巻号一覧
63 巻, 9 号
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斎藤 英之, 長沼 裕朗, 三澤 俊平, 田村 卓也, 栗岩 貴寛, 亀川 厚則, 岡田 益男, 大西 俊之1999 年 63 巻 9 号 p. 1085-1088
発行日: 1999年
公開日: 2008/04/24
ジャーナル フリーTritium radioluminography and tritium autoradiography have been applied to V3.5(Zr, Ti, Ni) protium absorption alloy with a two-phase structure of BCC phase and Laves phase to examine the behavior of protium. By these methods, tritium distribution has been graphically displayed, and both the tritium and protium concentration on the surface of the alloy have been evaluated. The protium concentration in the BCC phase and Laves phase in this alloy has been determined to be 1.4 mol% and 2.3 mol% respectively. It has been found that the preferential path for the protium penetration into the alloy is not the BCC phase but the Laves phase.抄録全体を表示PDF形式でダウンロード (530K) -
中村 雄一, 立花 夏織, 吉田 剛志, 藤本 浩之1999 年 63 巻 9 号 p. 1089-1092
発行日: 1999年
公開日: 2008/04/24
ジャーナル フリーSilver addition to REBa2Cu3Ox(RE123:RE=Y, Sm, Nd,…) is thought to be effective to improve mechanical properties. However, such improvements were mainly reported in the case of sintered samples and few quantitative studies of the mechanical and superconducting properties on the melt grown samples with silver were reported. In this study, flexural strength and superconducting properties of melt grown Y123 sample with silver were measured to evaluate the effect of silver addition on the mechanical and superconducting properties. The average flexural strength increased as increasing the silver content. However, the minimum strength of the samples was almost the same irrespective of silver content. This means that the silver addition will decrease the defects in the melt grown samples to increase the average strength, but a few defects still remain and keep the minimum strength low. On the other hand, the relation between Jc and the magnetic field of the Y123 sample with silver addition showed a typical peak effect at 77 K.
Furthermore, Tc values of the sample with silver was about 0.8 K higher than that without silver. A reason for this difference of superconducting properties could be explained by the substitution of Ag with Cu in Y123 crystal. Since the substitution will cause the difference in a stable oxygen configuration in Y123, the suitable oxygen annealing condition will differ from with and without silver samples. This will cause the difference in Tc value under the same annealing condition.抄録全体を表示PDF形式でダウンロード (375K) -
平川 裕一, 川原 浩一, 吉田 冬樹, 中島 英治, 阿部 弘1999 年 63 巻 9 号 p. 1093-1096
発行日: 1999年
公開日: 2008/04/24
ジャーナル フリーUltra-high purity polycrystalline silicon was deformed by compression at temperatures from 1123 to 1643 K and at strain rates from 1×10−5 to 1×10−4 s−1, and the dislocation structures developed during high temperature deformation were also observed by transmission electron microscopy to obtain the fundamental knowledge on the high temperature deformation of polycrystalline silicon.
It was found that the flow stress for the polycrystalline silicon deformed at 1123 K and at a strain rate of 1×10−4 s−1 was much greater than that for the single crystalline silicon (FZ-Si) deformed under the same condition. The observed difference in the flow stress was considered to be attributed to the existence of stable and fine twin boundaries, which could operate as the barriers for dislocation motion. The steady-state deformation, where the flow stress was almost independent of strain, was observed at temperatures over 1473 K. The stress exponents, n, were found to be about 7 at 1473 K and about 5 at 1573 and 1643 K, respectively. The activation energy for deformation at temperatures, where the stress exponent was about 5, was in good agreement with that for the lattice self-diffusion in silicon. Therefore, it is concluded that the recovery controlling mechanism governed by the lattice diffusion is the rate controlling mechanism for the deformation of polycrystalline silicon at these temperatures.抄録全体を表示PDF形式でダウンロード (684K) -
吉田 昌二, 水嶋 隆夫, 牧野 彰宏, 井上 明久1999 年 63 巻 9 号 p. 1097-1100
発行日: 1999年
公開日: 2008/04/24
ジャーナル フリーStructure and soft magnetic properties for the bulk Fe70Al5Ga2P9.65C5.75B4.6Si3 glassy alloy prepared by pulse current sintering with uniaxial pressure were investigated. The sample consolidated in the temperature range of the supercooled liquid region consisted only of amorphous phase and had a very high relative density of 99%. The flux density at the applied magnetic field of 800 A/m, maximum permeability, coercive force and relative permeability at 1 kHz for the sample sintered at 703 K in as-made state are 1.1 T, 7600, 12 A/m and 1700 respectively. The soft magnetic properties of the sintered bulk Fe-based glassy alloy were much superior to the other magnetic materials of consolidated amorphous powders. It is concluded that the high relative density and good soft magnetic properties for the bulk Fe-based glassy alloy should depend upon its high structural homogeneity originated from its high deformability, that is based on the viscous flow arisen from the appearance of supercooled liquid region.抄録全体を表示PDF形式でダウンロード (412K) -
川上 裕二, 瀬戸 章文, 小澤 英一1999 年 63 巻 9 号 p. 1101-1104
発行日: 1999年
公開日: 2008/04/24
ジャーナル フリーTungsten ultra-fine particles were synthesized by the irradiation of two synchronized-pulse Nd: YAG lasers on a tungsten substrate in a low pressure inert gas atmosphere. Two types of lasers, which include the main laser (max. power: 10 J/pulse, wavelength: 1064 nm, pulse width: 0.2 ms) and the assist laser (max. power: 150 J/pulse, wavelength: 1064 nm, pulse width: 10 ms), were used to form the tungsten ultra-fine particles. Pulsed irradiation of the main laser was delayed 9 ms after the assist laser pulsed irradiation. In order to efficiently form ultra-fine particles, the laser irradiation conditions were a 10 J/pulse for the main laser power, and a 46.5-132 J/pulse for the assist laser. The ambient pressure was 1.3×103-6.7×104 Pa for the He gas atmosphere.
