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Volume 54, Issue 12
Displaying 1-19 of 19 articles from this issue
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Shigeru Aoki1990 Volume 54 Issue 12 Pages 1297-1301
Published: 1990
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSSilicon specimens containing stacking faults (SFs) are cut out of Czochralski-grown wafers for observation with a transmission electron microscope (TEM). ⟨100⟩-oriented silicon wafers normally used for large scale integrated circuit devices are subjected to thermal treatments in N2 and O2 ambients in order to form bulk-type SFs. Then, TEM specimens are carefully prepared for observing the whole image of the SF in the fault plane. For this purpose the specimen is cut off along the {111} plane being inclined from the (100) wafer surface by 55 degrees. It is found that a bulk-type multiple stacking fault consists of a cluster of SiO2 precipitates located in the center of a circular Frank dislocation loop, and of many SiO2 precipitates on the loop.View full abstractDownload PDF (2373K) -
Naoto Sumida, Tsuneo Mishima, Hiroshi Fujita1990 Volume 54 Issue 12 Pages 1302-1307
Published: 1990
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSA tetragonal high-temperature phase (ζα-phase) and an orthorhombic low-temperature phase (ζβ-phase) exist in iron disilicide FeSi2. Electron microscope observation shows that most of the grains in the ζβ-phase alloy have lamellae.
These lamellae produce streaks perpendicular to the (100) plane in a diffraction pattern of the [021] zone axis. Contrast of the lamellae in a bright field image observed from the exact [011] zone axis disappears completely. There is no irregularity on the periodic arrangement of bright dots in a lattice image taken from the [011] zone axis. Therefore, it is concluded from these results that the lamellae are not thin precipitates but stacking faults on the plane parallel to the (100) plane with the [011] displacement vector.
Comparing the observed lattice image taken from the [021] zone axis with the simulated image, the positions of bright dots are assigned to be a group of iron atom rows lying in the first and the sixth stacking plane along the [100] direction in the unit cell. Taking into the consideration of the crystal structure of the ζβ-phase, we suggest the stacking fault is formed by the 1/2 [011] displacement between the third and the fourth stacking plane in the unit cell.View full abstractDownload PDF (2020K) -
Ryoichi Monzen, Kazuo Kitagawa, Masaharu Kato, Tsutomu Mori1990 Volume 54 Issue 12 Pages 1308-1313
Published: 1990
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe boundary precipitation of BCC Fe-Co precipitates in a Cu-1.4Fe-0.6Co alloy has been studied, using [011] symmetric tilt and [001] twist boundaries. The misorientation angle dependence of the density of the precipitates is similar to that of the boundary energy in Cu for the two types of boundaries. In general, the lower the boundary energy, the lower the density of the precipitates. The minima of the density exist where the cusps of the boundary energy exist; θ=70.5°(Σ3) and 130°(Σ11) for [011] tilt and θ=13°(Σ41), 23°(Σ13), 28°(Σ17), 37°(Σ5) and 44°(Σ29) for [001] twist boundaries. The boundary energy plays a predominant role in governing the boundary precipitation, except for the 130.5°[011] tilt boundary. In the latter case the density of the precipitates is high, because the precipitates can have the K-S orientation relationships to both abutting grains. Accordingly, the precipitates have two flat habit planes with a low interfacial energy. The general shapes of the precipitate density, volume and the PFZ width vs the misorientation angle curves are similar in the two types of boundaries.View full abstractDownload PDF (1231K) -
Joo Ishihara, Toshio Ogawa, Teturo Uchida1990 Volume 54 Issue 12 Pages 1314-1319
Published: 1990
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe growth characteristics of the Cr7C3 type carbide in austenite containing various chromium contents have been investigated in the ranges of 1173 to 1473 K and 0.6-12 ks. The specimens for this investigation were made by the rapid quenching method which is used for making amorphous metals and a highly supersaturated solid solution was obtained. The observed coarsening rate of the Cr7C3 type carbide, however, is much higher than the theoretical rate expected from the mechanism of Ostwald ripening. This disagreement has been interpreted as being caused by precipitation from the highly supersaturated solid solution which is induced by the rapid quenching method. In proportion as the chromium concentration increases, the growth rate of the Cr7C3 type carbide became slower. This tendency was thought to be in good agreement with the theory of Ostwald ripening.View full abstractDownload PDF (766K) -
Kuniyasu Nakamura, Kiyoshi Kasai, Michihiko Nagumo1990 Volume 54 Issue 12 Pages 1320-1328
Published: 1990
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSCrystallization kinetics of amorphous Cu50Ti50 alloy prepared by mechanical grinding of the intermetallic compound powder with a high energy ball mill was studied. Kinetics at the isothermal annealing was well analyzed in terms of the Johnson-Mehl-Avrami equation, giving a velocity exponent of 0.85 and an activation energy of 183 kJ/mol. Both figures are less than the corresponding values of the material prepared by a rapid cooling process. Kinetics at the athermal annealing was analyzed using the Kissinger method and an activation energy of 154 kJ/mol was obtained in accord with the analysis with the JMA equation.
