Journal of Japan Institute of Light Metals
Online ISSN : 1880-8018
Print ISSN : 0451-5994
ISSN-L : 0451-5994
Volume 40, Issue 5
Displaying 1-10 of 10 articles from this issue
  • Yibin ZHANG, Toshimi YAMANE, Keiichi HIRAO
    1990 Volume 40 Issue 5 Pages 337-343
    Published: May 30, 1990
    Released on J-STAGE: October 30, 2008
    JOURNAL FREE ACCESS
    Al-4, 10 and 25mass%Cu alloy ribbons were produced by a rapid solidification method using a single roller technique. Cooling rates were estimated to be about 104-106K/s. The microstructures, differential scanning calormetry, tensile strength/yield stress and hardness of the ribbons were investigated. The structures of cross-section of ribbons were composed of fine crystalline grains, fine dendrites and non-equilibrium celluar eutectic structures formed in coupled zone. The precipitation in the rapidly solidified ribbons started at lower temperatures and was observed at a wider temperature range than that in the solution treated alloys. This was explained by the increased dislocation density and grain boundary area in rapidly solidified ribbons. The maximum tensile strength and yield stress were obtained in the alloys annealed at about 400-500K. The microstructure and hardness of the chilled surface were different from those of the free surface. The increased annealing temperature resulted in the similar values of hardness in both surfaces of ribbons.
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  • Tadashi TAKEMOTO, Masami MIZUTANI, Ikuo OKAMOTO, Tetsuo ABIKO, Shousuk ...
    1990 Volume 40 Issue 5 Pages 344-350
    Published: May 30, 1990
    Released on J-STAGE: October 30, 2008
    JOURNAL FREE ACCESS
    Effect of curvature of convex and concave planes on the fillet size formed after brazing of aluminum was investigated in relation to the brazing method. The fillet size was measured by throat thickness and vertical fillet leg length on the inside (concave plane) and outside (convex plane) of an aluminum pipe braze specimen. Fillet size estimated by the Laplace's equation was larger on the inside than that on the outside. In vacuum brazing inside fillet was larger than outside one under limmited test conditions, while in dip brazing inside fillet was always larger than outside one, which agreed well with the prediction of the Laplace's equation. The discrepancy between the calculation and experimental results in vacuum brazing was attributed to the poor flowabilty of molten filler metal.
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  • Kazuyoshi KATO, Hiroshi TOKISUE
    1990 Volume 40 Issue 5 Pages 351-355
    Published: May 30, 1990
    Released on J-STAGE: October 30, 2008
    JOURNAL FREE ACCESS
    2024 aluminum alloys naturally aged, artificially aged and annealed were friction welded using a brake type friction welding machine. The hardness distribution of both naturally and artificially aged friction welded joints showed that the softened areas existed at the heat affected zone. Regardless of the preheat-treatment, maximum tensile strength and elongation of the friction welded joints were obtained when friction time was 2 seconds, but they were lower than those of the base metals. All the impact specimens with the notch into the weld interface showed impact strength inferior to that of the base metals. This tendency was remarkable for the artificially aged friction welded joint. The fatigue specimens of both naturally and artificially aged friction welded joints showed lower fatigue strength than that of the base metal, but fatigue strength of the annealed friction welded joint was slightly higher than that of the base metal. Fatigue strength of both artificially and annealed friction welded joints showed slightly lower than that of the naturally aged friction welded joint.
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  • Atsushi MORIBE, Mineo GONDA, Ryozi TANAKA, Tohru YAMADA, Katsuzo HAYAS ...
    1990 Volume 40 Issue 5 Pages 356-362
    Published: May 30, 1990
    Released on J-STAGE: October 30, 2008
    JOURNAL FREE ACCESS
    Al-4%Mg-0.3%Cu alloy castings were solution heat treated at temperature of 530°C between solidus temperature and final solidification temperature, quenched into water at 25°C and artifically aged at 200°C. These casting have yield stress, ultimate tensile strength and elongation which are superior to those of AC7A (Al-5%Mg alloy). These phenomena are notable in the slowly solidified castings. The improvements of mechanical properties are brought about by the easy dissolution of Al-Cu-Mg compounds in the solution treatment, by the precipitation hardening due to the second phase particles and by the good castability of this alloy.
