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Volume 56, Issue 3
Displaying 1-18 of 18 articles from this issue
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Atsushi Tsuboi, Yoshiyuki Hamakawa, Kenji Sumiyama, Masayuki Shiga1992 Volume 56 Issue 3 Pages 227-231
Published: 1992
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSFe1−xBix alloys sputter deposited on a water-cooled substrate have been investigated by X-ray diffraction, magnetization and the Mössbauer effect. Although Fe and Bi are immiscible with each other even at 2000 K, a bcc phase appears for 0<x<0.1, an amorphous phase for 0.1<x<0.2, and a rhombohedral phase for x>0.6, These Fe1−xBix alloys are ferromagnetic for 0<x<0.7. The magnetic moment of an Fe atom is about 2.2 μB and independent of x for 0<x<0.15. Coercive force of the amorphous phase is smaller than those of the other crystalline phases. The electrical resistivity, ρ, is large in these alloys. Very large values of ρ in Bi-rich alloys are probably due to the low density and discontinuity of the films.View full abstractDownload PDF (524K) -
Haruo Doi, Kenki Hashimoto, Kazuo Kasahara, Tokuzou Tsujimoto1992 Volume 56 Issue 3 Pages 232-237
Published: 1992
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSSite occupation ratios of additional third elements (Fe, Ni, Cu, Ag, Pt, Ga and Sb) in the L10-type compound TiAl are determined by using the X-ray diffraction method. The results obtained are compared with the theoretical predictions reported previously for preferential occupation sites. The conditions necessary for accurate determination of the occupation ratios of third elements with the X-ray diffraction method are clarified.
It turned out that Fe and Ag atoms occupy predominantly the Al site, whereas Cu and Sb atoms occupy the Ti site and Ni, Pt and Ga atoms occupy both sites; the amount of mutual exchanges of Al and Ti atoms in lattice sites increases with the addition of Cu, Ag, Pt, Ga and Sb into the Al-rich TiAl phase whereas it does not change with the addition of Fe and Ni into the Ti-rich TiAl phase. Errors in determination of the occupation ratio of the additive elements decrease exponentially with increase of the difference in atomic number between Ti and the additive elements, and the magnitude of the errors becomes as small as 0.5 at% as the difference exceeds nine.View full abstractDownload PDF (635K) -
Masato Ohnuma, Hisashi Kuwano, Yoshikazu Hamaguchi1992 Volume 56 Issue 3 Pages 238-246
Published: 1992
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe morphology of primarily crystallized α-Fe in Fe-B-(Si, Ge) amorphous alloys has been investigated by using transmission electron microscopy. Several kinds of shapes which have been observed in electron micrograph, depend on their growing stage and sectioning directions of crystals. The shapes can be explained by assuming that the general form of primarily crystallized phase is dendritic, and has primarily and secondary arms growing in the ⟨111⟩ direction. The general form is independent of Si and Ge contents, but the number of α-Fe nuclei decreases and dendritic arm length increases with increasing Si content.View full abstractDownload PDF (2483K) -
Shuji Yamada, Tadashi Hamada, Junji Imai, Eiji Tsuji, Tomoyuki Mizukos ...1992 Volume 56 Issue 3 Pages 247-253
Published: 1992
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSWe have examined the structure and hardness of FeCrNiAl alloys, in which the alumina layer is formed at their surfaces by heat treatment.
