巻号一覧
73 巻, 1 号
選択された号の論文の11件中1～11を表示しています
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伊藤 孝至, 門井 崇, 金武 直幸2009 年 73 巻 1 号 p. 1-6
発行日: 2009年
公開日: 2009/01/01
ジャーナル フリーBismuth antimony telluride has the best performance among the p-type thermoelectric materials used in the range of temperature between 300 K and 500 K. This material has a trigonal-hexagonal scalenohedral crystal structure and the cleavage parallel to the basal plane of the crystal can readily occur. Suppression of the electrical resistivity and the thermal conductivity will be effective for further improvement of the performance of the thermoelectric elements made from this material. The compressive torsion forming is a severe plastic deformation technique, in which loads of compression and distortion are simultaneously subjected to the materials without change in its shape. In this work, we applied this technique to the powder of bismuth antimony telluride for consolidation and improvement of the thermoelectric performance by refining the grain structure and by controlling the crystal orientation. The samples consolidated under various forming conditions were investigated with respect to density, microstructure, XRD, texture, and thermoelectric properties. It was found out that the compressive torsion forming is effective for the microstructure control, the grain structure less than 10 μm can be obtained, and the thermoelectric performance is obviously improved by the compressive torsion forming.
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丸山 典夫, 三部 真智, 片田 康行, 金澤 健二2009 年 73 巻 1 号 p. 7-14
発行日: 2009年
公開日: 2009/01/01
ジャーナル フリーTwo kinds of high nitrogen-containing Ni-free austenitic stainless steels for medical applications were used for evaluation of fatigue behavior. One was a Fe-23%Cr-2%Mo-1%N stainless steel heat-treated in a N2 gas atmosphere (NA) and the other was a Fe 23%Cr-1%Mo-1%N stainless steel fabricated with an electro-slag remelting method in a pressurized N2 gas atmosphere (P-ESR). Fatigue tests were carried out both in air and in the phosphate-buffered saline solution, PBS (−). Cyclic stress with a sine waveform was applied to the specimen in a tension-to-tension mode with a stress ratio of 0.1 at a frequency of 20 Hz in air and 2 Hz in PBS (−). During testing, the saline solution was kept at 310 K and at the pH of 7.5. A nitrogen-4% oxygen gas mixture was bubbled into the PBS (−).
The results obtained are as follows. There was no difference between S-N (stress-number of cycles to failure) curves in air and in PBS (−) for each stainless steel. The fatigue strength at 107 cycles for NA was 245 MPa. No difference was found in the fatigue strength between the NA specimens heat- treated for 259.2 ks and 129.6 ks. The fatigue strength at 107 cycles for P-ESR was 320 MPa. The fatigue life at various stress amplitudes depended on preparation of the test specimens for P-ESR. The fatigue life was decreased by the plastic deformation layer and/or cracks on the specimen surface caused by machining and increased by elimination of the deformation layer and/or cracks. The fracture surface exhibited a cleavage-like appearance at the fatigue crack initiation site for both the stainless steels.
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長谷川 信一2009 年 73 巻 1 号 p. 15-18
発行日: 2009年
公開日: 2009/01/01
ジャーナル フリーTo establish a rapid trace-quantification scheme for elements contained in highly purified tungsten, we studied the most suitable conditions for separating the elements using solid-phase-extraction as a pretreatment for inductively coupled plasma-mass spectrometry (ICP-MS). We used chemically bonded silica gels belonging to the functional group of benzylsulfonic acid as extracting agent. Tungsten was anionized by adding hydrogen peroxide solution to a sample that had been decomposed with acid. We separated the cation trace impurities that were present in the chemically bonded silica gel of the ion-exchange type. The target elements retained in the chemicals were then eluted using 10 cm3 of 2 kmol/m3 nitric acid. Quantities of the obtained target elements were determined using ICP-MS.
