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Volume 47, Issue 5
Displaying 1-7 of 7 articles from this issue
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RESEARCH REPORT
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Shigehiro TANIIKE, Yutaka KITAGUCHI, Shigeharu KAMADO, Yo KOJIMA, Isao ...1997 Volume 47 Issue 5 Pages 261-266
Published: 1997
Released on J-STAGE: March 30, 2007
JOURNAL FREE ACCESSThe forgeability into a cup shape, a basic shape for a engine piston, was evaluated on the heat and corrosion resistant Mg-heavy rare earth metal alloys. Furthermore, aging characteristics and tensile properties of the die-forged specimens were also investigated. Mg–10%Gd–3%Nd–Zr (GN103K), Mg–10%Dy–3%Nd–Zr (DN103K) and Mg–10%Gd–3%Y–Zr (GY103K) alloys are formed into a cup shape by die-forging under conditions of the specimen temperature of 500°C, mold temperature higher than 300°C and forging rate lower than 0.3 m/s. Coarse equilibrium precipitates are observed to be already existing in GN103K and DN103K alloys after die-forging. Hardness increase by aging is, therefore, small in GN103K alloy and little in DN103K alloy. On the other hand, GY103K alloy exhibits only fine recrystalized grains without coarse precipitates, resulting in marked hardness increase by aging. The age hardening of the alloy is caused by both the fine β''–phase with the D019 structure and fine/β'–phase with the bco structure. At temperatures between 200 and 250°C, the proof stress and tensile strength of the specimens prepared from the bottom and side of the forged GY103K alloy in a cup shape are higher than those of the conventional WE54A heat resistant magnesium alloy.View full abstractDownload PDF (1699K) -
Nobuyuki KOURA, Koichi UI1997 Volume 47 Issue 5 Pages 267-272
Published: 1997
Released on J-STAGE: March 30, 2007
JOURNAL FREE ACCESSThe rocking chair type lithium secondary battery using an LiCl saturated AlCl3–1–ethyl–3–methylimidazolium chloride (EMIC) melt as a nonflammable electrolyte operated at room temperatures has been developed. LiCl was soluble in the acidic melts (50 mol%<AlCl3). In this study, Li metal was added to the melt in order to reduce Al2Cl7− remained in the melt to Al and AlCl4−. As a result, the potential window of the melt became about 4.4 V between the reduction potential of EMI+ and the oxidation potential of AlCl4−. Lithium was only deposited on an Al electrode from this melt. Cyclic voltammograms for an Al electrode in the melt showed reversible depositing and resolving behavior for lithium. From X-ray diffraction analysis, it was confirmed that Li–Al alloy was formed on the Al substrate at room temperature. Chronopotentiograms for an LixAl electrode in the melt showed ca. 280 Ah/kg of discharge capacity at the potential plateau range about −1.5 V vs. Al.View full abstractDownload PDF (704K) -
Nobuyuki KOURA, Koichi UI, Kazuyuki TAKEISHI1997 Volume 47 Issue 5 Pages 273-278
Published: 1997
Released on J-STAGE: March 30, 2007
JOURNAL FREE ACCESSThe rocking chair type lithium secondary battery using a nonflammable LiCl saturated AlCl3–1–ethyl–3–methylimidazolium chloride (EMIC) electrolyte operated at ambient temperatures has been developed. In this paper, the positive electrode (crystalline V2O5) characteristics and the discharge-charge cycle performance in this electrolyte were investigated. The content of the intercalated lithium in V2O5 and the structure of LixV2O5 were observed. As a result, the main reaction during the discharge-charge cycle was considered to be the intercalation and deintercalation reactions of lithium in the V2O5. When the discharge-charge cycle of the V2O5 electrode was performed, the life of the cycle ability was over more than 100. The nonflammable rocking chair type Li–Al¦LiCl saturated AlCl3–EMIC ¦ V2O5 secondary cell showed 3.2~2.0 V discharge voltage and 150 Ah/kg of discharge capacity.View full abstractDownload PDF (731K) -
Hideaki YAMADA, Isao ITOH, Hiroshi NAKATA, Yasuo OTOGURO1997 Volume 47 Issue 5 Pages 279-284
Published: 1997
Released on J-STAGE: March 30, 2007
JOURNAL FREE ACCESSEffects of single addition of Sn and combined addition of Sn and other element (Cu, Mg, Zn, Ti, Si, Bi, Cr, Mn, Ni) to aluminum on the diffusion bondability of molybdenum and aluminum alloys in the atmosphere were investigated. Diffusion bonding was carried out at 873 K for 3.6 ks under the pressure of 2 MPa. After the bonding, Al12Mo, Al4Mo and Al8Mo3 whose total thicknesses range from about 25 μm to 45 μm according to different alloying elements in aluminum, are formed in the diffusion layer. There is not correspondence between the shear fracture strength and the total thickness. The combined addition of Sn and Mg to aluminum produces the couple showing good bondability with the strength of about 40 MPa, while the single addition of Sn shows the strength of only 25 MPa. All bonding couples except Mo/Al–0.5Sn and Mo/Al–0.5Sn–1Bi, which fractures at near the interface of aluminum alloy and Al12Mo, tear at the interface of Al8Mo3 and molybdenum.View full abstractDownload PDF (1115K) -
Keitarou YAMAGUCHI, Ken TOHMA1997 Volume 47 Issue 5 Pages 285-291
Published: 1997
Released on J-STAGE: March 30, 2007
JOURNAL FREE ACCESSElectrochemical measurements showed the results as follows. Pitting potential of solution heat treated alloy increased with Cu content. After precipitation heat treatment at 200°C for 60 min and for 180 min, pitting potential of Cu containing alloys decreased to −720~−730 mV (vs. SCE), accompanying intergranular corrosion. Dissolution potential of Mg2Si compound was found to be −730 mV (vs. SCE), which agreed with the pitting potential of precipitation heat treated Al–Mg–Si–Cu alloys. Intergranular corrosion of Al–Mg–Si–Cu alloys was concluded to be caused by preferential dissolution of less noble Mg2Si phase at grain boundary.View full abstractDownload PDF (1530K) -
Ichinori SHIGEMATSU, Mamoru NAKAMURA, Michihide MACHIDA1997 Volume 47 Issue 5 Pages 292-297
Published: 1997
Released on J-STAGE: March 30, 2007
JOURNAL FREE ACCESSLaser surface treatments of Al–Si casting alloys were carried out by CO2 laser. Laser surface melting was attempted to obtain surface layers with micro-crystalline structure. And further, laser surface alloying was carried out using silicon powder and cobalt base self-fluxing alloy powder as sources of alloying elements. JIS AC3A aluminum alloy and hypereutectic Al–24%Si alloy were used in this experiments. Multi-mode continuous wave beam was adopted. Laser irradiation was carried out in argon atmosphere in order to avoiding oxidation of specimens. With a beam scanning apparatus, an area in 8 mm width was irradiated. After the laser treatments, the large primary Si crystals of as-received materials are transformed to fine particles and dispersed uniformly in surface layer because of rapid solidification after melting. In the case of laser surface alloying using silicon powder, the porous alloyed layers consisting of needle primary Si crystals are formed. While, by cobalt base self-fluxing alloy powder, the alloyed layer develops a dense structure except some blow holes formed by some gas contained in the alloy powder or Al–Si alloy specimens.View full abstractDownload PDF (1986K)
REVIEW
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Tadayoshi TSUKEDA, Ken SAITO1997 Volume 47 Issue 5 Pages 298-305
Published: 1997
Released on J-STAGE: March 30, 2007
JOURNAL FREE ACCESSDownload PDF (1262K)
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