In FeCrNiAl alloys, the Ni and Zr contents are fixed at 21 mass% and 0.2 mass% respectively, and the Al content is changed to 4.6, 5.3, 6.0 and 6.7 mass% and the sum of Cr and Al contents is changed to 33, 36 and 39 mass%, These samples are heated at 1423 K for 54 ks in air and then examined. The heat treatment produced alumina layers of 3∼4 μm thickness at the surface and root like alumina of 20∼30 μm length stretching out from the alumina layers. The austenite phase appears in the alloys in which the Al content is less than 4.6 mass%, and also it appears in those in which the sum of Cr and Al contents is less than 33 mass% and the Al content is less than 6.0 mass%. The austenite phase is as low as 102 in vickers hardness, so it is harmful to hardening the alloys. NiAl based intermetallic compound particles of about 5 μm diameter (large size) are produced in the alloys, but a region free from the large particles appears extending from the surface to a certain depth. The depth depends on the Cr and Al contents. Even in this region the particles of the NiAl based intermetallic compound of about 0.3 μm diameter are formed. The vickers hardness of the region free from the large size particles is greater than 450. This region is harder than the region with about 5 μm particles.View full abstractDownload PDF (1952K) -
Hideharu Nakashima, Hideo Yoshinaga1992 Volume 56 Issue 3 Pages 254-261
Published: 1992
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSFor the high-temperature deformation of Al-Mg alloys, the dislocation densities which were obtained by the stress change and stress relaxation tests using the theoretical edge dislocation-mobility of Cottrell, were about 10 times as large as the densities measured by transmission electron microscopy. The mobility of edge dislocations dragging solute-atmospheres was re-evaluated by assuming that the interaction energy between edge dislocation and solute atom is relaxed with increase in solute concentration. The obtained results are summarized as follows.
(1)The re-evaluated mobility in an Al-5.0 mol%Mg alloy, for example, is about 5 times as large as Cottrell’s mobility.
(2)The mobility tends to saturate with increase in the solute concentration.
The dislocation densities obtained in Al-Mg alloys by the stress change and stress relaxation tests were re-estimated using the re-evaluated mobility. It was found that the re-estimated dislocation densities agree approximately with the densities obtained by transmission electron microscopy.View full abstractDownload PDF (1092K) -
Fukuji Inoko, Takashi Yoshikawa1992 Volume 56 Issue 3 Pages 262-270
Published: 1992
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSIn order to clarify the formation mechanisms of recrystallized grains along grain boundaries, 99.99 mass% copper bicrystals were prepared by using the modified Bridgman method. They were deformed in tension to the strain of 30-40% and annealed at certain conditions to get the early stage of primary recrystallization along the grain boundaries. The formation of recrystallized grains along the grain boundaries due to the strain induced boundary migraion (SIBM) was observed, especially by the in situ observation by TEM. The formation of recrystallized grains due to the SIBM occurs along the grain boundaries with high tilt component, towards which dislocations with large edge components piled up. The formation due to the ⟨111⟩ rotation mechanism occurs on the other hand along the grain boundaries with high twist component, towards which dislocations with large screw components piled up. During the migration of the original grain boundaries many annealing twins are formed.View full abstractDownload PDF (2113K) -
Mitsunori Tsutsui, Takashi Yamada1992 Volume 56 Issue 3 Pages 271-277
Published: 1992
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSFine alumina fiber-reinforced aluminum alloys were formed by means of a squeeze casting process. The microstructures of composites were observed through optical and scanning electron microscopes. The fiber and aluminum alloy were joined intimately, and there was little evidence of chemical reaction at the interface. In order to clarify the effect of fiber and silicon contents on the corrosion behavior of the composites, the specimens were immersed in a sulfuric acid aqueous solution, and the mass-loss of specimens was measured after removing the corrosion products. The cathodic and anodic polarization curves were measured to investigate the corrosion behavior of the composites. From the anodic polarization curves, it was presumed that the dissolution reaction of aluminum alloy increased with increasing fiber content. Microstructural observation revealed that the corrosion of aluminum was advanced along fibers. Therefor, the corrosion rate of specimens increased with increasing fiber content. However, the corrosion rate of the composites which contained more than 12 mass% silicon in the matrix decreased in comparison with that of the fiber-free specimens. This shows that silicon is effective for the corrosion inhibition of this composite material.View full abstractDownload PDF (1573K) -
Yutaka Kagawa, Akimitsu Okura1992 Volume 56 Issue 3 Pages 278-284
Published: 1992
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSA thin specimen push-out technique for measuring interfacial shear debonding and sliding strength in fiber-reinforced metal matrix composites has been developed. An experimental set-up for measuring load-displacement relation of the fiber during pushing down the fiber axis was developed. An analytical form to obtain interfacial shear strengths based on shear-lag analysis using the load-displacement relation, which was obtained by push-out experiment, was also developed. The developed equipment and analytical procedure have been applied for the measurement of interfacial shear strengths in a SiC(CVD) fiber-reinforced Ti-15Mo-5Zr-3Al matrix composite. The fiber axial load-displacement relation during pushing down of the composite sample was successfully obtained and the interfacial shear strengths were calculated using this relation and the developed analytical form. The determined interfacial shear debonding and shear sliding strength of the composite were approximately 97 and 114 MPa, respectively. These values were considerably smaller than the shear yield stress of the Ti alloy matrix. Some comments are made on the comparison with the previously reported experimental procedure.View full abstractDownload PDF (1828K) -
Toshio Shimoo, Yoshihiro Konishi1992 Volume 56 Issue 3 Pages 285-293
Published: 1992
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe kinetics of smelting reduction of (Fe0.5Mg0.5)(Cr0.8Al0.2)2O4 in molten silicate flux with graphite has been investigated at temperatures from 1773 to 1973 K. The reduction rate was described with a first-order-type rate equation: log (1−R)=−k·t. In the early stage of reduction, in which FeCr2O4 component was preferentially reduced, the rate constant k was virtually independent of the flux composition and the wetting of the flux to the graphite. The activation energies were 200∼250 kJ/mol. The reduction rate was controlled by the dissolution of the chromite into the flux.