TEM observations shows that the primary particles are several nm in diameter under each condition. An agglomeration of the primary particles occurred under high pressure and high laser power conditions. It is concluded that the size distribution and shape of the generated ultra-fine particles can be controlled by the pressure and laser power conditions. As for the electron diffraction of the tungsten ultra-fine particles, both the crystalline and amorphous phases were observed under this condition. The size distribution was measured by a low pressure differential mobility analyzer (LP-DMA) for each condition. The peak of the size distribution was shifted from the several nm to the tens of nm level with increasing the high pressure and high laser power conditions.抄録全体を表示PDF形式でダウンロード (871K) -
川上 裕二, 佐々木 信也, 小澤 英一1999 年 63 巻 9 号 p. 1105-1108
発行日: 1999年
公開日: 2008/04/24
ジャーナル フリーW ultra-fine particles have been produced from W single crystal substrates using a Q-switch pulsed Nd: YAG laser and observed using a scanning electron microscopy (SEM) and atomic force microscopy (AFM). The laser irradiation was done in a low-pressure inert gas atmosphere. A new coherent array of W ultra-fine particles of about 500-800 nm are formed at and around a laser-irradiation marking. The coherent arrays are of the square type and rhombic type, and their directions are independent of the laser incident angle and polarization.抄録全体を表示PDF形式でダウンロード (889K) -
権 湧宰, 小橋 眞, 金武 直幸, 長 隆郎1999 年 63 巻 9 号 p. 1109-1112
発行日: 1999年
公開日: 2008/04/24
ジャーナル フリーBonding between a copper matrix composite and aluminum with the help of the heat of reaction was investigated. The copper matrix composite was synthesized by a combustion reaction between copper, titanium, and AlB12. The reaction between these elemental powders initiated at 1368 K, which was very close to the melting point of copper. As a result of the reaction, TiB2 particles were formed in Cu-Al alloy matrix. The defects (i.e. unbonded parts and/or cracks) at the interface between aluminum and copper matrix composites were reduced by increasing the mixture ratio of both titanium and AlB12 against copper. The formation of the defects at the interface was prevented by the insert of pure copper layer to the aluminum/Cu-composite interface.抄録全体を表示PDF形式でダウンロード (867K) -
岡 昭宏, 小山 敏, 和泉 輝郎, 塩原 融1999 年 63 巻 9 号 p. 1113-1116
発行日: 1999年
公開日: 2008/04/24
ジャーナル フリーA fabrication process of orthorhombic untwinned Nd123 single crystals was studied. In this study, in order to fabricate the complete untwinned single crystals, the Nd123 samples were cut from the as-grown tetragonal crystals into rectangular plates, of which the sides corresponded to {110} planes. Furthermore, the tetragonal cut samples were oxygenated under uni-axial compression in ⟨100⟩ direction from the corner of the samples. Almost twin-free orthorhombic Nd123 single crystals with dimensions of 2 mm × 2 mm × 0.5 mm, of which the sides of 2 mm × 0.5 mm corresponded to {110} planes, could be obtained by modifying the heat treatment conditions from the viewpoint of the uniformity of the oxygen contents in the samples during annealing. Here, the samples were oxygenated by cooling slowly from 973 to 573 K for 200 h with a shear strain of about 1.4×10−3 from the corner of the samples. The critical current density (Jc)-magnetic field (H) properties for the untwinned Nd123 single crystals were compared with those for the twinned Nd123 single crystals, which were fabricated by the same heat treatment condition as that for the untwinned single crystals without the uni-axial compression. The Jc-H curve with c\varparallelH at 77 K for the untwinned single crystals showed a much larger peak effect than that for the twinned single crystals. This result suggested that the wavelength of the Nd/Ba ratio fluctuation appearing in these crystals during annealing became shorter for the untwinned single crystals so that the number of pinning centers of the Nd-rich phases increased.抄録全体を表示PDF形式でダウンロード (552K) -
山室 佐益, 日原 岳彦, 隅山 兼治, 鈴木 謙爾1999 年 63 巻 9 号 p. 1117-1120
発行日: 1999年
公開日: 2008/04/24
