiable compositional changes due to the evaporation of constituent atoms and the reaction between thin films and substrates.View full abstractDownload PDF (528K) -
Kazushi Ishiyama, Ken Ichi Arai, Takashi Honda, Masaki Nakano, Jirou H ...1993 Volume 57 Issue 1 Pages 108-113
Published: 1993
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSVery thin (<100 μm) grain oriented silicon steel sheets can be made by using tertiary recrystallization. The tertiary recrystallization behavior is changed by the contents of impurities. in this study, the purity dependence of cold rolled and recrystallized texture was observed. The main findings were as follows;
(1) The texture of cold rolling was strong {111}⟨112⟩ and weak (100)[011]. The primary recrystallized texture was very strong (110)[001]. These textures were independent of the contents of impurities. In the low-purity samples, the primary grains grow up with increasing annealing temperature. On the other hand, the growth of primary grains was not observed in the high-purity samples.
(2) Secondary recrystallization behavior depended on the purity of the samples. In the low-purity samples, the secondary recrystallization began at 1073 K. The main texture of secondary recrystallized grains was (410)-(430)[001]. A weak (110)[001] texture was also observed. In the high-purity samples, the temperature of beginning of secondary recrystallization was higher than that of the low-purity samples. The main texture of secondary recrystallized grains of the high-purity samples was {111}⟨112⟩. In the high-purity samples the amount of (110)[001] grains in the secondary recrystallized grains as the seeds of tertiary recrystallization was larger than that of the low-purity samples.View full abstractDownload PDF (769K) -
Kazushi Ishiyama, Ken Ichi Arai, Takashi Honda, Masaki Nakano1993 Volume 57 Issue 1 Pages 114-118
Published: 1993
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSIt is well known that very thin (<100 μm) grain oriented silicon steel sheets having lower iron losses than iron-based amorphous materials can be made by using tertiary recrystallization. In this study, the relation between impurities and the tertiary recrystallization behavior was investigated.
The main findings are as follows:
(1) The tertiary grain growth of the samples with less impurities is observed on annealing at a lower temperature and for a shorter time than that of the sample without purification. It was shown that Cu is the dominant element for the inhibition of tertiary recrystallization.
(2) Using the sample having less Cu content, the tertiary recrystallization is observed by annealing in hydrogen atmosphere.
(3) With decreasing content of impurities, the size of a tertiary grain becomes smaller. But the preferred grain orientation of (110)[001] is not changed with the amount of impurities.View full abstractDownload PDF (638K) -
Kazushi Ishiyama, Ken Ichi Arai, Takashi Honda, Masaki Nakano1993 Volume 57 Issue 1 Pages 119-124
Published: 1993
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSBy using tertiary grain growth, thin grain oriented silicon steels having very low iron losses can be obtained. In this work, the effects of thickness of the samples, annealing temperature and atmosphere upon tertiary grain growth were observed.
The main findings were as follows.
(1) Before the beginning of tertiary grain growth, the grain growth behavior showed no differences between the grains having the (110) face and other faces. From this result, it was found that the motive force for grain growth before the beginning of tertiary grain growth was the boundary energy.
(2) Tertiary grains begin to grow after some induction period and grow at a constant rate. The higher the annealing temperature, the shorter becomes the induction period and the larger the growth rate of tertiary grains.
(3) In the samples having thinner thicknesses, the growth rate of tertiary grains becomes larger. One reason for the increase in motive force of tertiary grain growth is the increase in surface energy by the increase in area ratio between the surface and the grain boundary. Another reason is the increase in grain boundary energy because of the decrease in size of matrix grains around the growing tertiary grains.
(4) The growth rate of tertiary grain becomes smaller in the annealing atmosphere of low vacuum or hydrogen. This is due to the change in surface energy by the contamination of the sample surface.View full abstractDownload PDF (479K)
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