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Volume 49, Issue 11
Displaying 1-18 of 18 articles from this issue
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Mechanism of Nb-Al Intelligent MaterialMitsuru Kambe2002 Volume 49 Issue 11 Pages 945-949
Published: November 15, 2002
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSA concept of the crack propagation resistant intelligent materials to avoid brittle fracture in case of a shock loading and to provide with excellent mechanical property is investigated. Potential needs for nuclear power plants, aircraft and space structure are expected to provide with reliability and safety. One of the candidates is an Nb and Al fiber reinforced composite. In case of a hypervelocity impact, dynamic energy will provide with Nb3Al which features high temperature resistance. It may be effective to reduce damage as minimum as possible. Such candidate material has been manufactured by the mechanical alloying (MA) process to avoid formation of intermetallide during sintering, and was subjected to laser beam and arc attack to simulate hypervelocity impact. An EPMA analysis revealed possibility of Nb3Al and NbAl3 formation in the vicinity of a heat affected zone of the attack. Therefore Nb and Al interdiffusion in the order of 20μs has been confirmed.View full abstractDownload PDF (6662K) -
Yoshihiko Matsuyama, Takashi Mitamura2002 Volume 49 Issue 11 Pages 950-957
Published: November 15, 2002
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSThere have been developed various hard ferrite powders with a high magnetocrystalline anisotropy which are very useful for the bonded ferrite magnets. However, the conventional bonded hard ferrite magnets have not given the most of their intrinsic anisotropy. In this study, strontium ferrite (SrO.6Fe2O3) plastic bonded magnet was fabricated by the powder injection molding method using a metal mold in which the closed magnetic circuit may induce. The pellet was manufactured by heating strontium ferrite powder having small specific area. From the observation of crystal-orientation of the obtained specimens, it was proved that the anisotropic magnetic field induced from the closed magnetic circuit in the metal mold directly attributed to the improvement of coercive force of the plastic bonded strontium ferrite magnet. Further, the mechanism of enhancement of crystal-orientation degree was discussed.View full abstractDownload PDF (4581K) -
Osami Haruyama, Makoto Tando, Hisamichi M. Kimura, Nobuyuki Nishiyama, ...2002 Volume 49 Issue 11 Pages 958-963
Published: November 15, 2002
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSThe structural relaxation behavior in the Pd40Cu30Ni10P20 and the Pd43Cu27Ni10P20 metallic glasses was examined by the differential scanning calorimetry and the electrical resistivity experiment. A sharp endothermic peak in the DSC thermogram appeared just before the supercooled liquid region for the sample annealed at 540K during a given time ranged from 864 to 2940ks. Although the peak area, ΔHg, increased with annealing time, it did not saturate within the experiment. The room temperature Mossbauer experiment was performed to examine the change in the amorphous structure of the Pd40Cu30Ni9 57Fe1P20 glass accompanied with the structural relaxation at 540K. A Mössbauer spectrum showed an asymmetrical doublet peculiar to the paramagnetic metallic glass. The average isomer shift and quadrupole splitting decreased with time up to 1440 ks and thereafter increased. The behavior of these parameters was interpreted within the framework of the free volume theory.View full abstractDownload PDF (465K) -
Nobutaka Oguro, Yoshinari Kaieda2002 Volume 49 Issue 11 Pages 964-968
Published: November 15, 2002
Released on J-STAGE: December 04, 2009
