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Volume 44, Issue 6
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[in Japanese]1997 Volume 44 Issue 6 Pages 522
Published: June 15, 1997
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSDownload PDF (85K) -
Yoshikazu Suzuki, Katsuyoshi Shimokawa, Yoshinobu Ueda1997 Volume 44 Issue 6 Pages 523-529
Published: June 15, 1997
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSSHS Process has been applied to the production of ceramic and metallic compound materials as powder metallurgy method.
Authors have examined the mechanism of the high speed reaction in Ni-Ti compacts and made a porous shape memory alloy from the compacts under microgravity by use of a drop shaft.
In the results, it was recognized that SHS process showed the effect of rapid heating and cooling in a short duration during microgravity experiment.
In this paper, the author discribes the reviews of the recent studies on the Ti-Ni intermetallic compound through a new processing of appling the SHS reaction and microgravity environment.View full abstractDownload PDF (5029K) -
Fabrication of Mo-Si System Intermetallic Compounds by Pulse Discharge Pressure-Combustion SynthesisTae Young Um, Yong Ho Park, Hitoshi Hashimoto, Shinichi Sumi, Toshihik ...1997 Volume 44 Issue 6 Pages 530-534
Published: June 15, 1997
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSIn this study, Mo-Si and Mo-Si-Nb system were fabricated by the pulse discharge pressure-combustion synthesis method (Nb was added into Mo-Si, in order to improve ductility at room temperature and high temperature strength). During the synthesis of Mo-Si and Mo-Si-Nb mixed powders, samples abruptly shrunk at 1323K. It is clear that combustion reaction occurred at this temperature and compounds were formed by combustion reaction. The relative density of fabricated samples was 96 to 98% and no internal defects were foundby ultrasound images in the samples. The formed phases of the fabricated samples were as follows;only MoSi2 phases were formed for Mo:Si=1:2 mixed powders, and, for the Nb added samples, MoSi2, Nb5Si3 and Mo5Si3 phases were formed and unreacted Nb remained. Young's modulus and the bending strength of fabricated samples showed similar results. Monolithic MoSi2 sample had the highest value of Young's modulus and bending strength, and for Nb added samples, Young's modulus and bending strength decreased with the increase in Nb content.View full abstractDownload PDF (4725K) -
Hiroshi Mabuchi, Satoru Shiraishi, Hiroshi Tsuda, Kenji Morii1997 Volume 44 Issue 6 Pages 535-541
Published: June 15, 1997
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSTo enhance the negligible low-temperature strength and ductility and low high-temperature strength of titanium aluminides, TiAl-(TiB2+Ti2A1C) composites were made by the combustion reaction processing using Ti, Al, and B4C powders, and homogenized by arc melting. The alloy composition included Ti52.2A145.6(B4C)2, 2 in at.%. The resulting composites had about 14 vol.% (TiB2+Ti2AIC) in the matrix TiAl with a lamellar structure of Ti3Al. In the homogenized specimens, such lamellar structures were not observed, therefore, the matrix after the homogenizing treatment consisted predominantly of the TiAl phase which is expected from the Ti-Al equilibrium phase diagram. On the other hand, smaller particles were visible in the matrix, and appeared to form in place of solutionizing lamellae. These particles have also identified as a Ti2A1C phase with an average particle size of about 100-200 run. This suggested that carbon atoms in the matrix, probably in the Ti3Al phase, formed carbide Ti2Al particles when the lamellar Ti3Al phase was disappeared during the homogenization treatment. It was found that the composite material has a high strength at both ambient and elevated (at 1173 K) temperatures ; about 900 and 500 MEN, respectively, and ambient-temperature ductility as large as 0.8% was obtained in bending.View full abstractDownload PDF (4191K) -
Hitoshi Hashimoto, Hiraku Sato, Sundeep Chauhan, Toshihiko Abe1997 Volume 44 Issue 6 Pages 542-546
Published: June 15, 1997
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSThe authors formerly found out that intercurrent introduction of nitrogen gas into the milling atmosphere during mechanical alloying of Ti-Al powder mixture promotes the synthesis of alloy powder and named this process "nitrogen shock mechanical alloying". It was confirmed by x-ray diffraction analysis that nitride, Ti2AIN was formed in sintered bodies of the alloy powder synthesized by the nitrogen shock MA. It is expected that TiAl matrix can be strengthened by the nitride, if the nitride precipitates in the form of fine particles dispersed in the matrix.
