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Volume 38, Issue 1
Displaying 1-27 of 27 articles from this issue
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[in Japanese]1991 Volume 38 Issue 1 Pages 2
Published: January 25, 1991
Released on J-STAGE: May 22, 2009
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Kazuo Akaoka, Nozomu Tamura, Koich Komamura, Koji Yano1991 Volume 38 Issue 1 Pages 3-5
Published: January 25, 1991
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSCalculation results using a gas diffusion model suggested that a reduction time of Cr-alloyed steel powder in vacuum annealing was in proportion to the 2nd power of the thickness of the packed powder. However, the reduction time actually required in a vacuum furnace was in proportion to the 1/8 power of the thickness. It was therefore concluded that the reduction time was influenced as well by the heat transfer in the packed powder and the atmospheric pressure in the furnace.View full abstractDownload PDF (211K) -
Tomio Satoh, Kunio Okimoto, Chul-Jin Choi, Won-Wook Park1991 Volume 38 Issue 1 Pages 6-9
Published: January 25, 1991
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSRapidly solidified Zn-22Al superplastic ribbon was produced by melt spinning process. The ribbon was pulverized and compacted in a closed-die, then subjected to forward extrusion under a condition at temperature of 250C. Tensile test of the extruded compact was carried out at 250C. Characteristics of the ribbon, the pulverized ribbon and the extruded compact were compared to those of rapidly solidified Zn-22Al superplastic powder and the extruded compact made by centrifugal atomization process already investigated.
The ribbon had a fine and homogeneous microstructure similar to that of the powder by the centrifugal atomization. It was estimated that cooling rate of the rapidly solidified ribbon was almost equal to that of the powder, namely, 105C/s. Elongation of the extruded compact made by the pulverized ribbon was inferior to that made by the powder because of existence of pores in the compact.View full abstractDownload PDF (4617K) -
Katsuhiro Nishiyama, Yuichi Yoshida, Masashi Mohri, Noburu Eguchi, Sok ...1991 Volume 38 Issue 1 Pages 10-13
Published: January 25, 1991
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSSinterability of NiAl powder with the composition of Ni-49.4at%Al prepared by a self-propagating high-temperature synthesis(SHS) method were examined in a hot-pressing process. The sintered compacts with density of 97-99% were obtained by a hot-pressing at 1200 to 1400°C for 0.5hr under a pressure of 60MPa in vacuum. The bending strength of sintered NiAl hot-pressed at 1200°C reaches a maximum value of 1080MPa. The room-temperature strength of NiAl is strongly dependent on grain sizes.View full abstractDownload PDF (3585K) -
Tokuhiko Nishida, Susumu Chida, Masao Yamamiya1991 Volume 38 Issue 1 Pages 14-17
Published: January 25, 1991
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSThe effect of addition of Tic powders on the sintering behavior, microstructure and mechanical properties of atomized low alloy steel powder compacts by liquid phase sintering using Fe-Ni-B master alloy powder has been studied. The rate of grain growth during liquid phase sintering in the specimen with no additive followed a time to the 1/3 power dependence. Small amount of TiC inhibited the grain growth without having been accompanied by a lower densification rate. A good combination of 1000 MPa in strength and 7 % in elongation was obtained in the liquid phase sintered compacts added 1 % TiC with fine upper bainite structure.View full abstractDownload PDF (4321K) -
Fatigue Stremgth of Sintered and Heat Treated Compacts made from Composite-type Alloyed Steel PowderOsamu Furuki, Koji Yano, Shigeaki Takajo1991 Volume 38 Issue 1 Pages 18-21
Published: January 25, 1991
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSCompacts made from a composite-type alloyed steel powder with 2% Ni and 1% Mo attained high endurance limits of rolling bending and contact fatigue strengths of 460MPa and 2560MPa, respectively, after case hardening. These endurance limits were much higher than those of a conventional 4%Ni-0.5%Mo-1.5%Cu alloyed steel powder, which were 410MPa and 2430MPa, respectively. When double pressed, double sintered and bright quenched, compacts made from the 2%Ni-1%Mo alloyed steel powder showed endurance limits of rotating bending strength of 390MPa and contact fatigue strength of 2710MPa, both higher than those of the compacts made from the conventional alloyed steel powder, which were 350MPa and 2330MPa, respectively.
