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Volume 43, Issue 1
Displaying 1-10 of 10 articles from this issue
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Hideo OGASHI1993 Volume 43 Issue 1 Pages 1-2
Published: January 30, 1993
Released on J-STAGE: October 30, 2008
JOURNAL FREE ACCESSDownload PDF (330K) -
Tsugio HASHIMOTO, Nobuhiro MIKI1993 Volume 43 Issue 1 Pages 3-7
Published: January 30, 1993
Released on J-STAGE: October 30, 2008
JOURNAL FREE ACCESSAn aluminum-boron alloy containing high boron concentration has been synthesized by the reaction of aluminum and potassium fluoroborate at 700-830°C. The heat of the reaction is calculated to be 559.0kJ/mol and the temperature of the synthtic reaction must be controlled below 830°C. Microscopic observation of microstructures of an Al-B alloy shows that high viscosity of the molten alloy is due to the formation of a net structure of the AlB2 crystal. The net structure is broken by the K2TiF6 flux treatment and the fluidity of the molten alloy is improved. The reaction mechanism is discussed for the process of producing aluminum boride, the subsequent destruction of the net structure by the K2TiF6 treatment and the formation of the AlB2 crystal.View full abstractDownload PDF (1015K) -
Haruyuki NAKANISHI, Yoshiki TSUNEKAWA, Naotake MOHRI, Masahiro OKUMIYA ...1993 Volume 43 Issue 1 Pages 8-13
Published: January 30, 1993
Released on J-STAGE: October 30, 2008
JOURNAL FREE ACCESSIn order to achieve low pressure or pressure-less infiltration of metal matrix composites with a non-wetting reinforcement/molten metal system, lowering a contact angle was investigated by applying ultrasonic vibration. The water droplet/paraffin coated substrate and molten aluminum/alumina pipe system, of which contact angles are more than π/2rad, were selected as a model system. The stepwise increment of ultrasonic power up to 11.6kW/m2 decreased the contact angle from 1.82 to 1.01rad. With a short period, the water droplet did not change its volume under ultrasonic vibration spread over on the substrate. Alternatively, when the alumina pipe with an inside diameter of 2.0mm was immersed in molten aluminum below 30mm from the surface at 1023K, the molten aluminum did not enter into the pipe. However, the infiltration of molten aluminum into the pipe was observed approximately 23mm from the pipe end by applying ultrasonic vibration. The improvement of apparent wettability by ultrasonic vibration is possible to apply to liquid infiltration process of metal matrix composites.View full abstractDownload PDF (896K) -
Haruyuki NAKANISHI, Yoshiki TSUNEKAWA, Naotake MOHRI, Masahiro OKUMIYA ...1993 Volume 43 Issue 1 Pages 14-19
Published: January 30, 1993
Released on J-STAGE: October 30, 2008
JOURNAL FREE ACCESSUltrasonic vibration is expected to improve the apparent wettability between reinforcements and molten metals and to achieve full infiltration with an extremely low applied pressure in the liquid processing of metal matrix composites. Non-infiltrated defects at contact points of reinforcements are, then, inhibited. In this work, ultrasonic vibration (resonant frequency=20.5kHz) was applied to alumina particle/molten aluminum as a model composite system at 1023K. The threshold infiltration pressure of 19.5kPa drops to zero by applying ultrasonic vibration with the power of 500kW/m2. Therefore, full infiltration is achieved even with no applied pressure. Non-infiltrated defects are not formed at contact points of the particles in the pressure-less ultrasonic infiltration, while they are formed in the pressure infiltration without ultrasonic vibration. The infiltrated region with a semi-sphere was observed in the ultrasonic infiltration using particle preforms fixed by alumina sol. Ultrasonic vibration yields an ultrasonic pressure distributed radially throughout molten aluminum ahead of an ultrasonic horn. The ultrasonic pressure plays a vital role in the pressure-less infiltration as well as the hysteresis effect of contact angles at the interface between particle and molten aluminum does due to melt vibration.View full abstractDownload PDF (2003K) -
Gaohui WU, Norio KONO, Tsuneo TAKAHASHI, Hisafuji WATANABE1993 Volume 43 Issue 1 Pages 20-25
Published: January 30, 1993
Released on J-STAGE: October 30, 2008