The amorphous state and the crystallization process were discussed from these results. In an amorphous material prepared by mechanical grinding, the crystalline fraction remains and is likely to act as nuclei of crystallization. Crystallization is likely to proceed two-dimensionally on these nuclei. The number and average size of nuclei were estimated to be 1024/m3 and of 103 unit cells of Cu50Ti50, respectively.
The activation energy of diffusion estimated by assuming the two-dimensional crystal growth kinetics is 214 kJ/mol and the diffusion of Ti atoms is likely to be rate-controlling. Atom migration necessary for the crystallization is considered to take place in a short range of the order of 5-10 nm.View full abstractDownload PDF (1127K) -
Setsuo Takaki, Shunji Iizuka, Kouki Tomimura, Youichi Tokunaga1990 Volume 54 Issue 12 Pages 1329-1335
Published: 1990
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe changes in carbide morphology and matrix microstructure that occur during 973 K annealing have been investigated for a low alloy 0.2%C lath martensitic steel by optical and transmission electron microscopy. For optical metallographic observation, striking changes were not found out even in long-time annealed specimens because carbides preferentially precipitate on block and lath boundaries to maintain the structural character of lath martensite. The morphology of carbides and matrix microstructure, however, are gradually changed during the annealing.
Stick type carbides, which were formed along lath boundaries in the early stage of annealing, play an important role in suppressing the recovery of dislocations within the lathes. The dislocation density of matrix pronouncedly decreases when the morphology of lath boundary carbides changes from stick to oval or sphere, leading to a discontinuous change in tensile properties. It was also confirmed that the deformation to a pre-annealed specimen containing the stick type lath boundary carbides does not greatly affect the recovery behavior during the following annealing. The result also reveals the fact that the growth of lath boundary carbides controls the recovery of lath martensite matrix.View full abstractDownload PDF (2332K) -
Keijiro Nakasa, Jianping Liu1990 Volume 54 Issue 12 Pages 1336-1343
Published: 1990
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSAn X-ray diffraction analysis was carried out both for bowed-specimen and ball-indented specimen, which were cathodically hydrogen charged in sulfuric acid solution under a current density of 3000 A/m2, to investigate the effect of tensile and compressive stresses on the behavior of hydride formation in Ti-6Al-4V alloy.
For the bowed-specimen, γ-hydride (fcc) was formed more easily under tensile stress than under compressive stress. The formation of δ-hydride (fct), on the other hand, was only slightly easier under tensile stress than under compressive stress. The γ-hydride formed under tensile stress was decomposed to the α-titanum phase when the stress was reversed to compression, leaving the δ-hydride unchanged. However, the γ-and δ-hydrides formed under compressive stress did not change when the stress was reversed to tension. For the ball-indented specimen, the amount of γ-and δ-hydrides showed a minimum in the center of indentation with the largest compressive stress. Besides, the indentation on a plate specimen after hydrogen charging decreased the γ-hydride but increased the δ-hydride. The effect of stress on the hydride formation and decomposition appear to be explained by the habit planes of hydride relative to α-lattice, and the expansion during hydride formation.View full abstractDownload PDF (1016K) -
Koh-ichi Sugimoto, Tsuneaki Sakaki, Mitsuyuki Kobayashi, Shin-ichi Yas ...1990 Volume 54 Issue 12 Pages 1344-1349
Published: 1990
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe Bauschinger effect behavior and the influences of retained austenite on that of 0.1∼0.4%C-1.5%Si-1.5%Mn in mass% TRIP (Transformation-Induced Plasticity)-aided dual-phase steels containing the retained austenite of 6 to 20 vol% were measured, and the relations between the Bauschinger stress and mean internal stress calculated on the basis of a continuum theory were investigated.
The Bauschinger effects in TRIP-aided dual-phase steels were characterized by remarkable transitional-softening and subsequent permanent-softening proposed by Orowan, the amounts of which were relatively small compared to ones of conventional ferrite-martensite dual-phase steels. Retained austenite was found to make the Bauschinger effect small, although strain-induced transformation of retained austenite to martensite, which was particularly promoted during deformation in tension, enhanced a strain hardening rate and flow stress in tension.
