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 11
November
Displaying 1-9 of 9 articles from this issue
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Special Issue: Optimized Microstructure Formation and Multi-Functionalization of Powder Materials
Summarization
Memorial Lecture of JSPM Award
  • Advanced Powder Metallurgy Non-Ferrous Materials
    – PM Ti–Ni Shape Memory Alloy with High Strength and Excellent Shape Recovery Rate –
    Katsuyoshi KONDOH, Takayuki YONEZAWA, Junko UMEDA, Hisashi IMAI, Ryoic ...
    2014 Volume 61 Issue 11 Pages 501-513
    Published: November 15, 2014
    Released on J-STAGE: November 28, 2014
    DOIhttps://doi.org/10.2497/jjspm.61.501
    JOURNAL OPEN ACCESS
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    The Ti–Ni–Fe elemental mixture powder was consolidated by spark plasma sintering and hot extrusion process. The homogenization and aging heat treatment was applied to the Ti–Ni–Fe sintered alloys for uniform precipitation of ultra-fine Ti3Ni4 needle-like intermetallics with 50 − 100 nm length in TiNi matrix. ALCHEMI analysis clarified the additive Fe elements were completely solid-soluted into Ni atom sites of the TiNi alloy after aging heat treatment. The plateau stress gradually increased with increase in Fe content because the Martensite transformation temperature drastically decreased. The measured plateau stress corresponded well with the calculation result by using Clausius-Clapeyron equation. The shape recovery rate under 8 % strain was 89～95 % when Fe content was over 0.3at.%. This is also due to solid-soluted Fe atoms causing the decrease of Austenite transformation temperature. PM Ti–50.5at.%Ni alloy with 1.0at.%Fe after aging heat treatment showed an excellent balance of mechanical properties; 906 MPa plateau stress, 1260 MPa UTS and 95.4 % shape recovery rate.
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Review
  • Developments of Eco-Friendly Silicide-based Thermoelectric Materials Using Powder Metallurgical Processes
    Takashi ITOH
    2014 Volume 61 Issue 11 Pages 514-520
    Published: November 15, 2014
    Released on J-STAGE: November 28, 2014
    DOIhttps://doi.org/10.2497/jjspm.61.514
    JOURNAL OPEN ACCESS
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    Both of high performance and low cost of the thermoelectric materials are required for the practical use of a thermoelectric power generation using waste heat. The silicide-based thermoelectric materials constituted of the eco-friendly raw materials that are less toxic and abundant in the earth’s crust has been attracting attention. In this study, material developments of the dimagnesium silicide (Mg2Si) and the higher manganese silicide (HMS) have been carried out for high thermoelectric performance using powder metallurgical processes. The Mg2Si compounds were synthesized via the liquid-solid phase reaction process and consolidated by pulse discharge sintering. For production of the HMS compounds, a series of processes of pulverization, mixing and pulse discharge sintering was used. Various synthesizing conditions were attempted for improving the thermoelectric performance of these materials.
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Paper
  • Microstructure and Mechanical Properties of Harmonic-Structured Cu–Sn Alloy
    Hiroshi FUJIWARA, Takashi NISHIMOTO, Hiroyuki MIYAMOTO, Kei AMEYAMA
    2014 Volume 61 Issue 11 Pages 521-525
    Published: November 15, 2014
    Released on J-STAGE: November 28, 2014
    DOIhttps://doi.org/10.2497/jjspm.61.521
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    Harmonic-structured Cu–Sn alloys were produced via mechanical milling (MM) followed by spark plasma sintering (SPS), and their microstructure and mechanical properties were investigated. Microstructural observation of the MM powders and SPS compacts was achieved using scanning electron microscopy (SEM)/energy dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD). The mechanical properties of the SPS compacts were evaluated using results of the tensile test and Vickers hardness test. SEM/EDS micrographs and XRD profile indicated that the harmonic-structured Cu–Sn alloy compacts have the network region with highly Sn solid solution, which is including some γ phase, and the dispersed region with pure Cu. The harmonic-structured Cu–Sn alloy compacts demonstrate the stabilized high strength, sufficient ductility and high hardness compared with the incomplete harmonic-structured Cu–Sn alloy in spite of the same addition of Sn. In the specimen after the tensile testing, many cracks were observed in only network region. This result indicates that advanced ductility of the harmonic-structured materials is attributed to the obstruction of the crack propagation by the dispersed region. The network structure in the harmonic-structured materials is effective for an improvement of the mechanical properties.
