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Volume 39, Issue 2
Displaying 1-11 of 11 articles from this issue
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Hiroshi ANADA, Hideyuki NAKANE, Shizuo TADA, Shigenori HORI1989 Volume 39 Issue 2 Pages 81-87
Published: February 28, 1989
Released on J-STAGE: October 30, 2008
JOURNAL FREE ACCESSOptical micrography was performed on Al-5 mass%Mg alloy billets unidirectionally solidified from seed crystals. When a feathery-columnar bicrystal seed is grown, the feathery crystal grows preferentially to columnar one under the same solidifying conditions. The twin boundary in reared crystals grows in the direction of seed crystals placed in differrent orientations. It is suggested from the fact that when two grains on both sides of a boundary bear a particular orientation relation to each other, the boundary gradually transforms to a twin boundary with epitaxial growth of <100> dendrite arms in each crystal. Radiated spread of twin boundaries is attributed to that the <100> dendrite arms on either side of a twin boundary turn gradually to the heat flow direction.View full abstractDownload PDF (2395K) -
Norio KONO, Hisafuji WATANABE, GAOHUI Wu1989 Volume 39 Issue 2 Pages 88-93
Published: February 28, 1989
Released on J-STAGE: October 30, 2008
JOURNAL FREE ACCESSAluminum alloys containing Al2O3 particles with 0.15 to 3.0μm in diameter were prepared by means of squeeze casting and extrusion. Mechanical properties were evaluated at room and elevated temperatures. It was difficult to make the composite materials containing Al2O3 particles smaller than 0.15μm by the ordinary squeeze casting. It became feasible to make Al-Al2O3 composite material by the addition of gas collected area at upper part of the preform with 0.015μm Al2O3 particle or the addition of vent hole at the bottom of the casting mold. The hardness and interstice fraction increased with increase in volume fraction of Al2O3 particle from 15% to 40%, and the heat resistance was improved. The tensile strength at 300°C was 22kgf/mm2 for the composite contaning 30vol% of Al2O3 particles with a diameter of 0.3 μm. The finer the particle size, the higher became the hardness and the tensile strength at room temperature.View full abstractDownload PDF (1202K) -
Shigenori ASAMI, Takeyoshi DOKO, Keisuke YAGI1989 Volume 39 Issue 2 Pages 94-100
Published: February 28, 1989
Released on J-STAGE: October 30, 2008
JOURNAL FREE ACCESSDirect chill cast ingots of 3004 aluminum alloy were homogenized in the three conditions in order to vary the size and dispersion of α-Al(Fe, Mn)Si precipitates particle. The ingots were subsequently submitted to the single pass hot rolling by 50% reduction, and the rolled plates were held at exit temperature of 350-425°C. Subgrains form neither during rolling nor holding, in case where the ingots containing small particles in dense dispersion are rolled. On the other hand, the subgrain structure is formed during rolling, when the ingots having the relatively large particles in sparse dispersion are rolled. Moreover, recrystallization progresses and stops during holding, which results in the partially recrystallized structure. When the holding temperature gets higher, the recrystallization stops at the shorter time and the fraction of recrystallized area becomes larger. The recrystallization continues long, while the fraction of recrystallized area gets small, in case the solute content in matrix is large. These phenomena will depend on such factors as the driving force for recrystallization which decreases during holding, the pinning effect of particles and the migration velocity of the boudary of recrystallized grain.View full abstractDownload PDF (2207K) -
Tadashi MOMONO, Kazuhiko ENDO, Toshio ENJO, Kenji IKEUCHI1989 Volume 39 Issue 2 Pages 101-108
Published: February 28, 1989
Released on J-STAGE: October 30, 2008
JOURNAL FREE ACCESSDiffusion welding of SiC fiber-reinforced aluminum (FRM) to aluminum was performed using insert metals of Al-Cu-Mg alloys (JIS A2017 and A2024). The faying surface of FRM was polished mechanically with emery paper or electrolytically in order to compare the diffusion weldability. The joint strength was higher for the electro polished surface than for the surface polished with emery paper. The projection of fibers from electro polished surface of FRM played an important role in the improvement of tensile and bend strength of the joint. The highest tensile strength was obtained by welding in the temperature range where 1-5vol% of liquid phase coexist with solid phase. In this case, the strengthening of aluminum matrix due to the solution of copper was observed together with the reaction of magnesium with SiC fiber.View full abstractDownload PDF (1926K) -
