Journal of the Japan Institute of Metals and Materials
Online ISSN : 1880-6880
Print ISSN : 0021-4876
ISSN-L : 0021-4876
Volume 68 , Issue 5
Showing 1-16 articles out of 16 articles from the selected issue
  • Daisuke Shindo, Akira Taniyama
    2004 Volume 68 Issue 5 Pages 263
    Published: 2004
    Released: June 24, 2005
    JOURNALS FREE ACCESS
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  • Shigeo Arai, Shunsuke Muto, Jyunya Murai, Tsuyoshi Sasaki, Yoshio Ukyo ...
    2004 Volume 68 Issue 5 Pages 264-268
    Published: 2004
    Released: June 24, 2005
    JOURNALS FREE ACCESS
    The ceria-zirconia solid solution (Ce2Zr2O7+x, 0≤x≤1) has an excellent ability for oxygen absorption/release. Ce2Zr2O7 with pyrochlore structure is fully oxidized to Ce2Zr2O8, in which the absorbed oxygen occupies particular atomic sites, depending on the degree of oxidation. The local atomic arrangement of CeO2-ZrO2 solid solution has been studied in order to analyze the valence change of cations by means of electron energy-loss spectroscopy (EELS) in a transmission electron microscope. EEL spectra from Ce2Zr2O7, Ce2Zr2O7.5 and Ce2Zr2O8 showed a systematic change in the relative intensity ratio of cerium-M4,5 white-line peaks, which corresponds to the valence change of cerium. The valence number of cerium ions in the CeO2-ZrO2 solid solution changes from 3 to 4 according to its oxygen content; Ce3+ in Ce2Zr2O7, Ce4+ in Ce2Zr2O8. By contrast, the valence of the zirconium ion remains quaternary on either case. The energy-loss near edge structure (ELNES) of cerium-M4,5 edge in Ce2Zr2O7.5 is well reproduced by the equiweight sum of the ELNES profiles of Ce2Zr2O7 and Ce2Zr2O8, the phenomenon of which is known as the ‘valence fluctuation’, often observed in rare earth compounds.
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  • Akira Taniyama, Hisashi Amaya, Kazuhiro Ogawa, Masakatsu Ueda, Hiroyuk ...
    2004 Volume 68 Issue 5 Pages 269-274
    Published: 2004
    Released: June 24, 2005
    JOURNALS FREE ACCESS
    Precipitations and a Cr depletion zone in a coarse-grained HAZ of welded joints by Gas Metal Arc Welding (GMAW) of martensitic stainless steel were examined to reveal their effects on intergranular stress corrosion cracking (IGSCC) by means of a TEM/EDS analysis. The welded joints in as-welded condition, which suffered IGSCC in the HAZ, and the welded joints with post weld heat treatment (PWHT), in which no IGSCC was observed, were used as samples. Thin film samples including the coarse-grained HAZ were prepared by a focused ion beam machining. No Cr carbide was observed in the HAZ of welded joints either with or without PWHT. In the as-welded condition, a Cr depletion zone was observed near the grain boundary adjacent to the oxide layer formed on the root surface of the welded joints. However, no Cr depletion zone was observed in the welded joints with PWHT. The susceptibility to IGSCC correlates closely with the Cr depletion, therefore, it is suggested that the Cr depletion formed by the GMAW due to the oxidation during welding would be the initiation of the IGSCC in the welded joints.
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  • Kentaro Asakura, Yasuhisa Hirohata, Toshihiro Suzuki, Yoshinori Hoshin ...
    2004 Volume 68 Issue 5 Pages 275-281
    Published: 2004
    Released: June 24, 2005
    JOURNALS FREE ACCESS
    The authors have developed the nano cutting force detector (NCFD), and obtained the cutting characteristics of the epoxy resin, the rat kidney, and the platinum spatter film of 40 nm thick. There was no inferiority for the ultra thin sections made by NCFD when comparing with a ready-made ultramicrotome. Consequently, (1) it was possible to measure the cutting force in the nano level order sectioning. (2) The cutting force profile greatly depends on the shape of the surface. (3) The cutting force increases with increasing of the cutting speed. (4) The cutting force increases with the thickness at a constant speed. (5) The cutting force increases with the hardness in the range of HV1-25. (6) The 40 nm thick layer was detectable by using semiconductor strain gauge type sensor. Sectioning force profile of the NCFD reflected the chatter, the condition of the ultra-thin section, and the contact with knife and cutting surface. This new evaluation technology was established with NCFD.