In this study, the nitrogen shock MA was applied to a mixture of Ti, Al and B powders to make a Ti-Al-B alloy powder and the alloy powder was consolidated by spark plasma activated sintering, in order to investigate effects of nitrogen on the microstructure and properties of sintered bodies. Boron was added in expectation of the formation of fine TiB2 particles which strengthen the matrix as well as the nitride. As a result, it was found that nitrogen taken in the alloy powder enhances amorphization of the powder. It was also found that the nitride increases hardness and Young's modulus of the sintered bodies. However, the nitride formed excessively made the microstructure of the sintered bodies uneven.View full abstractDownload PDF (1589K) -
M.Sherif El-Eskandarany, Mamoru Omori, Kenji Sumiyama, Toshio Hirai, K ...1997 Volume 44 Issue 6 Pages 547-553
Published: June 15, 1997
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSNanocrystalline titanium nitride (Ti56N44) powder with an average grain size of 5 nm has been synthesized by ball-milling elemental Ti powder under flow of nitrogen gas at room temperature. During the first stage of the reactive ball milling time (0 ks-3.6 ks), the metallic Ti particles agglomerate to form powder particles with larger diameter. At the second stage (3.6 ks-22 ks), these agglomerated particles are disintegrated to form smaller particles. The disintegrated particles which have fresh surfaces begin to react with nitrogen (milling atmosphere) during the third stage of milling (22 ks-86 ks) to form TiN powder coexisting with unreacted metallic Ti powder. Towards the end of milling (86 ks-173 ks), a single phase of nanocrystalline TiN with NaCI-structure was obtained. The powder of this end product has spherical like morphology with an average particle size of about 0.4 μm in diameter. A consolidation procedure using a plasma activated sintering method has been employed to consolidate the powder particles at the several stages of the reactive ball milling. The density measurements of the consolidated samples show that after 86 ks to 173 ks of the reactive ball milling time, the compacted samples are fully dense. The results have shown also that the consolidated TiN compacts still maintain their unique nanocrystalline properties with an average grain size of about 65 run. The hardness and some mechanical properties of the consolidated TiN compacts have been determined as a function of the reactive ball milling time.View full abstractDownload PDF (5751K) -
Keizo Kobayashi, Akira Sugiyama, Kimihiro Ozaki, Cui'e Wen1997 Volume 44 Issue 6 Pages 554-559
Published: June 15, 1997
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSTi-5mass%Al, Ti-I0mass%A1, Ti-32mass%Al and Ti-64mass%Al were synthesized by mechanical alloying (MA) of Ti powder and Al powder using a planetary ball milling for 360ks in 66kPa argon gas atmosphere. Ti-64mass%Al powder milled for 360ks was Al solid solution. Non stoichiometric Ti-Al powder milled for 360ks became amorphous state with an increase of Al content in the MA powder.
The mixture of MA powder and Al powder, which contained 64mass%Al, was consolidated by spark plasma sintering(SPS). The starting temperature for shrinkage in SPS process was decreased by the addition of Al powder into MA powder. In the mixture of Ti-5mass%Al MA powder and Al powder, the consolidated TiA13 was obtained by SPS at 1073K for 0.3ks. This sintered body had a homogeneous fine microstructure.View full abstractDownload PDF (2934K) -
Norio Matsui, Keizo Kobayashi, Akira Sugiyama, Kimihiro Ozaki1997 Volume 44 Issue 6 Pages 560-564
Published: June 15, 1997
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSFe32Cr68, Fe42Cr58, Fe52Cr48, Fe62Cr38 and Fe72Cr28 were synthesized by mechanical alloying (MA) of Fe powder and Cr powder using a planetary ball milling for 180ks in 1.33kPa argon gas atmosphere. In particular, the influence of milling time on structural phase of Fe52Cr48 has been studied. Because according to the phase diagram, a phase is expected to form on the composition of Fe52Cr48. As the Cr content of MA powder increased, the time for homogenization by MA became longer.
These MA powders were compacted by Spark Plasma Sintering (SPS) process. Mechanical alloyed Fe52Cr48 was rapidly shrunk at above 800K and completely condensed above 1073K. Fe52Cr48 which compacted by SPS at 1073K had no pore and its density was 7.46g/cm3.
