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Volume 43, Issue 5
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[in Japanese]1996 Volume 43 Issue 5 Pages 566
Published: May 15, 1996
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSDownload PDF (77K) -
Kenji Sumiyama1996 Volume 43 Issue 5 Pages 567-572
Published: May 15, 1996
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSWith decreasing a material size, its characteristic properties may diminish at around a nanometric scale. Since nanometric clusters and particles have such crucial sizes, so called an unit of functional element, they will reveal a basic perspective in solid state physics and a new concept for material designing. There are two ways to obtain nanometric size materials: crushing bulk materials and building up from atoms and molecules. In this review, we describe the characteristic features of nano-scale fine Ni particles produced by mechanical milling and chemical leaching, (crushing), and Fe/Ag nano-granular films by using a cluster beam source, (building up). (1) Nonequilibrium bcc and amorphous phases have been realized in Ni particles, being paramagnetic at low temperatures. (2) Fe/Ag granular films have been obtained by direct dispersion of Fe clusters in Ag matrices. They reveal a giant magnetoresistance effect without any heat treatment. The nanometric heterogeneity has been detected by small angle X-ray scattering measurements and distorted Fe clusters in Ag matrices by extended X-ray absorption fine structure measurements.View full abstractDownload PDF (386K) -
Isamu Yamauchi, Makoto Ohmori, Itsuo Ohnaka1996 Volume 43 Issue 5 Pages 573-578
Published: May 15, 1996
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSA combination process of the rapid solidification and the chemical leaching processing was applied to get metastable nanocrystalline materials of Co-Cu. The structure and magnetic properties of the as-solidified and the leached alloys were examined by the X-ray diffraction, differential scanning calorimetry, scanning electron microscopy, transmission electron microscopy and magnetization measurements. The rapid solidification of various Al75CoxCu25-x (x=0-25at%) alloys was quite effective to get supersaturated powders. The structure of the powders by the leaching of aluminum atoms in sodium hydroxide solution was drastically changed to a fcc phase with broad X-ray diffraction patterns. Very fine particles were observed by the transmission electron microscopy. The larger particles more than 40nm were facetted. The heat treatment of the leached specimen at 1073K for 1800s changed the structure to two fcc with sharp X-ray diffraction patterns corresponding to those of Co and Cu. The saturated magnetization of the leached specimen increased by the heating and its magnitude was larger in the specimens prepared by this combination process than that of the binary mechanically alloyed or rapidly solidified specimens.View full abstractDownload PDF (4592K) -
M. Sherif El-Eskandarany, Toyohiko J. Konno, Kenji Sumiyama, Kenji Suz ...1996 Volume 43 Issue 5 Pages 579-583
Published: May 15, 1996
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSMechanical alloying via high energy ball-mill operated at room temperature has been used for preparing TiC and SiC compounds, starting from elemental Ti, Si and graphite powders. X-ray diffraction, transmission electron microscope, scanning electron microscope and infrared absorption have been used to follow the progress of the mechanical reactions between the reactant materials of Ti-C and Si-C, binary systems. A complete single phase of NaCl-type structure of Ti44C56, compound is yielded after 20 ks of milling. The lattice parameter (a0) of this compound was calculated to be 0.4326 nm. This end-product of Ti44C56 consists of fine grains of about 5 nm in diameter and possesses homogeneous powders with an average particle diameter of less than 0.5 μm in diameter. In Si-C binary system, a complete stoichiometric β-SiC phase was obtained after 1080 ks of milling. The a0 for final-product of β-SiC powders was calculated to 0.4357 nm. The existence of transverse optical (TO) and longitudinal optical (LO)-like phonon modes for β-SiC compound are observed. The internal structure of the particles are marked by fine cell-like features of about 6 nm.View full abstractDownload PDF (5768K) -
Yuuji Kimura, Setsuo Takaki, Hideto Goto1996 Volume 43 Issue 5 Pages 584-589
Published: May 15, 1996