Ken-ichi OHSASA, Toshinori OHSHIMA, Tadayoshi TAKAHASHI1989 Volume 39 Issue 2 Pages 109-115
Published: February 28, 1989
Released on J-STAGE: October 30, 2008
JOURNAL FREE ACCESSThe solid-liquid coexisting zone was classified into two regions, q and p according as the fluidity of interdendritic liquid. In the q zone in which the fraction of solid is in the range from 0 to 0.67, the interdendritic liquid can easily flow through the solids, whereas in the p zone with solid fraction ranging from 0.67 to 1.0, the interdendritic liquid can not flow because the liquid is entrapped by the solids. The morphology of microporosities in unidirectionally solidified Al-Si alloy ingots was related to the width of the q and p zones and the mechanical properties of the alloy were evaluated by bending test. The width of the p zone was comparatively large in the solidification of an Al-1%Si alloy and plate-like porosities were observed in a fracture surface even though the total volume of porosities was small. On the other hand, p zone the width became narrower in the solidification of an Al-3%Si alloy and globular porosities were observed in a fracture surface. The bending strength and absorbed energy of specimens with plate-like porosities are related to the ratio of observed area of interdendritic separation to that of the fracture surface.View full abstractDownload PDF (1484K) -
Katsumi MURAMATSU1989 Volume 39 Issue 2 Pages 116-122
Published: February 28, 1989
Released on J-STAGE: October 30, 2008
JOURNAL FREE ACCESSFatigue test was performed by using rotating-bending machines on the notched 5083-O extruded alloy to investigate the relation between the P-Nf diagram and the fracture surface morphology in crack initiation and propagation. The relation between the length Li (mm) of the crack initiation and the stress amplitude S (kgf/mm2) can be written in the form Li=28.8/S2. When the length of the microcrack which propagates at the notch root surface ranges Li and the crack front forms a semi-ellipse in which the long axis is Li and the aspect ratio is about 0.3, the microcrack becomes crack. The fracture surface morphology in crack initiation is classified into three types, and is related to the P-Nf diagram. When two or more main cracks originate at the notch root surface, the fatigue life is controlled by crack propagation. When only one main crack originates, or when the main crack originate in the subsurface region, the fatigue life is controlled by crack initiation.View full abstractDownload PDF (1600K) -
Hajime YAMADA, Takio TANAKA1989 Volume 39 Issue 2 Pages 123-128
Published: February 28, 1989
Released on J-STAGE: October 30, 2008
JOURNAL FREE ACCESSLubricated wear resistance of Al-Mg, Al-Mg-Si and Al-Zn-Mg alloys to die cast aluminum alloy JIS ADC12 was examined. Al-Mg-Si alloy has a best wear resistance in these alloys. Wear resistance of Al-Zn-Mg alloy is inferior to others and its resistance decreases with increase in the amounts of alloying elements, because wear resistance of high concentrated solid solution of this alloy is worse than that of low concentrations. Primary inclusions or precipitated particles is preferable for wear resistance of these alloys, especially, cast structure including primary inclusion is notably effective in the Al-Mg-Si alloys. However, such cast structure is hardly effective in the Al-Zn-Mg alloys. Anodic oxide film gives a notable effect to protect the lubricating wear of these aluminum alloys in such a case.View full abstractDownload PDF (1060K) -
Japan Magnesium Association, Committee Of MWT1989 Volume 39 Issue 2 Pages 129-135
Published: February 28, 1989
Released on J-STAGE: October 30, 2008
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Hideo NAKAE1989 Volume 39 Issue 2 Pages 136-146
Published: February 28, 1989
Released on J-STAGE: October 30, 2008
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Junichi KANEKO, Takeshi MURAKAMI, Norio FURUSHIRO1989 Volume 39 Issue 2 Pages 147-166
Published: February 28, 1989
Released on J-STAGE: October 30, 2008
JOURNAL FREE ACCESSDownload PDF (5213K) -
Hiroaki NAKAGAWA1989 Volume 39 Issue 2 Pages 167-168
Published: February 28, 1989
Released on J-STAGE: October 30, 2008
JOURNAL FREE ACCESSDownload PDF (234K)
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