Fe-Cr alloy prepared by this process contained no σ-phase.View full abstractDownload PDF (292K) -
Kenji Arata, Nobutaka Takeuchi, Masaru Yoshinaka, Ken Hirota, Osamu Ya ...1997 Volume 44 Issue 6 Pages 565-569
Published: June 15, 1997
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSFunctionally graded MoSi2/ZrO2(2Y) materials with high density (97.5% of theoretical) have been fabricated by uniaxial wet-molding, followed by hot pressing (1000°C/1h/30MPa) and hot isostatic pressing (1400°C/2h/196MPa). Their composition profiles are much influenced by the viscosity of the mixed solutions of glycerin and ethanol used as dispersion media; a linear compositional gradient from MoSi2/ZrO2(2Y)≈70/30 to≈20/80 mol% is obtained from the solution (50/50 vol%) with the viscosity of 20 mPa⋅s. Vickers hardness Hv and fracture toughness KIc increase from 9.7 to 12.4 GPa and 5.1 to 12.5 MPa⋅m1/2, respectively, with increasing ZrO2(2Y) composition.View full abstractDownload PDF (1798K) -
Yoshiharu Doi, Chitoshi Hayashi, Takekazu Nagae, Shouichi Ochiai1997 Volume 44 Issue 6 Pages 570-576
Published: June 15, 1997
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSThe NiAl(β)+Ni3Al(γ) two phase intermetallic compounds containing TiC particles were produced by various milling processes followed by hot press method, i.e. ball milling and both the dry milling and the wet milling using the vibrational mill. The changes of microstructures and the mechanical properties as well as the oxidation behavior for the hot pressed specimens were investigated. The obtained results were summarized as follows: Intermetallic composites consisting of (β+γ') matrix with the diameter of less than 1-2μm and submicron TiC particles were produced by wet milling process in hexane. Matrix alloy without TiC showed larger bending strength at 673K than that at room temperature, because of the increasing ductility at higher temperatures. Maximum bending strength of about 2100MPa was obtained for the 30vol.%TiC alloy at 673K. Matrix alloy deformed with extreme plasticity at 1073K, suggesting the occurrence of superplastic deformation. Vickers hardness at any temperature up to 1073K and the mass gain during oxidation at 1273K increased with increase of TiC volume fraction.View full abstractDownload PDF (6057K) -
Shouichi Ochiai, Hitoshi Takeda, Yoshiro Kojima, Shunji Kikuhara1997 Volume 44 Issue 6 Pages 577-581
Published: June 15, 1997
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSUsing pure Ti, Al and TiN powders as starting materials, TiAl base composites were produced by MA-HIP method. Microstructures and mechanical properties at elevated temperatures were investigated for HIPed compacts in addition to the MA process. Results are as follows. Though the mixed state was mostly maintained even after MA treatment, the formation of amorphous phase was confirmed in part. With the increase of volume percent of TiN particles, microstructures of HIPed compacts became finer. Ti2AIN phase was observed as well as TiAl and Ti3Al phases for compacts for which TiN was added initially. This shows the occurrence of the reaction between TiAl and TiN during sintering. The flow stress was increased with increase of TiN volume percent and the effect of dispersion strengthening was not on the decline at higher temperatures. The strain rate sensitivity exponents (m values) were found to be 0.45 at 1373K for matrix and 10vol%TiN alloys, suggesting the development of superplasticity.View full abstractDownload PDF (2482K) -
Masahito Fujita, Yasushi Saito, Kazuo Matsuo1997 Volume 44 Issue 6 Pages 585-589
Published: June 15, 1997
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSAn attempt was made to develop an automotive plane bearing material having improved wear-resistant and anti-seizure properties to meet severe requirements for the greater load and boundary lubrication. Wear-resistant and hard cobalt-base alloy powder up to 7wt% was blended in the soft Cu-3%Sn-23%Pb matrix alloy powder. The mixture was spread over the backing steel sheet, primarily sintered in the decomposed propane gas, rolled for densifying and secondarily sintered. The cobalt-base hard particles containing molybdenum and chromium are evenly dispersed in the soft matrix. These dispersoids having heterogeneous microstructure lead to hardening of the sintered composite alloy and to improvements in its wear-resistance and anti-seizure property. The wear of shaft is also lightened.View full abstractDownload PDF (5190K) -
Hisakazu Tomino, Yoshihito Kondo, Munehide Katsumura1997 Volume 44 Issue 6 Pages 590-595
Published: June 15, 1997
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSWe studied vaccum sintering behavior of an atomized cast-iron powder of two Fe-C systems containing hypo-eutectic carbon and the microstructures of sintered bodies. The results were as follows:
(1) Sintering of atomized cast-iron powder rapidly progressed independent of carbon contents within a temperature range from about 1090 to about 1110°C. This temperature range was narrow in comparison with temperature deviation in isothermal state of actual vaccum sintering furnace. Therefore, the porosity controll in vaccum sintering was very difficult in order to obtain porous sintered body.
(2) In more detail, at a same sintering temperature, sintered body of 3.96 mass% C powder was more dense than that of 2.46 mass% C powder.
