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Volume 54, Issue 6
Displaying 1-18 of 18 articles from this issue
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Osamu Taguchi, Yoshiaki Iijima, Ken-ichi Hirano1990 Volume 54 Issue 6 Pages 619-627
Published: 1990
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSReaction diffusion between pure Cu and Ti has been studied in the temperature range from 963 to 1143 K. Formation of six intermetallic compounds, Cu4Ti, Cu2Ti, Cu3Ti2, Cu4Ti3, CuTi and CuTi2, has been observed in the diffusion zone, as predicted by the equilibrium phase diagram of the Cu-Ti system.
The layer thickness of these intermetallic compounds except Cu4Ti has been found out to obey the parabolic law, showing that the growth of the phase layer has been controlled by diffusion process. Above 1083 K the growth of the Cu3Ti2 phase has been observed after an incubation time.
The temperature dependence of the growth rate constants of Cu4Ti3, CuTi and CuTi2 phase layers has satisfied the Arrhenius relationships.View full abstractDownload PDF (1782K) -
Yo Tomota, Min Piao, Takashi Hasunuma, Yoshisato Kimura1990 Volume 54 Issue 6 Pages 628-634
Published: 1990
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSAustenite (γ: fcc)→epsilon (ε: hcp) martensitic transformation behaviour in Fe-16 wt%Mn, Fe-24 wt%Mn, and Fe-24 wt%Mn-6 wt%Si alloys has been studied to clarify the influences of plastic strain and applied stress.
Microstructures of as-quenched specimens in these alloys consist of γ and ε. The specimens were heated up to 673 K above the Af temperature and then cooled to a test temperature at which the tension test was carried out. Positive temperature dependence was found under the 0.2% proof stress due to the stress-induced γ→ε transformation in each of the Fe-Mn alloys and the Fe-24Mn-6Si alloy. Extremely low yield strength and high work hardening were observed in the beginning of deformation due to the γ→ε martensitic transformation, when deformation was given at room temperature in the Fe-24Mn alloy in which the γ phase was stabilized by ten times that of cyclic transformations.
The change in the length of the specimens was measured during cooling from 673 K under a constant tensile stress. When the applied stress was larger than the yield strength at 673 K, a rapid elongation in the tensile direction was observed from a temperature between As and Ms. This is ascribed to a preferential transformation shear, i.e. the movement of Schockley partial dislocation caused by a linked effect of the plastic strain at 673 K and the applied stress. The change in the specimen length vs. temperature curve showed a slightly different trend between the Fe-Mn alloys and the Fe-24Mn-6Si alloy. Furthermore, a remarkable shape recovery due to the ε→γ reverse transformation was observed in the Fe-24Mn-6Si alloy but scarcely in the Fe-16Mn and Fe-24Mn alloys, when the elongated specimens were again heated above Af under an applied stress of 2 MPa. The solid-solution hardening by Si appears to be responsible for the observed refinement of the shape memory effect.View full abstractDownload PDF (1193K) -
Toshiyuki Koyama, Hiroshi Kawaguchi, Toru Miyazaki1990 Volume 54 Issue 6 Pages 635-641
Published: 1990
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSRecently Koyama et al. (Ref. 2) proposed a Temperature-Time-Composition diagram which was named the T-t-c system diagram. By using this diagram, the sequence of phase transformation and the development of the microstructure with progress of ageing can comprehensively be described. In this paper we experimentally determined the T-t-c system diagram for the start of cellular precipitation in the Al-Zn alloy system by means of optical and electron microscopic observations and hardness measurements. The results obtained are as follows:
(1) With increasing Zn content and with increasing ageing temperature, the cellular precipitation starts in a short time ageing.
(2) The cell growth rate decreases with ageing time. This decrease will be attributed to the influence of the continuous precipitation on the cell growth.