Highly sensitive quantification was established for 15 trace elements in highly purified tungsten, and for Be, Al, Mg, Mn, Fe, Co, Ni, Cu, Zn, Ga, Cd, In, Tl, Pb, and Bi with the following detection limits [3σ; ng/g (ppb)]: Be 0.11, Al 0.14, Mg 0.12, Mn 0.15, Fe 1.81, Co 0.086, Ni 0.082, Cu 0.092, Zn 0.12, Ga 0.074, Cd 0.012, In 0.069, Tl 0.082, Pb 0.071, and Bi 0.036.
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橋本 等, 孫 正明2009 年 73 巻 1 号 p. 19-25
発行日: 2009年
公開日: 2009/01/01
ジャーナル フリーTiC-Ti3SiC2 composites having the microstructure of fine Ti3SiC2 grains dispersed in TiC matrix were synthesized by two processes, that is, mechanical alloying of a powder blend of Ti, Si and C followed by hot-pressing (MA-HP process) and hot-pressing of a powder blend of Ti, Si and TiC (MIX-HP process). The microstructure, damage tolerance and 4-point flexural strength of the composites were investigated. It was found that more uniform dispersion of Ti3SiC2 grains in TiC matrix was achieved by MA-HP process than by MIX-HP process, while the flexural strength of the composites synthesized by MA-HP process was lower than that by MIX-HP process, which may be attributed to micropores formed in the composites synthesized by MA-HP process. Preferential orientation of Ti3SiC2(001) and TiC(111) occurred in the composites synthesized by MA-HP process. We proposed two mechanisms of the preferential orientation. We also found that the dispersion of Ti3SiC2 in TiC matrix is effective in improving the damage tolerance of the brittle TiC, evidenced by the fact that no cracks emanated from the corners of Vickers indentations at a load of 9.8N.
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澤田 俊之, 柳谷 彰彦2009 年 73 巻 1 号 p. 26-32
発行日: 2009年
公開日: 2009/01/01
ジャーナル フリーShot peening is a surface treatment effective to obtain compressive residual stress on shot peened surface and to improve fatigue strength, and it is applied to automobile parts such as springs and gears. Based on recent trend for further reduction of automobile parts weight, high hardness of automobile parts will be required more and more through various treatments such as carburizing.
In this study to develop gas atomized powder for shot peening with high hardness, high density, high ductility and relatively low cost, Fe-8Cr-6.5B alloy was made by gas atomizing and its various properties were examined. The resultant Vickers hardness was 1260HV, density was 7.4Mg/m3, and no crack initiated near indentation by 1000 g load. No rust was observed in the condition of 343 K-95%RH-96h. Various properties of gas carburized JIS SCM420 with shot peening by developed Fe-8Cr-6.5B powder were compared to that with shot peening by high speed steel powder. JIS SCM420 with Fe-8Cr-6.5B powder shot peening showed higher compressive residual stress at the surface by 110 MPa, higher Vickers hardness (load=100 g) by 60HV and higher fatigue strength by about 100 MPa than that with high speed steel powder shot peening.
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有賀 康博, 尾崎 良一, 梶原 桂2009 年 73 巻 1 号 p. 33-39
発行日: 2009年
公開日: 2009/01/01
ジャーナル フリーIt is well known that low temperature anneal-hardening (LTAH) appears in highly alloyed copper such as a Cu-30 mass%Zn alloy. On the other hand, it has been said that the LTAH could not emerge in a dilute alloy even if with a greater reduction during cold rolling. Therefore, the effect of alloying concentrations of order 0.1 mass% on the LTAH behavior has been hardly discussed.
In this work, changes of material properties and microstructure in a Cu-0.12 mass%Fe-0.04 mass%P alloy during low temperature annealing after cold rolling up to 90% were investigated. The LTAH appeared under a limited combination of cold rolling and low temperature annealing conditions. In the surface region hardened by the LTAH, the dislocation density decreased by half whereas the volume fraction of Fe-P clusters quadrupled, compared with the condition before low temperature annealing. The estimated change in hardness due to the combination of dislocation hardening and elastic strain hardening is in reasonably good agreement with the experimental increase in Vickers hardness.
