巻号一覧
66 巻, 5 号
選択された号の論文の17件中1～17を表示しています
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片桐 昌彦, 小野寺 秀博2002 年 66 巻 5 号 p. 431-433
発行日: 2002年
公開日: 2008/04/24
ジャーナル フリーWe discuss the elastic stability of binary compounds by the equation of state using Lennard-Jones interatomic potentials. The critical volumes at which the elastic instability occurs by isotropic tensile load are calculated as a function of atomic-radius ratio for C15 Laves phase AB2 compounds. The elastic constants of sublattices of A and atoms are defined, and the stabilities at sublattice level are analyzed. It is known that bulk-modulus stability of the sublattice of B atoms is lower than that of A atoms in the region of which A atoms contract and B atoms expand. Experimentally, Hydrogen-Induced Amorphization (HIA) occurs in the compounds belonging to this region. We also discuss L12 and B2 structures.抄録全体を表示PDF形式でダウンロード (319K) -
尾和 智信, 篠田 剛, 加藤 喜久2002 年 66 巻 5 号 p. 434-437
発行日: 2002年
公開日: 2008/04/24
ジャーナル フリーWe suggested the deposition process of NiTi intermetallic compounds on carbon steel substrates using a plasma transferred arc (PTA) surfacing process. In order to prevent the formation of iron-based intermetallic compounds and hardening of the NiTi coatings, nickel interlayer was used during the PTA surfacing process.
Nickel interlaying leads to the prevention of cracks and hardening of the NiTi coatings. The microstructure of NiTi-deposited metals features Ni3Ti phase and the grain boundary showing the eutectic structure of NiTi and Ni3Ti. The wear resistance of the NiTi coatings made by using the nickel interlayer is superior to the resistance of Stellite #6 coatings.抄録全体を表示PDF形式でダウンロード (1756K) -
崔 漢哲, 崔 異川, 金 官烋, 安 徳洙, 黄 金衍2002 年 66 巻 5 号 p. 438-444
発行日: 2002年
公開日: 2008/04/24
ジャーナル フリーIt has been investigated constitution phases and corrosion resistance of Zn-Cr coatings fabricated by electroplating method and electron-beam physical vapor deposition method (EB-PVD).
The electroplated Zn-Cr alloy consisted mainly of η′-Zn phase for the lower Cr content than 7.9 mass%Cr and γ′-ZnCr phase for the higher Cr content. In the Zn-Cr coating fabricated by EB-PVD the γ′-ZnCr phase appeared clearly at 3 mass%Cr and it became the sole phase at 50 mass%Cr. The amount of η′-Zn phase decreased obviously with increasing Cr content when it exceeded 15 mass%Cr.
The electrochemical measurement of the electroplated Zn-Cr film has shown corrosion potential of about −1000 mV vs. SCE. The current density of active region and the amount of dissolved Zn and Cr decreased significantly with increasing Cr content. The electrochemical characteristics of Zn-Cr alloy fabricated by EB-PVD have shown that the alloy of 50 mass%Cr had the highest corrosion potential(−500 mV) and the lowest critical passive current density than that of the electroplated.抄録全体を表示PDF形式でダウンロード (1246K) -
伊藤 義康, 須山 章子, 斎藤 雄二2002 年 66 巻 5 号 p. 445-450
発行日: 2002年
公開日: 2008/04/24
ジャーナル フリーA shot coating process for metalizing at the surface of ceramics has been newly developed as the shot peening treatment. However, residual stress characteristics of shot coatings, which have an important effect on the adherent strength of coatings and the strength of ceramic substrates, have not always been clarified.