In the late stage of reduction, Mg(Cr0.6Al0.4)2O4 component was reduced. The wider contact of the flux with the graphite increased k. The dependences of k on the flux composition and temperature were complicated. The reduction in the flux with a low melting point at a higher temperature was controlled by the chemical reaction at the flux-graphite interface. The reduction in the flux with a high melting point at a lower temperature was mixed-controlled by both the dissolution and the interfacial reaction.View full abstractDownload PDF (1653K) -
Satoshi Yamaguchi, Nobuyoshi Hara, Katsuhisa Sugimoto1992 Volume 56 Issue 3 Pages 294-302
Published: 1992
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSElectrochemical polarization and corrosion properties of carbon steels having TiN films 0.1-10 μm thick formed by reactive sputtering have been examined in 1 kmol·m−3 H2SO4, 1 kmol·m−3 HCl and 3 mass%NaCl, comparing with those of TiN prepared on Ti plates by nitriding. It was found that the corrosion resistance of the TiN-coated steels in short-range immersion in the solutions was improved with increasing thickness of TiN film, dTiN: In 1 kmol·m−3 H2SO4, an active dissolution current density at 0.1 V (vs. Ag/AgCl-3.33 kmol·m−3 KCl) decreased by a factor of 1000 as dTiN increased from 0.1 to 8 μm, and the corrosion rate measured after immersion for 84.6 ks decreased correspondingly. In 3 mass%NaCl, a sharp increase in current due to pitting was observed on the anodic polarization curves of the steels having dTiN<6 mm. No such increase, however, was observed on the curves of the steels having dTiN>8 μm. The improvement of corrosion resistance with increasing dTiN can be attributed to the decrease in the amount of open pinholes in TiN films. After prolonged immersion, the steels covered with thicker TiN films also suffered from pitting corrosion because of the penetration of the solutions through microdefects in the films. From the measurement of cathodic polarization curves of TiN and galvanic current densities of carbon steels coupled to TiN, it was found that in an aerated NaCl solution the TiN films on carbon steels acted as cathodic sites and thus galvanic corrosion occurred on the steel substrates. In a deaerated H2SO4 solution, however, no galvanic corrosion was presumed to occur because the hydrogen overvoltage of TiN was fairly large in this solution.View full abstractDownload PDF (1541K) -
Masaaki Takada, Shinichi Umino, Koji Hayashi1992 Volume 56 Issue 3 Pages 303-307
Published: 1992
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe powder mixtures of (Ba, Sr)(Ti, Sb)O3 PTC ceramics and 0.5∼11 vol%Pt, Au or Ag metal powders were sintered mainly at 1600 K for 3.6 ks in air and their properties were investigated. It was found that the specific resistivity at room temperature increased with increasing amount of the additive for each metal, for example, up to about 10 vol% for Pt, although the PTC characteristics remained at a small amount of metal. The thermal conductivity and fracture toughness, however, were improved about 1.6 and 1.9 times respectively by the addition of 10 vol%Pt.View full abstractDownload PDF (866K) -
Masamichi Matsuura, Nakaya Chida, Haruko Fujinuma1992 Volume 56 Issue 3 Pages 308-314
Published: 1992
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSMolybdenum metallization of Si3N4 SiC and Al2O3 substrates for metal-ceramic bonding was performed using an ion beam dynamic mixing method. In this method, a cylindrical ceramic substrate 5 mm in diameter and 5 mm in length was irradiated simultaneously with a 8.0×10−15 J (50 keV), 1-2×105 μA/m2 Ti+ ion beam and a Mo molecular beam at a substrate temperature of 573 K. The substrate metallized with a Mo film 2-5 μm in thickness was bonded to a copper pin 2.5 mm in diameter with an amorphous Cu-9Ni-4Sn-7P solder at 973 K in a depressurized Ar gas atmosphere. Tensile strength of the copper/ceramic joint was determined by a universal testing machine. A strong joint of more than 120 MPa for each ceramic could be obtained.
