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Volume 41, Issue 8
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[in Japanese]1994 Volume 41 Issue 8 Pages 898
Published: August 15, 1994
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSDownload PDF (83K) -
Akihisa Inoue1994 Volume 41 Issue 8 Pages 899-906
Published: August 15, 1994
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSThis paper aims to review our recent results on the microstructure and mechanical properties of rapidly solidified Al-based alloys. The formation of non-periodic structures such as amorphous or icosahedral (I) phase by rapid solidification was found to cause the achievement of high tensile strength ( σf ) exceeding 1200 MPa combined with good bending ductility. The highest σf was 1260 MPa in an amorphous phase, 1560 MPa in coexistent amorphous and nanoscale Al phases and 1340 MPa in coexistent I and Al phases. The extrusion of atomized powders having the amorphous or I+A1 structure at appropriate temperatures caused the formation of bulky alloys with finely mixed structures consisting of Al+compound or Al+I+compound, respectively. The former mixed phase alloys exhibit high σf of 800 to 1000 MPa and elongation ( εp) of 1 to 7%, while the latter mixed phase alloys have high σf of 500 to 600 MPa combined with large εp of 15 to 25 %. These good mechanical properties allow us to expect that new type of high-strength and high-ductility alloys are produced as practical materials by utilizing the feature of the non-periodic structure.View full abstractDownload PDF (6420K) -
Kiyoaki Akechi1994 Volume 41 Issue 8 Pages 907-911
Published: August 15, 1994
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSP/M aluminium alloy made from incorporating the rapidly-solidified aluminium alloy powders and hot working, for example, extrusion or forging, possesses excellent properties such as low thermal expansion coefficient, excellent wear resistance, and high strength. Therefore, in Japan, the technologies on powder-extrusion and powderforging of aluminium alloy powders are developed for ten years, and applied to many components, such as rotors and vanes of compressors for car air conditioners, orbital scrolls of compressors for room air conditioners, cylinder liners of motor cycle engines, and so on. In this report, the applications such as rotors and vanes are presented, and the industrial technologies on near-net-shape extrusion with good dimensional accuracy and without cracks or defects are described. Moreover, cylinder liners made of particle-dispersed composites with fine alumina and graphite, which are recently manufactured in mass production, are in detail mentioned.View full abstractDownload PDF (2636K) -
Yoshihito Kawamura, Akihisa Inoue, Tsuyoshi Masumoto1994 Volume 41 Issue 8 Pages 912-917
Published: August 15, 1994
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSMechanical properties of crystalline Al100-x(Ni0.33Y0.54Co0.13)x (9≤x≤15at.%) compacts fabricated by the combination of the high-pressure gas atomization method and extrusion of amorphous powders have been investigated. Furthermore, mechanical properties of Al89Ni3.7Y5.9Co1.4 compacts prepared by the closed P/M processing have been investigated and compared with those prepared by the ordinary processing. Crystalline aluminum alloy compacts showing the high strength above 900MPa were obtained by the ordinary processing. The strength and elongation were furthermore improved by the closed processing. For the extrusion of low reduction area of 60% (2.5 in the extrusion ratio), high strength compacts showing the strength above 800MPa were fabricated by the closed processing. The present work demonstrates that the structural modification through the crystallization of amorphous phases in the closed P/M processing are more effective for obtaining the high strength aluminum alloy compacts rather than the ordinary rapid solidification and the ordinary P/M processing.View full abstractDownload PDF (2890K) -
Masato Otsuki, Koichi Yuri, Kinya Kawase, Tohru Kohno1994 Volume 41 Issue 8 Pages 918-921
Published: August 15, 1994
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSPowder forging processing of rapidly solidified aluminum alloys has benefits of excellent material properties attained by rapid solidification process and of high production efficiency of PM parts. In this study, powder forged Al-Si and Al-Fe base alloys were prepared using double action forging press and the mechanical properties were examined. In this process, it is possible to conduct two steps of compaction and deformation of preforms in one shot. It was confirmed that the mechanical properties of Al-Fe base alloy powder forged by double action forging press has good mechanical properties as of the extrusion. The double action forging give good metallurgical bonding between powders by efficient dispersion of surface oxides even the amount of plastic deformation is relatively low.View full abstractDownload PDF (1556K) -
Masato Otsuki, Koichi Yuri, Tohru Kohno1994 Volume 41 Issue 8 Pages 922-926
Published: August 15, 1994
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSCavitation erosion resistance is an important mechanical property required to high-speed hydrodynamic machine parts materials such as oil pump rotor. In this study, vibratory cavitation erosion test was conducted on rapidly solidified powder Al-Si base alloys to investigate relations between cavitation erosion resistance and their composition or microstructure. It is confirmed that powder forged Al-Si alloys containing large amount of transition metals such as Fe or Cr has as good resistance to cavitation erosion as that of Fe base sintered alloy especially when the powder has fine microstructure owing to high cooling rate of the powder production. The cause of the high resistance to cavitation erosion can be attributed to that the matrix was dispersion strengthened by large amount of fine dispersoids of aluminides of Fe, Cr and Si.View full abstractDownload PDF (5613K) -
Naoki Tokizane, Hideo Sano, Kazuhisa Shibue, Yoshimasa Ohkubo1994 Volume 41 Issue 8 Pages 927-932
Published: August 15, 1994
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSAluminium alloy materials prepared by rapidly solidification process are expanding applications with their superior properties such as lightness, strength and wear resistance. In this prospective field, spray forming (SF) is now a matter of the special interest because of its simpler process, lower cost and lower oxygen content in products.
