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Volume 22, Issue 7
Displaying 1-8 of 8 articles from this issue
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Harumi KOSUGE, Ichiro MIZUKAMI1972 Volume 22 Issue 7 Pages 437-444
Published: July 30, 1972
Released on J-STAGE: July 23, 2008
JOURNAL FREE ACCESSThis study was made to investigate the change of "fir-tree" structure in D. C. cast Al-Fe-Si alloys during heating at elevated temperatures.
The specimens used were Al-0.6%Fe and Al-0.6%Fe-0.1%Si alloy, some of which had been hot-rolled or cold-rolled. They were soaked at several temperatures of 560640°C.
The experiments were carried out by anodizing, X-ray diffraction, optical microscopy, and electron microscopy.
The results obtained were summarized as follows:
(1) FeAl3 phase was present in the inner region of "fir-tree" structurs, while FeAl3 phase was found in the outer region. Another unknown phase would possibly be present in the outer region.
(2) The "fir-tree" structure was eliminated by the transformation of FeAl6 into FeAl3 during heating at elevated temperatures.
(3) The relation between the time required to eliminate the "fir-tree" structure and the reciprocal of the temperature conformed to Arrhenius' equation. The activation energy was evaluated to be 75 kcal/mol from the slope of the equation. The activation energy depended neither on the presence of 0.1%Si, nor on plastic deformation.
(4) The following two processes were observed by heating thin foils in an elctron microscope.
One was dissolution of FeAl6 phase in matrix and precipitation of FeAl3 phase on grain boundaries. The other was transformation of FeAl6 into FeAl3 in place, though the exact position of nucleation could not be determined.
(5) Being derived from the above-mentioned activation energy, the rate determining step of the transformation seemed to be the diffusion of Fe or Al in the intermetallic compounds.View full abstractDownload PDF (2515K) -
Mitsuo TANAKA, Shinichiro FUJIKAWA, Kenichi HIRANO1972 Volume 22 Issue 7 Pages 445-452
Published: July 30, 1972
Released on J-STAGE: July 23, 2008
JOURNAL FREE ACCESSRecrystallization of cold-worked Al-Zr alloys containing 0.03 to 0.33wt%. of Zr was investigated by internal friction measurement with an inverted torsional pendulum apparatus. Two typical heat treatments were carried out before final cold working. In one type of the treatment (solution treatment), specimens were water-quenched after annealing at 640°C for 24 hours and in the other (precipitation treatment), specimens were aged at 250°C for 300 hours after water-quenching from 640°C. The results obtained are as follows:
(1) An internal friction peak which was related with recovery and recrystallization appeared in the temperature range between 250°C and 400°C. The peak temperature was proportional to the logarithm of Zr concentration. This peak temperature was identified as a measure of the temperature at which recrystallization was completed, because the recrystallization temperature of Al-Zr alloys determined by hardness measurement peak proportional to the peak temperature of the internal friction and also to the logarithm of Zr contents. The was temperature was found to attain to 400°C.
(2) There was no significant difference of the peak temperature between the solution treated and the precipitation treated specimens when Zr concentration was identical. However, the peak temperature of the solution treated specimens was slightly higher than that of the precipitation treated specimens.