ジャーナル フリーWe have deposited monodispersed Co clusters on substrates using a plasma-gas-condensation-type cluster deposition system. We have studied their two-dimensional assembling process by transmission electron microscopy, in situ electrical conductivity and magnetization measurements in terms of the percolation theory. The electrical conductivity measurement indicates that the critical thickness and conductivity critical exponent depend strongly on the cluster size. The soft-percolation model, which takes into account the wide distribution of connectivity between clusters, is a candidate model to explain this nonuniversality. The critical coverage of clusters (0.63) is much higher than the predicted one (0.45) irrespective of d, due mainly to the partial overlapping of deposited clusters, and partly to an attractive interaction between clusters. The magnetic properties evolve at around and/or below geometrical and electrical percolation thresholds for all the samples.抄録全体を表示PDF形式でダウンロード (446K) -
槇田 顕, 山下 治1999 年 63 巻 9 号 p. 1121-1124
発行日: 1999年
公開日: 2008/04/24
ジャーナル フリーFe-6.2%Si sintered body with an average grain size of 50 μm has been synthesized by a powder metallurgy method. Mixture of carbonyl iron powder and the jet-milled powder of Fe-50%Si alloy ingot was spray-dried using polyvinyl alcohol as a binder. Slabs with a thickness of 1 mm were obtained by sintering the green compacts at 1160°C for 5 h under vacuum. These slabs were successfully cold-rolled to sheets with a thickness of 0.1 mm at room temperature without being annealed. The X-ray pole figures of cold-rolled sheets with reduction rate more than 90% revealed (100)[011] texture, while the recrystallized texture after annealing at 1100°C was (111)[11\bar2]. The magnetic properties of stamped ring after annealing were μm: 10500, B8: 1.25 T, Br: 1.11 T, Hc: 30 A/m, respectively. The extreme ductility of 1 mm thick slabs may be due to both reduced grain size of the sintered body and the adequate balance between pressure stress and tensile stress during cold-rolling.抄録全体を表示PDF形式でダウンロード (362K) -
山口 洋1999 年 63 巻 9 号 p. 1125-1128
発行日: 1999年
公開日: 2008/04/24
ジャーナル フリーTo obtain a high strength copper alloy with ultra fine grain size, a brass with β′ precipitates was investigated. A Cu-37.3 mass%Zn brass was 95% cold rolled and annealed at 180°C to 300°C. It was confirmed by SEM, TEM, SAD, and X-ray analysis that the alloy was sub-micron grained (α+β′) dual-phase. The proof stress of this alloy was 400 to 500 MPa, and was higher than double of ordinarily annealed α brass. The relationship between proof stress and grain size of this alloy was on the extrapolated line of the Hall-Petch relation of α brass. A high strength due to ultra fine grain, 680 MPa in proof stress and 220 MPa in fatigue strength, was obtained by cold rolling and low temperature annealing after the recrystallization annealing. The Portevin-LeChatelier effect and increase of stress relaxation due to ultra fine grain sizes were observed.抄録全体を表示PDF形式でダウンロード (435K) -
笠原 和男, 橋本 健紀, 木村 隆, 山本 恭永1999 年 63 巻 9 号 p. 1129-1132
発行日: 1999年
公開日: 2008/04/24
ジャーナル フリーTo evaluate the effect of heat-treatment and vanadium addition on the microstructure and the room-temperature ductility of the L12-type (AlMn)3Ti titanium trialuminides alloy, the alloys with addition of vanadium up to 6 mol% were homogenized in a temperature range of 1450∼1530 K for a time less than 259.2 ks. The microstructure characterizations were performed by using the laser optical microscopy, scanning electron microscopy and X-ray diffraction. The residual strain which was induced during the milling of the L12 single-phase alloys into powder specimens was determined form X-ray diffraction peak profiles. All of the alloys exhibit a single-phase microstructure containing only the L12 phase, irrespective of the homogenization condition. These alloys also exhibit a small amount (0.1∼1.0% in area) of porosity which decreased with increasing vanadium content and the amount of porosity was independent of the homogenization temperature. A relatively large residual strain was obtained from the alloy with higher vanadium content, while the residual strain has shown a small change depending on the homogenization temperature. These results suggest that the effect of heat-treatment on microstructure and room-temperature ductility is not so remarkable as those of the change of alloy compositon.抄録全体を表示PDF形式でダウンロード (494K) -
