Journal of Japan Institute of Light Metals
Online ISSN : 1880-8018
Print ISSN : 0451-5994
ISSN-L : 0451-5994
Volume 34, Issue 2
Displaying 1-9 of 9 articles from this issue
  • Hideo NAGASAKA
    1984 Volume 34 Issue 2 Pages 67-68
    Published: February 28, 1984
    Released on J-STAGE: July 23, 2008
    JOURNAL FREE ACCESS
    Download PDF (356K)
  • Yoshihiro SUGAI, Ken TOHMA, Yo TAKEUCHI
    1984 Volume 34 Issue 2 Pages 69-77
    Published: February 28, 1984
    Released on J-STAGE: July 23, 2008
    JOURNAL FREE ACCESS
    To investigate pitting growth characteristics of aluminum alloys observations of dissolution morphology within the pits formed after immersion corrosion test in tap water were carried out, and they were discussed in comparison with the anodic dissolution morphology in AlCl3 solution assuming localized corrosion environment. Dissolution morphology within the pits after immersion corrosion test could be well simulated with that after anodic dissolution in AlCl3 solution. The morphology was closely related with the electrochemical properties of the alloys, such as the level of pitting potential. For example, in aluminum and the more noble alloys (100) type of crystallographic pits, while, in the less noble alloys less crystallographic dissolutions were observed, respectively. On the other hand, (100) type of crystallographic pits could be observed even in the less noble alloys after the dissolution in the sufficiently noble potentials. With these results it can be concluded that the difference of dissolution morphology of aluminum alloy is caused, not by the additional elements themselves, but by variation of dissolution potentials.
    Download PDF (4875K)
  • Shiro HORIE, Tadahisa NAKAMURA, Yasushi FUKUZAWA
    1984 Volume 34 Issue 2 Pages 78-85
    Published: February 28, 1984
    Released on J-STAGE: July 23, 2008
    JOURNAL FREE ACCESS
    The effect of magnesium content on the transition process of dynamic restoration during hot deformation of aluminum alloys was investigated. The hot workability of Al-Mg casting alloys were estimated by the observation of the deformation stress, ductlity and deformation structure in hot torsion tests. These tests were conducted on pure aluminum and Al-Mg alloys under the conditions of a strain rate range of 1.45 × 10-3 to 2.54 × 10-1sec-1 and temperature range of 300 to 600°C.
    The dynamic restoration process was two folds; for pure aluminum, the dynamic restoration was always by dynamic recovery; but the dynamic restoration in Al-Mg alloys were changed dynamic recovery to dynamic recrystallization which were controlled by magnesium contents and deformation condition (strain rate and temperature).
    The ductility of Al-Mg alloys at high temperature deformation was dependent on the dynamically recrystallized grain size. The grain size increased with increasing magnesium content and decreased with the increase of Z factor.
    Download PDF (1752K)
  • Yoshio OHTA, Ken-ji MORINAGA, Tsutomu YANAGASE
    1984 Volume 34 Issue 2 Pages 86-90
    Published: February 28, 1984
    Released on J-STAGE: July 23, 2008
    JOURNAL FREE ACCESS
    Hot-thermocouple has two functions, that is, measuring the temperature like ordinary thermocouple and heating the molten samples with the same Pt-Rh filament. The molten samples held on the filament can be observed through the microscope. By applying this method, the liquidus temperature of Na3AlF6-Al2O3-X•F systems (X = Li, Na, Mg, Ca, Al) has been determined.
    Our liquidus lines show a good agreement with the previous result which was determined by the direct observation like our method. Na3AlF6-Al2O3 system has a eutectic point at the composition of 10.6wt%Al2O3 and its temperature is 961°C. The effects of additive flouride on liquidus temperature of Na3AlF6-Al2O3 system have been also measured. LiF seemed to give a remarkable effect to lower the liquidus temperature in small addition.
    Download PDF (625K)
  • Tatsuhiko EJIMA, Kazuyoshi SHIMAKAGE, Masayoshi HOSHI, Hiroshi SAEKI, ...