(3) The T-t-c system diagram can be regarded as the phase diagram with time scale. Therefore the phase decomposition will be understood more deeply and clearly by using this T-t-c system diagram.View full abstractDownload PDF (2003K) -
Fukuji Inoko, Masao Kurimoto, Keizo Kashihara1990 Volume 54 Issue 6 Pages 642-649
Published: 1990
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSIn order to clarify the relationship between activated slip systems and orientations of recrystallized grains, deformation bands and recrystallized grains in aluminum single crystals were examined. Consequently, it was considered that the nucleation of the recrystallized grains occurred in the regions surrounded by two or three groups of dislocation loops with their common cross slip planes in and near the deformation bands. The growth rate of the recrystallized grains was larger on the direction parallel than that normal to the deformation bands.View full abstractDownload PDF (1758K) -
Toshiya Shibayanagi, Hideaki Takatani, Shigenori Hori1990 Volume 54 Issue 6 Pages 650-656
Published: 1990
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe change in frequency of grain boundaries with low mobility were investigated during grain growth by using the Monte Carlo simulation. 4900 cells were generated and each grain consisted of several cells in an initial condition. Each grain was given a real number randomely. Two kinds of grain boundaries with different mobilities were characterized by the difference of each grain’s number. The mobility ratios were 1:1, 1:2, 1:10 or 1:100 and the fractions of grain boundary with low mobility in the initial state were 8, 32 and 73%.
Grain boundaries with lower mobility tended to increase their existence ratio during grain growth, and this tendency increased with increasing mobility ratio. The frequency of grain boundary with lower mobility increased from 32% of the initial state to 55% as the grain size increased by four times. The drastic change of the fraction was observed when the grain size became large enough compared to the specimen area.
From the initial state of 73%, the frequency of grain boundary with lower mobility increased up to 83%. However, little change of the frequency was observed from 8%. Meanwhile, there existed some areas of localized grain boundaries with lower mobility, and the change of microstructure in these areas were less than the other areas.
Thus, the controlling factors for changing the fraction of the grain boundaries with lower mobility are; (1) the initial fraction of grain boundaries with lower mobility, (2) a ratio of the mobility and (3) a distribution of the boundaries with lower mobility.View full abstractDownload PDF (895K) -
Koh-ichi Sugimoto, Mitsuyuki Kobayashi, Syun-ichi Hashimoto1990 Volume 54 Issue 6 Pages 657-663
Published: 1990
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe influences of forming temperature and strain rate on the ductility and strengths of 1000 MPa Grade TRIP-aided dual-phase steels containing fine and stable retained austenite of 10-15 vol% have been investigated. Enhanced elongations of up to 50% were obtained at temperatures ranging between 100 and 200°C and at strain rates of less than 2.8×10−4/s. Under these optimum forming conditions, the flow curves were characterized by intensive serration and the increased strain hardening rate over an extensive strain range. Retained austenite was remarkably stable to strain-induced transformation. Therefore, the enhanced elongation was ascribed to the transformation-induced plasticity of retained austenite to martensite. The increase in carbon and manganese concentrations in the retained austenite was expected to lower the peak temperature at which the total elongation became maximum.View full abstractDownload PDF (1352K) -
Tomoki Tomita, Yasuyuki Takatani, Genzo Hashizume, Yoshio Harada1990 Volume 54 Issue 6 Pages 664-670
Published: 1990
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSCarbide dispersed overlay weld alloys with the Ni-Cr-Fe matrix phase containing various amounts of NbC particles were prepared by a plasma powder welding process. Effects of the dispersion of NbC particles on wear characteristics of the alloys were investigated at sliding speeds of 0.12 to 4.39 m/s under the unlubricated condition, using the Ogoshi wear tester.
The wear resistance of the alloys containing NbC particles less than 10 vol% was not remarkably improved. But it was found that the wear rate of the alloys with NbC contents more than 25 vol% was about 1/10∼1/100 times that of the NbC-free alloys and the wear loss of counter material was also very small. Especially the wear rate of the alloy with 30 vol%NbC was smaller than that of Stellite No. 6 alloy at any sliding speeds in the range of measurement.
