All issues
Volume 47, Issue 1
Displaying 1-8 of 8 articles from this issue
- |<
- <
- 1
- >
- >|
RESEARCH REPORT
-
Yoshiaki KAWAGUCHI, Makoto SUGAMATA, Junichi KANEKO1997 Volume 47 Issue 1 Pages 3-9
Published: 1997
Released on J-STAGE: March 30, 2007
JOURNAL FREE ACCESSFor the purpose of attaining property improvement of commercial aluminum casting alloys by the rapid solidification and P/M method, rapidly solidified flakes were produced by argon gas atomization and subsequent splat quenching onto a water-cooled copper roll. The flakes were consolidated to P/M materials by cold pressing, vacuum degassing and hot extrusion at a reduction of 25:1. The P/M material of JIS AC9A alloy shows the highest hardness and that of JIS AC4C alloy shows the lowest hardness among the tested alloys. Both tensile strength and elongation of as-extruded P/M materials are higher than those of I/M materials. The highest increase of tensile strength was obtained in hyper-eutectic AC9A alloy. Increase in tensile strength due to rapid solidification is in correlation with the total amount of alloying elements forming second phase particles in the aluminum matrix.View full abstractDownload PDF (1024K) -
Shinji MOTOYA, Yasuhiko KANOUYA, Shigeharu KAMADO, Yo KOJIMA, Mamoru M ...1997 Volume 47 Issue 1 Pages 10-14
Published: 1997
Released on J-STAGE: March 30, 2007
JOURNAL FREE ACCESSThe influence of casting rate and pouring method on the formation of columner crystals and floting crystals were invest igated for the purpose of improving the quality of aluminum alloy ingots. Columnar crystals are created in the center of the billet ingot when casting is performed with a slow casting rate without the reduction of the melt-flow rate. But the reduction of melt-flow rate has a possibility of making the structure equiaxial. Moreover, floating crystals crystallized inside the ingots, move from the center of the ingot to the surface, and coarsen. Its amount increases with an increase of casting rate without the reduction of melt-flow rate. Nucleation and growth of floating crystals largely depend on the flow rate of molten metal rather than on the electromagnetic stirring rate. Floating crystals are, therefore not crystallized provided melt flow in the meniscus is restricted by the reduction of melt-flow rate from the spout.View full abstractDownload PDF (1224K) -
Mamoru MATUO, Toshiki MURAMATSU, Akira ASANUMA, Shinya KOMATSU, Masahi ...1997 Volume 47 Issue 1 Pages 15-20
Published: 1997
Released on J-STAGE: March 30, 2007
JOURNAL FREE ACCESSSolute Fe and Mn concentration in aluminum alloys were estimated with the phenol filtrate analysis method. This method consists of extraction of intermetallic compounds by dissolving aluminum matrix with phenol and direct analysis of the filtrate. It was found that solute Fe and Mn concentration is well estimated by selecting an appropriate filtration procedure. As the results, estimated solute Fe and Mn concentration showed a good correlation with the specific resistivity. The degree of contribution of Fe and Mn to the specific resistivity also agreed well with the previous work. The solid solubility curves of both Al–Fe and Al–Mn binary systems were determined based on the method. The obtained solubility curves were also well consistent with the previous results. The phenol filtrate analysis is a useful method to measure solute concentration in Al directly without disturbance by coexisting elements and dislocations.View full abstractDownload PDF (746K) -
Sadao KOKUBO, Masatoshi ENOMOTO, Shinya ABE, Kazuhiro NAKATA1997 Volume 47 Issue 1 Pages 21-27
Published: 1997
Released on J-STAGE: March 30, 2007
JOURNAL FREE ACCESSLaser remelting process with Nd–YAG laser is investigated in order to improve the adhesion and wear resistance of low pressure plasma sprayed layer on the surface of aluminum extruded plate (6063) using the atomized powder of Al–50 mass%Fe, Al–15 mass%Fe–17 mass%Si and Al–50 mass%Si. The effects of pulse energy of laser beam on the microstructure, the microhardness, and the wearing rate of these laser-remelted layers are examined. Laser-remelted layer has smoother surface and better adhesion than those of the layer as sprayed. The microhardness of laser-remelted layer is kept constant toward the depth direction. In the microstructure of laser-remelted layer of Al–50 mass%Fe, fine needle-like Al3Fe and massive Al2Fe is dispersed. The microhardness increases with a decrease of the pulse energy of laser beam, but the wearing rate of laser-remelted layer increases due to the initiation of cracking. In the matrix of Al–15 mass%Fe–17 mass%Si laser-remelted layer, ultra fine needle-like and massive (Al, Fe, Si) ternary crystals are aggregated. In the microstructure of Al–50 mass%Si laser-remelted layer is ultra fine hypereutectic. Microhardnesses of these layers which are remelted at any pulse energy are HV250–350, HV150–200, respectively, and these wearing rates of them are 1/7 or less than anodized surface.View full abstractDownload PDF (1249K) -