JOURNAL OPEN ACCESSIt is revealed recently that the familiar chemical compound MgB2 is a superconducting material and the superconducting transition temperature Tc is 39K.It is not easy to produce the good MgB2 by conventional production method. The simple method to produce the MgB2 in a short time is developed by means of a combustion synthesis process with the heat of formation of elements. MgB2 is not able to be produced by a direct combustion synthesis process of Mg and B. Some main reasons are that the heat of formation of MgB2 is small, Mg tends to vaporize, and the Mg powder is very rough but B powder is very fine. On the other hand, MgB2 is able to be produced by the combustion synthesis process of Mg and B using the combustion synthesis of Ti and B proposed in the present paper. The oxidation and the vaporization of Mg are suppressed because the production is done in a very short time in a high vacuum. Moreover, the ratio of Mg and B is stabilized. Therefore, the superconducting properties are assumed to be improved and the production process of MgB2 becomes simple.View full abstractDownload PDF (3311K) -
Yoshinari Kaieda, Nobutaka Oguro2002 Volume 49 Issue 11 Pages 969-973
Published: November 15, 2002
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSThe combustion synthesis of the material mainly composed of γ-TiAl as a promising candidate of a light-weight high-temperature structural material is carried out. Moreover, the plasma activated sintering method is adopted as a means to make high density material, and the validity of the combination of this method and the combustion synthesis process is investigated. The oxidation is deteriorated though Mn is added to improve mechanical properties of TiAl. Then, the TiAl-Mn material manufactured by the combustion synthesis process is sintered by the plasma activated sintering method. The oxidation examination is carried out, and the feature of the combustion synthesis process is investigated compared with the conventional production process. The material manufactured by the combustion synthesis process put out the result more than the equal when made by a conventional arc melting method. Moreover, without using a very high-level process such as HIP, the good result with the sample which was able to be sintered in simple plasma activated sintering method is obtained. The usage of the combustion synthesis process can be expected to extend further.View full abstractDownload PDF (330K) -
Sayo Katou, Nobuya Machida, Yoshiyuki Ikeda, Toshihiko Shigematsu2002 Volume 49 Issue 11 Pages 974-983
Published: November 15, 2002
Released on J-STAGE: July 12, 2010
JOURNAL OPEN ACCESSOrganic-Inorganic composites were prepared as lithium ion conducting materials. Organic thermo-elastic co-polymer SEPS (styrene-ethylene-propylene-styrene) and inorganic lithium ion conductor a-60Li2S⋅0SiS2 (mol%), which was prepared by mechanical milling processes, were used as raw materials for the preparation of the composite materials. The mixture of the raw materials were heated at 90°C under a pressure of about 3×107 Pa for 1 h to obtain the composite materials in sheet shape. The obtained composite sheet containing 7wt% of SEPS showed ion conductivity 4.9×10-5 Scm-1 at room temperature. Electronic polarization measurements suggested that the main carrier of the composite sheet was lithium ions and that the ion transport number of the sheet was almost unity.View full abstractDownload PDF (3906K) -
Tool Wear in Cutting of Stainless SteelTadahiro Wada, Takaomi Toihara2002 Volume 49 Issue 11 Pages 984-988
Published: November 15, 2002
Released on J-STAGE: July 12, 2010
JOURNAL OPEN ACCESSIn this study, the (Ti, V)N coated cemented carbide tools that have several contents of Ti and V are used. In order to clarify the effective tool material for the turning of SUS310S, the tool wear of the (Ti, V)N coated cemented carbide tool is experimentally investigated. The main results obtained are as follows: (1) The Ti75V25N coated cemented carbide has high micro-hardness and high critical scratch load. (2) The Ti75V25N coated cemented carbide tool is the most effective tool material for the turning of SUS310S.
KEY WORDS turning, PVD, (Ti, V)N coatings, micro-hardness, critical scratch load, tool wear, SUS310SView full abstractDownload PDF (3587K) -
Hiroyuki Suzuki, Masato Murai, Shunzo Tashima, Hidenori Kuroki2002 Volume 49 Issue 11 Pages 989-995
Published: November 15, 2002
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSHigh purity (99.99%) and fine (0.2μm) alumina powder was prepared as aqueous slip and compacted by High-Speed Centrifugal Compaction Process (HCP) with a centrifugal acceleration of above 10, 000g. Green compacts were then sintered by high frequency (28GHz) microwave furnace with a holding temperature of 1423-1523K. No sintering aid was added into the compacts in any processing steps.