It is considered that these excellent characteristics of wear resistance of the alloys was due to the following phenomena caused by the dispersed NbC particles. Thus at the high sliding speed (above 3.53 m/s) the coefficient of friction could be decreased with the result that the unmelted NbC particles became the true contact surface for counter material. On the other hand, at the intermidiate and low sliding speed (below 3.53 m/s) the unmelted NbC particles prevented the plastic flow of the matrix phase and the adhesion could be depressed by NbC powder made from the pulverized unmelted NbC particles.View full abstractDownload PDF (3593K) -
Keisuke Matsuura, Meikon Chou, Norio Matsuda1990 Volume 54 Issue 6 Pages 671-678
Published: 1990
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSCreep tests were carried out on an aluminum composite reinforced with continuous alumina fibres at temperatures of 573 to 773 K to examine the mechanism of high temperature deformation and fracture of the composite.
The creep behaviour was different in low and high stress ranges. Creep curves in the low stress range showed only almost the primary or slight secondary stage without reaching the tertiary stage. The creep strain consisted of an irreversible component, possibly due to the plastic deformation of matrix around the misaligned fibres and the fracture of fibres at weak points, beside a reversible component due to the elastic and anelastic deformation of the matrix and fibres.
In the high stress range, the creep deformation proceeded by the local fracture of fibres and the plastic deformation of the matrix resulting in fracture of the specimen. The creep curves showed the primary, secondary and tertiary stages.
The critical stress which distinguished between the low and high stress ranges was about 500 MPa at 573 K and 450 MPa at 773 K. The critical stress was consistent with the threshold stress which was recognized in the stress dependence of the minimum creep rate. The critical stress, or the threshold stress is considered to be the minimum stress for the individual cracks of fibres to propagate extensively and to cause the fracture of the whole specimen.View full abstractDownload PDF (2057K) -
Yuji Muramatsu, Kohmei Halada, Takehiro Dan, Yukihiro Isoda1990 Volume 54 Issue 6 Pages 679-684
Published: 1990
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSIn order to determine the solid-liquid interfacial tension and its temperature dependence of the W-Cu system, the contact and dihedral angles were measured by multiphase equilibrium experiments in the range of temperature, 1573∼1873 K.
In these experiments, the contact angle at the solid-liquid-vapour line was determined by the sessile drop method. The dihedral angle (φSL) at the grain boundary groove in contact with liquid was determined from the SEM microstructure of liquid-phase sintered materials, and the dihedral angle (φSV) at the groove in contact with vapour was determined from the groove configuration trace by a SEM height meter.
The temperature dependence of the solid-liquid interfacial tension determined (σSL) was examined together with those of the grain boundary tension (σSS) and surface tension (σSV) of solid tungsten.
The following results have been obtained:
(1) The contact angle was 5° at 1473 K. At temperatures higher than 1573 K spreading of copper took place and the contact angle was estimated to be 0°.
(2) φSL and φSV were 85.3-95.0° and 143.7-144.3°, respectively. Both values decreased with an increase in temperature.
(3) A plot of σSL against temperature shows a linear relationship as represented by the following equation:
(This article is not displayable. Please see full text pdf.)
\ oindentThe experimental error of σSL was in ±5% and d(σSL)⁄dT was −0.63±0.03 mN/(m·K).
(4) The temperature dependence of σSS and σSV can be represented by the following linear relationships:
(This article is not displayable. Please see full text pdf.)