Compared to sputtering as a metallization technique, the dynamic mixing resulted in a joint of superior tensile strength and allowed greater versatility in selection of the chemical type of ceramic substrate. With regard to the chemical type of ion beam used for the dynamic mixing, an active metal ion beam such as Ti+ was found to be much more effective in obtaining a strong joint than an inert gas ion beam like Ar+.
The ceramic-metal interface region of the Mo-coated Si3N4 or SiC was observed using a high resolution TEM and an XPS. There were differences between the two ceramics in damage and amorphisation of the ceramic crystal grains caused by the high energy Ti+ ion beam. An amorphous layer, composed of the implanted Ti, the evaporated Mo and some of the ceramic’s constituent elements, was observed in both interface regions. In addition, a precipitated TiN crystal was detected in the Si3N4 system.View full abstractDownload PDF (1383K) -
Kiyoshi Nogi, Hiroyuki Takeda, Kazumi Ogino1992 Volume 56 Issue 3 Pages 315-320
Published: 1992
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSStrengthening of the zirconia-zirconia joining brazed by aluminum was attempted. In this work the ionic conductivity of zirconia was utilized. DC voltage was applied across two zirconia specimens to strengthen the joining. The application of DC voltage gave rise to the reaction contributing to the strengthening at the aluminum-zirconia interface. Effects of the applied electric current, the applied electric quantity and the initial thickness of aluminum filler on the strengthening were examined. The joining strength depended on these three factors. Especially, the applied electric current and the applied electric quantity strongly affected the joining strength. The results obtained in this study suggest that this method is applicable to the strengthening of a brazed zirconia-zirconia joining.View full abstractDownload PDF (1532K) -
Tsuyoshi Mihara, Shinji Asano, Mitsuo Obata, Ryuzo Watanabe, Akira Kaw ...1992 Volume 56 Issue 3 Pages 321-326
Published: 1992
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe elastic constants of the sintered composites of zirconia/stainless steel were measured by a LFB acoustic microscope as a function of volume mixing ratio. Specimens from various fabrication routes were used to see the applicability of the LFB acoustic microscope to the composites having specific sintered microstructures. It has been shown that the present method enables us to measure the local elastic constants, such as Young’s modulus and Poisson’s ratio, of the sintered metal/ceramic composites with sufficient accuracy. It has also been emphasized that the LFB acoustic microscope would be one of the most viable methods to evaluate the elastic constant distribution of the recently developed functionally gradient materials, which have definite compositional gradients and the pertaining microstructural transitions.View full abstractDownload PDF (1161K) -
Kanji Ueda, Keiji Manabe1992 Volume 56 Issue 3 Pages 327-332
Published: 1992
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe subject of this study is to elucidate cutting mechanism in single crystal materials by numerical simulation. The chip formation mechanism in single crystal cutting of β-brass, which exhibits the characteristics of bcc metals, is investigated by rigid-plastic FEM (Finite Element Method) simulation. The plastic anisotropy of single crystal is introduced in the algorithm of the rigid-plastic FEM by applying the maximum plastic work principle. The chip formation process of single crystal of β-brass is simulated from the initial state to the steady state. The changes of cutting mechanism due to crystallographic orientation such as chip morphology and shear angle are appropriately simulated. In the simulation, the shear angle changes from about 17° to 57° according to the crystallographic orientation. The simulated results are compared with cutting experiments which have been done by in-situ SEM (Scanning Electron Microscope) observation technique. The simulated results are in good agreement with the experimental results in terms of the chip morphology and the shear angle.View full abstractDownload PDF (646K) -
Isao Tsuchitori, Hideharu Fukunaga1992 Volume 56 Issue 3 Pages 333-341