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSFe-C system hard alloys were produced from mechanically alloyed powders and their properties were examined by means of hardness testing and microstructural examinations. Mixtures of iron and graphite powders (Fe-2-6mass%C) were mechanically alloyed with vibration-ball-mill in Ar atmosphere. MA powders obtained were packed in stainless steel tubes and then sealed in vacuum after degassing at 873K. The stainless steel tubes were hot-rolled in the temperature range of 923K-1273K to consolidate MA powders. Bulk materials were subjected to isothermal annealing at 1273K, followed by water quenching. After the ball-milling of 360ks, extremely large deformation energy was stored within powder particles. This leads to the formation of ultra-fine α-Fe grain and very fine dispersion of graphite. On heating to a consolidation temperature, the reaction forming Fe3C takes place at around 600K. MA powders were completely densified to full density by hot-rolling at 1123K where the structure is of (Fe3C+γFe) two-phase, and this consolidation process does not accompany significiant coarsening of the microstructure. In a case of an Fe-6mass%C MA bulk material, the structure at room temperature is composed of 80vol% Fe3C and 20vol%α-Fe, so that hardness of a bulk material reaches to Hv900. But, Fe3C is not so stable at elavated temperatures that it easily decomposes to Fe and graphite after long annealing.View full abstractDownload PDF (3325K) -
Keizo Kobayashi, Kimihiro Ozaki, Teruo Haibara1996 Volume 43 Issue 5 Pages 590-594
Published: May 15, 1996
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSFe-x at%Ti (x=20, 30, 40, 50, 60, 70, 80) were synthesized by mechanical alloying(MA) of Fe powder and Ti powder using a vibrational ball milling for 720ks in 35kPa argon gas atmosphere. The hardness of the MA powders containning from 30at%Ti to 70at%Ti are about 700Hv. The MA powder of Fe-60at%Ti is in the amorphous state in this experimental condition. This amorphous powder was subjected to stress relief at about 627K and was crystallized at 800K. The crystalline phases were FeTi, Fe and Ti. The addition of B to Fe-60at%Ti in MA process promoted to form the amorphous phase.View full abstractDownload PDF (291K) -
Hyun-Goo Kim, Kenji Sumiyama, Kenji Suzuki1996 Volume 43 Issue 5 Pages 595-601
Published: May 15, 1996
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSAmorphous and nanocrystalline powders of TixCu90-xNi10 (x=20, 30, 40, 50 and 60 at.%) have been synthesized by the mechanical alloying method under argon atmosphere. The mechanically alloyed powders show halo patterns in the X-ray diffraction patterns for 30 ?? × ?? 60 and disordered fcc structures, with nanocrystalline grains for x=20. In the amorphous powders, the peak position of 2θ shifts to the low angle side almost linearly with increasing x. In particular, the amorphous phase is earlier formed with increasing x from 20 to 50. In the differential scanning calorimetry experiment, crystallization temperature and peak temperature increase linearly for 30 ?? ×<60. The average particle size estimated by scanning electron microscopy is about 11 gm for 30 ?? × ?? 60.View full abstractDownload PDF (4114K) -
Tatsuhiko Aizawa, Junji Kihara, Osamu Kobayashi1996 Volume 43 Issue 5 Pages 602-607
Published: May 15, 1996
Released on J-STAGE: December 04, 2009
JOURNAL OPEN ACCESSNeither conventional melting/solidification and powder metallurgy nor mechanical alloying by ball-milling mechanical alloying processes are suitable to fabrication of bulk alloy metarials with significant differences in melting temperature and density of mass; hence, microgravity alloying is selected and used to yield bulk solids in Bi-Al and Pb-Al systems. In the present paper, superiority to our developed high speed mechanical alloying for these material systems is theoretically discussed by using the Navie-Stokes equations. Both Bi-Al and Pb-Al systems are employed to demonstrate experimentally that homogenization and refining should take place with the number of cycles in the present mechanical alloying.View full abstractDownload PDF (2829K) -
Hiroshi Nagai, Ken-ichi Nagai, Shigeru Katsuyama, Kazuhiko Majima1996 Volume 43 Issue 5 Pages 608-612
Published: May 15, 1996
Released on J-STAGE: December 04, 2009
JOURNAL OPEN ACCESSThermoelectric properties of β-FeSi2 with SiC dispersion prepared by mechanical alloying were investigated. The FeSi2 alloys doped with Mn or Co (p-type Fe0.92Mn0.08Si2, n-type Fe0.98Co0.02Si2) were prepared by arcmelting in Ar. Mixtures of these FeSi2 alloys with Si+C powders were mechanically alloyed for 72ks, and hot pressed at 1173K for 3.6ks under 25MPa. XRD showed that β-FeSi2 and SiC were formed during hot pressing Si+C addition had little influence on the thermoelectric power of β-FeSi2. On the other hand, the resistivity increased with increasing Si+C addition. The thermal conductivity drastically decreased by about 30% with increasing Si+C addition in all temperature range. This is considered to be due to the SiC dispersion in β-FeSi2. SiC phase restrained the growth of β-FeSi2 phase and phonons scattering at grain boundaries increased, therefore thermal conductivity decreased. SEM photographs showed that 10-20μ m SiC particles dispersed in the β-phase. The figure of merit, Z=α2/(ρ⋅k), where α : thermoelectric power, ρ : resistivity, K : thermal conductivity, of Fe0.92Mn0.08Si2 added 5wt.% Si+C is higher than that of Fe0.92Mn0.08Si2 without Si+C addition. As a result, it is effective to add Si+C to p-type Fe0.92Mn0.08Si2.View full abstractDownload PDF (1512K) -