\ oindentIn the above equations d(σSS)⁄dT and d(σSV)⁄dT were −0.49±0.02 and −0.91±0.03 mN/(m·K), respectively.View full abstractDownload PDF (1216K) -
Nobuo Kobayashi, Hiroyuki Ichinose1990 Volume 54 Issue 6 Pages 685-691
Published: 1990
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSIn order to find the corrosion behavior in a 3%NaCl flowing aqueous solution (2 m·s−1) of copper sheets which was cold-rolled up to 90% total reduction under the condition of 10% reduction per pass, a study has been carried out by the natural potential and polarization measurements, and investigated in comparison with corrosion behavior in the static immersion test. The time effect in the natural potential showed almost a stationary state immediately after immersion. It was about the same value at each total reduction. The cathodic polarization curves showed a limited diffusion current, and the corrosion current density which was obtained by extrapolating the limiting diffusion to the natural potential was different at each total reduction. The relation between corrosion current density and total reduction showed two maxima at 30 and 80% total reductions and a minimum at 50%. It was found that the relation between corrosion current density and total reduction corresponded to the relation between the corrosion rate and total reduction in the static immersion test, and the residual stress and total reduction. It is considered that in the flowing aqueous solution, the residual stress increases the corrosion rate through increasing the limiting diffusion current and shifting the potential to less noble.View full abstractDownload PDF (2379K) -
Takayuki Nishi, Tadanori Sano, Hiroyuki Takeshita, Toshio Oishi, Katsu ...1990 Volume 54 Issue 6 Pages 692-699
Published: 1990
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSTrace amounts of oxygen (0.5-106 mass ppm) and sulfur (1.8-446 ppm) in copper were determined by secondary ion mass spectrometry (SIMS).
Oxygen in copper could be detected in the form of 16O− ion or 79(63Cu16O)− ion without the interference of residual gas. Either ionic intensity of 16O− or 79(CuO)− normarized with matrix 63Cu− varied linearly with the bulk oxygen concentration in the range of 0.5-106 ppm. Because of the dynamic range, the oxygen analytical limit evaluated in this study was ueder 0.5 ppmO.
The 32S− ion was applied to the quantitative sulfur analysis in copper. Detection of the 32S− ion was required to separate the (16O)2− ion with a high resolution mode. Ionic intensity 32S− normarized with the matrix 63Cu− ion varied linearly with the bulk sulfur concentration in the 1.8-446 ppm range. But the intensity ratio of the 0.6 ppmS sample deviated largely from the working curve. The intensity could not be detected for the 0.3 ppmS sample because of sensitive deficiency.View full abstractDownload PDF (1070K) -
Tatsuya Ohmi, Masayuki Kudoh1990 Volume 54 Issue 6 Pages 700-705
Published: 1990
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe Duplex Casting process, in which two kinds of molten alloys with different compositions are cast in mold in sequence at a given interval, was applied to hypereutectic Al-Si alloys as the refinement process for the primary silicon crystals which grow to a considarable size under the conventional castings.
It this study, three combinations of alloy compositions were used to make Al-22 mass%Si ingots: (1) Al-12 mass%Si as the first molten alloy and Al-32 mass%Si as the second molten alloy; (2) Al-32 mass%Si and Al-12 mass%Si; and (3) Al-22 mass%Si and Al-22 mass%Si.
When the liquidus temperature of the second molten alloy was higher than the first one, the primary silicon crystals were drastically refined. Furthermore, they were finer when the temperature of each molten alloy at the time of mixing was lower. Under the most effective condition for refinement, the mean size of primary silicon crystals was reduced to about 40 μm, while it was 70-90 μm in the ingots produced by the conventional casting.