(3) It was concluded that the heat resistance mechanism of Al-Zr alloys was attributed largely to the presence of Zr as a solute in the supersaturated solid solation below 400°C. Diffusivity of volume diffusion of Zr in Al is extremely smaller than that of self-diffusion of Al. Thus, the solute Zr had a pinning effect on motion of dislocations and migration of grain and subgrain boundaries during annealing, and consequently thermal stability of cold worked structure was increased.View full abstractDownload PDF (1032K) -
Akiyasu YUKI, Shigeo ZAIMA1972 Volume 22 Issue 7 Pages 453-457
Published: July 30, 1972
Released on J-STAGE: July 23, 2008
JOURNAL FREE ACCESSThis paper reports influences of environment on hole surface formation of aluminum and aluminum alloys drilling. Oxygen, carbon dioxide, nitrogen and compressed air were used to jet-blow through a lead hole toward a direction opposite to the feeding direction of a drill. The results obtained are as follows:
Surfaces of 5056-H and 6061-T8 alloys were smooth when oxygen and carbon dioxide were used, while they were rough when compressed air and nitrogen were used. Active action of these gases presumably affected adhesion during friction between a drill and hole surfaces. Effects of gases on surfaces roughness of drill holes were smaller in 2017-T3 and 2024-T3 alloys than in 5056-H and 6061-T8 alloys. Environmental effects were hardlly seen in aluminum, 1100-F. Shapes of chips were sensitive to environment and indicated a process of finish surface formation.View full abstractDownload PDF (624K) -
Studies on the solidification of Al-Si alloys in a shell mold (2nd report)Masatoshi TSUDA, Shoichi EGAWA, Kozo TOKUCHIN1972 Volume 22 Issue 7 Pages 458-466
Published: July 30, 1972
Released on J-STAGE: July 23, 2008
JOURNAL FREE ACCESSAl-Si alloys containing 6.6%, 11.6% and 20% silicon were modified by metallic sodium or the special flux containing phosphorus, so called P flux developed in our laboratory. Alloying elements such as iron, manganese, magnesium, calcium and copper were added in Al-20%Si alloy in various quantities. From the above experiments the effects of modification and additional elements on the solidification in a shell mold were discussed.
The results obtained are as follows:
(1) Although Al-Si alloys were modified by metallic sodium or P flux there was little change in a cooling process of Al-Si alloys in a shell mold.
(2) It was also found that the time required for solidification was slightly shortened by the modification and proportional to (volume/surface area)2) for casting as far as this value was less than 0.3. The proportional constant was the largest for the Al-20%Si alloy and the smallest for the Al-11.6%Si alloy.
(3) Solidification time decreased with increase of thickness of a shell mold wall.
(4) Primary crystallization and eutectic temperature falls were found in Al-6.6%Si and Al-11.6%Si alloys modified with sodium. On the other hand the crystallizing temperature of primary silicon of Al-20%Si alloys treated with P flux was higher than that of ordinary Al-20%Si alloys.
(5) Cooling velocity during primary crystallization of A-20%Si alloys treated with P flux was considerably reduced by calcium addition and eutectic solidification time was shortened by copper or magnesium addition.
(6) Because of significant ability of calcium and magnesium to coarsen primary silicon, addition of extremely small quantity of calcium or more than 2% of magnesium disturbed the effect of P flux on refinement of primary silicon crystals considerably.View full abstractDownload PDF (3113K) -
Hiroyuki YAMADA, Tsuneyoshi OKAMOTO1972 Volume 22 Issue 7 Pages 467-475
Published: July 30, 1972
Released on J-STAGE: July 23, 2008
JOURNAL FREE ACCESSStudies were made on influence of chemical conversion coatings (see Table 3) on corrosion resistance of aluminum and aluminum alloys by immesing coated metals in corrosion liquids with pH of 311. The followings are the results.
(1) Boehmite films showed the highest resistance to acid solutions containing H2SO4 (pH = 3 or 5). Other films were inferior to boehmite films.
(2) Films made with chemical treatments shown in Table 3 all showed satisfactory resistance to alkaline solutions containing NaOH (pH = 9 or 11). Difference of the resistance among various films was small.
(3) After giving chemical conversion coatings shown in Table 3, specimens in Table 1 were immersed in acid corrosion liquids (pH = 3 or 5) at 45°C for 12 weeks. Among these specimens, only A1050P with boehmite films showed no corrosion pit. Other films were found to be ineffective in preventing aluminum alloys from corrosion pit formation.View full abstractDownload PDF (1456K) -
Yoshio MATSUDA1972 Volume 22 Issue 7 Pages 476-488
Published: July 30, 1972
Released on J-STAGE: July 23, 2008
JOURNAL FREE ACCESSDownload PDF (2017K) -
Saburo ARAI1972 Volume 22 Issue 7 Pages i-ii
Published: July 30, 1972
Released on J-STAGE: July 23, 2008
JOURNAL FREE ACCESSDownload PDF (303K) -
1972 Volume 22 Issue 7 Pages iii
Published: 1972
Released on J-STAGE: July 23, 2008
JOURNAL FREE ACCESSDownload PDF (93K)
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