Akinori Kojima, Takao Mizushima, Akihiro Makino, Akihisa Inoue, Tsuyos ...1996 Volume 43 Issue 5 Pages 613-618
Published: May 15, 1996
Released on J-STAGE: July 12, 2010
JOURNAL OPEN ACCESSNanocrystalline bulk Fe90Zr7B3 alloys with grain sizes of 20 to 30 nm were prepared by spark-plasma sintering of amorphous powders and subsequent annealing. The bulk alloys sintered at the temperature (Ts) between 673 and 723 K are composed of a mostly single amorphous phase and the alloy sintered at Ts of 873 K is composed of a mostly single bcc-Fe phase in as-sintered state. The former alloys show better soft magnetic properties in spite of porous consolidated state than the latter alloy after annealing at 923 K. For the bulk alloy sintered at Ts of 723 K, the effective permeability (μe) increases by accelerating the heating rate (α) in sintering and the density becomes higher by increasing the sintering pressure (Ps). The nanocrystalline alloy sintered at Ts of 723 K, Ps of 780 MPa and α of 1.7 K/s shows the maximum permeability of 29800, effective permeability of 3430 at 100 Hz and coercivity of 12 A/m with a relative density of 97 %.View full abstractDownload PDF (3062K) -
Mikio Ito, Kazuhiko Majima, Shigeru Katsuyama, Hiroshi Nagai1996 Volume 43 Issue 5 Pages 619-623
Published: May 15, 1996
Released on J-STAGE: December 04, 2009
JOURNAL OPEN ACCESSThe preparation of Sm2Fe17Nx permanent magnet powders was tried by mechanical grinding (MG) and the subsequent nitriding without crystallization heat treatment which was usually needed to obtain Th2Zn17 structure in the conventional method by MG or mechanical alloying (MA). MG was carried out in NH3 gas with a rotary ball mill. The powder after MG for 324ks (90hr) had the sufficient nitrogen content of about 35000ppm. The magnetic properties of this powder, however, was insufficient because of the influence of distortion introduced during MG. In order to decrease the distortion, powders were prepared by MG for short time of 18ks-72ks (5hr-20hr). Although these powders contained an insufficient nitrogen of around 10000ppm, nitriding at 723K for 21.6ks in N2 raised nitrogen content up to 35000ppm. The powder after MG for 18ks and the subsequent nitriding showed the good rectangularity in the demagnetization curve. From this curve, the saturation magnetization and the remanence were confirmed to be about 1.23Wb⋅m-2 and 1.06Wb⋅m-2, respectively.View full abstractDownload PDF (328K) -
Kazuhiko Majima, Mikio Ito, Katsuhiro Matsukado, Shigeru Katsuyama, Hi ...1996 Volume 43 Issue 5 Pages 624-628
Published: May 15, 1996
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSUsing two kinds of Sm2(Fe, Mn)17 powders whose grain sizes are 32-74 μm and 74-100 μm, the nitriding behaviour of Sm2(Fe, Mn)17 in a mixed-gas atmosphere of ( NH3+H2) and their magnetic properties have been investigated . Sm2(Fe, Mn)17Nxspecimens with 0<X<6 were fabricated in both of the above mentioned two cases . Though the coercivity increased with increasing X, the saturation of magnetization tended to decrease with increasing X in both of two specimens . The (BH)max was highest at X=4.8 in case of the specimen using 32-74 μm powder, and at X=4.3 in case of the specimen using 74-100 μm powder ; the value of (BH)max was 85.20kJ/m3 in the former and 63.05kJ/m3 in the latter. The magnetic anisotropy was also recognized in both of the two specimens. These magnetic properties were confirmed to be related to the grain refinement observed during nitriding process.View full abstractDownload PDF (1330K) -
Kazuhiko Majima, Mikio Ito, Takashi Umemoto, Shigeru Katsuyama, Hirosh ...1996 Volume 43 Issue 5 Pages 629-633
Published: May 15, 1996
