Journal of the Japan Institute of Metals and Materials
Online ISSN : 1880-6880
Print ISSN : 0021-4876
ISSN-L : 0021-4876
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Volume 77, Issue 5
Displaying 1-6 of 6 articles from this issue
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Regular Article
  • Plastic Working Characteristics of AZ31B Magnesium Alloy Sheet Produced by Continuous Casting Using Semisolid Slurry
    Futoshi Kido, Atsushi Haishima, Tetsuichi Motegi
    2013 Volume 77 Issue 5 Pages 165-169
    Published: 2013
    Released on J-STAGE: May 01, 2013
    DOIhttps://doi.org/10.2320/jinstmet.J2012052
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      We produced AZ31B magnesium alloy sheet by our semisolid casting method to cast slurry produced using an inclined cooling plate into the twin-roll. In this paper, the sheet obtained by this process was examined for texture, roll workability and Erichsen value compared with the chill cast plate and commercial AZ31B sheet. The results are as follows. The microstructure of continuously cast sheet exhibits fine grains of primary Mg-crystals. A (0001) pole figure of the continuously cast sheet confirms that the crystal direction was random and there was little rolling anisotropy. Influence of different heating temperatures on accumulative rolling reduction of the twin-roll cast sheet was not appeared by different roll directions versus the casting direction. The accumulative rolling reduction of the twin-roll cast sheet is higher than chill cast sheet in case of heating temperature of 473 K or less. The Erichsen test indicated excellent value.
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  • Tensile Rate Dependency of Mechanical Properties of Inconel 718 Nickel-Based Superalloy around Solidus Temperature
    Shota Ogino, Tsubasa Ohashi, Naoki Kasuya, Makoto Yoshida
    2013 Volume 77 Issue 5 Pages 170-173
    Published: 2013
    Released on J-STAGE: May 01, 2013
    DOIhttps://doi.org/10.2320/jinstmet.J2012054
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      Nickel-based superalloys have been applied to gas turbine and aircraft jet engine parts due to superior high temperature strength and corrosion resistance. However, casting defect such as solidification cracking often occurs. In order to increase productivity of precision casting and various shape casting processes, predicting the occurrence of solidification cracking by using CAE (Computer Aided Engineering) should be essential. Therefore, it is necessary to obtain mechanical properties in the state of solid-liquid coexistence.
       In the previous reports, high temperature mechanical properties were examined but tensile rate dependency wasn't examined. In this study, high temperature (around solidus temperature) mechanical properties and tensile rate dependency of their alloy were examined by using originally developed tensile test.
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  • Preparation of Supersaturated Fe-In Alloy Thin Films by Ion-Plating Process
    Mao Amano, Yumiko Ezaki, Kadek Fendy Sutrisna, Yoshihito Matsumura
    2013 Volume 77 Issue 5 Pages 174-176
    Published: 2013
    Released on J-STAGE: May 01, 2013
    DOIhttps://doi.org/10.2320/jinstmet.JBW201210
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      In this study, Fe-In (Fe-IIIB system) alloys of ferromagnetic thin films with supersaturated indium concentration were prepared by a triode-type ion-plating process with dual vapor sources. The preparation of the supersaturated Fe-In thin films was discussed on the basis of the effects of excess energy on the nanostructure of thin films. The kinetic energy of ions and the ionization rate in evaporation particles were measured using a Langmuir probe and a Faraday cup respectively. The excess energy of IP process increased with increasing applied bias voltage of discharge electrode. In X-ray diffraction analysis, crystal structures of supersaturated film samples were shown to be α-Fe bcc structures of Fe solid solution alloy. The ion-plating process can control the solubility limit and nanostructure of Fe alloy thin films.