The results of micro-X-ray analysis indicated the decrease in the amount of austenite phase near the fatigue-fractured surface, The improvement of fatigue strength was therefore attributed to the strain-induced martensitic transformation of Ni-rich austenite.View full abstractDownload PDF (2074K) -
Mitsuru Nakamura, Ko-ichi Kamada1991 Volume 38 Issue 1 Pages 22-26
Published: January 25, 1991
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSInfluence of the addition of boron and the sintering temperature on the mechanical properties, especially ductility and toughness, of P/M Austenite type stainless steels were investigated.
As a result, in order to obtain the high strength value, it was necessary to add 0.57-1.04wt.% boron to P/M steels. The tensile strength values of these specimens were 450MPa over. This reason was precipitation hardening behavior with many and fine borides without melting. In order to obtain the high ductility value, it was necessary to add 0.16-0.23wt.% boron to in P/M steels. The elongation values of these specimens were 30% over. This reason was high sintered density of austenitic matrix by the melting of minor borides. On the other hand, the high toughness value was independent of boron contents. It was necessary to obtain high sintered density of matrix because of the reduction of pore.View full abstractDownload PDF (5649K) -
Akira Fujiki, Ichirou Tanimoto, Akiyoshi Ishibashi, Kazutoshi Takemura1991 Volume 38 Issue 1 Pages 27-30
Published: January 25, 1991
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSPM steels containing Fe-Mo, Fe-Cr-Mo-Co powder hard particles have been used for engine valve seat inserts. Possibility on replacement of the Fe-Mo, Fe-Cr-Mo-Co powder particles with high speed steel powder particles of M3/2 and M42, were examined in order to improve properties of the above PM steels.
The results obtained were summarised as follows.
1)Addition of M3/2 and M42 powder particles is effective for strength up to 5wt%, however over 5wt% addition is harmful for strength.
2)PM steel contained M3/2 and M42 powder particles each 2wt% together showed best properties for wear.View full abstractDownload PDF (1856K) -
Kazutoshi Yamada, Hidenori Kohzuki, Yasuo Okuno1991 Volume 38 Issue 1 Pages 31-34
Published: January 25, 1991
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSThe effect of VC on mechanical properties of sintered high speed steel(PX16; equivalent for SKH51) made from water atomized powder has been studied. The mechanical properties such as transverse rupture strength and microvickers hardness have been measured and optical and electron microscopic observation have been carried out. The results obtained were summarized as follow;
1) Microvickers hardness of the composite increases with the increase of the mass fraction of VC.
2) Transverse rupture strength decreases with the increase of the mass fraction of VC.
3) In consequence of added VC, M6C type carbides were extinguished.
4) Carbide grain size in this alloy is growing with the increase of the mass fraction of VC.View full abstractDownload PDF (2473K) -
[in Japanese]1991 Volume 38 Issue 1 Pages 36
Published: January 25, 1991
Released on J-STAGE: May 22, 2009
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Hitoshi Hashimoto, Ryuzo Watanabe, Yong-Ho Park1991 Volume 38 Issue 1 Pages 37-41
Published: January 25, 1991
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSThe motion of each milling ball during vibratory ball milling of metal powders was simulated by a computer using one-. two- and three-dimensional models of a vibratory ball mill. In these models, the consumpton of impact energy of the balls by the micro-compaction of metal powder particles during impact was assumed to be equivalent to the energy loss by an imaginary viscosity given to the balls and mill container. As a result of the simulation by using the three models, it was found that the motion of the milling balls is strongly dependent on the ball charge fraction. With an increase in the ball charge, the impact frequency increased, while an average of impact velocity normal to each contact surface decreased.View full abstractDownload PDF (260K) -
Katsuhisa Yamauchi, Yong Ho Park, Hitoshi Hasimoto, Ryuzo Watanabe1991 Volume 38 Issue 1 Pages 42-46
Published: January 25, 1991
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSMechanical alloying process of Ti-Al powder mixtures during vibratory milling was investigated by optical microscopy, SEM, X-ray diffraction analysis, XMA and micro-hardness measurement.Microstructures and phases of HIPed compacts of the milled powders were also investigated. As a result it was found that the amorphization behavior and morphology of the powder particles during milling were strongly dependent on the milling ball size. The phases and the microstructures of the HIPed compacts were affected by the starting powder composition.View full abstractDownload PDF (5268K) -
Yoshiro Arami, Osamu Iwatsu1991 Volume 38 Issue 1 Pages 47-50
Published: January 25, 1991
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSOxide dispersion strengthened nickel powders containing fine Al2O3, ZrO2 or Y2O3 particles as the dispersoids were prepared by mechanical alloying of carbonyl nickel powders with Al-, Zr- or Y-alkoxide in the air atmosphere followed by heat-treatment in a hydrogen atmosphere at 600°C. The powders thus obtained were then consolidated by compacting and sintering at temperatures from 600°C to 1200°C in a hydrogen atmosphere. Results obtained were as follows:
1) The microstructure of each powder obtained was very fine, and the crystallite sizes of them were in the range of 35nm to 71nm.
