All issues
Volume 21, Issue 12
Displaying 1-7 of 7 articles from this issue
- |<
- <
- 1
- >
- >|
-
Hiroyasu MITANI, Hiroshi NAGAI1971 Volume 21 Issue 12 Pages 789-795
Published: December 30, 1971
Released on J-STAGE: July 23, 2008
JOURNAL FREE ACCESSThis paper describes the reactions of Al2O3-SiO2, Al2O3-SiO2-Fe2O3 and Bauxite+SiO2 with carbon by the plasma jet for clarifying the conditions suitable to the direct reduction of bauxite.
Large amounts of metals and aluminum could be obtained from Al2O3-SiO2-C and Al2O3-SiO2-Fe2O3-C systems having compositions lying on A-B line, in which the point A means 70wt% Al2O3 in Al2O3-C binary system and point B means 80wt% SiO2 in SiO2-C binary system. The maxinum weights of metals and aluminum were obtained in the center of A-B line. The above relation was effective in the direct reduction of bauxite.
The reason for obtaining large amounts of metals and aluminum from raw materials having compositions lying on A-B line can qualitatively be explained by the reactions of Al4O4C-Al4C3, Al4C3-SiO2, Al2O3-SiC and SiC-SiO2 system.View full abstractDownload PDF (799K) -
Seiki NISHI, Takeo SHINODA, Eiji KATO1971 Volume 21 Issue 12 Pages 796-802
Published: December 30, 1971
Released on J-STAGE: July 23, 2008
JOURNAL FREE ACCESSBe or Ag was added to Al-Si-Mg-Zn alloys to study their mechanical properties at elevated temperatures.
The results obtained were as follows:
The addition of Be or Ag had no effecte on the tensile strangth of these alloys at temperatures up to 150°C, but it improved the tensile and yield strengths by 23kg/cm2 at 200°C, At 250°C, the addition of Be increased the both strengths by 57kg/mm2, but the addition of Ag had no effects. At above 300°C, the addition of Be or Ag had no effects.
The addition of Ag or Be had effects on the precipitation process of these alloys. The coagulation was retarded by the adhesion of Be atoms to the vacancies. On the other hand, Ag promoted the nucleation of precipitates to change their properties and structure with the dispersion of fine and uniform precipitation phase so that the high strengths at elevated temperatures were obtained by preventing the coagulation of the phase at these temperatures.View full abstractDownload PDF (1479K) -
Dependenee of dynamic moduli of elasticity of aluminum wrought alloys on temperature (1st report)Shigeo ZAIMA, Yoichiro TAKEUTI, Hiroshi NYUKO1971 Volume 21 Issue 12 Pages 803-808
Published: December 30, 1971
Released on J-STAGE: July 23, 2008
JOURNAL FREE ACCESSThe dynamic moduli of elasticity (moduli of longitudinal and transverse elasticity) and Poisson's ratio of aluminum wrought alloys were measured in the temperature range of 20 400°C by ultrasonic reflection method originated by the authors to examine their dependence on temperature.
The results showed that the both elastic moduli tended to decrease with the rise of temperature. The rate of decrease was slow up to about 100°C and became much higher at 200 300°C. In the range of these experiments, the materials showing great temperature dependences of elastic moduli were 1100-O, 2011-T3, 2040-O, 7075-T6, and in particular, 2017-O. On the other hand, the materials showing considerably less temperature dependences were 2014-T6, 2017-T4, 5056-O, 7075-O and in particular, 2024-T4. The elastic moduli differed with different materials and also much differed with different heat treatments of the same material.
In the range of experiments, the materials having large moduli at room temperature were 2011-T3, 2014-O, 2014-T6, 2024-O, 2024-T6, 7075-O, 7075-T6, etc.;and the materials showing considerably smaller moduli were 1100-O, 2017-T4, 5656-O, etc.