野田 和彦, 西村 俊弥, 升田 博之, 小玉 俊明1999 年 63 巻 9 号 p. 1133-1136
発行日: 1999年
公開日: 2008/04/24
ジャーナル フリーCorrosion resistance of designed different low alloy steel was evaluated for the purpose of the development of low alloy steel to use in the ocean beach part by the ion selective permeability of the rust that it is formed on the steel. The rust layer was formed on the two kinds of low alloy steel (Fe-Co, Fe-Ni alloy) by the corrosion cyclic examination which imitated the atmospheric corrosion environment. The form of a rust film was maintained and put so that both sides of a rust film might be next to the diffrerent KCl bath of the concentration, and the measurement of membrane potential between both rust surface side was done. The ion selective permeability of rust on low alloy steels was investigated by measurement of membrane potential. The rust layer on the carbon steel was anion selective. It was shown that changed cation selective permeability as a result of determining the membrane potential of the rust on Fe-1 mass%Co and Fe-3 mass%Co low alloy steel. The addition of a few %Co was sufficient to decrease the corrosion rate because the rust layer being cation selective was obstructed the invation of chloride. Anion permeability was shown from the fructification of the membrane potential measurement of the rust that it was formed on the Fe-3 mass%Ni, however, the corrosion rate of the Fe-Ni low alloy steel was decreased. The material characterization technique with the form of the rust maintained was established through this measurement, and it was effective in the characterization of the rust.抄録全体を表示PDF形式でダウンロード (373K) -
福田 正1999 年 63 巻 9 号 p. 1137-1140
発行日: 1999年
公開日: 2008/04/24
ジャーナル フリーEffects of morphology of grain boundary nitride on the ductility of Fe-30 mass%Cr alloys containing N from 0.004 to 0.13 mass% were investigated. Two kinds of heat treatments were adopted to obtain the morphologies of continuous grain boundary nitride and of discontinuous grain boundary nitride. Tensile tests were carried out at temperatures ranging from 4.2 K to room temperature. Ductility was evaluated by transition temperatures in reduction of area.
The results obtained are summarized as follows:
(1) Upper shelf in reduction of area of the specimen containing discontinuous grain boundary nitride is higher than that of the specimen containing continuous grain boundary nitride.
(2) Transition temperature of the specimen containing discontinuous grain boundary nitride is lower than that of the specimen containing continuous grain boundary nitride.
(3) The area rate of intergranular fracture surface which appears in cleavage fracture surface observed in the specimen containing discontinuous grain boundary nitride is smaller than that which appears in cleavage fracture surface observed in the specimen containing continuous grain boundary nitride. The area rate of intergranular fracture surface which appears in dimple fracture surface also shows similar observation result.
(4) Initiation of microcracks for brittle fracture may be caused by decohesion at the interfaces between the matrix and grain boundary nitride.抄録全体を表示PDF形式でダウンロード (647K) -
藤田 充苗, 内海 美砂子, 野田 哲二1999 年 63 巻 9 号 p. 1141-1144
発行日: 1999年
公開日: 2008/04/24
ジャーナル フリーA database for transmutation and radioactivity of nuclear materials under neutron is important in view of selection and design of materials for various nuclear reactors. A database based on the FENDL-II on the Internet and additional data collected from several references has been developed on the NRIM “Data-Free-Way” site on the Internet. A user interface has been constructed for retrieval of necessary data and for graphical presentation of the relation between the energy spectrum of the neutrons and the neutron capture cross section. The possibility of chemical compositional change and radioactivity in a material caused by nuclear reactions can be easily retrieved using a browser such as netscape or explore, though the evaluation is qualitative.抄録全体を表示PDF形式でダウンロード (1282K) -
杉山 明, 小林 慶三, 松本 章宏, 尾崎 公洋, 西尾 敏幸1999 年 63 巻 9 号 p. 1145-1148
発行日: 1999年
公開日: 2008/04/24
ジャーナル フリーThe formation process and Seebeck coefficient of a Mg2Si-FeSi2 thermoelectric device made by mechanical alloying (MA) and pulsed current sintering was investigated.
