Journal of Japan Institute of Light Metals
Online ISSN : 1880-8018
Print ISSN : 0451-5994
ISSN-L : 0451-5994
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Volume 47, Issue 10
Displaying 1-9 of 9 articles from this issue
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RESEARCH REPORT
  • Effect of iron content on the occurrence of Al–Fe–Si intermetallic phases in 6063 aluminum alloy ingots
    Hiroyuki TANIHATA, Kenji MATSUDA, Susumu IKENO
    1997 Volume 47 Issue 10 Pages 515-520
    Published: 1997
    Released on J-STAGE: March 30, 2007
    DOIhttps://doi.org/10.2464/jilm.47.515
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    The effect of iron content ranging from 0.1 to 0.5 mass% on the occurrence of Al–Fe–Si intermetallic compound particles in a 6063 aluminum alloy was investigated in the as-cast state using X-ray diffraction and transmission electron microscopy (TEM). The compound particles were extracted from the ingot by the thermal phenol method. In the 0.1% Fe alloy, monoclinic β, hexagonal α' and simple cubic α phases were observed. When the iron content increased to 0.2%, the relative frequency of the β phase sharply increased to about 80% and became the main phase. In contrast, in the 0.3%Fe alloy with additional iron, the relative frequency of the β phase decreased to about 20%, while that of the α phase increased to about 70%. When the iron content was 0.5% above the specified iron content, this tendency became remarkable, and no β phase was observed. As mentioned above, it is found that a slight change in the iron content of this alloy causes considerable changes in the relative frequency of the Al–Fe–Si intermetallic phase.
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  • Microstructure and fracture characteristics in reactive sintering TiAl intermetallic compound
    Mitsuo NIINOMI, Shin NAKANO, Takashi HASEGAWA, Kazuhisa SHIBUE
    1997 Volume 47 Issue 10 Pages 521-526
    Published: 1997
    Released on J-STAGE: March 30, 2007
    DOIhttps://doi.org/10.2464/jilm.47.521
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    Microstructure and fracture characteristics of TiAl intermetallic compound fabricated by reactive sintering process was investigated by microstructural observations, tensile tests and fracture toughness tests. The greater volume fraction of equiaxed γ grain gives greater elongation, and smaller 0.2% proof stress and tensile strength while the effect of the volume fraction of equiaxed γ grain on the fracture toughness is significantly small in duplex structural materials. The greater lamellar grain size gives smaller 0.2% proof stress, tensile strength and elongation while that gives greater fracture toughness in fully lamellar structural materials. The balance of strength and fracture toughness in this reactive sintering TiAl is the best in coarser fully lamellar structure, and is superior to that of the cast TiAl at a greater strength level.
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  • Age-precipitation behavior in SiC particle dispersed Al–1 mass%Mg2Si alloy composite materials
    Susumu IKENO, Kenji MATSUDA, Takeshi TERAKI, Kiyoshi TERAYAMA, Seichi ...
    1997 Volume 47 Issue 10 Pages 527-532
    Published: 1997
    Released on J-STAGE: March 30, 2007
    DOIhttps://doi.org/10.2464/jilm.47.527
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    Aging process of SiC particle dispersed Al–lmass%Mg2Si alloy composite materials was investigated by micro-Vickers hardness measurement and transmission electron microscope observation. In the SiC particle dispersed composite materials, preferential precipitates on dislocations which had been introduced during quenching after solid solution treatment are observed. The age hardenability slightly decreased as compared with that of the matrix alloy. At peak aged condition of composite materials, most of the precipitates have the structure that is characteristic by parallelogram shaped arrays of bright dots with the intervals of 0.77 and 0.67 nm. The arrays of bright dots of the precipitates also posses an adjacent interior angle of 75 degrees. At over aged conditions, one kind of intermediate precipitates, the type–C precipitate having the lattice parameter of a=1.04 nm and c=0.405 nm are observed at relatively higher frequencies corresponding to the tendency of the type–C precipitates to precipitate preferentially on the dislocation.
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  • Formation of the chemical conversion coatings on aluminum with lithium salts and the increasing treatment
    Takayoshi FUJINO, Masaaki YOGORO, Hajime MIZUMOTO, Hayao NOGUCHI
    1997 Volume 47 Issue 10 Pages 533-538
    Published: 1997
    Released on J-STAGE: March 30, 2007
    DOIhttps://doi.org/10.2464/jilm.47.533
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    The study of anodic oxidation of aluminum was carried out for the improvement of corrosion resistance and wear resistance, and for the addition of various kinds of function. In this investigation, the chemical conversion coatings of micron order was studied using a 1%–lithium carbonate bath and a 2%–lithium hydroxide bath. The coatings were analyzed and characterized by secondary ion mass spectrometry, scanning electron microscope and x-ray diffraction instruments. The corrosion resistance and the alkali resistance of the coatings were studied comparing with anodic oxidation coatings and EW method film. The coatings were superior to anodic oxidation coating and EW method film in corrosion resistance. The structure of the chemical conversion coating was comfirmed as α–lithium aluminate and γ–alumina with x-ray diffraction. The film thickness increased by secondary dipping in mixing bath of 2%–sodium silicate and 2%–sodium fluoride. The content of lithium fluoride or aluminum fluoride in the secondary treated film was confirmed by secondary ion mass spectrometry. The fluorine was it uniformly dispersed in secondary film, and lithium silicate was observed not only at the surface but the inside of the film.
