Journal of Japan Institute of Light Metals
Online ISSN : 1880-8018
Print ISSN : 0451-5994
ISSN-L : 0451-5994
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Volume 62, Issue 4
Displaying 1-8 of 8 articles from this issue
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RESEARCH ARTICLE
  • Fabrication of aluminum based photoluminescence materials by mechanical alloying and spark plasma sintering and its properties
    Yui Watanabe, Masahiro Kubota
    Article type: Research Report
    2012 Volume 62 Issue 4 Pages 139-145
    Published: April 30, 2012
    Released on J-STAGE: May 30, 2012
    DOIhttps://doi.org/10.2464/jilm.62.139
    JOURNAL FREE ACCESS
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    Air-atomised pure aluminum powder together with photoluminescence powder (LG) was mechanically alloyed (MAed) using a vibrational ball mill, and the MAed composite powders were consolidated into bulk materials by spark plasma sintering (SPS) in order to fabricate the aluminum based composite materials exhibiting photoluminescence properties. Changes in hardness, particle sizes, constituent phases, luminance and microstructures of both the MAed powders and SPS materials were examined by microhardness measurements, scanning electron microscope, X-ray diffraction, luminance meter, and optical microscopy, respectively. The Vickers microhardness of the MAed powders increased by both an increase in MA time and the amount of LG powder addition. The mean particle size of the MAed powders for 60 min was smaller compared to that for 5 min. The Vickers hardness of the bulk SPS materials increased by both an increase in sintering temperatures and the amount of LG powder addition. No solid-state reactions could be detected in the bulk SPS materials during MA and SPS process. Bulk SPS materials showed luminance in a darkroom after they were irradiated by black light. Aluminum based composite materials exhibiting photoluminescence properties were successfully fabricated by a combination of MA and SPS process.
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  • Casting of aluminum alloy strip by a single-roll caster equipped with a scraper
    Kazuya Akitsu, Keisuke Kamakura, Toshio Haga, Shinji Kumai, Hisaki Wat ...
    Article type: Research Report
    2012 Volume 62 Issue 4 Pages 146-152
    Published: April 30, 2012
    Released on J-STAGE: May 30, 2012
    DOIhttps://doi.org/10.2464/jilm.62.146
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    A SRCES (Single-Roll Caster Equipped with a Scraper) was devised in order to improve the free-solidified surface. A scraper contacted to the free-solidified surface at the constant force. The some amount of semisolid metal on the solid layer was removed and the surface condition becomes flat. The melt pool was mounted on the top of the roll. Therefore, the scraper was easily operated. In our study, aluminum alloy strip was cast by the SRCES. The scraped surface condition of the cast strip was investigated. The as-cast strip could be cold-rolled and the roughness of the free-solidified surface was reduced. There was no difference between the free-solidified surface and roll-contact surface after cold-rolling. The cross-section of the as-cast strip was observed. The porosity of the free-solidified surface was less than the porosity at center area of the strip cast by a TRC (Twin-Roll Caster). The mechanical properties of the cast strip were investigated by deep-drawing test and tensile test. As a result of deep-drawing test, there was no difference between the free-solidified surface and the roll-contact surface after cold-rolling. As a result of tensile test, mechanical properties of cold-rolled strips were similar to the strip cast by the D.C.casting. These result shows that the free-solidified surface could be improved up to the roll-contact surface by the scraper and cold-rolling.
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  • Fabrication of Mg-based functionally graded materials by a reaction centrifugal mixed-powder method
    Yoshimi Watanabe, Masafumi Shibuya, Hisashi Sato, Eri Miura-Fujiwara, ...
    Article type: Research Report
    2012 Volume 62 Issue 4 Pages 153-159
    Published: April 30, 2012
    Released on J-STAGE: May 30, 2012
    DOIhttps://doi.org/10.2464/jilm.62.153
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    In this study, as a novel centrifugal mixed-powder method, reaction centrifugal mixed-powder method was applied for Mg–Si system to fabricate Mg/Mg2Si functionally graded materials (FGMs). In advance, the mixed powder of Mg and Si particles is inserted into a rotationable mold, and then the molten Mg is poured into the mold with the powder mixture. As a result, the molten metal matrix penetrated into the space between the particles due to the pressure exerted by the centrifugal force. At the same time, Mg particles were melted by the heat from the molten Mg, and it allowed the occurrence of Mg/Si reaction. Using this method, Mg/Mg2Si FGMs with gradual distribution of Mg2Si particles was successfully fabricated. Particles size and morphology of Mg2Si particles in the FGMs depend on the amount of Si particles in mixed powder. This is because the reaction heat due to the reaction of Si particles and molten Mg is influenced by the amount of Si particles. Therefore, it can be concluded that the reaction heat is important factor for the reaction centrifugal mixed-powder method, and it controls the microstructure of the FGMs.
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  • Polarization curve and its analysis of aluminum in sulfuric acid solution
    Osami Seri, Yuji Hosoi, Daichi Sasaki
    Article type: Research Report
    2012 Volume 62 Issue 4 Pages 160-164
    Published: April 30, 2012
    Released on J-STAGE: May 30, 2012
    DOIhttps://doi.org/10.2464/jilm.62.160
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    Polarization measurement of aluminum in 0.1 mol·dm−3 sulfuric acid solution was carried out. Polarization resistance calculated by differentiating polarization curve above was electrochemically analyzed. It is shown that the polarization resistances in cathodic and anodic polarization were about 0.02 and about 1 kΩ·cm2, respectively. The analysis of the polarization resistance reveals that hydrogen evolution reaction as cathodic rate-determining step has electrochemical parameters of change transfer number z=1 and transfer coefficient α=0.4. It was found that corrosion rate of aluminum in 0.1 mol·dm–3 sulfuric acid solution calculated by polarization resistance analysis was estimated as about 0.02 mA·cm−2, which almost corresponded with converted corrosion rate (0.01 and 0.03 mA·cm−2) shown in the ASM database and published papers elsewhere.
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