The MA was performed in a planetary ball mill using three elemental powders. The powders were prepared by the mixing of Mg2Si-xmass%FeSi2(x=0, 20, 40, 60 ,80, 100). The MA powders were consolidated by pulsed current sintering method. The Seebeck coefficient of Mg2Si sintered at 823 K under 350 MPa was −366 μV/K at room temperature. However, the Seebeck coefficient of Co doped FeSi2 sintered at 1073 K was 4 μV/K because the sintered structure of FeSi2 was consisted of α and ε phase. After heat treatment at 973 K for 108 ks, the structure of FeSi2 became almost pure β phase and the Seebeck coefficient became −245 μV/K. Mg2Si-80 mass%FeSi2 was held at 823 K for 180 s and at 1073 K for 600 s during pulsed current sintering, in order to attain the densification. After sintering, the sample was heat treated at 973 K for 108 ks. Therefore, Mg2Si phase and β-FeSi2 phase coexisted in the sample. However, the Seebeck coefficient of Mg2Si-80 mass%FeSi2 was about −110 μV/K. There was no improvement of the Seebeck effect.抄録全体を表示PDF形式でダウンロード (357K) -
女川 淳1999 年 63 巻 9 号 p. 1149-1152
発行日: 1999年
公開日: 2008/04/24
ジャーナル フリーSpark plasma sintering (SPS) is a technique to produce various alloys with low cost. The titanium alloys of Ti-M (M=Co, Ni, Nb, Mo, Ru, Pd, Ta, W and Re) were prepared by SPS and those microstructures and corrosion resistance were examined.
A powder of M was mixed with the powder of titanium at at% of M from 0.1 to 1.0. The mixed powder was sintered by SPS at temperatures of 1073, 1373 and 1773 K to form the Ti-M alloys. Microstructure of the alloys were observed by scanning electron microscopy (SEM) and examined by X-ray diffraction. Corrosion resistance of the alloys were measured by a potentiodynamic polarization in a 5 mass% HCl solution.
The alloys prepared at 1073 K were the particle dispersion type in which the added element phases were dispersed granularly in the Ti matrix. The compound phases of Ti-Ni and Ti-Co generated in SPS were selectively corroded at relatively low potential and the selective dissolution of the added element phases were enhanced by potential cycles. In the alloys prepared at 1373 K, the dispersion of elements and compounds were progressed to increase a ratio of the metastable βTi phase. The alloy structures approached to a solid solution type. Cathodic current densities of the alloys in the polarization curve were similar as those of the solid solution types of the alloys. In the anodic potential region active dissolution of the added element phases disappeared, the anodic current density became low, and a selective corrosion of a specific phase was not observed. The alloys prepared at 1773 K were generally the solid solution type. The polarization curves of the alloys were similar as those of the arc-melted Ti-0.1 Pd alloy and thus the alloys prepared are conceivable to reveal the corrosion resistance almost same 0.5 that of the Ti-Pd alloy.抄録全体を表示PDF形式でダウンロード (534K) -
遠藤 浩光, 六浦 満夫, 村山 武海1999 年 63 巻 9 号 p. 1153-1156
発行日: 1999年
公開日: 2008/04/24
ジャーナル フリーEngines for passenger cars have intake valves and exhaust valves. Especially, exhaust valves are exposed to emission after combustion in cylinders: they are in the corrosive environment with sulfuric acid, hydrochloric acid, nitric acid or the adhesion of residue. Such an environment causes various kinds of corrosion. Recently, the result that we investigated the valve which had broken in motion, sulfuric acid corrosion phenomenon was found out on the neck taper. It occurred to an exhaust valve for a diesel engine made of SUH35 steel, of the austenitic heat resistant steel with solution and aging treatment. The corrosion was going ahead in the grain-boundary choosing-ly and on the grain-boundary, the corrosive substance such as sulfur and oxygen were detected. Also, the corrosion had the characteristic that we could observe metallic gloss on the surface and the valve didn’t degrade by the corrosion and so on. It is expected that such a grain-boundary corrosion declines material strength remarkably. Therefore, we thought that we need to reproduce corrosion in order to clarify the mechanism of this corrosion phenomenon.
This study was to experimentally reproduce the grain-boundary corrosion which occurred to the valve, with various corrosion experiments. Moreover, we examined about the relation between the corrosion and the fatigue strength by performing fatigue examination in the test pieces which had reproduced corrosion. The results we have obtained are as follows.
(1) The grain-boundary corrosion which occurred to the valve could be reproduced experimentally in performing the corrosion examination with the condensed liquid of sulfuric acid.
(2) It has been proved that grain-boundary corrosion’s occurrence caused the fatigue strength decline.