In this experiment, we prepared three SF preforms of Al-Si alloy sprayed with various "gas to metal (G/M) ratio". The microstructure and mechanical properties of the preforms and extruded materials were investigated, and found to be controled by G/M ratio. The increase of G/14 ratio reduces primary Si size and hence lowers wear resistance. On the contrary, strength of the extruded materials increases with G/M ratio.View full abstractDownload PDF (3079K) -
Tomio Satoh, Kunio Okimoto, Shin-ichi Nishida, Kenji Matsuki, Yoshitak ...1994 Volume 41 Issue 8 Pages 933-938
Published: August 15, 1994
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSRapidly solidified Al-10Mg-0.8Zr pre-alloyed powder have been produced by a rotating disk atomization method. Tensile strength and elongation of the extrudate prepared from the powder have been evaluated at elevated and room temperatures.
The tensile strength and the elongation of the extrudate at room temperature are 540MPa and 28%, respectively, and these values are comparable to those of high strength aluminum alloys, for example, A7075 with T6 treatment. The specific strength of the extrudate is 208MPa⋅m3/Mg, which is comparable with high strength titanium alloy. The elongation of the extrudate increases with increasing strain rate in the temperature range between 400 and 480°C, and the optimum strain rate showing the maximum elongation is more than 4.2×10-1 s-1. The maximum elongation is 185% at an initial strain rate of 4.2×10-1 s-1 at 480°C.View full abstractDownload PDF (2487K) -
Hidekazu Sueyoshi, Tsudoi Eguchi, Chieko Hayashi, Yuzo Nakamura1994 Volume 41 Issue 8 Pages 939-944
Published: August 15, 1994
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSHardness, and sliding friction and wear properties of composite materials composed of aluminum, aluminum borate whisker and solid lubricant such as boron nitride or graphite, were investigated. The hardness of aluminum/aluminum borate whisker composite materials decreases with the amount of either boron nitride (particle size:-500 mesh) or graphite (100-325 mesh). The addition of boron nitride deteriorates the wear property of the composite materials. The addition of graphite greater than 20vol% in content, however, not only decreases the coefficient of friction but improves wear property markedly, while graphite of the contents less than 20 vol% has no influence on the coefficient of friction and rather causes poor wear property. The role of graphite in improving friction and wear properties is clarified by the EPMA analyses of sliding surfaces.View full abstractDownload PDF (3165K) -
Hideshi Miura, Tadatoshi Honda1994 Volume 41 Issue 8 Pages 945-948
Published: August 15, 1994
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSExplosive compaction is one of the efficient compacting method in forming the hard material powders. In this study, cylindrically axi-symmetric direct explosive method has been applied to the rapidly solidified Al-Si alloy powders for forming the light weight, heat- and wear-resistant materials. The effects of the mass of explosive and the sintering on the structures and properties of compacts have been investigated by means of microscopy and mechanical tests.