It was also observed that the macroscopic segregation of the primary silicon was alleviated as the primary silicon crystals were refined by the Duplex Casting process.View full abstractDownload PDF (2262K) -
Tadakazu Ohnishi, Akihiko Okamura, Tsuyoshi Nakayama1990 Volume 54 Issue 6 Pages 706-712
Published: 1990
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSFabrication of Al-Zn-Si alloy wires by the horizontal in-rotating-water spinning method, in which the molten metal jet was ejected into the coolant formed on the inner surface of the horizontal rotating drum, was investigated. Continuous wires with good quality were obtained only when the jet velocity and the flow rate of coolant were relatively low and close with each other. The roundness and homogeneity of wires deteriorated with increasing ejection temperature and jet diameter. Using a coolant with lower density and larger cooling ability, for example, the precooled ethyl alcohol instead of the water at room temperature, improved the roundness and homogeneity of wires.View full abstractDownload PDF (1471K) -
Tadatomo Suga, Kun’ichi Miyazawa, Hideki Takagi1990 Volume 54 Issue 6 Pages 713-719
Published: 1990
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe surface activation method was employed to bond Al and Cu to various ceramics and Si at room temperature. The surfaces of the specimens are activated by the irradiation of an Ar fast atom beam before the bonding. Al was bonded successfully to various oxides and nitrides in a vacuum of 9×10−5∼2×10−6 Pa with a bond strength between 50 MPa and 100 MPa, while no macroscopic bonding could be achieved between Cu and the ceramics. The TEM observation of the interfaces showed an amorphous intermediate layer in the Al-Al and Al-Si interfaces, which might be formed by the irradiation of the Ar fast atom beam in some residual gases. No intermediate layer but interfacial dislocations could be observed in the Cu-Cu interface. It means that a direct bonding between Cu lattices is formed.View full abstractDownload PDF (2286K) -
Katsuhisa Nagayama, Hiromitsu Ino, Takateru Umeda1990 Volume 54 Issue 6 Pages 720-728
Published: 1990
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSCrystallization processes for a wide range of amorphous Fe1−x(Nd1−yBy)x alloys (0.1≤x≤0.6, 0≤y≤1) have been investigated by calorimetry, X-ray diffraction, Mössbauer spectroscopy and magnetization. The phase regions of formation of various kinds of phases included metastable ones have been determined in detail. The metastable Nd2Fe23B3 phase is formed at boron-rich region (0.18≤x≤0.27, 0.61≤y≤0.78) at a temperature range from 900 to 1000 K. Instead, the metastable NdFe12B6 phase only appears together with Nd2Fe23B3 and is not formed in the alloy of the stoichiometric composition of the compound (Fe0.63Nd0.05B0.32).View full abstractDownload PDF (1212K) -
Masateru Nose, Hisae Minatono, Tsuyoshi Masumoto1990 Volume 54 Issue 6 Pages 729-736
Published: 1990
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSMagnetic properties of Co-Ni-Mo-Zr amorphous alloys prepared from the melt by rapid quenching were investigated. Ring samples (φ10-φ6) were stamped out from the ribbons and treated by the conventional annealing (CA) and/or rotating-magnetic-field annealing (RFA).
The soft magnetic properties of Co79Ni4Mo8Zr9 amorphous alloys, whose Tx was higher than Tc by 65 K, were improved slightly by the single process of these techniques. However, the two step annealing method (CA+RFA) improved the soft magnetic properties of this alloy remarkably. The relative permeability of this alloy depended on the external magnetic-field at the 2nd stage of the two-step annealing method. The highest relative permeability at 1 kHz was obtained by the sample annealed in the maximum field of 1.2 MA/m. This result is attributed to the large induced anisotropy of Co-Zr base alloys compared with the metal-metalloid base alloys.View full abstractDownload PDF (1050K) -
Sakae Saito, Senri Ikeda, Keisuke Ikeda, Shuji Hanada1990 Volume 54 Issue 6 Pages 737-740
Published: 1990
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSNb3Al superconducting wires are fabricated by the Clad-Chip Extrusion (CCE) method which is characterized by extruding the chipped Nb-Al clad sheets. Maximum reduction ratio in CCE-processed Nb-Al composite wires is 3×106, which corresponds to the Nb-layer thickness of 80 nm. The obtained wires with reduction ratios from 1×105 to 3×106 are heat-treated at temperatures below 1300 K to form Nb3Al by solid-state diffusion and the influence of reduction ratio on superconductive properties is studied. The Nb-Al composite wires with a higher reduction ratio allow the preferential formation of A15 phase at those temperature ranges, which enhances the critical current density. The wire heat-treated under an optimized condition shows the critical transition temperature of 17.1 K and the critical current density of 108 A/m2 in the applied magnetic field of 18.8 T at 4.2 K.View full abstractDownload PDF (810K) -
Tadatomo Suga, Yutaka Takahashi, Hideki Takagi, Yoichi Ishida, G. Elss ...1990 Volume 54 Issue 6 Pages 741-742
Published: 1990
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSDownload PDF (598K)
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