The Bauschinger effect and the Bauschinger stress were found to be controlled by a long range internal stress arising from unrelaxed plastic strain between the matrix and the second phase islands. The internal stress was estimated from continuum theory considering the effects of strain-induced transformation and plastic relaxation during straining.View full abstractDownload PDF (1009K) -
Shin-ichi Yasuki, Koh-ichi Sugimoto, Mitsuyuki Kobayashi, Shun-ichi Ha ...1990 Volume 54 Issue 12 Pages 1350-1357
Published: 1990
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSLow cycle fatigue behavior of 0.1∼0.4%C-1.5%Si-1.5%Mn (in mass%) TRIP-aided dual-phase steels containing retained austenite of 6 to 20 vol% has been measured at room temperature and a role of retained austenite on this behavior has been investigated in terms of the measured Bauschinger stress.
Low cycle fatigue of TRIP-aided dual-phase steel was generally characterized by severe initial fatigue-hardening and successive small fatigue-hardening or fatigue-softening. The amount of initial fatigue-hardening increased with increasing initial retained austenite content and total strain amplitude. The fatigue properties were superior to those of the conventional ferrite-martensite dual-phase steel.
The fatigue-hardening was principally ascribed to the increased internal stress arising from a misfit strain between soft and hard phases. Retained austenite enhanced the internal stress due to the increase in fresh martensite content produced by the strain-induced transformation.View full abstractDownload PDF (1566K) -
Hiromichi Takebe, Tsuneya Okano, Takuya Semba, Kenji Morinaga1990 Volume 54 Issue 12 Pages 1358-1362
Published: 1990
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe tetragonal to monoclinic transformation in Y-TZP specimens and mullite/Y-TZP composites containing 5 vol% mullite, which progresses from surface to interior by annealing at 373 K in boiling water, was investigated by scanning acoustic microscope (SAM). The Rayleigh wave velocity, VR, which was measured on surfaces of the specimens, was lowered by the transformation. We obtained relationships between the transformation depth which was converted from the VR and annealing time. The depth after the annealing for 612.0 ks in the Y-TZP specimens was 7.2 μm, while in the mullite/Y-TZP composites it was less than 1.0 μm. Apparently the relationships suggested that a nucleation-growth stage existed in the process of the transformation. The transformation mechanism was discussed from changes of the transformation depth and SAM image contrast with the annealing time.View full abstractDownload PDF (1013K) -
Naotaka Sakamoto, Kenji Morinaga1990 Volume 54 Issue 12 Pages 1363-1368
Published: 1990
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe glass-forming region in the binary system SnF2-P2O5 has been determined as the composition range 45-90 mol%SnF2, and all of the glasses were clear, colourless, and durable. This wide region indicated that SnF2 contributed to glass-forming as a network former (NWF). Glass transition temperature (Tg), dilatometric softening temperature (Tg), melting point (Tm) of the glasses, and viscosity of the melts were measured. The variations in these properties as a function of SnF2 content showed the maximum at 60SnF2-40P2O5 as mixed composition, and Sn4+/Sn2+ in the glasses had the maximum value at this composition judging from the chemical shifts of SnLβ2 in the glasses. IR spectroscopic study of the glasses revealed that relative amount of P=O bond decreased and ν3 vibration of PO4 units became symmetric with increasing SnF2 content. From these results, Sn in this system was assumed to be able to bridge between PO4 units when SnF2 changed to SnOF2(Sn4+) and interacted with P=O bonds in the glass. On the basis of these results, a structure model of Sn-P-O-F glass is proposed.View full abstractDownload PDF (766K) -
Masao Morishita, Masahiro Chikuda, Yoshio Ashida, Masahiko Morinaga, N ...1990 Volume 54 Issue 12 Pages 1369-1375
Published: 1990
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSIn order to understand cathodic reactions of Ti-based alloys, the localized electronic states of a cathode were simulated by the DV-Xα cluster method. The results were interpreted on the basis of an electron theory.
A local electronic cell is considered here. The anode is the titanium-matrix region and the cathode is the alloying-element containing region. It is likely that the cathodic reaction is enhanced strongly when many conduction electrons localize in the cathode, and then thses electrons discharge to H+ smoothly and forming H2 on the cathode. The tendency of electron localization can be evaluated by the number of electron vacancies on the Fermi level. On the other hand, the tendency of discharging electron to H+ appears to be associated with the height of Fermi level.