Microwave sintering in vacuum condition improved densification of HCP alumina and it reached almost full density at 1443K, which was about 70K lower than conventional sintering. On the other hand, the concurrent grain growth during microwave sintering was suppressed, thus a finer microstructure was achieved in comparison with conventionally sintered ones. The hardness and four-point strength of microwave sintered alumina, Hv 2160 and 1130MPa respectively, surpassed those of conventionally sintered HCP alumina as well as many of other alumina ever reported.View full abstractDownload PDF (1682K) -
Akihiro Matsumoto, Keizo Kobayashi, Toshiyuki Nishio, Kimihiro Ozaki, ...2002 Volume 49 Issue 11 Pages 996-1000
Published: November 15, 2002
Released on J-STAGE: July 12, 2010
JOURNAL OPEN ACCESSElemental powders of chromium and silicon have been mixed to give the desired composition of Cr-66.66 at%Si and milled in a planetary ball mill under an argon atmosphere. CrSi2 has been synthesized in situ during ball milling. The obtained powder milled for 360ks consisting nano-sized Cr, Si and CrSi2 enables us to prepare dense compacts at the consolidating temperature 1290K which is about 170K lower than that of the other milled powders for various times. This is due to a decrease of powder particles and grains. Power factor of Cr-66.66 at%Si compact prepared by mechanical alloying and pulse current sintering is higher than that of other silicides below 650K, and shows the maximum value of 1.4×10-3 (W⋅K-2⋅m-1) at 550K.View full abstractDownload PDF (4767K) -
[in Japanese]2002 Volume 49 Issue 11 Pages 1002
Published: November 15, 2002
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSDownload PDF (87K) -
Sachiko Masuoka, Yoshiro Arami, Syozo Nagai2002 Volume 49 Issue 11 Pages 1003-1008
Published: November 15, 2002
Released on J-STAGE: December 04, 2009
JOURNAL OPEN ACCESSIn order to accelerate sintering of Al-Bronze powder covered with passive oxide film, we focused on the way to add Al-Ca fluoride consisting of AlF3 and CaF2, examined effect of CaF2 mixing rate in Al-Ca fluoride, amount of added Al-Ca fluoride and sintering temperature on sintering properties of Al-Bronze powder and considered the mechanism of acceleration of sintering. Al-Bronze powder was sintered most effectively by adding Al-Ca fluoride with CaF2 mixing rate of 20 mass%. If amount of added fluoride was over 0.05 mass% and sintering temperature was over 1123K, the acceleration of sintering of Al-Bronze powder began to appear. On the mechanism of acceleration of sintering, it was presumed that Al2O3 film on the surface of Al-Bronze particles was removed in process of the formation of gaseous AlOF by, the reaction with AlF3, and the reaction was accelerated further by the presence of liquid phase appeared in Al-Ca fluoride.View full abstractDownload PDF (4667K) -
Xue-Dong LIU, Cha-Hurn Bae, Yong-Ho Park2002 Volume 49 Issue 11 Pages 1009-1014
Published: November 15, 2002
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSA combination of mechanical alloying and pulse discharge sintering was employed to fabricate the bulk (Bi0.2Sb0.8)2Te3 thermoelectric alloys with addition of Ag up to 1.0mass%. Addition of Ag up to 0.5mass% has little influence on the microstructure of the compact. However, when 1.0mass% Ag was added, an abnormal grain growth was observed in the compact during sintering at 618K. In this bulk sample, Ag particles were detected by scanning/transmission electron microscope. Thermoelectric property measurements indicate that addition of Ag optimizes the power factor, but simultaneously considerably enhances the thermal conductivity and finally markedly degrades the room-temperature figure of merit of the (Bi0.2Sb0.8)2Te3 alloy.View full abstractDownload PDF (3925K) -
Junjirou Takekawa2002 Volume 49 Issue 11 Pages 1015-1019
Published: November 15, 2002
Released on J-STAGE: December 04, 2009
JOURNAL OPEN ACCESSThe maraging steels are the excellent structural materials having both ultra-high strength and high toughness. To fabricate components of these steel, the conventional powder metallurgical process using a mixture of elemental powders including carbonyl iron powder was applied. The influences of ball-milling and sintering conditions on densification and alloying of the mixed powder compacts were investigated, and also the mechanical properties of the sintered and aged compacts were measured. The mixed powder compacts showed very high sinterability. When sintered at 1300°C, for 5h, the mixed powder compact reached to almost full density. In this compact, homogeneous alloying was confirmed by X-ray diffraction. The maximum tensile strength (1544 MPa) was obtained for the steel by the aging at 530°C for 2h. The elongation of the sintered maraging steels increased with the aging temperature.View full abstractDownload PDF (2754K) -
