Journal of Japan Institute of Light Metals
Online ISSN : 1880-8018
Print ISSN : 0451-5994
ISSN-L : 0451-5994
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Volume 59, Issue 12
Displaying 1-8 of 8 articles from this issue
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RESEARCH REPORT
  • Effect of twin formation by repetitive bending on texture of AZ61 magnesium alloy sheet and improvement of formability
    Yoshifuru Sunaga, Yoshinori Tanaka, Motoo Asakawa, Masahito Katoh, Mas ...
    Article type: Research Report
    2009 Volume 59 Issue 12 Pages 655-658
    Published: December 30, 2009
    Released on J-STAGE: January 30, 2010
    DOIhttps://doi.org/10.2464/jilm.59.655
    JOURNAL FREE ACCESS
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    Magnesium alloy is the lightest metal among structural metals being used today. However, because the rolled sheets of magnesium alloy are expensive and poor in press formability, the reduction of manufacturing costs and especially the improvement of formability are eagerly required. In order to overcome these problems, the dispersion of texture of rolled sheets caused by twin formation in repetitive bending at room temperature would be effective. In present experiment using the rolled sheets of AZ61 magnesium alloy, the relationship between the times of repetitive bending and the change of texture was investigated. In 4-times repetitive bending, the tensile twin formation and the dispersion of basal plane texture were observed by X-ray diffraction and SEM-EBSD analysis. As the result of formability test, severe 90° V shape bending (R/t=1) and nearly twice bulging formability were attained in comparison with those of conventional rolled sheets at 473 K. The results of this study suggest that the press formability of rolled sheets of AZ61 magnesium alloy would be effectively improved by repetitive bending at room temperature.
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  • Fabrication of high strength pure titanium by mechanical milling and spark plasma sintering and its properties
    Takuya Ohno, Masahiro Kubota
    Article type: Research Report
    2009 Volume 59 Issue 12 Pages 659-665
    Published: December 30, 2009
    Released on J-STAGE: January 30, 2010
    DOIhttps://doi.org/10.2464/jilm.59.659
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    Pure titanium powder was mechanically milled (MMed) using a vibrational ball mill in the presence of stearic acid, which was added as a process control agent (PCA) . The MMed powders were subsequently consolidated into bulk materials by spark plasma sintering (SPS) to enhance the mechanical properties of the titanium. Changes in hardness, constituent phases and powder particle size resulting from the milling process were investigated by microhardness measurements, X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. The hardness and microstructure of the SPSed materials was also studied by hardness measurements and optical microscopy, respectively. The Vickers microhardness of the titanium powders with 0.25 g of PCA was found to increase sharply from 189 to 513 HV after 8 h of mechanical milling (MM), and SEM observations revealed that the mean particle size changed from 24 to 10 μm. Following SPS for 0.5 h under an applied pressure of 49 MPa at a temperature of 1073 K, near-full density was achieved for the sintered material. Formation of TiC by solid-state reaction was observed for the SPS materials consolidated from 4 h and 8 h of MMed powders. In addition, formation of TiN was observed for the SPS materials consolidated from 8 h of MM with 0.50 g of PCA. A maximum Vickers hardness of 1253 HV exhibited for the SPSed material fabricated from 8 h MMed powder with 0.50 g of PCA.
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  • Properties of aluminum based magnetic materials produced by mechanical alloying and spark plasma sintering
    Sho Aoki, Masahiro Kubota
    Article type: Research Report
    2009 Volume 59 Issue 12 Pages 666-671
    Published: December 30, 2009
    Released on J-STAGE: January 30, 2010
    DOIhttps://doi.org/10.2464/jilm.59.666
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    Air-atomized pure aluminum powder together with Fe2ZnNiCuO6 (FR) powder 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 Al-based composite materials having magnetic properties. Changes in hardness, constituent phases and soft magnetic properties of both the MAed powders and SPS materials were examined by microhardness measurements, X-ray diffraction (XRD) and vibrating sample magnetometry (VSM), respectively. The Vickers microhardness of the MAed powders increased by both increase in MA time and the amount of FR powder addition. No solid-state reactions could be detected in the MAed powders. The saturation magnetic flux density for the MAed powders were found to depend only on the amount of the FR powder present. The coercive force was suppressed by MA processing for FR powder with the present of aluminum. FR was decomposed to ZnO when the MAed powder was SPSed at 673 K and 773 K, whereas Al13Fe4, α-Al2O3 and Al4C3 were detected when the MAed powder was SPSed at temperatures above 873 K. Therefore, magnetic properties with the SPS material fabricated at 773 K was shown. In fabricating aluminum based composite materials having magnetic properties, the best SPS condition was showed at 773 K.