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSThe preparation of (Sm-Co)+Fe nanocomposite magnetic powder has been tried by mechanical alloying (MA) and subsequent heat treatment. The powder annealed at comparatively low temperature.in vacuum after MA was composed of fine grains whose size was 10-30nm in diameter and showed superior magnetic properties. When the annealing temperature was raised to 1073K, most of a -Fe was consumed for the growth of 2-17 phase. This consumption of a-Fe and the growth of 2-17 phase resulted in the decrease of the remanence and coercivity. The powder to which Fe was not added showed low remanence, and its maximum energy product was as low as 38.7kJ/m3. On the other hand, remanence enhancement was found in the powder to which Fe was added, and the remanence increased with increasing Fe concentration. Though the shape of demagnetization curve varied with Fe concentration, the maximum energy product of about 100kJ/m3 was obtained for both high and low Fe. concentration samples. Such superior magnetic properties seemed to be the result of exchange interactions between hard phase and soft phase.View full abstractDownload PDF (1442K) -
Krishnamurthy Raviprasad, Satoru Kakoo, Ken Makita, Minoru Umemoto1996 Volume 43 Issue 5 Pages 634-639
Published: May 15, 1996
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSThe possibility of producing isotropic permanent magnets with enhanced energy product has drawn lot of attention recently. The synthesis of two phase (hard and soft) nanocrystalline exchange coupled magnets by many research groups using different techniques and the various combination of two phases is an indication to the level of research interest in this area. The nitrogenated or carburized rare earth compounds with 2:17 or 1:12 structure as the hard phase was the focal point of many groups. However, the choice of Nd2Fe14B as the hard phase with the attractive advantages of single stage heat treatment, no drawbacks of incomplete nitrogenation or carburization and the possibility of higher sintering temperature has tilted the scale in its favor. The present article reports on the results of the synthesis of exchange spring magnets of Nd2Fe14B and α-Fe and their magnetic properties by mechanically alloying the powder mixture of Nd2Fe14B and iron. The magnets exhibit a spring back greater than 80% and a maximum energy product of 45 kJ/m3. The observed large spring back is an indication of the good coupling between the hard and the soft phases. The low energy product is attributed to the low coercivity of the starting Nd2Fe14B powder and requires further improvement.View full abstractDownload PDF (324K) -
Hiroyuki Takemata, Tadao Iwadate, Hajime Kuromasa, Yasuhiko Tanaka1996 Volume 43 Issue 5 Pages 643-648
Published: May 15, 1996
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSFracture toughness behavior of W-Ni-Fe sintered alloys with three strength levels was investigated. With increasing tensile strength, dynamic fracture toughness Kld decreases dramatically, especially in the upper shelf. In low strength material, cracks propagate by the coalescence of boids created in binder, whereas in high strength material, cleavage fractures of W particles precede the void formation of binder. Fracture toughness Kmax significantly depends on specimen size. The Kmax increases with increasing specimen size, which is caused by larger amount of stable crack extension in larger specimens. No effect of loading rate on Kmax was observed.
Relationship between the Charpy absorbed energy and dynamic fracture toughness was also investigated.View full abstractDownload PDF (2947K) -
Manwar Hussain, Atsushi Nakahira, Shigehiro Nishijima, Koichi Niihara1996 Volume 43 Issue 5 Pages 649-655
Published: May 15, 1996
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSPhase morphology and its effects on mechanical properties have been investigated for ternary composites in tetrafunctional epoxy resin-poly(ethersulphone) thermoplastics blends and A12O3 inorganic filler systems. Different microstructures were found to be occurred as the concentration of the thermoplastic component and the inorganic filler was varied. Young's modulus measurement, glass temperature analysis and SEM observation clearly showed the existence of phase separation in the blends depending on the concentration of Al2O3 filler and poly(ethersulphone) content. This different microstructure was discussed in terms of thermodynamics parameter. And, the relationship between the microstructure and mechanical properties was explored. The results suggested that the control of microstructure leads to improved mechanical properties of epoxy composites for high performance applications.View full abstractDownload PDF (4115K) -
Hiroyuki Jinushi, Hideki Kyogoku, Kazumitsu Shinohara, Yoshihiro Takey ...1996 Volume 43 Issue 5 Pages 656-662
Published: May 15, 1996