An experimental investigation on the reseidual stress was carried out for the shot coating of aluminum powder on four kinds of sintered-ceramics, such as zinc oxide, zirconia, silicon nitride and silicon carbide. As a result, it was confirmed by X-ray diffraction technique that the residual stress of aluminum coatings over ceramics was always compressive irrespective to the kind of ceramic substrates. It was thought that the compressive residual stress of aluminum coatings was induced by the shot peening effect of aluminum particles and low thermal conduction of substrates.抄録全体を表示PDF形式でダウンロード (761K) -
川浦 宏之, 西野 和彰, 斎藤 卓2002 年 66 巻 5 号 p. 451-458
発行日: 2002年
公開日: 2008/04/24
ジャーナル フリーThe aim of the present study is to obtain new TiAl-base alloys that are more resistant to foreign object damage (FOD). Ballistic impact tests were performed on TiAl alloys under the conditions closely simulating those in the turbine wheel of an automotive turbocharger. Several parameters including impact velocity, thickness of test specimens, and proportion of aluminum and additional alloying elements (boron, niobium, and vanadium) in the alloys were varied. The addition of boron and niobium caused degradation in the FOD resistance. On the other hand, the FOD resistance of TiAl alloys was improved by vanadium additions. Furthermore, the particular balance of additional vanadium and aluminum percentage was found to be important in determining the FOD resistance of TiAl alloys. The improvement of FOD resistance by vanadium addition specifically is an increased resistance to crack propagation across the lamellar grains, which is due to serrated grain boundaries formed thereby.抄録全体を表示PDF形式でダウンロード (2065K) -
坂田 智浩, 三木 貴博, 森田 一樹2002 年 66 巻 5 号 p. 459-465
発行日: 2002年
公開日: 2008/04/24
ジャーナル フリーRemoval of Fe and Ti from Si by acid leaching method was examined, the optimum condition for acid leaching was obtained and the mechanism of removal of impurities in Si was estimated.
Si-Ca-(Fe, Ti) alloys with various compositions were subjected to acid leaching procedure using aqua regia. For most of the samples, 85∼96% of Fe and 80∼93% of Ti were removed from Si and the effects of cooling rate and alloy composition were studied.
Slow cooling (4.4 K/min) was found to be better for effective removal of impurities than quenching. In order to give a higher removal rate of iron, acid soluble CaSi2 phase should be precipitated as a secondary phase, namely XCa⁄XFe>6.5. On the other hand, the optimum composition for the removal of Ti is considered to be XCa⁄XTi=3.抄録全体を表示PDF形式でダウンロード (1037K) -
花田 信子, 折茂 慎一, 藤井 博信2002 年 66 巻 5 号 p. 466-469
発行日: 2002年
公開日: 2008/04/24
ジャーナル フリーNew ternary Laves phase structures with compositions of MgYNi4, MgCaNi4 and CaYNi4 were prepared, and the relationship between structures and hydriding properties were studied in detail. Only in case of MgYNi4, Mg and Y were found to be ordered. The control of their order/disorder in Laves phase structures may provide the hydriding properties with higher hydrogen concentrations and flatter plateau regions.抄録全体を表示PDF形式でダウンロード (323K) -
李 星煕, 稲垣 肇, 宇都宮 裕, 齋藤 好弘, 左海 哲夫2002 年 66 巻 5 号 p. 470-475
発行日: 2002年
公開日: 2008/04/24
ジャーナル フリーMulti-layer stack accumulative roll bonding (ARB) process is suggested and applied to commercial purity aluminum for ultra grain refinement. The six aluminum sheets 0.5 mm thick, 50 mm wide and 400 mm long were stacked to each other after degreasing and wire brushing, and then cold-rolled by 50% reduction. The roll-bonded sheet was subsequently rolled by four passes so that the thickness would be 0.5 mm. The sheet was then cut to the six pieces of same length and processed by the same procedure. The ARB process up to six cycles (an equivalent thickness strain of 13.2) was successfully performed. The tensile strength of the ARB processed aluminum increases with the number of ARB cycles, and it reaches a maximum of 287 MPa at the third cycle. The tensile strength is lower in six-layer stack ARB than that in two-layer stack ARB. The elongation slightly decreases with the number of the ARB cycles. TEM observation revealed that the ultrafine grains begin to develop at the first cycle, and after the 3rd cycle almost whole regions are covered with them, and the aspect ratio of them reduces at the 6th cycle. The grain size of the 6-layer stacked ARB is larger than that of 2-layer stacked ARB. The differences with the number of the layers in stacking are explained by the redundant shear deformation. It is concluded that the multi-layer stacked ARB is a suitable process for the industrial production of ultrafine grained coils.抄録全体を表示PDF形式でダウンロード (1319K) -
伊藤 勉, 駒 正幸, 柴崎 聡, 大塚 正久2002 年 66 巻 5 号 p. 476-484
発行日: 2002年
公開日: 2008/04/24