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  • Mechanical sidewall joints in forming of deep containers using developed blank of aluminum sheet
    Nobuo Hatanaka, Takashi Iizuka, Norio Takakura, Katsuhiko Yamaguchi
    Article type: Research Report
    2009 Volume 59 Issue 12 Pages 672-677
    Published: December 30, 2009
    Released on J-STAGE: January 30, 2010
    DOIhttps://doi.org/10.2464/jilm.59.672
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    The deep drawing process using developed blanks is one method by which the fabrication of a deep container can be done in one process. However, deep containers processed by the method tend to have lower strength than the hoop stress and less air tightness, because it has some joints on the sidewalls. In the forming process with developed blanks, in cases where the blank shape is not proper, gaps and overlaps occur between adjoining flanges. In this study, a deep drawing process was conducted with the use of a developed blank with grooves on the flange. Under the deep drawing process, the flanges are mechanically joined using the grooves on the flanges. The experimental results show that the deep container processed by the developed blank with grooves on the flange has higher strength than the hoop stress. The mechanical joining method applied to the sidewall leads to the optimum groove shape on the flange.
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  • Effect of microstructure on pore morphology in Al–Mg–Si alloys fabricated by unidirectional solidification
    Tae Bum Kim, Shinsuke Suzuki, Hideo Nakajima
    Article type: Research Report
    2009 Volume 59 Issue 12 Pages 678-684
    Published: December 30, 2009
    Released on J-STAGE: January 30, 2010
    DOIhttps://doi.org/10.2464/jilm.59.678
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    Aluminum and Al–Mg–Si alloys ingots with pores were fabricated by unidirectional solidification through thermal decomposition of Ca (OH)2 powders. The porosity of aluminum and Al–Mg–Si alloys is 10–17% and 0.1–2%, respectively. While pores with 250–400 μm in diameter were observed in a grain or across several grains in the aluminum ingot, smaller pores with 50–300 μm were observed in an eutectic region between primary α dendrites in the Al–Mg–Si ingots. In the alloys with Mg (0.25–0.5 mass%) and Si (0.2–0.4 mass%), the directional pores are aligned between columnar dendrites grown in the unidirectional solidification. With higher Mg and Si contents, the equiaxed dendrite zone with spherical pores were observed in a region with a low temperature gradient. The results of thermal analyses showed that constitutional supercooling tends to occur with increase in Mg and Si contents and with a low temperature gradient at the solid-liquid interface, and thus spherical pores are evolved. Thus, it is concluded that the pore growth direction has a strong relation with the direction of dendrites.
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  • Preparation of aluminumtriethoxide by application of aluminum corrosion
    Osami Seri, Daichi Sasaki
    Article type: Research Report
    2009 Volume 59 Issue 12 Pages 685-688
    Published: December 30, 2009
    Released on J-STAGE: January 30, 2010
    DOIhttps://doi.org/10.2464/jilm.59.685
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    Aluminumtriethoxide were obtained when aluminum powder was refluxed in dehydrated ethanol containing aluminum chloride for 10 ks. It is shown that aluminumtriethoxide powder made in our laboratory coincided with that supplied in commercial market by similar pattern of XRD-analysis, particle size distribution analysis and particle morphology observation. It is considered that aluminumtriethoxide in our laboratory was electrochemically interpreted as corrosion product which has been oxidized in ethanol containing aluminum chloride as catalyst.
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