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三井 好古, 小山 佳一, 中森 裕子, 折茂 慎一, 渡辺 和雄2009 年 73 巻 1 号 p. 40-45
発行日: 2009年
公開日: 2009/01/01
ジャーナル フリーX-ray powder diffraction, magnetization measurements, and differential thermal analysis (DTA) of polycrystalline MnBi were carried out in zero magnetic field as will as in magnetic fields of up to 14 T and in the temperatures range of 300-773 K, in order to investigate magnetic phase transition. In zero magnetic field, a magnetic phase transition from ferromagnetic to paramagnetic state is exhibited at temperature (Tt) of 628 K, accompanied by decomposition. With increasing magnetic field up to 14 T, Tt increases linearly with the rate of 2 KT-1. A metamagnetic transition between the paramagnetic and field-induced ferromagnetic states was observed just above Tt. The exothermic and endothermic peaks were detected in the magnetic field dependence of DTA signals in the interval of 626-623 K, which relates to the metamagnetic transition. The obtained results are discussed on the basis of a mean field theory.
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岩田 圭祐, 西 義武2009 年 73 巻 1 号 p. 46-51
発行日: 2009年
公開日: 2009/01/01
ジャーナル フリーAn effect of electron beam (EB) irradiation on the fracture resistance of soda lime glass was studied. EB-irradiation with small dose less than 1 MGy and low potential less than 170 keV could not change the plastic deformation energy to propagate the crack (Efp), which was estimated by fracture toughness (KIC) using standard indentation fracture method. On the other hand, EB irradiation of less than 0.43 MGy increased the plastic deformation energy to generate the crack (Ef). If EB-irradiation annihilated the spontaneous crack origins, it could be explained the increasing Ef value. In addition, if EB-irradiation formed dangling bonds in glassy network structure, they probably relaxed the residual stress and should prevent the crack generation. As the result of electron spin resonance spectra showed, the EB irradiation generated dangling bonds in the soda lime glass and partial relaxation of the residual strain mainly occurred around these dangling bonds of the weakly bonded metal (Na and Mg)-oxygen pairs in the network structure. The increased crack generation energy was therefore mainly due to the relaxation of the strongly bonded metal-oxygen atomic pairs in the network structure, as well as the annihilation of crack origin.
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平 良夫, 岩田 圭祐, 西 義武2009 年 73 巻 1 号 p. 52-57
発行日: 2009年
公開日: 2009/01/01
ジャーナル フリーAn effect of dissolution treatment on the fracture resistance of transparent glass was studied. The plastic deformation energy to propagate the crack was estimated by fracture toughness using standard indentation fracture method with Vickers' hardness tester. Although the influence of dissolution on the plastic deformation energy to propagate crack was not observed, dissolution of less than 0.2×106 s increased the plastic deformation energy to generate the crack. The increased crack generation energy was mainly due to the stress relaxation on the tip of the crack origin, which was induced by dissolution.
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岡安 和人, 竹腰 弘毅, 榊原 将之, 福富 洋志2009 年 73 巻 1 号 p. 58-63
発行日: 2009年
公開日: 2009/01/01
ジャーナル フリーUniaxial compression tests are conducted on Al-5 mass%Mg and Al-10 mass%Mg alloys under various amounts of strain at 673 K and 723 K with a final strain rate of 5.0×10-4 s-1. The results of these two kinds of alloys are compared with the results on Al-3 mass%Mg alloy, in order to clarify the mechanism of texture change from {011} to {001} during high temperature compression deformation. High temperature yielding phenomena are observed at all deformation conditions. Texture examination elucidates that fiber textures are constructed in all the deformation conditions. {001} (compression plane) texture developed with an increase in strain. Increasing Mg concentration results in the earlier development of {001} texture. It is concluded that development of {001} texture is attributed to the orientation stability and low stored energy of {001} orientation during deformation.
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訂正
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小川 道治, 野田 俊治, 上田 正人, 池田 勝彦2009 年 73 巻 1 号 p. 64
発行日: 2009年
公開日: 2009/01/01
ジャーナル フリーPDF形式でダウンロード (245K)
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