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  • Tadashi ARIGA, Yasuo MIYAMOTO, Katsumasa HOSOI
    1990 Volume 40 Issue 5 Pages 363-368
    Published: May 30, 1990
    Released on J-STAGE: October 30, 2008
    JOURNAL FREE ACCESS
    Interface reactions between the fibers and the matrix have been investigated on the CVD-SiC fiber reinforced aluminum and Al-Si alloys. The cross sectional area of the reaction zone around the type SCS-6 SiC fiber was larger than that around the type SCS-2 SiC fiber. The amount of reaction products around SiC fiber depends not only on the silicon content in the matrix but also on the type of fiber, and it is larger around the type SCS-2 SiC fiber than around the SCS-6 SiC fiber, in correspondence with the differences in the carbon rich layers.
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  • Taku SAKAI, Chiori IINO
    1990 Volume 40 Issue 5 Pages 369-376
    Published: May 30, 1990
    Released on J-STAGE: October 30, 2008
    JOURNAL FREE ACCESS
    Hot deformation of 7075 aluminum alloy was studied in compression in the temperature range of 723K to 803K and at constant true strain rates from 5.4×10-6s-1 to 0.78s-1. The flow characteristics were classified into three types and analysed in every region of testing conditions, as follows; L, M, and H. In the region H where flow stress was over 30MPa, high temperature yield point phenomenon appeared. Yield stress and steady state flow stress showed almost the same dependence on strain rate. These suggest that the flow in H can be controlled by the dragging motion of dislocations. In the region M where flow stress was between 15MPa and 30MPa, flow softening took place clearly at high strains with increasing temperature or decreasing strain rate. The stress of 30MPa was equal to the Orowan stress resulted from the dispersion of insoluble compound particles. In the region L where flow stress was below 15MPa, flow softening mentioned above occurred more clearly and flow stress depended sensitively on grain size. These suggest that grain boundary sliding takes place frequently during deformation. It is concluded that the flow softening in the regions of L and M results from the apparent grain refinement based on the buckling of pan-caked grain structure and grain boundary sliding.
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  • Kazuyoshi SHIMAKAGE, Mitsuru YUHKI, Tadao SATO
    1990 Volume 40 Issue 5 Pages 377-381
    Published: May 30, 1990
    Released on J-STAGE: October 30, 2008
    JOURNAL FREE ACCESS
    Al-TiB2 composite alloy powder was produced by a plasma arc CVD method using TiCl4, BCl3 and Al vapours. A plasma arc generated between a pair of Al or Al-Ti alloy electrodes was utilized both for the heating of reactants and for the vaporization of Al electrodes. The experimental results obtained are summarized as follows: (1) The reaction products were determined as Al-TiB2 and Al-TiB2-Al3Ti composite alloys by X-ray diffraction method. (2) A plot of molar ratio of reactant vapour against TiB2 content in the product showed a peak at molar ratio of TiCl4 ranging from 0.6 to 0.63 in the mixture vapour of TiCl4 and BCl3. (3) Al-TiB2-Al3Ti composite alloy was formed when the molar ratio of TiCl4 in CVD gas involving TiCl4 and BCl3 was larger than 0.5 and when Al-Ti alloys were used as electrodes. (4) The synthesized particles were considered to be consisted of the clusters of fine particles of Al-Ti alloy containing TiB2 cores.
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  • G. C. TU, I. T. CHEN, Kenichi SHIMIZU
    1990 Volume 40 Issue 5 Pages 382-389
    Published: May 30, 1990
    Released on J-STAGE: October 30, 2008
    JOURNAL FREE ACCESS
    The temperature rise in the substrate as well as in the bulk solution and the development of a local brown-coloured 'burnt' region on the anodic film are the characteristics of high rate anodizing of aluminum in oxalic acid. In this study, measurement of the barrier layer thickness in both the predicted burning region and the normal region indicates that they increase simultaneously as the voltage builds up to form the secondary voltage peak on the voltage/time transient; a depletion of oxalate anions allied with the temperature rise at the pore base is thought to govern this behaviour. Characteristic strong dotted anodic glows occurred simultaneously with a slight drop of voltage, about 1V, from the secondary peak value were observed just prior to the initiation of the local burning sector; also, the local substrate temperature always rises when burning is approaching. These studies suggest that a thermal modified electronic breakdown process is responsible for the burning phenomenon.
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  • Takashi KUNIMOTO
    1990 Volume 40 Issue 5 Pages 390-405
    Published: May 30, 1990
    Released on J-STAGE: October 30, 2008
    JOURNAL FREE ACCESS
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  • Yoshishige TSUMURA
    1990 Volume 40 Issue 5 Pages 406-407
    Published: May 30, 1990
    Released on J-STAGE: October 30, 2008
    JOURNAL FREE ACCESS
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