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  • Chiko Yorita, Yuko Imamura, Yasuhisa Hirohata, Kentaro Asakura
    2004 Volume 68 Issue 5 Pages 282-287
    Published: 2004
    Released: June 24, 2005
    JOURNALS FREE ACCESS
    Observing interface states is especially important in evaluating solder joint reliability. Cross-section samples of intermetallic compounds generated by copper metallization with lead-free solders (Sn8Zn3Bi, and Sn9Zn, Sn3Ag0.5Cu), with Sn37Pb as a reference, were prepared using an ultramicrotome. We used an instrumented ultramicrotome to study the cutting force profiles of the intermetallic compounds. When we measured them with a needle-like diamond knife (60 μm in width), we found peaks in the profiles consisting of two elements that corresponded to those of the intermetallic compounds. These profiles also correlated well with the hardness of the constituent phases at the solder joint interface.
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  • Akira Taniyama, Kentaro Asakura, Hirotsugu Niwa, Yasuhisa Hirohata
    2004 Volume 68 Issue 5 Pages 288-292
    Published: 2004
    Released: June 24, 2005
    JOURNALS FREE ACCESS
    Recently, the instrumented ultramicrotome, which can measure the cutting force required to shave off a thin film for TEM observation with ultramicrotomy, has been developed. In this study, the cutting force of various metals was measured with the instrumented ultramicrotome to reveal their mechanical properties which the measured cutting force reflects. A pure Pb, Al, Zn and Cu were used as specimens. The measured cutting force tended to have a little relationship with Vickers hardness of the specimens. Especially, the cutting force showed almost constant value without depending on the Vickers hardness in the pure Cu specimens whose hardness was varied with a cold rolling and an annealing. Therefore, the shear stress of the specimens, which is needed to deform the thin film, was estimated with assuming that the measured cutting force consists of two elements, the shear stress and the tear force which is needed to remove a thin film from a specimen block. The shear stress was unique to each specimen, and it had a good relationship with the shear modulus of specimen. The value of the shear stress was about 1/60 of the modulus in each specimen. This indicates that dislocations are not concerned with the shear deformation in the thin films of 100∼300 nm in thickness obtained with ultramicrotomy.
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  • Toshiaki Suzuki, Masateru Sibata, Eiji Okunishi, Noriaki Endo, Toshiko ...
    2004 Volume 68 Issue 5 Pages 293-298
    Published: 2004
    Released: June 24, 2005
    JOURNALS FREE ACCESS
    Interface fine structure can be analyzed in detail by transmission electron microscope (TEM) observation. Sample is frequently prepared by focused ion beam (FIB) and pick-up method (lift-out method). However, it is difficult that thin film of interface, which consists of different materials with their own etching rates, is prepared in uniform thickness. Also, interfaces in a plate of a semiconductor device to be analyzed have various depth from less than 10 μm to more than 20 μm from the surface. In the case of preparing a thin film of these samples accurately, reprocessing is necessary, that is to say, FIB processing may be carried out again after observing secondary electron images and scanning transmission electron images. Also, sample pre-cutting methods are necessary taking into account its shape and observing direction (cross section and plan view). Here, we report a bulk-pick-up method where the conventional pick-up method is improved and reprocessing with FIB is possible. Eventually, it is found that interface characterization can be effectively carried out on a variety of samples prepared by FIB.
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  • Satoshi Tsuji, Katsuhiro Tsujimoto, Kotaro Kuroda, Hiroyasu Saka
    2004 Volume 68 Issue 5 Pages 299-304
    Published: 2004
    Released: June 24, 2005
    JOURNALS FREE ACCESS
    The fragile locations of process-induced defects in hydrogenated amorphous silicon thin-film transistors (a-Si : H TFTs), which are used as elements of active-matrix liquid crystal displays, are investigated by combining focused ion beam (FIB) techniques with cross-sectional transmission electron microscopy (X-TEM). This article also describes how an array can be characterized by using a TFT array tester and a scanning force microscope that can detect, accurately locate, and identify pixel faults. The rapid FIB technique is applied to TFT failure analysis problems which require very localized etching without inducing mechanical stress. We demonstrate how these techniques are used to characterize TFT defects such as portions of the TFT multilayer damaged by micro-scratch and foreign materials. These layers cause short-circuit failures. These observations lead to identification of the fault and analysis of its cause, which in turn lead to a marked yield improvement.
