Journal of the Japan Society of Powder and Powder Metallurgy
Online ISSN : 1880-9014
Print ISSN : 0532-8799
ISSN-L : 0532-8799
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Volume 61, Issue 2
February
Displaying 1-9 of 9 articles from this issue
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Paper
  • Effects of Grain Size on the Strengths and Ductility of Molybdenum Alloy
    Takanori KADOKURA, Yutaka HIRAOKA, Akihiko IKEGAYA
    2014 Volume 61 Issue 2 Pages 67-72
    Published: January 31, 2014
    Released on J-STAGE: April 17, 2014
    DOIhttps://doi.org/10.2497/jjspm.61.67
    JOURNAL OPEN ACCESS
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    Effects of grain morphology, particularly grain size, on the strengths and ductility of molybdenum alloy were investigated. Grain size after recrystallization of TZM alloy was generally smaller than that of pure molybdenum. Both the strengths and ductility of TZM alloy were much better than those of pure molybdenum and not worse than those of carbon-added molybdenum. However, after correcting difference of grain size, the strengths and ductility of TZM alloy became to be not better than those of carbon-added molybdenum, although still much better than those of pure molybdenum.
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  • Synthesized Phases and Microstructure of TiAl – Ni3Al Composite Intermetallic Compounds by Two-Step Combustion Synthesis
    Shinji TAKEUCHI, Yotaro HIRABAYASHI, Atsushi HIBINO
    2014 Volume 61 Issue 2 Pages 73-81
    Published: February 15, 2014
    Released on J-STAGE: April 17, 2014
    DOIhttps://doi.org/10.2497/jjspm.61.73
    JOURNAL OPEN ACCESS
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    In order to develop highly efficient intermetallic compound material, synthesis process of a multi-component system needs to be established. In this paper, two-step combustion synthesis process of Ti – Ni – Al ternary intermetallic compound was investigated. In the first step combustion synthesis, elemental Ti and Al powders were mixed, and a compact made from the Ti/Al mixed powder was reacted by combustion synthesis. The synthesized product was crushed by a mortar and a ball milling machine, and fine TiAl powder was prepared. In the second step combustion synthesis, the TiAl powder and elemental Ti, Ni and Al powders were mixed, and a compact made from the (TiAl) + (Ti + Ni + Al) mixed powder was reacted by combustion synthesis. For the products obtained, density measurement, microstructure observation, X-ray analysis, Vickers hardness test, and SEM – EDX analysis were performed.
    By using the two-step combustion synthesis process, products of about 85 − 90 % density were able to be synthesized. The synthesized product was consisted of matrix phase and dispersed phase. The synthesized phases were ternary intermetallic compound such as Ti2NiAl3(τ3), TiNi2Al(τ4), TiNiAl2(τ2), and the phases corresponded well with Ti – Ni – Al ternary phase diagram. It was confirmed that Ti – Ni – Al ternary intermetallic compound was able to be synthesized by the two-step combustion synthesis process.
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Special Issue: Recent Trend of Functional Powders through Green Processing
Summarization
Memorial Lecture of JSPM Award
  • Development of Cr – Cu Heat-sink for Semiconductor Devices
    Hoshiaki TERAO , Hideaki KOBIKI, Takashi ITOH, Naoyuki KANETAKE
    2014 Volume 61 Issue 2 Pages 85-92
    Published: February 15, 2014
    Released on J-STAGE: April 17, 2014
    DOIhttps://doi.org/10.2497/jjspm.61.85
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    Cr – Cu materials have been developed for heat-sink application using P/M processing: Cr powder is sintered and Cu infiltrated. W – Cu and Mo – Cu materials, with low thermal expansion and high thermal conductivity, have been used for heat-sink application. However these materials having poor deformability and poor machinability raise processing costs for making heat-sink parts. W and Mo powder are both rare metals, very expensive and unstable to be supplied. Chromium is also a strong candidate for the heat-sink application, because it is the same 6A group element as W and Mo, its powder price is lower and more stable but its thermal properties are a little inferior to these of W and Mo. Pore free and inclusion free structure of Cr – Cu infiltrated compact, showing high quality of the following processes: rolling, pressing and Ni plating has been developed. To realize thermal properties of Cr – Cu close to those of Mo – Cu and W – Cu, the original three processes have been developed: secondary precipitation heat treatment, rolling and cladding with Cu. The developed materials could have high cost effectiveness for making parts though rolling and pressing to net-shape parts. Consequently Cr – Cu materials have succeeded in substitution for W – Cu and Mo – Cu materials for the heat-sink application.
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Paper
  • Low-temperature Synthesis of 12CaO • 7Al2O3 Particles by Solution Plasma Processing
    Shiori MANEYAMA, Naonori SAKAMOTO, Naoki WAKIYA, Tomoya OHNO, Takesh ...
    2014 Volume 61 Issue 2 Pages 93-98
    Published: February 15, 2014
    Released on J-STAGE: April 17, 2014
    DOIhttps://doi.org/10.2497/jjspm.61.93
    JOURNAL OPEN ACCESS
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    12CaO • 7Al2O3 (C12A7) crystal has 12 cages in the unit cell, and two free oxygen ions are encaged in the cages. These ions can be replaced with various anions by the appropriate processing to show various characteristics. Solution plasma processing is a method of synthesizing the material by vaporization of the liquid with a electric discharge, to be a plasma, as a reaction field. This method has advantage of rapid reaction at lower temperatures over conventional powder preparation methods because of the high density reaction field localized at the interface between liquid and gaseous phases. However, this method has been started to study in the recent years, therefore,there are many issues to be solved to apply it as a powder preparation method. In this study, C12A7 particles were synthesized from alkoxide-derived precursor solution by solution plasma processing for the low-temperature synthesis. The obtained C12A7 precipitates were characterized by XRD, TEM, and so on. As a result, C12A7 particles were successfully synthesized at low temperature of 200 ˚C or less by solution plasma processing, showing that this method will be a powerful tool to obtain nanopowders at low temperatures.
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  • Fabrication of Vanadium Dioxide Nano-particles by Microemulsion Method with Controlled Phase Transition Temperatures
    Takuya OKUDA, Naonori SAKAMOTO, Naoki WAKIYA, Hidetoshi MIYAZAKI, Tos ...
    2014 Volume 61 Issue 2 Pages 99-103
    Published: February 15, 2014
    Released on J-STAGE: April 17, 2014
    DOIhttps://doi.org/10.2497/jjspm.61.99
    JOURNAL OPEN ACCESS
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    Vanadium dioxide, VO2, undergoes the phase transition from monoclinic to tetragonal with property change from semiconductor to metal, respectively, at about 68 ˚C. Metallic tetragonal structure reflects infrared light, and semiconducting monoclinic structure transmits it, leading to the thermochromic smart window. On the other hand, the phase transition temperature is slightly higher than the room temperature and can be lowered by tungsten or the other metal cation doping. Furthermore, VO2 nanoparticles with lower transition temperature and particle size less than 100 nm is essential for the smart window because the light scattering can be dramatically suppressed by reducing the particle size to obtain a high transparency. In this study, we tried to control the particle size and phase transition temperature of VO2 nanoparticles by the microemulsion method. The resultant VO2 particles were characterized by XRD, DSC, SEM and TEM. Primary particle size of the resulting VO2 nanoparticles was estimated to be 25 nm with average agglomeration size of about 300 nm. The phase transition temperature for the W doped VO2 was 37 ˚C. As a result, we successfully synthesized the VO2 nanoparticles with controlled particle size and phase transition temperature by microemulsion method.
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