All issues
Volume 23, Issue 1
Displaying 1-7 of 7 articles from this issue
- |<
- <
- 1
- >
- >|
-
Michihiro TAGAMI, Yo SERITA1973 Volume 23 Issue 1 Pages 1-7
Published: January 30, 1973
Released on J-STAGE: October 30, 2008
JOURNAL FREE ACCESSIt has been known that sodium addition modifies the structure of primary silicon crystals in hypereutectic Al-Si alloys. The present work was carried out to study effects of heating temperature, heating time, amount of sodium addition and cooling condition on spherodization of primary silicon crystals in a hypereutectic Al-20% Si alloy by sodium addition. The results obtained are as follows:
When 1% sodium was added to a melt, which was heated at low temperature, spherodization of the primary silicon crystals was observed even after a melt was heated for a long time. The addition of more than 0.2% sodium to a melt, heated at 750°C for 5min, resulted in the modification of the primary silicon crystals. The cooling condition influenced the spherodization of the primary silicon crystals when an Al-Si alloy was heated at 750°C for 5min and treated with 0.5% sodium. An X-ray microanalysis showed that the spheroidal primary silicon crystals contained both components, Al and Na.View full abstractDownload PDF (2909K) -
Toshiyasu FUKUI, Keizo NAMBA1973 Volume 23 Issue 1 Pages 8-16
Published: January 30, 1973
Released on J-STAGE: October 30, 2008
JOURNAL FREE ACCESSExperiments were conducted to study effects of Fe and Si on notch toughness and tear resistance of Al-Mg-Mn alloy plates and welds. Notch toughness was evaluated by a ratio of notch-tensile strength to tensile strength (notch-tensile ratio), that of notch-tensile strength to yield strength (notch-yield ratio) and Charpy impact values and tear resistance by crack initiation and propagation energies in the Navy tear tests.
The notch-tensile ratio, the yield ratio and the Charpy impact value of annealed plates and welds as well as crack initiation and propagation energies in the Navy tear test were reduced with increasing amounts of Fe and Si. Fe, Si and Fe + Si, if these contents were equal, had the similar influence on the notch toughness and the tear resistance. However, in a strict sense, the effect of Si was most notable.
As the amounts of Fe and Si increased, the dimple pattern associated with ductile fracture gave way to the quasi-cleavage pattern associated with a relatively brittle fracture and the intergranular or interdendritic rupture was also noted. Fine lamellar cracks were observed in second phases containing Fe and Si. From these observations, it was considered that the crack initiation and propagation in the Al-Mg-Mn alloy plates and welds were closely related to the distribution of the second phases.View full abstractDownload PDF (2240K) -
Terumi MARUMO, Shinichiro FUJIKAWA, Ken-ichi HIRANO1973 Volume 23 Issue 1 Pages 17-25
Published: January 30, 1973
Released on J-STAGE: October 30, 2008
JOURNAL FREE ACCESSDiffusivities of Zr in polycrystalline specimens of 99.999% pure aluminum, Al-0.063 at% Fe alloys and Al-0.18 at% Si alloys were determined by the residual-activity method with the radioactive tracer, Zirconium-95. The zirconium-95 tracer used in the present work was purified from a zirconium-95-niobium-95 mixture containing oxalic acid with a liquid-liquid extraction technique5). The zirconium-95 tracer was deposited onsamples in the form of the chloride ZrCl4. The metallic tracer was produced by the reaction of the chloride with Al in the initial stage of diffusion annealing. The chlorine gas produced in the above process acted as an etchant, removing a thin oxide film from the surface and thereby allowing the tracer to diffuse into the bulk without impediment by the surface oxide layer.
The diffusivity of Zr in 99.999% pure aluminum in the temperature range between 531°C and 640°C was expressed as
D=(7.28+10.4-4.29)×102exp{-(57.8±1.55)Kcal/mol/RT}cm2/sec.
The diffusvities of Zr in Al-0.063 at% Fe alloys in the temperature range between 555°C and 640°C and that in Al-0.18 at% Si alloys in the temperature range between 531°C and 649°C were given by
D=(3.43+8.78-2.47)×10exp{-(52.1±2.18)Kcal/mol/RT}cm2/sec
and
D=(5.48+75.1-5.11)×105exp{-(69.1±3.04)Kcal/mol/RT}cm2/sec,
respectively. The pre-exponential factor and the activation energy for diffusion of zirconium in 99.999% Al, Al-0.063 at% Fe alloys and Al-0.18% Si alloys were very similar to those for diffusion of Fe, Mn and Cr in pure aluminum.View full abstractDownload PDF (1126K) -
Tsuneo TAKAHASHI, Akihiko KAMIO, Yo KOJIMA1973 Volume 23 Issue 1 Pages 26-32
Published: January 30, 1973
Released on J-STAGE: October 30, 2008
JOURNAL FREE ACCESSAn Al-Si-Cu-Mg alloy, free of Ni, was standardized as AC8C as a heat-resisting cast aluminum in Japan in 1971. The present paper studied effects of Ni and Fe additions to this alloy system on such various properties as aging characteristics, mechanical properties at room temperature and elevated temperatures, thermal expansion, permanent growth in dimensions and metallographic structures. The results obtained are summarized as follows:
(1) The Ni addition did not affect much tensile properties at elevated temperatures.
(2) Heat treatment affected a mode of permanent growth in dimensions significantly. When it was only solution treated, the Ni containing alloy showed larger permanent growth in dimensions than the Ni-free alloy. However, a reverse effect was seen when the solution treatment was followed by an aging treatment.
(3) The Fe addition to the Ni bearing alloy suppressed permanent growth in dimensions.View full abstractDownload PDF (1690K) -
Tamotsu IGARASHI, Mitsuo SASAKI1973 Volume 23 Issue 1 Pages 33-37
Published: January 30, 1973
Released on J-STAGE: October 30, 2008
JOURNAL FREE ACCESSEmpirical equations to describe annealing curves of Al-Cu alloys were tested and the best equation was chosen from 14 trial equations. The deviation, S, from the experimental curve was calculated as
S=[{mΣi=1(Hvti-Hviti)2}/m]1/2,
where Hvti, Hviti and m were the mean micro hardness of the specimens annealed for ti seconds, the micro hardness and the number of the specimens, respectively. It was found that Eq. (14) described the observed softening curve most satisfactorily.View full abstractDownload PDF (538K) -
Mamoru IMABAYASHI1973 Volume 23 Issue 1 Pages 38-49
Published: January 30, 1973
Released on J-STAGE: October 30, 2008
JOURNAL FREE ACCESSDownload PDF (1866K) -
1973 Volume 23 Issue 1 Pages iiia
Published: 1973
Released on J-STAGE: October 30, 2008
JOURNAL FREE ACCESSDownload PDF (73K)
- |<
- <
- 1
- >
- >|