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  • Masaaki Sugiyama, Tetsuya Suzuki, Yoichi Ikematsu
    2004 Volume 68 Issue 5 Pages 305-310
    Published: 2004
    Released: June 24, 2005
    JOURNALS FREE ACCESS
    A focused ion beam milling is a relatively new technique that has been developed for an efficient method to prepare a transmission electron microscopy specimen for such observations as the cross-section of individual structures. Especially, its selective thinning ability for a specific area is far superior to conventional methods such as an electropolishing or an Ar ion milling for metals and steels. However, the high energy Ga ion beam fabrication often causes a problematic damage to a sample with different manner, depending on the microstructure or the composition of materials. In the present study, the focused ion beam milling equipped with micro-sampling technique is mainly examined to prepare a thin foil specimen for a low melting Sn metal. The advantage of the micro-sampling method is to decrease the milling time, resulting in minimization of sample damage effects. Under such fabrication conditions, some artificial precipitation of a Cu-Sn alloy in a Sn layer of a tinning plate not including Cu atoms has been found. This precipitation is observed whenever the specimen is mounted on the Cu support holder in the micro-sampling method. Using an analytical transmission electron microscope, the Cu-Sn alloy is identified to be a Cu6Sn5 phase. Since the Cu6Sn5 phase is a type of peritectoid reaction indicated by the phase diagram, it is considered that a Cu atom or a Cu cluster with a high energy are firstly sputtered from the support holder, then reacted to the Sn layer. When a Mo support holder was used in the micro-sampling method, such an artificial precipitation was not induced in the Sn layer. The precipitation phenomenon is discussed on a view point of the difference in the sputtering ratio and reaction behavior of Cu and Mo atoms for Sn metal.
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  • Katsuhiro Tsujimoto, Masahiro Kitada
    2004 Volume 68 Issue 5 Pages 311-314
    Published: 2004
    Released: June 24, 2005
    JOURNALS FREE ACCESS
    Focused Ion Beam (FIB) systems have been steadily used as specimen preparation tools mainly in the semiconductor industry. However, this technology is largely unknown outside the semiconductor industry. Relatively few references exist in the literature on the preparation of cross-sectional TEM specimens of cultural properties. This article describes the application of FIB technique to “Negoro-nuri” which is traditional Japanese lacquer ware. The advantages of this technique are: the area of interest can be milled while observing images with a very high accuracy (less than 0.1 μm) and thin membrane samples can be lifted directly from the bulk samples without having to perform an initial mechanical grinding or polishing stage. We found that FIB/TEM technique successfully identified the pigments on this nonideal specimen and showed clearly the nanostructure of pigments in the Japanese lacquer (urushi).
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  • Tomokazu Hino, Yasukazu Murakami, Daisuke Shindo, Satoshi Okamoto, Osa ...
    2004 Volume 68 Issue 5 Pages 315-319
    Published: 2004
    Released: June 24, 2005
    JOURNALS FREE ACCESS
    Magnetic domain structure of FePt(001) films, which show huge magnetocrystalline anisotropy, was observed by electron holography and Lorentz microscopy. Although these methods have advantages for the microanalysis of magnetic domains, e.g., the high spatial resolution, detection of the magnetic signal is rather difficult when the magnetization vector is parallel to the incident electron beam like the case of FePt(001) films. Here we demonstrate that the intensive observations are possible when the specimen is tilted in a microscope so that the magnetic flux perpendicular to the incident beam is generated. The holography experiment using the cross-sectioned specimen also provided useful information about the stray magnetic field of the FePt(001) films.
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  • Akira Yasuhara, Daisuke Shindo, Masahiro Tobise
    2004 Volume 68 Issue 5 Pages 320-325
    Published: 2004
    Released: June 24, 2005
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    Microstructures and magnetic domain structures of isotropic and anisotropic Sm-Fe-N bonded magnets were investigated by transmission electron microscopy and electron holography, respectively. In addition to mechanical polishing, ion-milling and focused ion beam methods were utilized to prepare thin specimens for transmission electron microscopy. With these thin specimens, the sizes of particles in anisotropic and isotropic bonded magnets were estimated, and also magnetization distributions in these particles were clarified. Furthermore, by changing the direction of the incident electron beam against a thin specimen, a pair of holograms were observed to separate the electric and magnetic fields. Thus, detailed magnetization distribution in Sm-Fe-N was clarified at the specimen edge.