2) Among these powders, only Ni-Al2O3 powder showed superior sinterability. The 0.2% -bending strength of the specimen obtained by sintering this powder at 1200°C was 870MPa, which was more than eight times as high as that of the specimen obtained by sintering pure nickel powder.
3) In the case of Ni-Al2O3 powder, sintering began to proceed rapidly in the temperature region where losing the coherency between matrix and Al2O3 particles were significant.View full abstractDownload PDF (4421K) -
Keizo Kobayashi, Takeshi Takayanagi, Hideaki Ohta, Itsuo Ohnaka1991 Volume 38 Issue 1 Pages 51-54
Published: January 25, 1991
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSMechanical alloying of Titanium, Molybdenum, Nickel and graphite powders was performed using a vibrational ball-mill. Mechanical alloying process of cermet powder was studied by X-ray diffraction, electron probe micro analysis (EPMA) and scanning electron microscopy.
Results from X-ray diffraction and EPMA suggested the synthesis of TiC was carried out for about 50 hours and the addition of Ni assisted this synthesis. The difference of mechanical alloying atmosphere had an effect on particle size of TiC after sintered. Mechanical alloyed Ti-C-20mass%Ni-10mass%Mo was able to sinter at low temperature and had a minute structure.View full abstractDownload PDF (4816K) -
Masahiro Anzai, Toru Sudo, Hiroshi Endo, Hisanori Otaki, Takeo Nakagaw ...1991 Volume 38 Issue 1 Pages 55-58
Published: January 25, 1991
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSMagnetic abrasive polishing process experimentally tried to finish the mold surface. Magnetic abrasives are playing a very important role in this process. SiC whisker-Fe magnetic abrasive was newly fabricated by Mechanical Alloying (MA) method. This study ails to investigate the fabrication process of the MA magnetic abrasives and its finishing properties. SiC whisker-Fe magnetic abrasive by MA was superior to SIC powder-Fe, NbC powder-Fe, dia. ond-Fe or Al2O3 powder-Fe magnetic abrasives in its gringability.
The as machined surface roughness value of 2.5, μm Rmax or 0.2μm Ra decreases to the finished value of 0.2μm Rmax or 0.06μm Ra respectively using 6.5 vol.% SIC whisker-Fe magnetic abrasive for 10hr of milling ti.e. Fabrication process of magnetic abrasive by MA will be hopeful for final finishing abrasives of magnetic polishing of mold surface. In order to obtain the higher efficiency magnetic abrasive, it is nesessary to investigate the influence of finishing conditions and other kinds of abrasives-Fe system magnetic abrasives in more detail.View full abstractDownload PDF (7287K) -
M. Sherif EL-ESKANDARANY, K. AOKI, K. SUZUKI1991 Volume 38 Issue 1 Pages 59-62
Published: January 25, 1991
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSA rod-milling technique has been investigated for producing Al30Ta70 amorphous alloy powders. To follow the amorphization reaction, the rod-milled powders were characterized by X-ray diffraction, differential thermal analysis, optical microscopy, scanning electron microscopy, electron probe microanalysis and chemical analysis. The results obtained by rod-milling were compared with those from a conventional ball-milling technique. The rod-milled Al30Ta70 amorphous alloy powders have high amorphization rate, high thermal stability and a low contamination content.View full abstractDownload PDF (3691K) -
Masaki Sakurai, Toshiharu Fukunaga, Kenji Sumiyama, Kenji Suzuki1991 Volume 38 Issue 1 Pages 63-66
Published: January 25, 1991
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSCrystalline BiFeO3 (perovskite) is easily amorphized at room temperature by ball milling. The amorphization of crystalline ZnFe2O4 (spinel) by ball milling is very difficult. Nearly half of Fe atom sites change from octahedral [FeO6] to tetrahedral [FeO4] in amorphous BiFeO3. Ball milled amorphous BiFeO3 is more relaxed than melt-quenched amorphous BiFeO3. Antiferromagnetism in the crystalline state is partially converted into a ferromagnetic-like state in ball milled amorphous BiFeO3-ZnFe2O4 under magnetic field.View full abstractDownload PDF (235K) -
Toshiharu Fukunaga, Masakatsu Misawa, Kenji Suzuki, Uichiro Mizutani1991 Volume 38 Issue 1 Pages 67-70
Published: January 25, 1991
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSThe starting powders of Ni24.3Ti75.7 composition were amorphized by mechanical alloying(MA). The concentration-concentration correlation function was directly observed by neutron diffraction, because the average coherent scattering length of the alloy powders is adjusted to be zero, i.e., <b>=0.