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSOn Fe-4mass%Ni alloy compacts shaped by metal injection molding, the relationship between the C and O contents of debound compacts and those of sintered compacts was examined by introducing a parameter, ΔCd≡Cd-aOd, which represents the stoichiometric ratio of C and O contents(Cd and Od, respectively) of the debound wmpacts. Specimens were made of carbonyl Fe(reduced grade; 5.0μm, 0.05mass%C, 0.2mass%O)and carbonyl Ni(2.0μm)and additional C powder. The amount of additional C powder was 0 to O.8g per 100g of Fe-4mass%Ni mixed powder. The specimens were debound in air at temperatures ranging from 503 to 553K for 7.2ks, and were sintered in a reduced pressure of 1Pa at 1523K for 7.2ks. The obtained results were as follows. The reaction MxO+C→xM+CO(M=Fe, Ni)was dominant for reducing metal oxides during sintering process. In the case of ΔCd>-0.2, the relative densities of sintered compacts were about 95%, regardless of the amount of additonal carbon. Theadditional carbon did not improve the densification of sintered compacts.View full abstractDownload PDF (2164K) -
Tatsuro Isomoto, Hiroshi Nagai1996 Volume 43 Issue 5 Pages 663-668
Published: May 15, 1996
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSEffects of hot working on elevated temperature tensile and creep rupture properties at 1000°C were investigated in powder metallurgy(PM) Ni-base alloy, Alloy X, with 50 ppm oxygen content consolidated by hot extrusion process in comparison with cast and wrought materials. It was found that the ductility of PM material at temperatures above 850°C was improved by the application of hot forging while the tensile strength was relatively unchanged. Furthermore, it was found that creep rupture properties of PM materials were not significantly affected by extrusion ratio ranging from 6 to 25, but improved by hot forging. Although aluminum oxides originating from powder surface oxidation during atomization aligned along grain boundaries in the extruded material, these oxides were redistributed within grains by nonuniform deformation of hot forging. It was considered that the improvement of creep rupture properties was realized by a decrease in cavity formation initiated at oxides at grain boundaries.View full abstractDownload PDF (6903K) -
Fuxing Yin, Tadakazu Matsunaga, Nobuya Machida, Toshihiko Shigematsu, ...1996 Volume 43 Issue 5 Pages 669-674
Published: May 15, 1996
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSThe deformation of Heusler alloys during ball milling resulted in a drastic decrease in the crystallite size to a nanometer level. Nanocrystalline Heusler alloys with a disordered bcc structure were obtained by mechanical milling. This was accompanied by the disappearance of ferromagnetism. These nanocrystalline states were stable up to 523 K and ferromagnetism appeared after annealing at around 413 K. The nanocrystalline state with a L21 type structure was obtained by annealing at around 473 K. The nanocrystalline state lost stability and recrystallized with a D03 type structure when annealed at 573 K. The ferromagnetism almost disappeared in the powders after annealing at 573 K. In the recrystallized state, an increase in magnetization was observed with increasing annealing temperature. This came from the increase in the long range order parameter for the L21 type structure at room temperature.View full abstractDownload PDF (317K) -
Magnetic Properties of Nd-Fe-B Magnets Sintered Using Granulated Powders by Spray Drying Method (II)Osamu Yamashita, Yoshihisa Kishimoto1996 Volume 43 Issue 5 Pages 675-681
Published: May 15, 1996
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSNd-Fe-B alloy powder was granulated by spray drying method using methylcellulose (MC) binder in the range from 0.1 to 0.5wt%, in order to improve the powder flowability during feeding and compacting. After adding MC binder, glycerin and pure water to alloy powder, the slurry was stirred at 278K in N2 atmosphere to suppress the oxidation of alloy powder. The granulated powders with MC binder exhibited higher flowability than granulated powders with polyvinylalcohol(PVA) binder. By heating in H2 at 673K after compacting in a magnet field, 96% of carbon in binder was removed, although the oxygen in binder remained unremoved. With the compacted body added 0.20wt% MC, these treatments can allow to suppress the residual contents of oxygen and carbon in the resulted sintered magnets within less than 8500ppm and 600ppm, respectively. The coercive force(iHc) and maximum energy product (BH) max for a sintered anisotropic magnet prepared by the above mentioned process are 0.96(MA/m) and 241.1 (kJ/m3), respectively, in which (BH)max is lower by 15% than that obtained by using PVA binder.View full abstractDownload PDF (1672K) -
1996 Volume 43 Issue 5 Pages 683
Published: 1996
Released on J-STAGE: May 22, 2009
JOURNAL OPEN ACCESSDownload PDF (19K)
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