    1984 Volume 34 Issue 2 Pages 91-99
    Published: February 28, 1984
    Released on J-STAGE: July 23, 2008
    JOURNAL FREE ACCESS
    For the production of aluminum chloride, chlorination behaviors of sandy alumina coated with pyrolytic carbon have been examined by changing the amount of carbon coated, coating temperature, and specific surface area of alumina etc. The experimental results obtained are summarized as follows:
    (1) The chlorination reaction of alumina was affected by the characteristic of carbon pyrolytically coated and the crystallization of γ-alumina.
    (2) The chlorination reaction rate of alumina having the specific surface area of 100-200 m2/g was faster than that of 10-100 m2/g.
    (3) For the complete recovery of aluminum chloride at 600°C, it was required to deposit carbon of about 17.2wt% on alumina by thermocatalytic cracking. At temperature of 500°C600°C, the carbon consumption increased by 5wt% as the temperature increased by 25°C.
    (4) For the effective utilization of chlorine, the bed height of sample in chlorination reactor had to be adjusted by considering the chlorination temperature.
    (5) Chlorination reaction of alumina coated with pyrolytic carbon was accelerated by the addition of a small amount of NaCl or KCl. However, the chlorination reaction was decreased when these salts were excessively added because the contact of chlorine with alumina particle was prevented by NaAlCl4 or KAlCl4 formed.
    Download PDF (1280K)
  • Tatsuhiko EJIMA, Kazuyoshi SHIMAKAGE, Masayoshi HOSHI, Hiroshi SAEKI, ...
    1984 Volume 34 Issue 2 Pages 100-109
    Published: February 28, 1984
    Released on J-STAGE: July 23, 2008
    JOURNAL FREE ACCESS
    Rates of chlorination reactions of floury and sandy aluminas with carbon deposited by thermocatalytic cracking have been investigated over the temperature range of 500°to 700°C. The experimental results obtained are summarized as follows:
    (1) Reactivity for the chlorination of sandy alumina was superior to that of floury alumina.
    (2) When the chlorination of sandy alumina was made under the optimum conditions: temperature 600°C, reaction time 60 minutes, amount of chlorine introduced 1.18 chemical equivalent to alumina, the recovery efficiency of aluminum chloride exceeded more than 95%.
    (3) The chlorination reaction of sandy alumina sigmoidally proceeded with the prolonged time. The chlorination rate was accelerated by increasing temperature and the partial pressure of chlorine. The apparent activation energy calculated from an Arrhnius plot was 17.3 kcal/mol at the temperature range of 525°to 600°C. The ratedetermining step of the chlorination reaction may be a chemical reaction process rather than mass transport one.
    (4) The chlorination rates of floury and sandy aluminas with carbon deposited by thermocatalytic cracking were much faster than those of the mixtures of active carbon and alumina measured by other investigators.
    Download PDF (1914K)
  • Tatsuo SATO, Tsuneo TAKAHASHI, Masashi IIZUMI, Kenji DOI
    1984 Volume 34 Issue 2 Pages 110-114
    Published: February 28, 1984
    Released on J-STAGE: July 23, 2008
    JOURNAL FREE ACCESS
    The aging phenomena in an Al-10%Mg alloy at room temperature has been investigated using mechanical properties, electrical resistivity measurement, neutron diffraction and high resolution electron microscope. The mechanical properties as the proof stress and elongation change gradually over a period of several years at room temperature. The electrical resistivity increases at the beginning to show resistivity maximum, subsequently decreases gradually with aging time. It was shown in TEM investigations that modulated structures were formed along the <100> direction in the early stage of aging, which later developed continuously into spherical G. P. zones having Ll2 ordered structure. The ordered G. P. zones, even if formed in the long-term aging, dissolve immediately by heating at 150°C.
    Download PDF (2305K)
  • Hisashi NISHIMURA
    1984 Volume 34 Issue 2 Pages 115-131
    Published: February 28, 1984
    Released on J-STAGE: July 23, 2008
    JOURNAL FREE ACCESS
    Download PDF (2863K)
  • Tadakazu OHNISHI
    1984 Volume 34 Issue 2 Pages 132-147
    Published: February 28, 1984
    Released on J-STAGE: July 23, 2008
    JOURNAL FREE ACCESS
    Download PDF (2432K)
feedback
Top