Published: 1992
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe reactivity of the improved potassium titanate whisker with aluminum alloys was investigated by differential thermal analysis (DTA) by using their composites which was fabricated by squeeze casting in low-temperature processing. It was found that the exothermic reaction occured at two different temperatures by DTA, that is, at near 883 K and at 1223 K. The reaction at the lower temperature was not affected by the elements in the matrix Al alloys. After heat treatment of 883 K-1 h for stimulation, the surface of extracted whisker from the composite was covered with particulated reactants which were considered as α-Al2O3. The apparent activation energy of the reaction at near 883 K was calculated about 277 kJ/mol from DTA data. On the other hands, the reaction at the higher temperature was affected by the elements in the matrix Al alloys, and the reactants on the whisker surface identified as Al3Ti and α-Al2O3. In the case of matrix Al alloys containing Mg, the DTA found the exothermic reaction undefined, and the fan shaped reactant was observed on the whisker surface extracted from the composites after heat treatment of 883 K-1 h.View full abstractDownload PDF (2145K) -
Hideo Mizukoshi, Kazuhisa Shibue1992 Volume 56 Issue 3 Pages 342-346
Published: 1992
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSIn spite of the high specific strength and stiffness of the TiAl intermetallic compound, its poor ductility at room temperature makes this material difficult for practical use. Therefore, it is necessary to comprehend the fracture property of this alloy. In this paper, the fracture toughness and fatigue crack growth rate of Ti-33.5 mass%Al-2.5 mass%Mn made by a reactive-sintering process has been examined according to the test methods of ASTM E-399 and E-647. The results obtained are summarized as follows.
(1) The fatigue crack growth rate increases with increasing stress ratio R. The relationship between the threshold stress intensity range ΔKth and the stress ratio is expressed as follows.
(This article is not displayable. Please see full text pdf.)
(2) The fracture toughness of reactive-sintered TiAl at room temperature is 14 MPa\sqrtm, which is greater than that of arc-melted TiAl because the grain size of reactive-sintered specimens is finer and more uniform than that of arc-melted specimens.View full abstractDownload PDF (1460K) -
Hideo Tanabe, Masahiro Kitada1992 Volume 56 Issue 3 Pages 347-353
Published: 1992
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe deposition rate effect on electrical resistivity, coercivity, and magnetostriction of very thin permalloy films (several ten nanometers) are investigated.
Permalloy films are deposited by the electron beam method. The deposition rate (R) is 0.2∼4 nm/s, and the vacuum pressure adjusted during deposition is 10−4 Pa and 10−6 Pa to compare the atmosphere effect. The substrate temperature is 473 K, and the film thickness is about 50 nm. All the deposited permalloy films are annealed in a hydrogen gas atmosphere to investigate the influence of oxygen on electrical resistivity of the films.
Electrical resistivity (ρ) increases as R decreases, but magnetoresistivity (Δρ) and coercivity (Hc) do not depend on R, for the films deposited in a vacuum of 10−4 Pa. On the other hand, for the films deposited in a vacuum of 10−6 Pa, ρ and Δρ do not depend on R, but Hc increases as R decreases. The crystalline grain size in the films deposited at 10−6 Pa increases as R decreases, but this is not found in the films deposited at 10−4 Pa. It is considered that the increase of Hc is attributed to the growth of the grain size. Moreover, the oxygen content in the films deposited at 10−4 Pa tends to increase as R decreases, and the ρ in those films is reduced sharply by H2 annealing. These results indicate that the increase of ρ is caused by the increase of the oxygen content, which is included during deposition. In addition, magnetostriction increases as R decreases for films deposited both in 10−4 Pa and 10−6 Pa vacuum, because the Fe concentration increases as R decreases.View full abstractDownload PDF (1654K)
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