(3) It has been admitted that fatigue strength has downward tendency with increasing of the grain-boundary corrosion depth.抄録全体を表示PDF形式でダウンロード (892K) -
野木 直行, 田中 知, 野田 哲二1999 年 63 巻 9 号 p. 1157-1160
発行日: 1999年
公開日: 2008/04/24
ジャーナル フリーWe have measured infrared-reflectance spectra at room temperature of isotopically (10B or 11B) enriched, blended (42 at%10B and 58 at%11B) and natural (19.8 at%10B and 80.2 at%11B) β-rhombohedral boron. For the A2u and Eu modes of 10B, 11B and natural boron which were observed with light polarization parallel or perpendicular to the c-axis, the mode frequency ω of each symmetry changed with the classical harmonic approximation.
The mode frequency of inter- or several intra- icosahedral modes of an isotopically mixed crystal was lower than expected frequency from the harmonic model. It is possible that isotopic disorder-induced frequency shifts, which is an anharmonic effect, is obtained by using isotope-modified samples.抄録全体を表示PDF形式でダウンロード (303K) -
小林 慶三, 松本 章宏, 尾崎 公洋, 杉山 明, 西尾 敏幸1999 年 63 巻 9 号 p. 1161-1164
発行日: 1999年
公開日: 2008/04/24
ジャーナル フリーIn order to fabricate the compacts with complicated shape, Ni-Ti powders were synthesized by mechanical alloying(MA) and consolidated by pulsed current sintering.
Ni-50 at%Ti powders were synthesized by MA of pure elemental Ni and Ti powders using a planetary ball milling for 180 ks, 360 ks and 540 ks. The X-ray diffraction profile of the obtained MA powders contained a broad peak. MA powders milled for 180 ks and 360 ks consisted of fine Ni and Ti grains and melted at about 1150 K by self-propagating high-temperature synthesis(SHS) during pulsed current sintering. The MA powder milled for 540 ks contained a large amount of Fe. This is because NiTi phase was produced by SHS during the MA process.
The addition of 2 at%B to the starting powders of the MA was prevented a SHS reaction during pulsed current sintering. Ni-49 at%Ti-2 at%B powders synthesized by MA were consolidated to compacts with complicated shapes by pulsed current sintering. The obtained compacts consisted of NiTi, Ti2Ni, Ni3Ti and TiB2 phases. The result of differential scanning calorimetry measurement for the compacts heat-treated at 673 K for 3.6 ks suggested that those possessed shape memory effects.抄録全体を表示PDF形式でダウンロード (507K) -
藤原 弘, 前田 太一, 飴山 惠1999 年 63 巻 9 号 p. 1165-1174
発行日: 1999年
公開日: 2008/04/24
ジャーナル フリーMorphology and crystallography of precipitates nucleated at grain boundary triple line (T.L.) and/or in the vicinity of T.L. in Fe-24 mass%Cr-7 mass%Ni and Ti-22 mass%V-4 mass%Al alloys have been studied using TEM and SEM. The relative orientation relationships (O.R.) of the matrix/matrix and the matrix/precipitate were determined by Kikuchi pattern analysis. According to the crystallographical and morphological features, the microstructure in the vicinity of T.L. were classified into three types; Type I: T.L. nucleated precipitate with a globular morphology. Type II: grain boundary face nucleated precipitate with a film-like precipitate, and Type III: precipitation free T.L. In the case of Type II, the T.L. was eliminated by growth of the grain boundary precipitate. The probability of the appearance of these Types I, II and III were 20.1%, 71.9% and 8.0% in the Fe-24 mass%Cr-7 mass%Ni alloy and 26.5%, 64.7% and 8.8% in the Ti-22 mass%V-4 mass%Al alloy, respectively. In the Fe-24 mass%Cr-7 mass%Ni alloy, the crystallographical analysis revealed that the Type I γ precipitate satisfies the {111}γ/{110}α plane parallel O.R. with respect to at least two adjacent α grains at the same time. The {110}α plane, in which the {111}γ plane of the precipitate was in parallel, had the smallest angle with the α grain boundary plane, since the precipitate was able to decrease its activation energy for the nucleation. Thus, the nucleation behavior of the Type I γ precipitate was strongly dependent on at least two grain boundary plane orientation. The low probability of the appearance of Type I was due to such a restricted crystallographical condition. The T.L. orientation, therefore, plays a very important role in the nucleation behavior and the morphology of precipitates at the T.L. since the T.L. is junction of grain boundary planes.抄録全体を表示PDF形式でダウンロード (2760K) -
小竹 茂夫, 鈴木 泰之, 妹尾 允史1999 年 63 巻 9 号 p. 1175-1180
発行日: 1999年
公開日: 2008/04/24
ジャーナル フリーAtomic force microscopy (AFM) was applied to investigate the characteristics of surface topography and the microstructure of nodular graphite (NG) in ductile iron. Surface topography was measured at different intersection planes in NG. Differences between the central profile and the surrounding profile were caused by the cleavage of graphite under radial orientation of NG.