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  • Deformation Mechanism of Harmonic-Structured Composite with High Speed Steel and Mild Steel by MM/SPS Process
    Hiroshi FUJIWARA, Yuki TSUZUKI, Hiroyuki MIYAMOTO, Kei AMEYAMA
    2014 Volume 61 Issue 11 Pages 526-530
    Published: November 15, 2014
    Released on J-STAGE: November 28, 2014
    DOIhttps://doi.org/10.2497/jjspm.61.526
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    The harmonic-structured composite that consists of a network fine grain region with a high speed steel and a dispersed coarse grain region with a mild steel was fabricated prepared using a mechanical milling and spark plasma sintering process. The microstructure of harmonic-structured composite compact was observed by a scanning electron microscope and mechanical properties were evaluated by a tensile test and Vickers hardness test. The harmonic-structured composite exhibited high strength and enough ductility compared with a conventional particle-dispersed composite with the same volume fraction of high speed steel/mild steel. The work-hardening rate of harmonic-structured composite is higher than the conventional particle-dispersed composite so that the harmonic-structured material demonstrates a high elongation. The microstructure observation of harmonic-structured composite reveals that the superior elongation of the harmonic-structured composite is attributed to the plastic deformation of the dispersed area around the cracks which initiate at the network area.
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  • Microstructures and Mechanical Properties of Al–10%Si–0.4%Mg Fabricated by Selective Laser Melting
    Takahiro KIMURA, Takayuki NAKAMOTO
    2014 Volume 61 Issue 11 Pages 531-537
    Published: November 15, 2014
    Released on J-STAGE: November 28, 2014
    DOIhttps://doi.org/10.2497/jjspm.61.531
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    In this study, the basic characteristics of Al–10%Si–0.4%Mg alloy fabricated by Selective Laser Melting (SLM) were investigated. First, laser irradiation conditions were optimized for densification by using an SLM machine equipped with a 400 W Yb fiber laser. As a result, SLM specimens with almost 100 % relative density were obtained. Secondly, the microstructures and mechanical properties of the dense specimens were investigated. The ultimate strength (UTS > 450 MPa) and breaking elongation (EL > 10 %) of the as-fabricated SLM specimens were much higher than those of high pressure die casting materials. This is because they had almost 100 % relative density and showed sub-micron order dendrite-cell microstructures. Moreover, the effects of T5/T6 heat treatment on microstructures and mechanical properties were also investigated. The behaviors of heat treatments in the SLM specimens were different from those of cast melting alloys. The EL of the SLM specimens in the T6 condition increased to about 20 % although the UTS decreased.
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Short Note
  • Fabrication of Textured Ti2AlN Ceramic by Slip Casting in a Strong Magnetic Field and Spark Plasma Sintering
    Shotaro MUSHA, Kimitoshi SATO, Tohru S. SUZUKI, Kenjiro FUJIMOTO, Yosh ...
    2014 Volume 61 Issue 11 Pages 538-543
    Published: November 15, 2014
    Released on J-STAGE: November 28, 2014
    DOIhttps://doi.org/10.2497/jjspm.61.538
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    MAX phase materials are known to show unique properties with the combination of metallic and ceramic properties. Recently textured MAX phase materials have been expected to show excellent properties. Here Ti2AlN powders were synthesized from Ti, Al and TiN powders, or Ti and AlN powders heating at 1573 K−1773 K. Then highly textured Ti2AlN was fabricated by slip casting in a strong magnetic field and spark plasma sintering at 1473 K−1773 K and the relative density was nearly 97 %. The c – axis of the Ti2AlN grains were oriented parallel direction of the magnetic field, the lotgering orientation factor was determined 0.96. The nacre like structure was observed in the side surface of the textured sample.
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