It was found that the cathode containing Ir, Pt, Rh, Pd and Ni had more electron vacancies and exhibited a higher Fermi level than the cathode containing other elements, and enhanced a cathodic reaction. However, these changes of electronic states on the Fermi level of the cathode occurred mainly in electron configurations of Ti atoms which were affected by the presence of alloying elements.View full abstractDownload PDF (791K) -
Shozo Inoue, Hitoshi Uchida, Mika Morii, Keiji Koterazawa1990 Volume 54 Issue 12 Pages 1376-1381
Published: 1990
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSRaman spectroscopy should be a useful technique for a nondestructive characterization of surface layers on metals. In this study, Raman spectroscopy has been used to examine oxide layers formed on stainless steels in air at elevated temperatures.
Specimens of commercial austenitic stainless steels (SUS304, SUS316 and SUS310S) were prepared by polishing with #1200 emery paper and degreasing in an ultrasonic bath of acetone. Oxidations were carried out in a preheated furnace at 573-1073 K for 1.8-3600 ks. Raman spectra were obtained from these oxide layers formed on stainless steels. Auger depth analysis was also used to study the oxide layers.
When oxidation temperature was below about 873 K, it was clarified that iron oxides such as Fe2O3 and Fe3O4 were formed. On the other hand, the surface oxide layers at above 873 K were composed of Cr2O3, MnCr2O4 and FeCr2O4. The composition of stainless steels was less dependent on these oxidation behavior. The thickness of the oxide layer formed at 1073 K for 7.2 ks was estimated at about 400 nm by Auger depth profiling. From a comparison of the Raman spectra with Auger depth profiling, it was concluded that the Raman spectra measured in this study were obtained from the whole layer of the surface oxide film. Therefore, Raman spectroscopy technique can be applied to the characterization of the oxide layers up to about 1 μm thickness formed on stainless steels.View full abstractDownload PDF (800K) -
Masaki Harata, Takao Choh, Makoto Kobashi1990 Volume 54 Issue 12 Pages 1382-1391
Published: 1990
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe effect of alloying elements on TiC particulate dispersion into liquid aluminum was investigated. TiC particles could be dispersed in liquid aluminum without excessive dissociation, because of their chemical stability. The time required for dispersion of TiC particles into molten aluminum is defined as the incorporation time. The results of measurement showed that the alloying elements were divided into three types concerning the effect on particulate incorporation time: shortening, prolonging the incorporation time and no effect.
The incorporation of TiC particles into molten aluminum proceeds accompanying TiC dissociation for wetting, resulting in the formation of an intermetallic compound of the Ti-Al system. In the case of additions of silicon, calcium and zirconium, EPMA showed that these elements promoted the reaction of TiC particulate dissociation; TiC→Ti+C and shortened the incorporation time by forming an intermetallic compound with titanium. On the other hand, although alloying elements such as magnesium, lead and bithmuth were not contained in the intermetallic compound, the incorporation time was shortened by the surface active effect of these alloying elements. Copper had a little effect on the incorporation time. Since TiC dissociation is controlled by the existence of titanium in melt, the incorporation time for the Al-Ti system was prolonged consequently.
It is clear from the microstructural observation that particles segregate along grain boundaries of the matrix under slow solidification rate as air cooling in the crucible. However, under the condition of rapid solidification rate, the sound composite showing a uniform particulate distribution was obtained.View full abstractDownload PDF (4118K) -
Shotaro Morozumi, Kazuhiko Hamaguchi, Masaaki Iwasaki, Michio Kikuchi, ...1990 Volume 54 Issue 12 Pages 1392-1400
Published: 1990
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSUsing two kinds of PLS-Si3N4 and CVD-Si3N4 joints, bonded with Al, Ni, Ti and Zr foils, and Al/Ti/Al, Al/Ni/Al and Ni/Ti/Ni three-layer foils, respectively, at 1073-1673 K in a vacuum or ambient atmosphere in three different furnaces, examinations have been made on the structure of the reaction layer by optical microscopy, EPMA and the X-ray powder method, and the bond strength of the joints, bonded with Al and Al/Ni/Al foils, by the four-point bend test.
The results obtained are as follows: (1) Since silicon nitride may decompose in a vacuum over the bonding temperature range, the composition and structure of the reaction layer are largely dependent on the atmosphere around the specimens. (2) The composition of the reaction layer is allso dependent on the state and property of silicon nitride itself. (3) As the highest bond strength of about 200 MPa has been obtained in the joints bonded with Al foil and Al/Ni/Al three layer foils, it is considered that the fused aluminum phase may have an important role for the joining.View full abstractDownload PDF (2933K) -
Kiyoshi Nogi, Koji Ikeda, Kazumi Ogino1990 Volume 54 Issue 12 Pages 1401-1407
Published: 1990
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe wettability of hot-pressed SiC, which had been made in present work, by liquid Cu-Ti alloy was investigated at 1393 K under reduced pressure.