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  • Yutaka Takahashi, Katsuhiro Asai
    2004 Volume 68 Issue 5 Pages 326-332
    Published: 2004
    Released: June 24, 2005
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    C60 solid was grown by liquid-liquid interfacial precipitation (LLIP, Miyazawa et al.: J. Mater. Res. 17(2002) 83). Toluene and methyl alcohol were used as good and poor solvents, respectively. A defect-free fcc single phase was obtained. Optical and scanning electron micrographs revealed that the size of grains was typically up to a few μm. However, coarse grains about 10-100 μm in size were mixed when ethyl alcohol was used. This is because nucleation and prolonged growth of the C60 solid also occurs on the inner wall of a glass bottle. The morphology of grains was examined using transmission electron microscopy. The micrograms indicate that the {111} and {200} planes of the fcc structure are crystal habits that preferentially develop in solution. The morphology is thermodynamically stable as observed in a sample prepared by the sublimation-recrystallization method, thus, it is suggested that grains in the LLIP method grew under near equilibrium conditions.
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  • Boyoung Jeong, Kazutoshi Nishimoto, Kazuyoshi Saida
    2004 Volume 68 Issue 5 Pages 333-341
    Published: 2004
    Released: June 24, 2005
    JOURNALS FREE ACCESS
    Grain growth of prior-austenitic grain in ultra fine-grained (UFG) steels during isothermal heat treatment at temperatures from 1173 to 1473 K was investigated quantitatively. The average grain size of UFG-T and UFG-B steels used was 1.25 μm and 1.21 μm, respectively. Grain growth of UFG steels followed Beck's theory with different time exponents in the early and later stages of grain growth. In the early stage of grain growth, grain growth was depressed by the pinning effect of (Nb, Ti) (C, N) particles in UFG-T steel and the particles composed of AlN and (Nb, Ti) (C, N) in UFG-B steel since the time exponent was 5. The time exponent was changed to 4 in the later stage of grain growth because of coarsening or dissolution of pinning particles. The distribution of prior-austenitic grain size in hyper interfacial bonded joints of UFG steels was estimated from the kinetics of grain growth considering thermal cycle and the transition of time exponent during the bonding process. The calculated grain size in the HAZ of hyper interfacial bonded joints was larger than the measured one. This fact suggested that thermo-mechanical factor would also act on the depression of grain growth during hyper interfacial bonding process.
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  • Takayuki Miyazaki, Minoru Tagami, Toshio Hama, Hitoshi Ogawa, Tatsuya ...
    2004 Volume 68 Issue 5 Pages 342-349
    Published: 2004
    Released: June 24, 2005
    JOURNALS FREE ACCESS
    To study the slip and recrystallization mechanisms in high purity aluminum, a single crystal of 99.999 mass% purity was tensile-deformed along a ‹001› direction at 77 K and subsequently annealed. The deformation stress decreased by about 15% (15 MPa), compared with the previously reported 99.99 mass% aluminum single crystal with the same tensile orientation. Slip structure was very uniform, characterized by frequent short-distance cross-slip. No deformation band was observed. After annealing, many recrystallized grains (RGs) were formed. About 80% of the RGs had ‹111› rotation relationship with the orientation of the deformed matrix. There was no large difference in the occurrences of the four ‹111› rotation relationships. For each ‹111› axis, both clockwise and counterclockwise rotations were found.
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  • Hidenori Kuroki
    2004 Volume 68 Issue 5 Pages 350-352
    Published: 2004
    Released: June 24, 2005
    JOURNALS FREE ACCESS
    The development of very coarse and columnar ferrite grains throughout γ/α transformation has often been observed. These structures could be recognized as typical ferrous structures. The transformation-grown ferrites form in irons which contain less than approximately 100 ppm interstitials, namely, carbon and nitrogen. Austenite may transform into ferrite through individual movements or diffusions of iron atoms across the phase boundary. The ferrite grains have been observed to grow extremely fast. The formation of ferrite nuclei may be limited since the sites for such formation are few in pure irons. Thus, once a ferrite nucleus is formed, it may grow extremely fast. The growth may lead to the development of very coarse grains or coarse columnar grains under a temperature gradient. Carbon and nitrogen, even if their sum is less than 100 ppm, may concentrate at phase boundaries, possibly leading to the formation of compounds. Such phase boundaries with carbon and nitrogen could be sites for the formation of new ferrite nuclei. The newly formed nuclei could interrupt the growth of columnar grains leading to rather equiaxed grains. In ultrahigh-purity irons with a carbon and nitrogen content of approximately 10 ppm, lattice defects in deformed austenite could become sites for the formation of ferrite nuclei leading to equiaxed structures.
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