The negative peak at r=2.54 Å in the reduced radial concentration correlation function GCC(r) can be taken as evidence for the preferential formation of the Ni-Ti unlike atom pair, the distance of which is smaller than that calculated from the diameters of Ni and Ti atoms. The Warren chemical short range order parameter of the Ni24.3Ti75.7 amorphous alloy was evaluated to be a negative value of -0.097. These findings clearly demonstate the preferential existence of Ni-Ti unlike atom pairs at the nearest neighbor coordination in the Ni24.3Ti75.7 amorphous alloy synthesized by MA.View full abstractDownload PDF (224K) -
Mitsuhiro Mori, Toshiharu Fukunaga, Uichiro Mizutani, Masakatsu Misawa1991 Volume 38 Issue 1 Pages 71-74
Published: January 25, 1991
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSBCC solid solution of Cu30V70 composition powders was produced by mechanical alloying(MA), although the solubility limit of solute Cu atom has been reported to be about 2 at% in the equilibrium Cu-V phase diagram. The neutron diffraction measurements, by taking a full advantage of a negligibly small scattering length of the V atom, allowed us to directly observe the evolution of the BCC structure phase composed of Cu atoms at the expense of FCC pure Cu.
MA of Fe50V50 composition powders produced an α-Fe50V50 solid solution instead of the σ-phase present at room temperature in the equilibrium Fe-V phase diagram. The α-Fe50V50 solid solution is a stable phase at high temperatures above 1200°C. Mechanical grinding(MG) of σ-FeV compound powders was carried out. The σ-FeV phase which possesses a tetragonal structure with 30 atoms in a unit cell was also transformed into the α-Fe50V50 solid solution of BCC structure after 120 hours of MG.View full abstractDownload PDF (201K) -
Nobuo Asahi, Tetsushi Habu, Tetsuo Yoshii, Osami Haruyama1991 Volume 38 Issue 1 Pages 75-78
Published: January 25, 1991
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSPure crystalline powders of Ni and Zr were mechanically alloyed by high-ener-gy ball milling in an argon atmosphere and amorphous NixZr100-x alloy powders (X=75, 80, 85 and 90) were synthesized. The alloying and amorphization process was examined by X-ray diffractometry and differential scanning calorimetry.
The X-ray scattering vector, Kp, of the broad amorphous maximum for the mechanically alloyed Ni-Zr amorphous powders are identical with those of liquid quenched amorphous alloys of the same compositions, except for x=90. The crystallization temperature and the crystallization enthalpy of the Ni-Zr amorphous powders as a function of Ni composition are investigated.View full abstractDownload PDF (205K) -
Hiroyuki Oomoto, Liu Ookubo, Akihiro Tani, Tsuyoshi Arakawa1991 Volume 38 Issue 1 Pages 79-82
Published: January 25, 1991
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSCrystalline powders of Ni or Cu and L(IV group element) in the composition ratio Ni(Cu) : L = 1 : 2 were mechanically alloyed by a laboratory ball mill in an inert atmosphere. The progress of the mechanical alloying was identified by X-ray diffraction. The milling time for Ni-L system was longer than that for Cu-L system until a amorphous state could be attained. Moreover, crystallization behavior was measured by differential thermal analysis for the mechanically alloyed materials. The crystallization temperature rised on going from Ti to Hf.View full abstractDownload PDF (186K) -
Chung Hyo Lee, Kenji Sakurai, Toshiharu Fukunaga, Uichiro Mizutani1991 Volume 38 Issue 1 Pages 83-86
Published: January 25, 1991
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSAmorphous Cu30Ta70 powders were prepared by mechanically alloying pure crystalline copper and tantalum powders. We characterized the reaction products as a function of ball-milling time by X-ray diffraction, neutron diffraction, EXAFS, DSC and Low-Temperature specific heat measurements. The progress of alloying and amorphization with increasing ball-milling time was revealed in all of these observations, even though Cu-Ta system is characterized by a positive heat of mixing. These results were dicussed consistently in terms of thermodynamic considerations.View full abstractDownload PDF (202K) -
Toshimasa Morooka, Eiji Yuasa1991 Volume 38 Issue 1 Pages 87-90
Published: January 25, 1991