The main results are summerized as follows:
(1) The wettability of SiC by liquid Cu-Ti alloy was improved by a small amount of Ti.
(2) A formation of TiC was observed at the initial interface between liquid Cu-Ti alloy and SiC.
(3) The improvement of the wettability was not attained by the formation of TiC but by the dissolution of Si and C into liquid Cu.View full abstractDownload PDF (1050K) -
Terunobu Miyazaki, Mikio Takahashi, Xingbo Yang1990 Volume 54 Issue 12 Pages 1408-1413
Published: 1990
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe formation of compounds in (Fe1−xCox)1−yPry and (Fe1−xCox)1−ySmy ternary alloys rapidly-quenched from the melt at disk surface velocities ranging from 4.3 to 41.9 m/s has been investigated by X-ray diffraction analysis. The following types of compounds were found to be formed: TbCu7-type: 0≤x≤0.6 in (Fe1−xCox)0.89Pr0.11 and 0≤x≤1.0 in (Fe1−xCox)0.89Sm0.11; CaCu5-type: 0.6≤x≤1.0 in (Fe1−xCox)0.83Pr0.17 and (Fe1−xCox)0.83Sm0.17; and Gd2Co7-type: 0.6≤x≤1.0 in (Fe1−xCox)0.78Pr0.22 and 0.7≤x≤1.0 in (Fe1−xCox)0.78Sm0.22. Both CaCu5-type and Gd2Co7-type ternary compounds do not exist in their equilibrium state. In the Fe-Co-Pr system, PuNi3- and MgCu2-types compounds were formed with a Th2Zn17-type stable compound at the compositions x=0.3 and x=0.4.View full abstractDownload PDF (813K) -
Terunobu Miyazaki, Mikio Takahashi, Shunji Ishio, Migaku Takahashi1990 Volume 54 Issue 12 Pages 1414-1421
Published: 1990
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSCoercivity, magnetization, Curie temperature and maximum energy product of rapidly quenched (Fe1−xCox)1−y(Sm, Pr)y (0≤x≤1.0; y=0.11, 0.17 and 0.22) alloys were measured. The coercivity at room temperature is: 480-1120 kA/m for (Fe1−xCox)0.83Sm0.17 (CaCu5 type, 0.6≤x≤1.0), 240-480 kA/m for (Fe1−xCox)0.83Pr0.17 (CaCu5 type, 0.6≤x≤1.0), 240-500 kA/m for (Fe1−xCox)0.78Pr0.22 (Gd2Co7 type, 0.6≤x≤1.0), 64-160 kA/m for (Fe1−xCox)0.89Pr0.11 (TbCu7 type, 0≤x≤0.6), and 4-64 kA/m for (Fe1−xCox)0.89Pr0.11 (TbCu7 type, 0≤x≤1.0).
The magnetic anisotropy and coercivity of the alloys are discussed on the basis of the single ion model. The composition dependence of coercivity in the (Fe-Co)0.83Sm0.17 and (Fe-Co)0.89Sm0.11 alloys are attributed to the change of both lattice constant and molecular field.View full abstractDownload PDF (1099K) -
Katsuaki Suganuma, Teruaki Fujita, Koichi Niihara1990 Volume 54 Issue 12 Pages 1422-1431
Published: 1990
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSSqueeze casting of potassium titanate whiskers reinforced 6061 aluminum alloy matrix composites was examined. Distribution of whiskers in a preform was varied by the milling of whiskers in water and by the surface activation treatment of whiskers during stirring in water by adding a surface activation agent. The surface activation treatment was proved to be the best to make a uniform distribution of whiskers in a preform, i.e. in a composite. Then, this treatment increased the tensile strength up to 350 MPa and the Young’s modulus up to 92 GPa and reduced the thermal expansion coefiicient down to 16×10−6 K−1. These properties are desirable for industrial uses of the aluminum matrix composite, combined with the low cost of composite. Sillica binder used to fix the whiskers preform reacted with aluminum melt during casting and disappeared from the FRM. Instead, small particles of γ-alumina were formed on the whisker by the reaction between whisker and aluminum. An amorphous-like layer exists between the precipitates and whiskers in a few nm thickness.View full abstractDownload PDF (4343K)
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