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  • Elevated-temperature strength of Al–7.8 mass%V–4 mass%Fe alloy containing icosahedral phase produced by extrusion of atomized powder
    Hisamichi KIMURA, Akihisa INOUE, Kenichiro SASAMORI, Yoshihito KAWAMUR ...
    1997 Volume 47 Issue 10 Pages 539-544
    Published: 1997
    Released on J-STAGE: March 30, 2007
    DOIhttps://doi.org/10.2464/jilm.47.539
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    The bulk material with a size of about φ8 mm × 300 mm was produced by extrusion of gas atomized Al–7.8 mass%V–4 mass%Fe alloy powder at 623, 673 and 723 K. The gas atomized powder consists of icosahedral, fcc–Al and Al11V phases and has a spherical shape with an average diameter of about 31 μm. The bulk material extruded at 623 K consists of icosahedral and Al phases and has a high packing density of approximately 100%. The ultimate tensile strength (σUTS), plastic elongation (εP), Vickers hardness (HV) and Young's modulus (E) at room temperature are 585 MPa, 4.5%, 190 and 84.8 GPa, respectively. And then the σUTS, εP and HV at 573 K are 305 MPa, 5.0% and 90, respectively. The HV remains unchanged even after holding for 432 ks at 573 K. The coefficient of thermal expansion is 21.4 × 10−6K−1, which is smaller by 15% than that of the 7075–T6 alloy. The bulk materials extruded at 673 and 723 K also have the similar high elevated temperature strength of 291 and 277 MPa, respectively, at the temperature 573 K. The extruded bulk materials with high elevated-temperature strength are expected to develop as a new type of high strength material.
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  • Fabrication of thin aluminum alloy slabs by electromagnetic casting
    Yasuhiko KANOUYA, Tadahiro KOSAKA, Shigeharu KAMADO, Yo KOJIMA, Mamoru ...
    1997 Volume 47 Issue 10 Pages 545-551
    Published: 1997
    Released on J-STAGE: March 30, 2007
    DOIhttps://doi.org/10.2464/jilm.47.545
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    In order to improve the electromagnetic casting process for manufacturing thin slabs, the influence of bottom block on the electromagnetic field in the E.M. coil was investigated. Effects of the spout shapes and casting rate were also evaluated on outward appearance and structure of thin slabs. Furthermore, the thin 5052 aluminum alloy slab was cold-rolled to a final thickness reduction of 80% and the outward appearance and tensile properties of the rolled sheets was evaluated. Increase in the thickness of bottom block in the E.M. coil extremely decreases the E.M. pressure. Furthermore, a convex line is formed at the surface of the slab due to the flow of molten metal from the spout during the formation of meniscus. Therefore, a spout with cover is used in the fabrication of the slabs for the purpose of adjusting the meniscus thickness. A slab with a flat surface and 13 mm in thickness is obtained by using the spout with cover. When the fabricated thin slab of 5052 alloy is cold-rolled to a final thickness reduction of 80%, there is no surface defect, but edge cracks generate in the rolled sheet. The thin slab has tensile strength and elongation which satisfies the JIS requirements and is almost same tensile properties of the cold-rolled commercial DC hot plate.
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  • Ductility loss of 5183 alloy at high temperature
    Fuyuki YOSHIDA, Shiho FUKUMOTO, Hideharu NAKASHIMA
    1997 Volume 47 Issue 10 Pages 552-558
    Published: 1997
    Released on J-STAGE: March 30, 2007
    DOIhttps://doi.org/10.2464/jilm.47.552
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    The ductility loss behavior of Al–Mg base 5183 alloys was studied at high-temperature. The ductility loss was observed above 500 K (grain size 28 μm samples) and 700 K (grain size 38 μm samples). However, the ductility loss behavior of 5183 alloys was not uniquely determined by the Zener-Hollomon parameter, and was different from those reported on single phase Al–Mg binary alloys. In addition, the presence of Al–Fe–Mn–Si compounds on grain-boundaries was confirmed by electron microscope observation. Based on this finding, the mechanism of the high-temperature ductility loss of 5183 alloy is discussed.
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