JOURNAL FREE ACCESSTemperature distribution in the squeeze-exhaust cast composite materials during casting was determined by the temperature measurement at the several portions in the preform. The permeation behavior of the molten metal, the solidification process and the optimal casting conditions (temperatures of mold and molten metal) for the SiO2/Pb composite material were clarified by this method. In order to obtain sound composite materials it is essential that the molten metal front moves from the upper part to the lower part of the preform in the planar or slightly concave manner and that the solidification front, on the contrary, moves from the lower part to the upper one. The casting conditions mentioned above for the fabrication of sound composite materials are limited to a narrow temperature range. In the case of the SiO2/Pb composite material the mold temperature is required not to be lower than Tm (melting point of the matrix), and the temperature of the molten metal is required not to be higher than 1.1Tm.View full abstractDownload PDF (898K) -
Isao TSUCHITORI, Hideharu FUKUNAGA1993 Volume 43 Issue 1 Pages 26-32
Published: January 30, 1993
Released on J-STAGE: October 30, 2008
JOURNAL FREE ACCESSRutile TiO2/Al composites were prepared by squeeze casting method and the reactivity between the reinforcement and the matrix was investigated. Three kinds of composite structures were found depending on the fabrication temperatures. The first one was the non-reacted composites of TiO2/Al, the second one was the reacted homogeneous composites and the last one was the reacted heterogeneous composites composed of complex multiple phases. The hardness of the reacted homogeneous composites was about HV1100, while the hardness of the reacted heterogeneous composites ranged from HV40 to 1250. X-ray diffraction pattern and SEM analysis showed that, the hardened reacted homogeneous composites was composed of fine α-Al2O3 dispersed in the Al-Ti intermetallic compound matrix.View full abstractDownload PDF (1675K) -
Yuzuru SATO, Sakae SAITO, Ei-ichi ARAIKE, Takeshi SUZUKI, Tsutomu YAMA ...1993 Volume 43 Issue 1 Pages 33-39
Published: January 30, 1993
Released on J-STAGE: October 30, 2008
JOURNAL FREE ACCESSElectrode behavior has been studied for producing Al-Li alloys in molten salts containing LiCl. A cathode is molten aluminum, and lithium deposits electrolytically into it. An anode is graphite and acts as a chlorine evolution electrode. The electrolysis has been carried out at 973K by using LiCl single melt, LiCl-NaCl and LiCl-KCl eutectic mixture melts in order to study the electrochemical behavior of the cathode related to the current efficiency and the impurities such as sodium and potassium. For the case of LiCl single melt, required composition of Al-Li alloy up to 10mass%Li was easily obtained with high current efficiency, 93-99%, and low level impurities less than 20ppm which is comparable to the level in the commercially pure aluminum. For the case of LiCl-NaCl melt, the current efficiency somewhat decreased and about 320ppm of sodium was contained in the alloy. For the case of LiCl-KCl melt, the current efficiency markedly decreased although no potassium increase was observed. The reason for the decrease in the current efficiency is considered to be that the impurities deposit by concentration overvoltage and dissolve into the melt. However, these effects are negligible unless the melt contains large amounts of impurity salts.View full abstractDownload PDF (862K) -
Yoshihiro NAKAYAMA, Tetsuya TAKAAI, Masahiro KINOSHITA1993 Volume 43 Issue 1 Pages 40-45
Published: January 30, 1993
Released on J-STAGE: October 30, 2008
JOURNAL FREE ACCESSEffects of side groove on the absorbed energy of the 5083 aluminum alloy were studied by Charpy impact test at 77K. Relations between the side groove and the laminated fracturing behaviors were also investigated. The results obtained are summarized as follows; (1) Absorbed energy of V and U type side groove specimens decreases as the side groove depth increases. The absorbed energy of V type side groove specimen is lower than that of U type specimen. (2) The growth of the laminated cracks of the side groove specimens is constrained effectively in the vicinity of the specimen ligament. (3) Six point height, which is closely related to the extent of the laminated cracks, decreases with increasing side groove depth for the V and U type side grooved specimens. Number of laminations, however, are not effected by the side groove depth.View full abstractDownload PDF (858K) -
Keizo NAMBA1993 Volume 43 Issue 1 Pages 46-56
Published: January 30, 1993
Released on J-STAGE: October 30, 2008
JOURNAL FREE ACCESSDownload PDF (1588K) -
Kunio ITO1993 Volume 43 Issue 1 Pages 57-64
Published: January 30, 1993
Released on J-STAGE: October 30, 2008
JOURNAL FREE ACCESSDownload PDF (1105K)
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