Lateral force images and in situ scratching measurements showed the existence of fine spheroidal platelets. Crystal orientation of nodular graphite was understood from the arrays of spheroidal platelets. Brachyaxes of spheroidal platelets were oriented in the radial direction to form a fan-shaped structure in NG. Some platelets, however, showed anomalous orientations.抄録全体を表示PDF形式でダウンロード (939K) -
三村 耕司, 斎藤 浩一, 一色 実1999 年 63 巻 9 号 p. 1181-1190
発行日: 1999年
公開日: 2008/04/24
ジャーナル フリーRemoval of oxygen and nitrogen of pure liquid iron and cobalt has been examined by Ar and (0.5% to 20%)H2+Ar plasma arc melting under atmospheric pressure. While the removal rates of oxygen and nitrogen were very low when the plasma gas was noly Ar, they rose remarkable with addition of a small amount of hydrogen such as 0.5 to 1%H2 and increased with hydrogen content of the plasma gas. The oxygen and nitrogen concentrations finally decreased to the very low levels as follows; O<2 and N<1 mass ppm for iron and O<5 and N<1 mass ppm for cobalt. This excellent refining effect is supposed to be caused by activated hydrogen atoms dissociated in the high temperature plasma arc and to be expressed as the following reactions; O+2H=H2O for deoxidation and N+3H=NH3 for nitrogen removal.
The deoxidation of iron proceeded through two steps by the fast 1st step at the beginning of melting and, thereafter, the slow 2nd step. Both steps were of a first order rate low and the deoxidation rate of 1st step was found to increase in proportion to the about 1/2th power of the hydrogen content in the plasma generating gas. So, it is considered that, for the 1st step of deoxidation, the chemical reaction on the surface of the liquid iron is the rate determining step.抄録全体を表示PDF形式でダウンロード (874K) -
木村 淳, 近藤 勝義, 武田 義信, 柴田 雅裕1999 年 63 巻 9 号 p. 1191-1196
発行日: 1999年
公開日: 2008/04/24
ジャーナル フリーWe have investigated the behavior of magnesium dissolved in aluminum alloy powders by X-ray photoelectron spectroscopy using synchrotron radiation (SR-XPS). The SR-XPS method allows free selection of X-ray energy to tune the kinetic energy of the photoelectrons for material surface analysis within 0.5 nm. Furthermore, due to the high intensity of the SR’s X-ray source and the larger photoionization cross section, measurements can be completed within a few minutes. We applied the SR-XPS system to analyze the chemical reactions of aluminum alloy powder surfaces. In heating the powders to 823 K, magnesium dissolved in the powders was concentrated to the surface oxide below 670 K, and finally, over 670 K, the magnesium reduced the aluminum oxide of powder surfaces by chemical reaction, broke the surface oxide films, and metallic aluminum appeared on the topmost surface of the powder. The reduction was the initial reaction in a new aluminum nitridation method developed by one of the authors.抄録全体を表示PDF形式でダウンロード (517K) -
中澤 崇徳, 鈴木 俊一, 田中 良彦, 天藤 雅之, 小松 肇1999 年 63 巻 9 号 p. 1197-1203
発行日: 1999年
公開日: 2008/04/24
ジャーナル フリーIn order to investigate the effect of carbon content on grain boundary sensitization of type 304L and 316L stainless steels during welding, grain boundary corrosion and carbide precipitation were examined using optical and transmission electron microscopy after thermomechanical cycles which simulated high temperature dynamic strain during welding. Compositional profiles at grain boundary were analyzed with EDS in FE-TEM. The total length of sensitized grain boundary was longer than that of grain boundary carbide in both steels. In type 304L steel grain boundary sensitization and carbide were both observed with carbon contents above 0.016%. In type 316L steel grain boundary sensitization occurred with carbon contents above 0.026%, while carbide precipitation on the grain boundary was observed at the carbon content of above 0.015%. The amount of chromium depletion at grain boundary in type 304L steel was larger than that of type 316L steel. The resistance to grain boundary sensitization of type 316L steel was higher than that of type 304L steel.抄録全体を表示PDF形式でダウンロード (1646K) -
林 重成, 成田 敏夫1999 年 63 巻 9 号 p. 1204-1211
発行日: 1999年
公開日: 2008/04/24