When the powders were compacted at the ratio of explosive mass to powder mass (E/M ratio) lower than 12, the compacts showed low density and hardness. On the other hand, radial cracks and mach stem were formed in the compacts at the E/M ratio more than 12. To form the sound and densfied compacts, it was found that all of the powders should be compacted at the E/M ratio of 12, resulting in high density (97-98%) and high hardness (97HRB) which is higher than that of the heat-extruded materials. However, the compacts were brittle even after the sintering. This seemed to be caused by some cracks and defects introduced by machining the tensile specimen.View full abstractDownload PDF (4464K) -
Keiichi Ishihara, Radenka Maric, Akihiro Kondo, Hideo Shingu1994 Volume 41 Issue 8 Pages 949-952
Published: August 15, 1994
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSRepeated folding and stretching is the process principle of mechanical alloying to produce fine structure. In the case of the system which forms intermetallic compounds, the formation of the intermetallic phase from the lamella structured sample occurres by heating, or, without heating when the lamella spacing is reduced to a critical value. In this study, the relationship between the ignition temperature at which the formation of intermetallic phase start and the lamella spacing was measured for AlCo, AlNi and NiTi systems.View full abstractDownload PDF (5120K) -
Suguru Inamura, Hideki Kume, Hiroki Miyamoto, Yutaka Imaida, Ken Hirot ...1994 Volume 41 Issue 8 Pages 955-958
Published: August 15, 1994
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSMetastable ZrO2 solid solution powders containing 25 mol% Al2O3 have been prepared by calcining the hydrolysis co-precipitates of zirconium and aluminium alkoxides and have been sintered by the hot isostatic pressing technique. The sintered specimen consists of mixture of tetragonal zirconia solid solution and monoclinic zirconia solid solution. The solid solution ceramics with about 55% of tetragonal phase which have homogeneous microstructure with the range of grain size from 10 to 50 nm give very high fracture toughness of 23 MPa⋅m1/2.View full abstractDownload PDF (3407K) -
Tomohiro Arashi, Yukie Nakano, Akira Sato, Junko Yamamatsu, Takeshi No ...1994 Volume 41 Issue 8 Pages 959-963
Published: August 15, 1994
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSEffect of chemical composition on aging behavior of X7R multilayer ceramic chip capacitors (MLCCs) with Ni-electrode was studied with reference to the microstructure. It has been shown that the aging behavior under DC field has a strong relation with Mn0 and Y203-contents in dielectric material, tetragonality, and microstructure. After aging test, residual polarization existed, resulting in the degradation of specific dielectric constant. High capacitance MLCCs with superior properties have been developed by employing the dielectric material composed of BaTiO3-MgO-Mn0-Y2O3-Ba0.6Ca0.4SiO3.View full abstractDownload PDF (3156K) -
Kouji Sugaya, Yasuyuki Ikeda, Setsuo Takaki1994 Volume 41 Issue 8 Pages 964-969
Published: August 15, 1994
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSA Ti-13mass%Cr alloy, which is the eutectoid composition in Ti-Cr binary alloy, was prepared by the technique of elemental powder mixing and sintering in the temperature range of S (bcc) field. The microstructure of the sintered compacts was investigated by means of optical microscopy, EPMA analysis and thermal contraction test. Mechanical properties of sintered compacts were also examined in terms of the precipitation of ω phase which takes place during continuous cooling from sintering temperature.
The structure of a compact at sintering temperature is of β phase, but during slow cooling after sintering, a phase precipitates on grain boundaries of β phase below β transus, and then ω phase precipitates in the β matrix below around 600K. As a result, a sintered compact is consisted of (β+α+ω) three phases at room temperature. Sintered compacts cooled slowly from the β field undergo brittle fracture. This brittle fracture is attributed not to the precipitation of α phase at grain boundary, but to the precipitation of ω phase. The degree of the ω embrittlement was reduced when the cooling rate in the temperature below 600K was increased over 1K/s(Air cooling), and could be fully suppressed when it was over 50K/s(Oil quenching).View full abstractDownload PDF (3978K) -
Mitsuhiro Takata, Sachio Toyota, Yasushi Onishi1994 Volume 41 Issue 8 Pages 970-974
Published: August 15, 1994
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSHot Isostatic Pressing (HIP) treatment was performed to improve the transparency of PLZT ceramics. High pressure and low sintering temperature were favorable to obtain a fine grain size of 2 μm. Transparency was mainly dependent on atmospheric conditions during HIP treatment. Transmittance at short wave length was dependent on stoichiometry of lead in PLZT. For application to electrophotographic printer, an array of microswitches (65×50 μm2 In cross section) was formed on the surface of thin plate of PLZT with thin dicing saws. The rise time of switching was less than 1 micro-second. Dispersion in the amount of optical outputs was within ±5% over the array of switches. Printing speed was more than 76 sheets of A4 size per minute.Color printing was also performed in resolution of 400 dots per inch.View full abstractDownload PDF (1636K) -
Kunihiro Nagata, Shuichi Kinoshita1994 Volume 41 Issue 8 Pages 975-979
Published: August 15, 1994
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSThe degradation of multilayer ceramic actuators were studied under appling DC field and AC field voltage. On the applied DC field, the logarithms of life time were in proportion to reciprocals of temperature and logarithms of applied voltage. The properties of life time when applied 50Hz AC field were similar to the properties of life time when applied DC field.View full abstractDownload PDF (237K) -
Mitsuru Nakamura, Toshihiro Yoshida, Ko-ichi Kamada, Sadato Hiratsuka, ...1994 Volume 41 Issue 8 Pages 980-984
Published: August 15, 1994
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSWC-Co type hard metals using for the die materials are mainly machined by grinding. The grinded wastes produced by grinding, which are very fine grains (<10μm ) were thrown into the discard at present. In this experiment, the recycling technique of grinded wastes were studied. The mechanical properties of recycled metals were examined by hardness test (HRA) and the transverse rupture strength test.