[in Japanese]2002 Volume 49 Issue 11 Pages 1022
Published: November 15, 2002
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSDownload PDF (79K) -
Wenbin Cao, Yoshinari Miyamoto2002 Volume 49 Issue 11 Pages 1023-1027
Published: November 15, 2002
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSThree-dimensional aluminum objects were fabricated by depositing molten Al droplets layer by layer. The effects of aluminum droplet temperature, droplet size, droplet deposition rate and the initial velocity of droplets on the micro joining of aluminum beads were investigated. The relative density of fabricated parts increased with an increase in the initial velocity of Al droplets. The relative density reached 92% when the velocity increased to 8.1m/s. Compared their CAD models, the length deformation of fabricated objects was 3-8%, and the diagonal deformation was -3%. Microstructure of the above samples was observed.View full abstractDownload PDF (5050K) -
Patama Visuttipitukul, Tatsuhiko Aizawa, Katsuyoshi Kondoh, Hideyuki K ...2002 Volume 49 Issue 11 Pages 1028-1035
Published: November 15, 2002
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSAluminum powder compacts were successfully plasma-nitrided under nitrogen-hydrogen mixture gas for various holding temperatures from 723K to 823K for 36ks (10h) to 144ks (40h). Two kinds of specimens were prepared for pure aluminum and Al-1mass%Ti alloy: the cold-pressed aluminum powder compact, and the refined aluminum powder compact via Bulk Mechanical Alloying (BMA). Before nitriding, the samples were sputtered to in situ eliminate surface oxide film by nitrogen plasma for varying the holding time from 0s to 15ks (5h). Glancing angle X-ray Diffraction (GIXD) at 1° incident angle and X-ray Photoelectron Spectroscope (XPS) were used for qualitative analysis of the nitrided surface. Aluminum nitride (AIN) was formed with the thickness up to 15μm. The refined microstructure by BMA enhanced the formation of AIN by increasing the fraction of high diffusion paths through the grain boundary. Degradation of AIN film adjacent to surface can be caused by its reaction with moisture. Detachment of AIN layer was partially observed in several samples. Detachment of nitrided layer might be introduced by the residual thermal stress in AIN layer during cooling down from the nitriding temperature.View full abstractDownload PDF (9653K) -
Eiji Yuasa, Kensuke Morita, Katsuyoshi Kondoh, Tatsuhiko Aizawa2002 Volume 49 Issue 11 Pages 1036-1041
Published: November 15, 2002
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSTo produce Al-Ni intermetallic compound, Al-42mass%Ni powder mixture was formed by back-forward extrusion at the temperature near to melting point of aluminum. The structure of alloy extruded at 910K consists of Al3Ni, Al3Ni2 and eutectic structure. In the alloy extruded at 1010K, it consists of the intermetallic compound Al3Ni and Al3Ni2. The volume fraction of each phase in the structure changes by the heat treatment, that is, the Al3Ni phase increases with increase of heat-treating temperature and the eutectic structure disappears. High temperature deformation behaviors of these alloys were characterized by compressive test at various temperatures. The alloy of intermetallic compound containing the eutectic structure have large ductility, the eutectic structure transforms to Al3Ni phase during the high temperature deformation and this transformation similarly occurs by the heat treatment at eutectic temperature. It was recognized that the compressive yield stresses in Al3Ni and Al3Ni2 phases became higher with rising deformation temperature, it is referred to as "anomalous strengthening behavior of intermetallic compound".View full abstractDownload PDF (3666K) -
Atsushi Kimura, Katsuyoshi Kondoh, Ryuzo Watanabe2002 Volume 49 Issue 11 Pages 1042-1051
Published: November 15, 2002
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSIn-situ directly nitrided and sintered Al-AIN composite material has been developed by utilizing a chemical reaction between aluminum and nitrogen gas at temperatures below 823 K. It shows an extremely low friction coefficient. We have investigated the behavior of magnesium dissolved in aluminum alloy powders by x-ray photoelectron spectroscopy using synchrotron radiation (SR-XPS). We clarified that magnesium played an important role in surface nitridation of aluminum.View full abstractDownload PDF (6785K)
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