Journal of Japan Institute of Light Metals
Online ISSN : 1880-8018
Print ISSN : 0451-5994
ISSN-L : 0451-5994
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Volume 55, Issue 4
Displaying 1-6 of 6 articles from this issue
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RESEARCH REPORT
  • Improvement of mechanical properties by high temperature solution treatment in an AC4CH aluminum cast alloy
    Yutaka IRINOUCHI, Hiroyuki TODA, Takayuki SAKAI, Toshiro KOBAYASHI, Le ...
    2005 Volume 55 Issue 4 Pages 159-163
    Published: 2005
    Released on J-STAGE: February 24, 2006
    DOIhttps://doi.org/10.2464/jilm.55.159
    JOURNAL FREE ACCESS
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    The authors have realized that solution treatment may be possible at a higher temperature than that by the conventional atmosphere furnace if a fluidized bed furnace is utilized. In this study, solution treatment temperatures close to binary or ternary eutectic temperatures were used for a JIS AC4CH cast aluminum alloy. Mechanical properties were tested with internal microstructures such as micro-pores and intermetallic compound particles then being correlated using high resolution computed tomography. It is clarified that the solution treatment at the ternary eutectic temperature brings the improvement of strength by about 15.7% for a relatively short solution treatment time (typically about 1/10 of the conventional condition by an atmosphere furnace). On the other hand, the solution treatment at the binary eutectic temperature causes significant degradation by coalescence of micro-pores forming crack-like pores. These behaviors can be assessed by visualizing internal microstructures using the high resolution CT. Overall, the combination of the superior heating furnace with the state-of-the-art temperature control and sophisticated visualization technique may enable the improvement of mechanical properties in aluminum cast alloys.
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  • Effect of Zr addition on microstructure of hot extruded P/M Al-Zn-Mg-Cu alloys
    Hiroki ADACHI, Kozo OSAMURA, Takuya TANAHASHI, Ken KIKUCHI, Jun KUSUI
    2005 Volume 55 Issue 4 Pages 164-168
    Published: 2005
    Released on J-STAGE: February 24, 2006
    DOIhttps://doi.org/10.2464/jilm.55.164
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    In this study, the microstructure of hot-extruded and under-extruded Zr bearing aluminum alloys (Mesoalite 10®-1.3mass%Zr) was investigated by high-resolution EBSP analysis and the effect of Zr addition on microstructure formation during hot extrusion was studied. In an extruded Zr free alloy, coarse fibrous grains elongated to the extrusion direction were predominantly evolved. And these grains were considered to be formed by elongation of the original equi-axial grains by extrusion. Whereas, in extruded Meso10-1.3Zr alloy, many fine grains were evolved near the grain boundaries of the fibrous grains. In under-extruded Meso10-1.3Zr alloy, inhomogeneous local strains were developed near random grain boundaries and new fine grains were formed by continuous dynamic recrystallization. It is considered that in aluminum alloys, the addition of Zr promotes continuous dynamic recrystallization during hot extrusion.
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  • Ostwald ripening of Al3Sc particles in an Al-Mg-Sc alloy
    Daizen WATANABE, Chihiro WATANABE, Ryoichi MONZEN, Kazue TASAKI
    2005 Volume 55 Issue 4 Pages 169-174
    Published: 2005
    Released on J-STAGE: February 24, 2006
    DOIhttps://doi.org/10.2464/jilm.55.169
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    The Ostwald ripening of Al3Sc particles in an Al-1 mass% Mg-0.27 mass% Sc alloy aged at 673, 698 and 723 K has been investigated. The size of the particles was determined by transmission electron microscopy and the Sc concentration in the Al matrix by electric resistivity measurements. The transition from growth to coarsening is found to occur. The Al3Sc particles grow more slowly at the coarsening stage than at the growth stage. The coarsening rate is identical with that of Al3Sc particles in an Al-0.28 mass% Sc alloy. Application of the Lifshitz-Slyozov-Wagner theory has enabled us to calculate independently the matrix/Al3Sc interface energy γ and volume diffusion coefficient D of Sc in Al during coarsening of particles. The estimates of γ and D are in agreement with those derived by the same method from data on coarsening of Al3Sc particles in the Al-Sc alloy. Whether the particles are coherent or semi-coherent with the matrix, the value of γ is nearly 230 mJm-2.
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  • Influence of acetic acid on corrosion behavior of 1100 pure aluminum
    Osami SERI, Yuuki HOSHI, Masahiro SAKAI
    2005 Volume 55 Issue 4 Pages 175-180
    Published: 2005
    Released on J-STAGE: February 24, 2006
    DOIhttps://doi.org/10.2464/jilm.55.175
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    Surface observation and electrochemical measurements were carried out to clarify the influence of acetic acid on corrosion behaviors of industrially pure aluminum alloy 1100. The consideration of the potential-pH-pOAc diagram and polarization analysis reveal that coexistence of citric acid and chloride ions will severely pitting-attack aluminum alloy 1100.
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  • Air bending of AZ31 magnesium alloy sheets
    Ratchanee PAISARN, Nobumasa YUGI, Nobuhiro KOGA
    2005 Volume 55 Issue 4 Pages 181-185
    Published: 2005
    Released on J-STAGE: February 24, 2006
    DOIhttps://doi.org/10.2464/jilm.55.181
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    Authors addressed the case of bending using a press brake, and experimentally investigated and evaluated the effects of various conditions on the bending limit and bending accuracy for an AZ31 magnesium (Mg) alloy sheet (thickness t = 0.5 mm) in air bending. The results indicate that cracks were generated on the surface of the Mg alloy sheet when the bending punch radius was smaller than 1.5 mm (three times of the sheet thickness). To prevent these cracks, warm bending was required, in which the sheet material was heated to 250°C. Also, the amount of springback of Mg was larger than steel when bending at room temperature, since the modulus of elasticity of Mg is smaller than that of steel. However, when the bending temperature was high, the amount of elastic recovery of Mg rapidly decreased, resulted in a significant decrease in springback. When the bending temperature was as high as approximately 300°C, bent products with near-zero springback were obtained. In addition, we quantitatively determined the effect of various bending conditions, such as bending punch radius, die opening and bending temperature, on the bend radius and bend allowance of products. The results provide useful data that can serve as guidelines in actual bending process.
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