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  • Preparation of Ni Aluminide Surface Layer Containing Yttrium at Different Depth by Molten Salt Electrodeposition and Cyclic Oxidation Resistance
    Hisato Fujii, Naka Sato, Motoi Hara
    2013 Volume 77 Issue 5 Pages 177-184
    Published: 2013
    Released on J-STAGE: May 01, 2013
    DOIhttps://doi.org/10.2320/jinstmet.J2012066
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      Attention has focused on a Ni aluminide containing a small amount of Y as a high-oxidation resistant material, and preparation of a coating consisting of this material was attempted by the molten salt electrodeposition which is a low-cost coating method. In the present study, the preparation of the coating consisting of this material was carried out by the electrodeposition of Ni using an aqueous solution as the electrolyte and the electrodeposition of Y and Al using a molten salt electrolyte. Furthermore, in order to change the depth of the region containing Y in the Ni aluminide layer, a three-step electrodeposition of Ni, Y and Ni was carried out, and the times of the first and third Ni electrodepositions were changed. As a result, surface layers consisting of Ni aluminide with a different depth of the region containing Y were formed. Furthermore, the cyclic oxidation resistance of these specimens was examined in air at 1423 K. As a result, for the specimen with a shallow Y-containing region in the Ni aluminide layer, the specimen mass reduction due to spalling of the scale was observed, whereas for the specimen with a deep Y-containing region, no specimen mass reduction was observed and a high-cyclic oxidation resistance was obtained. For the specimen with a deep Y-containing region, which showed the high-cyclic oxidation resistance, the scale formed on the coating after the oxidation test consisted of Al2O3 containing Y2O3, and this scale entered the metal substrate under the scale in the form of a wedge.
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  • Metallurgical Microstructure of the Spear Blade Manufactured from the End of the Muromachi Period to the Edo Period
    Nahoko Sugioka, Masahiro Kitada, Masahiko Nishijima
    2013 Volume 77 Issue 5 Pages 185-191
    Published: 2013
    Released on J-STAGE: May 01, 2013
    DOIhttps://doi.org/10.2320/jinstmet.J2012069
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      The metallurgical microstructure and mechanical properties of the spear blade manufactured in the Edo period have been investigated. The purpose of this work is to obtain metallographic data of the spear blade, and to clarify the manufacturing technique of the spear blade. The specimen examined was estimated to have been made from the end of the Muromachi period to the Edo period and has the signature of Shinano-no-Kami Minamoto Takamichi. The spear is 31 cm in length and 10.7 mm in maximum width. The metallurgical microstructure and nonmetallic inclusions of the spear blade are observed using an optical microscope. The carbon concentration is determined by chemical analysis. To evaluate the hardness, micro Vickers hardness (Hmv) is used. The microstructure is observed using an optical microscope and a scanning electron microscope (SEM). The concentration of nonmetallic inclusions is obtained by electron dispersive X-ray analysis (EDS).
       A cross-sectional image of the spear after chemical etching shows a metal flow pattern formed by deformation, possibly created by hammering. The striped structure of layers of two types of steel containing different carbon contents stacked on top of each other was observed. The bright areas after etching corresponded to the edges and ridges of the spear, which were cooled rapidly, forming the martensite structure. The other dark areas consist of pearlite and α-Fe (ferrite) grains. Optical micrographs of near-edge areas contain pearlite and martensite grains, and core areas contain pearlite and α-Fe grains. The nonmetallic inclusions in the core steel consist of a few metal oxide particles and a glass matrix. There are Fe-Ti oxide grains in the glass matrix, and an unknown oxide particle adhering on the Fe-Ti oxide grain surface was also observed.
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  • Fatigue Properties in Electrodeposited Nanocrystalline Ni-W Alloy
    Kazutaka Fujita, Kenta Nagaoka, Taiji Suidu, Takayuki Nabeshima, Tohru ...
    2013 Volume 77 Issue 5 Pages 192-197
    Published: 2013
    Released on J-STAGE: May 01, 2013
    DOIhttps://doi.org/10.2320/jinstmet.J2012067
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      The nanocrystalline Ni-W alloy fabricated by an electrodeposition method has a high-strength and high-bending ductility. However, its fatigue properties are not known yet. Therefore, fatigue tests were carried out to clarify the fatigue properties. Nanocrystalline Ni-W alloy specimens containing 16.9 at% W with about 20 μm in thickness, 200 μm in parallel part length, and 100 μm in width were produced by both UV photolithography and electrodeposition methods. The average grain size was about 6 nm in diameter and the tensile strength was about 2.8 GPa. The fatigue test was conducted at a stress ratio of 0.1 and a frequency of 10 Hz. The fatigue limit and fatigue ratio showed 2.1 GPa and 0.74, respectively. Macroscopic fractured morphology showed no necking and perpendicular fracture for the loading axis. However, microscopic fracture surface showed flat and featureless morphology at near the crack initiation region and it showed striations from the region where the striation spacing became more than about 10 nm. The final unstable fracture surface showed dimples with a diameter of 100~200 nm.
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