As a result, it was found out that the recycling process of the grinded wastes could be completed by 7 processes. Especially, the reducing process at 1073K and the recarburizing process before the compacting process were very important. The recarburizing process was to add graphite of total 6.0 mass%. The mechanical properties of recycled metals were almost satisfied with JIS standard values (H5501).View full abstractDownload PDF (3052K) -
Minoru Endoh, Mikio Shindo1994 Volume 41 Issue 8 Pages 985-988
Published: August 15, 1994
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSThe material design program has been developed for the Nd-Fe-B sintered magnets. This method enables to estimate the phase volume percent and magnetic properties. This program has been applied for the development of (BH)max=45MGOe with iHc=13kOe magnet and high energy product magnet. From the design of (BH)max=45MGOe magnet, the (BH)max=45.1MGOe has been obtained by the reasonable mass production process. In order to develop high energy product magnet, the behavior of crystal alignment has been studied for the compacting and sintering process. The high alignment (Br/Ms > 96%) has been obtained by increasing the applied field in the cavity as well as by reducing the magnetic agglomeration of powders and low pressure compaction. As a result, the (BH)max=53.2MGOe has been obtained.View full abstractDownload PDF (253K) -
Jiro Hirose, Shigeru Ito, Kazuo Akashi, Nobuyuki Koura1994 Volume 41 Issue 8 Pages 989-993
Published: August 15, 1994
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSFe4N powder, which is known as a softmagnetic material, was sintered by Hot Isostatic Pressing (HIP). The powder was obtained by heating a carbonyl iron powder at 500°C for 4h in the mixture of H2-NH3(60vol%). Then, the Fe4N powder was encapsulated into an Al tube in troidal shape. Hipping was performed below 500°C to prevent the decomposition of Fe4N. Single phase Fe4N compact with 99% relative density was obtained under the condition of 450°C, 200MPa and 120min. The saturation magnetization of the compact was 150emu/g.View full abstractDownload PDF (2721K) -
Yuji Yamasaki, Hiroshi Uchitomi, Shinya Ozaki, Masao Komai, Ken-ichi T ...1994 Volume 41 Issue 8 Pages 994-998
Published: August 15, 1994
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSAl die-casting machine parts need excellent corrosion resistance in a molten Al alloy. In this study, we investigated the corrosion resistance of Mo2NiB2 and M02FeB2 boride base cermets. The corrosion resistance of the boride base cermets was estimated by measuring the dimensional change after dipping in molten ADC-10 Al-Si-C alloy at 1023K for 36ks.
The boride base cermets had higher corrosion resistance than conventional materials, such as WC-10mass%Co, WC-15mass%Ni and SKD61 alloy tool steel.
The boride base cermets show good corrosion resistance with increasing their Mo/B atomic ratio and Cr content.
These results imply that boride base cermets are promising candidates for the Al die casting machine parts and molds.View full abstractDownload PDF (3089K) -
Hidenori Kuroki, Yamato Sakurai, Isao Tsuchitori1994 Volume 41 Issue 8 Pages 999-1005
Published: August 15, 1994
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSStoichiometric mixtures of titanium hydride and atomized aluminum powders for TiAl are pressed uniaxially into compacts, 10mm×10mm×10 or 5mm in size, and sintered in argon.
Differential thermal analysis curves demonstrate the decomposing endothermic reaction of the titanium hydride into titanium and hydrogen, and exothermic synthesizing reactions of compounds. The synthesizing reactions begin before the exothermic peak in a DTA curve and proceed through the peak. A subsequent holding at a high temperature for a long time is necessary in order to complete homogenization. The exothermic peak appears immediately after the melting of aluminum. The peak is attended with a rapid decrease in density of the compact. A subsequent heating to higher temperatures gives rise to a slow densification. Both swelling and shrinkage appear earlier in the compacting direction than in the lateral one.