ジャーナル フリーOxidation properties of Fe-3, 5 and 7 mass%Al alloys were investigated at 1073 K in an oxygen gas atmosphere for up to 14.4 ks using thermo-gravimetry, scanning electron microscope, electron probe microanalyzer, and X-ray diffraction analysis. Time dependence of oxidation amounts can be divided into three regions, i.e., an initial stage with very high oxidation rate, a transient stage with a rapid decrease in the rate, and then a steady state oxidation. The critical times among these stages are 0.1 and 3.6 ks. The 7Al alloy oxidized very slowly, due to the formation of a duplex Al2O3 and Fe2O3 scale, in contrast to rapid oxidation of both 5Al and 3Al alloys. The 5Al alloy oxidized faster than the 3Al alloy during the initial stage, while for longer oxidation the 3Al alloy became faster. The 3Al alloy oxidized to form a thick scale with a triplex structure of Fe2O3, Fe3O4 and FeAl2O4, accompanied with an internal oxidation of duplex FeAl2O4 and Al2O3 zones. These internal oxides grew perpendicular to the alloy/scale interface. Oxidation of the 5Al alloy, close to the internal-external transition composition, is very complex depending on portions and oxidation times. It has a thin scale like the 7Al alloy and a thick scale with internal oxides like the 3Al alloy. Further, a precipitate free zone (PFZ) formed in the internal oxidation, sandwiched in between the FeAl2O4 and Al2O3 zones, and the formation mechanism of PFZ was proposed.抄録全体を表示PDF形式でダウンロード (1223K) -
西田 智幸, 末吉 秀一1999 年 63 巻 9 号 p. 1212-1217
発行日: 1999年
公開日: 2008/04/24
ジャーナル フリーGraphite was bonded to SUS304 steel under a compressive stress of 25 MPa in a vacuum over a temperature range from 873 to 1023 K using a RF-induction furnace. The bending strength of the graphite/SUS304 steel joint, and changes of microstructure and hardness near the joining interface of SUS304 steel, were investigated. Thermal stress induced in the joint was estimated with a finite element method. On the basis of these results the influence of thermal stress on the bending strength of the joint was examined.
Good solid state bonding becomes feasible when the joining temperature exceeds 923 K. Axisymmetric thermoelastic finite element analysis suggests that maximum tensile thermal stress is induced at a distance of 0.64 mm from the joining interface on the surface of the graphite, increasing with increasing joining temperature. The position of fracture in a bending test corresponds approximately to that of the maximum tensile thermal stress. A part of the thermal stress is released with the deformation of SUS304 steel and graphite. The bending strength of the joint increases with decreasing residual tensile stress on the surface of graphite. Relaxation of thermal stress depends on the amount of carbon atoms which diffuse into SUS304 steel. This may be related to the changes in plasticity of SUS304 steel and graphite, that is, the changes in the amounts of Cr23C6 precipitated in SUS304 steel and point defect introduced in graphite.抄録全体を表示PDF形式でダウンロード (572K) -
住田 豊, 松川 義孝, 葉石 靖之, 大貫 惣明1999 年 63 巻 9 号 p. 1218-1223
発行日: 1999年
公開日: 2008/04/24
ジャーナル フリーThermal crystallization from amorphous TiNi has been investigated due to “in-situ” observation in a high voltage electron microscope. The specimens contained several types of nucleation sites, such as free surfaces, C-A interfaces and cracks, which enabled to comparing crystallization at each site. The heterogeneous nucleation developed at the specimen edge and the crystalline-amorphous interface, where the crystallization temperature depended on each nucleation sites. The crystal growth was liner relation at each temperature, and the activation energy from Arrhenius plot was evaluated as 2.7 eV. The preferential crystallization was observed also on pre-cracked area, which implies some stress-assisted effect on the crystallization.抄録全体を表示PDF形式でダウンロード (1394K) -
門前 亮一, 久世 卓矢1999 年 63 巻 9 号 p. 1224-1228
発行日: 1999年
公開日: 2008/04/24
ジャーナル フリーThe boundary diffusion of bismuth has been investigated as a function of the misorientation angle, for [001] and [011] twist boundaries and [001] and [011] symmetric tilt boundaries of Cu from observations of intergranularly fractured surfaces of Bi-doped bicrystals. It has been found that the misorientation dependence of the boundary diffusivity of bismuth shows a close correlation with that of the boundary energy. The minimum of the boundary diffusivity occurs where the cusps of the boundary energy exist. The larger degree of disorder in the atomic arrangement at a boundary may result in the higher boundary diffusivity. The diffusion of bismuth in the [011] twist boundaries has also been found to take place more easily than in the [001] twist boundaries.抄録全体を表示PDF形式でダウンロード (578K) -
江 莞, 内山 哲夫1999 年 63 巻 9 号 p. 1229-1230
発行日: 1999年
公開日: 2008/04/24
ジャーナル フリーThe oxidation behavior of MoSi2 dispersed with aluminosilicate was studied at 773 K. Aluminosilicate was dispersed into the grain boundary of MoSi2, and an oxide network was constructed without affecting its thermal shock property. The resulting MoSi2/oxide composites exhibited an excellent oxidation resistance at low temperatures.抄録全体を表示PDF形式でダウンロード (237K)
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