The Pisson's ratio showed no significant differences among the materials, even though it was relatively larger in 2014-T6, 5056-O and in particular, 7075-T6. Though there was slight increase of the ratio with the rise of temperature in a few materials, its temperature dependence was hardly observed.View full abstractDownload PDF (687K) -
Studies on aging phenomena of Al alloys (1st report)Seiki NISHI, Takeo SHINODA, Norio UESHIMA1971 Volume 21 Issue 12 Pages 809-816
Published: December 30, 1971
Released on J-STAGE: July 23, 2008
JOURNAL FREE ACCESSThe effects of Be and Na addition to Al-Mg-Zn alloys on the aging phenomena were investigated mainly by measurements of resistivity in liquid nitrogen. The results obtained were as follows:
(1) Experiments were conducted to investigate the effects of addition of Be (0.02 0.3%) and Na(0.005 0.01 %) on the formation of G. P, zones in Al-Mg-Zn alloys. When Be was contained in the G. P. zones of Zn and Mg atoms, their density of distribution was increased. When these alloys containing Be were aged at high temperatures, Be prevented the alloys from overaging.
(2) The addition of Na prevented the alloys from aging.
(3) The structural changes during age hardening were investigated by X-ray difractiometry. It was found that the precipitates of MgZn2 were formed by aging at low temperatures (up to 200°C) and those of (AlZn)49Mg32 were formed at above 300°C.View full abstractDownload PDF (6453K) -
Akihiko NAGATA, Osamu IZUMI1971 Volume 21 Issue 12 Pages 817-825
Published: December 30, 1971
Released on J-STAGE: July 23, 2008
JOURNAL FREE ACCESSHigh purity aluminum and binary alloys of Al-Mg, Al-Zn, Al-Mn, Al-Si and Al-Fe of various solute-concentrations (contents of the other metals in Al) were solidified rapidly and uni-directionally. Their microstructures were studied with respect to the origin and arrangement of dislocations.
The arrangement of dislocations was different from that of the foilcast specimens previously reported. Dislocations were rarely arranged along the cell boundaries where solute segregations were high. It would be explained that the origin of dislocations resulted from the constitutional stress on the cell boundaries due to the solute segregations as in the foilcast specimens. However, many dislocations in the bulk-specimens rapidly solidified would also be generated by the thermal stress.
Subboundary structures were more frequently observed with the increase in solute concentrations. They consisted of relatively regular networks of dislocations in Al-Mg and Al-Mn alloys, and of complicatedly tangled disocations in Al-Zn and Al-Si alloys.View full abstractDownload PDF (5198K) -
Akihiko NAGATA, Osamu IZUMI1971 Volume 21 Issue 12 Pages 826-835
Published: December 30, 1971
Released on J-STAGE: July 23, 2008
JOURNAL FREE ACCESSAl-3%Mg alloy and commercially pure aluminum were uni-directionally solidified at various speeds (0.530.008cm/sec) and their microstructures, especially subboundary structures and secondary phase decomposition, were studied by electron microscopic examination.
Many dislocations were observed in the both materials solidified at high speeds. They were considered to have resulted from the constitutional stress due to the solid segregations. Subboundary structures were more frequently observed with the decrease in the speed of solidification. They consisted of relatively regular networks of dislocations in Al-3%Mg alloy, and of densely tangled dislocations in commercially pure aluminum. These boundaries were arranged along dendritic cell boundaries with the secondary phase particles or along the secondary dendritic arms boundaries with high solute segregations.
In commercially pure aluminum, the secondary phase decomposes chiefly consisted of Al6Fe when solidified at a high speed. However, the amount of Al6Fe decreased and that of Al3Fe increased with the decrease in solidification speed. At the speed of 0.011cm/sec in commercially pure aluminum, no Al6Fe phase was observed, but there coexisted Al3Fe and an eutectic decompose of unknown structure (perhaps, AlFeSi ternary compound).View full abstractDownload PDF (5448K) -
Hideo YOSHINAGA1971 Volume 21 Issue 12 Pages 836-849
Published: December 30, 1971
Released on J-STAGE: July 23, 2008
JOURNAL FREE ACCESSDownload PDF (2152K)
- |<
- <
- 1
- >
- >|