The slower is the heating rate in the reaction temperature range, the less are the swelling and the anisotropic dimensional change. The finer particle size gives less swelling and anisotropy in dimensional change and more densification and independency of heating rate.View full abstractDownload PDF (2236K) -
Minoru Umemoto, Mamoru Kubosaka, Masamichi Udaka, Kazuhiro Kawasaki, I ...1994 Volume 41 Issue 8 Pages 1006-1011
Published: August 15, 1994
Released on J-STAGE: July 12, 2010
JOURNAL FREE ACCESSThe formation of metal and metal-nitride composite ultrafine powder (UFP) using a plasma jet method was examined. Pure elemental powder of Al, Fe, Cr, Cu, Ni, Si, Ti and pre-mixed elemental powders of Al-Cu, Al-Ni, Ni-Ti, Al-Ti, Si-Ti were injected into the plasma jet of Ar-N2 working gas. The main results obtained were as follows; (1) When UFP was produced from pure metal powders of Cu, Fe, Ni and Si, nitride UFP did not form at all. On the other hand, UFP of A1N, Cr2N and TiN was formed from pure metal powders of Al, Cr and Ti, respectively. (2) Formation of nitride UFP of Si, Cr, Al, Ti was not enhanced by using working gas containing a small amount of H2 On the contrary, AIN was eliminated by using working gas containing a small amount of H2. (3) The structure of composite UFP of Cu-AlN and Ni-A1N consisted of two different particle types. In one type, a number of hemispherical particles was attached on the surface of a hexagonal prismatic particle. In the second type, a spherical particle was attached on one side of a cylindrical particle. (4) The structure of ultrafine composite particles of Ni-TiN consisted of three different particle types. One type was dumbbell-like and second type was dice-like morphologies. In the last type, one or two large hemispherical particles were attached on faces of a cubic particle. (5) When UFP was produced from pre-mixed powder of the Si-Ti system, string-shaped UFP was observed.View full abstractDownload PDF (2973K) -
Jinsuke Takata, Nobuyasu Kawai1994 Volume 41 Issue 8 Pages 1012-1018
Published: August 15, 1994
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSA dilatometer, which has been used to investigate the sintering behavior in powder metallurgy, is most useful when the measurement is carried out systematically by simulating the operating conditions in a practical sintering furnace. This paper reports the dilatometric measure-ment of iron based compacts including lubricant at the fairly high heating and cooling rate in various atmospheres controlled by dew point.
A quick cooling system of sintering compacts and a safe equipment to prevent a leak of combustible gases are also described in addition to the calibration method and the accuracy of the dilatometer.View full abstractDownload PDF (453K) -
Shigenori Tanabe, Yoshihisa Hukui, Hiroyuki Ichinose1994 Volume 41 Issue 8 Pages 1019-1022
Published: August 15, 1994
Released on J-STAGE: July 12, 2010
JOURNAL FREE ACCESSOxidation behavior at high temperatures of the stainless steel( SUS304L ) powder compacts produced by MG (mechanical grinding) process and then hot pressing were studied. The results obtained are as follows;
(1)The compact with MG treatment developes fine grain structure, and shows improved oxidation resistance.
(2)The oxide film without MG treatment is composed of two layers ;the inner layer is spinel with the composition of Fe(FeCr)2O4 and the outer layer Fe3O4. On the other hand, the oxide film with MG treatment is composed of a thin but fine layer contained chromium oxide layer.
(3)The rapid diffusion of chromium to the surface along many grain boundaries produced by MG treatment results in the formation of the fine chromium oxide at early oxidation and then improved oxidation resistance.View full abstractDownload PDF (4795K) -
Toshimasa Morooka, Eiji Yuasa, Haruhiko Nishida1994 Volume 41 Issue 8 Pages 1023-1026
Published: August 15, 1994
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSIn this study, the sintered structures of Cu-0.7mass%Cr alloy powders prepared by mechanical alloying, grinding and filing of castings were compared. These powders were compacted and then sintered in an electrical vacuum furnace at 873 - 1273K for various times. When the sintering was conducted on mechanically alloyed powder or mechanically ground powder, Cu-rich phase was formed along the interface of grains. But this phase could not be observed in the sintered filed powder.View full abstractDownload PDF (2945K)
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