Susumu IKENO, Takeshi TERAKI, Kenji MATSUDA, Hiroshi ANADA, Yasuhiro U ...1997 Volume 47 Issue 1 Pages 28-33
Published: 1997
Released on J-STAGE: March 30, 2007
JOURNAL FREE ACCESSAging processes of TiC particle dispersed Al–4.0 mass%Cu, Al–4.3 mass%Cu–1.1 mass%”Mg and Al–4.3 mass%Cu–1.8 mass%Mg alloys were investigated by micro-Vickers hardness, electric resistivity measurement and transmission electron microscope observation. When TiC particles are dispersed into an Al–4.0 mass%Cu alloy at a constant volume fraction of 4 vol%, aging time to reach a maximum hardness is shortened at 423 K aging. On the contrary, at 473 K aging, the time is more prolonged than that in the mother alloy. Coarsened θ' phase precipitates on the dislocations are observed at the early stage of aging in the composite materials. At a peak aging condition, GP zones and almost identical size and density of the θ' precipitates are distributed in the both mother alloy and composite materials. Aging curves of the small amount Ti added alloy show almost a similar tendency as those of the composite materials. When Al–Cu–Mg alloys having compositions in which GPB zones and the S' intermediate phase are formed during aging are used as the mother alloy, the composite materials produce the same types as the mother alloy. In this case, both the Ti added alloy and composite materials also give the almost equal time to reach a maximum hardness at 473 K aging.View full abstractDownload PDF (1496K) -
Susumu IKENO, Tohru KATAYAMA, Kenji MATSUDA, Kiyoshi TERAYAMA, Yasuhir ...1997 Volume 47 Issue 1 Pages 34-38
Published: 1997
Released on J-STAGE: March 30, 2007
JOURNAL FREE ACCESSAge-hardened Al–5.4 mass%Zn–1.8 mass%Mg alloy specimens were deformed to 0.3% strain at room temperature. The accurate surface topography in the vicinity of the grain boundaries including folds which was generated in the grain interior from the triple point was observed by scanning tunneling microscopy. At a triple point, a fold was generated along the extension of the grain boundary having a larger step as well as a higher maximum resolved shear stress on the boundary plane than the other two. At another triple point, when a fold was generated ahead of a grain boundary by a shear displacement parallel to the specimen surface, one of the adjacent grain boundaries had a step. In this case, the surface topography had a sunk shape between the fold and the step. When two steps were formed simultaneously at two neighboring grain boundaries, fold was not generated. Among the grain boundaries surrounding a single grain, displacement was observed only in part. When a large step occurred at one of these boundaries, it caused a deformation at the grain interior up to a distance about 200 μm.View full abstractDownload PDF (903K) -
Teruto KANADANI, Keiyu NAKAGAWA1997 Volume 47 Issue 1 Pages 39-43
Published: 1997
Released on J-STAGE: March 30, 2007
JOURNAL FREE ACCESSDependence of precipitation hardening and aged structures of an Al–1.2 mass%Si alloy on the distance from specimen surface was studied by microhardness test and transmission electron microscopy. The specimen was water-quenched from 833 K or 853 K to 273 K, held for 60 s and subsequently aged at 373 K, 423 K or 473 K. Rate of age-hardening was slower in the surface layer than in the interior when the specimen was aged at relatively low temperatures (373 K and 423 K) .However the value of maximum hardness in the surface layer became the same as that in the interior. According to the results of electron microscopy, the size of Si phase precipitates formed in the surface layer was smaller than that in the center of specimen aged at 423 K. This difference was considered to be caused by the effect of the surface as a vacancy sink which slowed down the growth of Si phase precipitates near the surface.View full abstractDownload PDF (1107K)
LECTURE
-
Tatsuo SATO1997 Volume 47 Issue 1 Pages 54-66
Published: 1997
Released on J-STAGE: February 15, 2022
JOURNAL FREE ACCESSDownload PDF (19585K)
- |<
- <
- 1
- >
- >|