Journal of the Japan Institute of Metals and Materials
Online ISSN : 1880-6880
Print ISSN : 0021-4876
ISSN-L : 0021-4876
Volume 84 , Issue 4
Showing 1-4 articles out of 4 articles from the selected issue
Regular Article
  • Takashi Murata, Katsunori Yamaguchi
    Type: Regular Article
    2020 Volume 84 Issue 4 Pages 115-120
    Published: April 01, 2020
    Released: March 25, 2020
    [Advance publication] Released: January 31, 2020
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    PGMs (Platinum group metals) used as catalyst which reduces toxic substances in emission gas exhausted from an automobile should be recycled because they are precious metals produced only at the limited regions and scarcity. Rose process is employed to recover the platinum group metals from spent catalytic converters. The recycling process is to smelt an alumina honeycomb, in which PGMs are coated, with Cu, Cu2O, reductants and flux such as lime and silica.

    This study compared the recovery ability of the extractant of Cu or Cu2O for suspended platinum or palladium particles in the Al2O3-CaO-SiO2 molten slag. The collector material of Cu or Cu2O was added to the suspended PGM particles in the slag, the time dependence of platinum and palladium concentrations in the slag was investigated at 1723 K under carbon saturation. It was found that the Cu2O addition shows higher recovery of platinum and palladium than the metallic Cu. Copper oxide dissolved in the slag was reduced to metallic copper in the slag and alloyed with the suspended PGM particles to form the liquid Cu-PGM system. As the result, the particle size of the PGM increases and sedimentation rate in the slag is promoted.

    Fig. 5 Time dependence of Pt and Pt concentrations in the slag. Fullsize Image
  • Ken Harada, Teruo Kohashi, Masanari Koguchi
    Type: Regular Article
    2020 Volume 84 Issue 4 Pages 121-127
    Published: April 01, 2020
    Released: March 25, 2020
    [Advance publication] Released: January 27, 2020
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    Electron vortex beams are considered as probes for next generation electron beam instruments with unprecedented measurement capabilities because vortex beams carry intrinsic orbital angular momenta. In order to clarify the performance of vortex beams, we generated vortex beams by using fork-shaped gratings manufactured by focused ion beam instruments. In vortex beam generation experiment, we found that shapes and sizes of grating openings were superimposed on rings of diffraction spots, typical behavior of vortex beams. This paper discusses experimental results on the generation and control of vortex beams by changing grating opening shapes and sizes.

    Fig. 8 Effect of opening shapes on diffraction ring shapes: (a) circular opening, (b) triangular opening, (c) square opening, (d) pentagonal opening, and (e) star-shaped opening. The fork-shaped gratings have the third order edge dislocation and their average grid spacing is 400 nm. Fullsize Image
  • Takahiro Mineta, Seiji Miura, Kazuhiko Oka, Tatsuya Miyajima
    Type: Regular Article
    2020 Volume 84 Issue 4 Pages 128-134
    Published: April 01, 2020
    Released: March 25, 2020
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    In the present study, a newly established in situ indentation technique by the use of an optically transparent indenter and an immersion liquid, so-called “modified optical indentation microscopy”, was applied for an investigation on the plastic deformation behavior of various samples during indentation. In this technique, the gap between the indenter and the specimen surface is filled with the immersion liquid such as silicone oil and kerosene to widely observe the specimen surface during indentation. In the in situ observations by this technique using polycrystalline pure Mg, the occurrence of various plastic deformation mechanisms and the increase of the anisotropic contact area during indentation can be recognized. Moreover, the increase and the decrease of the contact area which is corresponding to superelasticity during indentation were observed by this technique using the TiNi superelastic alloy. The results of the in situ observations were consistent with the analysis results based on the Hertz theory.

    Fig. 3 (a)-(f) In situ images, (g)-(i) processed in situ images, (j) an optical micrograph after testing, and (k) EBSD analysis results of polycrystalline pure Mg. The red circles in (b) indicate the twins. Fullsize Image
Technical Article
  • Takeshi Otsuka, Yuka Otake, Masaya Hara, Yasunori Ohta, Satoshi Miyaza ...
    Type: Technical Article
    2020 Volume 84 Issue 4 Pages 135-140
    Published: April 01, 2020
    Released: March 25, 2020
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    Analysis of the particle size of metal specimens is important for quality control of metal alloys. In many cases, the EBSD method was used for grain size analysis. However, the EBSD method requires that the specimen be tilted at a significant angle. Therefore, we tried to observe the grain size using a new detector under non-tilted sample conditions. The detector is a segmented backscattered electron detector that can detect differences in signal intensity due to the EBSD pattern of each segment. The detected signal intensities were compared to obtain the particle shape, and the particle size was measured using this data.

    Fig. 10 (a) Image of grain boundaries extracted. (b) Composition image with the same field of view as in (a). Fullsize Image
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