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Volume 29, Issue 2
Displaying 1-7 of 7 articles from this issue
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Takaya HIRAOKA1979Volume 29Issue 2 Pages 45-46
Published: February 28, 1979
Released on J-STAGE: October 30, 2008
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Susumu IKENO, Norio FURUSHIRO, Shigenori HORI1979Volume 29Issue 2 Pages 47-51
Published: February 28, 1979
Released on J-STAGE: October 30, 2008
JOURNAL FREE ACCESSTensile tests were proceeded at temperatures from -196°to 550°C. The load-elongation curve has different shapes in accordance with rise of the testing temperature such as homogeneous deformation at low temperatures and larger deformation at elevated temperatures. Typical superplastic deformation is found at the temperatures 400°C or above. The elongation is represented by the work-hardening index n at low temperatures and by the strain-rate sensitivity index m at elevated temperatures. The elongation about 180% at 550°C is smaller than that predicted by the m-value 0.5. In such a case, coarsening and shape change of grains and a number of voids are found near the fracture surface.View full abstractDownload PDF (1398K) -
Yoshikiyo OGINO, Yoshitsugu AMANO1979Volume 29Issue 2 Pages 52-57
Published: February 28, 1979
Released on J-STAGE: October 30, 2008
JOURNAL FREE ACCESSGrain boundary internal friction in the Al-0.002 wt.% Fe alloy was measured to examine an interaction between moving boundaries and solute atoms. When both the alloys solution treated for a short time at 773K in which grains are growing and solution treated for a prolonged time in which grain growth has been ceased are subsequently aged at 593K, grain boundary precipitation occurs within a shorter time in the former. This fact is in consistent with the assumption that greater quantities of solute atoms segregate in moving boundaries than in stationary boundaries. If the alloy is solution treated at elevated temperatures above 823K, however, longer times are required for grain boundary precipitation when grains are growing in the solution treatment. This may be due to the breaking away of the moving boundary from the solute atmosphere.View full abstractDownload PDF (789K) -
Masao KIKUCHI, Takeshi MORITA, Koji HORII, Masao MIZUNO1979Volume 29Issue 2 Pages 58-63
Published: February 28, 1979
Released on J-STAGE: October 30, 2008
JOURNAL FREE ACCESSAl-4.5%Zn-1.2%Mg alloy welds were examined by means of hardness measurements, X-ray small angle scattering methods and transmission electron microscopy. Differences in macrostructures of each region in Al-Zn-Mg alloy weld metals have no effct on their aging characteristics. Differences between microstructures of weld metals and those of heat-affected zones in the alloy welds affect on their aging characteristics; subgrains in weld metals of Al-Zn-Mg alloy welds decrease their agehardenabilities at 80°C, but increase them at 150°C. These results are discussed in terms of solute segregations and preferred precipitations of η' phases at subgrain boundaries or on dislocations in weld metals of Al-Zn-Mg alloy welds.View full abstractDownload PDF (1349K) -
Harumi KOSUGE, Hideo TAKADA1979Volume 29Issue 2 Pages 64-69
Published: February 28, 1979
Released on J-STAGE: October 30, 2008
JOURNAL FREE ACCESSRapidly solidifed Al-0.6%Fe and Al-0.8%Fe-0.1%Mg alloys containing metastable Al6Fe and AlmFe were isochronally and isothermally heated at elevated temperatures. X-ray diffraction and optical and transmission electron microscopies were carried out on the phase change of these metastable phases. The metastable phases are directly transformed into stable Al3Fe not through any intermediate compound. The phase change mainly proceeds in the following process; that is, dissolution of the metastable phase in matrix and precipitation of Al3Fe phase at fresh sites of dendrite cell boundaries. The activation energy for the change is evaluated to be 70±10kcal/mol. The rate determining step of the change seems to be diffusion of Fe atoms in Al matrix.View full abstractDownload PDF (1435K) -
Mitsuteru NOMOTO, Hiroshi TOKISUE, Kazuyoshi KATO, Kenichiro AOKI1979Volume 29Issue 2 Pages 70-76
Published: February 28, 1979
Released on J-STAGE: October 30, 2008
JOURNAL FREE ACCESSThe effect of hydraulic pressure from 0 to 3, 000 kgf/cm2 applied during solidification on the cast structure and specific gravity of Al-3 to 6% Cu alloys was studied. All the alloys solidified under the atomospheric pressure have equiaxed crystals on their surfaces and coarse dendrite structures in the equiaxed zone. The castings solidified under the pressure have columnar crystals originated on the die surface and the equiaxed crystals at the center of the castings. The columnar zone is extended as the applied pressure is increased. Segregation found in the center of all the squeeze castings is intensified with increase in Cu content. Although the squeeze castings have the dendritic structures finer than the gravity die castings, the finess is independent of the applied pressure. The specific gravity is increased with increase in the pressure.View full abstractDownload PDF (2098K) -
Kazuo UCHIYAMA1979Volume 29Issue 2 Pages 77-80
Published: February 28, 1979
Released on J-STAGE: October 30, 2008
JOURNAL FREE ACCESSDownload PDF (666K)
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