(3) As sintering temperature was higher, microstructure of sintered body changed in the following sequence, (ferrite + free Fe3C), (ferrite + pearlite + free Fe3C), (pearlite + free Fe3C). No graphite in sintered body under sintering condition of this study was observedby means of optical microscope.View full abstractDownload PDF (3599K) -
Noriyuki Wada, Yoshimitsu Kankawa, Yasunari Kaneko1997 Volume 44 Issue 6 Pages 596-603
Published: June 15, 1997
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSIn this study, products obtained using Cu-Ni alloy powder and a Cu, Ni powder mixture in injection molding were compared. Both the alloy powder and the powder mixture were composed of 69.4 mass% Cu and 30.6 mass% Ni. Both feedstocks were composed of 56.0 vol% metal powder and 44.0 vol% organic binder. The binder system consisted of 25.0 vol% polybutylmethacrylate (PBMA), 35.0 vol% ethylene-vinyl acetate copolymer (EVA), and 40.0 vol% paraffin wax (PW) for both feedstocks. Sintered bodies of Cu-Ni alloy were produced from Cu-Ni alloy powder or Cu, Ni powder mixture using metal injection molding (MIM) technology. In nitrogen sintering, the density of sintered bodies produced using the Cu, Ni powder mixture was higher than that of sintered bodies produced using the Cu-Ni alloy powder. In vacuum sintering, the density of sintered bodies produced using the alloy powder was higher than that of sintered bodies produced using the powder mixture. Contents of oxygen and carbon in sintered bodies, and density depended on hydrogen treatment temperature. The maximum density, tensile strength and Vickers hardness (Hv) of sintered bodies produced using alloy powder were 8.39 g⋅cm-3, 213 MPa and 56.9-87.2, respectively. On the other hand, those of sintered bodies produced using the powder mixture were 8.36 g ⋅CM-3, 199 MPa and 86.9-123, respectively.View full abstractDownload PDF (3139K) -
Noriyuki Wada, Yoshimitsu Kankawa, Yasunari Kaneko1997 Volume 44 Issue 6 Pages 604-611
Published: June 15, 1997
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSIn this paper, the production of sintered bodies of electrolytic copper powder using metal powder injection molding (MIM) was discussed. Electrolytic powder suitable for MIM was selected from among three kinds of electrolytic copper powders, A, B and C, with mean particle sizes of 11.27 μm, 18.89 μm and 26.83 μm, respectively. The powder B was most suitable for MIM. To produce sintered bodies of high density, we chose copper powders with low oxygen and carbon contents, and determined the optimum hydrogen treatment temperature. When hydrogen treatment was performed at 973 K for 2 h with a binder content of 42.5 vol%, the sintered bodies had a relative density of 95.6%, oxygen content of 0.001 mass%, and carbon content of 0.001 mass%.View full abstractDownload PDF (4674K) -
Hiroshi Yamamoto, Masahiro Chono1997 Volume 44 Issue 6 Pages 612-617
Published: June 15, 1997
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSExperiments were carried out to investigate on the magnetic and physical properties of Ba-Zn-Li W-type hexagonal ferrites without atmosphere control. Compositions were chosen according to the formula Ba[Zn2(1-X) (LiFe)0.3Fe16O27, where X was varied between 0 and 0.6. And the effect of BaO addition after semisintering treatment on magnetic properties of Ba-Zn-Li compounds was examinend. It was found that BaO addition for Ba-Zn-Li compounds was very useful in stabilizing the W-type hexagonal. The optimum condition of making magnets and some properties ofa typical specimens are as follows: composition BaZn1.7(LiFe)0.3Fe16O27 in addition with 3wt% BaO; semisinterting condition 1275°C for 1.0h in air; sintering condition 1225°C for 0.5h in air; magnetic and physical properties are Jm=0.425 T, Jr=0.375 T, HcJ 100.2 kA/m, HcB=97.1 kA/m, (BH)max=20.4 kJ/m3, Tc=384°C, HA=983.6 kA/m, KA=2.06×105J/m3.View full abstractDownload PDF (1629K) -
Munetake Satoh, Takeshi Yanagida, Tomohiro Iwasaki1997 Volume 44 Issue 6 Pages 618-621
Published: June 15, 1997
Released on J-STAGE: July 12, 2010
JOURNAL FREE ACCESSUsing a high-speed elliptical-rotor-type powder mill, the dispersion and compounding process of particulate Ag-Ni alloy and nano-scale WC powder were investigated. This type of powder mill gives the powders a strong shear force periodically at the narrow clearance between the vessel and the rotor tip. Therefore, controllability of the granule growth with plastic deformation throughout the process was expected. The effects of the operating conditions on the dispersion and compounding processes have been discussed by mean of colorimetric method, X-ray diffraction and Scanning electron microscopy (SEM).View full abstractDownload PDF (2142K)
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