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSMixture of electrolytic copper and atomized zinc powders was mechanically alloyed for various periods of the milling by using an attritor ball mill. Changes of morphology and microstructure of the processed powder with the processing were studied. Content of zinc in the copper particle increases with the increasing of milling time. The zinc(η) phase disappears after the processing for a short period and ε or γ phases are formed at intermadiate stage of the processing. The Cu-30%Zn powder processed for 10hr reaches an equilibrational microstructure, but the alloying process in the Cu-40%Zn powder is late than that in the Cu-30%Zn powder. The mechanically alloyed powders for 5hr were extruded at various temperatures. Microstructure of the extrusions is constituted of an α phase in the Cu-30%Zn and α and 8 phases in the Cu-40%Zn which have fine grain size of about lμm in both extrusions.View full abstractDownload PDF (3459K) -
Wataru Nojiri, Hiromasa Imazato, Yosikazu Suzuki, Teruhisa Watanabe1991 Volume 38 Issue 1 Pages 91-94
Published: January 25, 1991
Released on J-STAGE: December 04, 2009
JOURNAL FREE ACCESSWe have recognized that A1-8wt%Fe P/M alloys made by mechanical alloying(MA) for 54ks had tensile Strength of 365MPa at 298K, 258Mpa at 523k. And Main reason is that very small Al-Fe intermetallic compound partickles are dispersed uniformally in the Alminum matrix, Therefore, we tried to clear on the formation process of Al-Fe intermetallic compounds in A1-8wt%Fe P/M alloys made by MA.
According to the XRD patterns of the dispersoids, the specimens of MA and non-annealed powder, MA and 673K annealed powder and MA, 673K annealed and 773K extruded alloy were deeply corroded by phenol at 433K in order to pick out from the aluminum matrix, the MA, non-annealed powder showed only Fe peaks, the MA, annealed powder showed some peaks like Al-Fe intermetallic compounds, and the MA, annealed and extruded alloy showed clearly A13Fe peaks.
On the other hand, according to DTA results of MA and non-annealed powder, two exothermic reactions were obserbed, the one appeared at about 5739, another appeared at about 673K.
From the results of shoves, on the production process of A1-8wt%Fe P/M alloys made by MA, only Fe particles were dispersed in the Aluminum matrix before heating treatments, and the time when the Fe particles began to change Al-Fe intermetallic compounds were in the heating treatment processes.View full abstractDownload PDF (3588K) -
Takeo Tanaka, Saburo Nasu, Susumu Imaoka, Keiichi N. Ishihara, P. Hide ...1991 Volume 38 Issue 1 Pages 95-98
Published: January 25, 1991
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSMechanical alloying (MA) and mechanical grinding (MG) for Fe-C and Fe-C-Si systems have been performed by the use of a conventional ball-mill. Elemental powders and cast iron powders have been used for MA and MG, respectively. Phases formed on the ball-milling process has been studied by X-ray diffractometry, 57Fe Mbssbauer spectroscopy, transmission electron microscopy, scanning electron microscopy and differential scanning calorimetry.
Results suggest that the partial amorphization of Fe-C system ball-milled for 200 hours has been occurred, while the single amorphous phase has been formed for Fe-C-Si system. The addition of silicon suppresses the formation of iron-carbides to promote the amorphization.View full abstractDownload PDF (4182K) -
H. Fukami, K.N. Ishihara, P.H. Shingu1991 Volume 38 Issue 1 Pages 99-102
Published: January 25, 1991
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSA Pseudo-HIP process has been applied for the synthesis and consolidation of intermetallic compounds of Ti and Al near the composition of stoichiometric TiAl. The Pseudo-HIP device used is furnished with an internal heating setting so that local heating around the specimen is possible. The pressure distribution inside the Pseudo-HIP chamber was measured when an uniaxial pressing was performed. Nearly hydrostatic condition was attained when the pressure was raised to about 2000kgf/cm2. Tensile strengths of synthesised TiAl compounds has been measured. Slightly Ti rich TiAl compound was found to show the maximum elongation as well as the maximum strength.View full abstractDownload PDF (1371K) -
1991 Volume 38 Issue 1 Pages 103
Published: 1991
Released on J-STAGE: May 22, 2009
JOURNAL FREE ACCESSDownload PDF (35K)
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