ジャーナル フリーHigh temperature deformation behavior of coarse grained Al-Mg alloys, the Mg content of which is 7 mol%, 9 mol% and 11 mol%, has been investigated with a special reference to the effect of solute contents on the ductility in the temperature range between 613 K and 753 K, and strain rate range between 1×10−4 s−1 and 1×10−1 s−1. At low strain rate, and hence at low stresses, the stress exponent (n) is three for all alloys, showing that the deformation is rate controlled by the viscous glide of dislocations, or by the solute drag creep. Especially extended elongation of over 250% is obtained for both Al-7Mg and Al-9Mg alloys, which should be called superplastic-like behavior. The elongation of Al-11Mg alloy, however, is smaller than 200% in spite of Class I type deformation behavior. This should probably be ascribed to void-like defects caused during the rolling process, in addition to the partial melting of low Tm phase segregating at grain boundaries. At high strain rates (and hence high stresses), the exponent n is about five, meaning that the deformation is rate controlled by power low creep, and the ductility remains relatively low.抄録全体を表示PDF形式でダウンロード (1051K) -
原田 泰典, 大森 正信2002 年 66 巻 5 号 p. 485-491
発行日: 2002年
公開日: 2008/04/24
ジャーナル フリーHigh purity chromium powders were sintered into a block by means of hot isostatic pressing. Pieces taken from the sintered block were thermo-mechanically treated, i.e., repeatedly rolled at 973 K up to 50 and 85% in total reduction with and without intermediate annealing at 1273 K. The ductile-brittle transition temperature, DBTT, was determined by a tension test with the specimens cut from the as-sintered block and the rolled sheets. DBTT for the specimen rolled without intermediate annealing was about 600 K, while DBTT of the specimen rolled with the annealing was 400 K much lower than the above temperature 600 K and the temperature 500 K which was found in the as-sintered material. The reduction in DBTT through the thermo-mechanical treatment probably comes from the decrease of susceptibility to the occurrence of brittle fracture at grain boundaries.抄録全体を表示PDF形式でダウンロード (1227K) -
黒木 高志, 森 信幸, 大城 桂作2002 年 66 巻 5 号 p. 492-498
発行日: 2002年
公開日: 2008/04/24
ジャーナル フリーMelt/growth mechanism and interfacial reaction of YBCO superconductive oxide with molten Ag and YBCO/Ag composite were analyzed to clarify the best fabricating condition of YBCO crystals junction.
The peritectic temperature of YBCO(liquid+Y2BaCuO5(Y211)→YBa2Cu3O7−x(Y123)) was lowered toward 1242(±2) K from 1280 K by the addition of Ag, and Y123 phase dissolved into liquid(containing Ag+)+Y211 phases above 1244 K. Therefore Ag and YBCO/Ag composites were used as the inserted low-melting point materials for Y123 crystals. The surface layer of YBCO crystal was melted due to Ag diffusion from inserted YBCO/Ag into the crystals. By cooling the joint under 1240 K, Y123 crystals developed from base YBCO and a superconductive joint was obtained.
It was clarified that Ag diffuses from inserted YBCO/Ag composite into YBCO crystals mainly along Y123-Y211 boundaries.抄録全体を表示PDF形式でダウンロード (1808K) -
伊坪 徳宏, 稲葉 敦2002 年 66 巻 5 号 p. 499-505
発行日: 2002年
公開日: 2008/04/24
ジャーナル フリーTo fulfill the requirements for the improvement of the transparency and reliability of impact assessment, the development of endpoint approach has been paid attention internationally. Endpoint approach concentrates on the estimation of damages for receptors. The actual damages are quite dependent on the emitted and exposed area. We are developing an endpoint type LCIA methodology for Japan. This paper describes an overview of this methodology and the result of a case study for stainless steel. We applied DALY concept to indicate the damage of human health. This enables us to directly compare the result with several well-known methodologies. According to the results of calculations, many similarities between the methodologies are found and the significances of the endpoint type methodology are proved.抄録全体を表示PDF形式でダウンロード (398K) -
王 栄光, 竹田 睦, 木戸 光夫2002 年 66 巻 5 号 p. 506-512
発行日: 2002年
公開日: 2008/04/24
ジャーナル フリーThe surface composition and micro-wettability of SUS304 steel by pure water before and after immersion in 3.5 mass% NaCl aqueous solution were investigated at room temperature. The surface composition was analyzed using X-ray photoelectron spectroscopy(XPS). Anode and cathode current distribution measurements on specimen surfaces in NaCl aqueous solution were performed with scanning vibration electrode equipment(SVE). The wetting morphologies of micro-pure water on specimen surfaces were observed and wettability was evaluated with an atomic force microscope(AFM) in AC non-contact mode. The relationship between micro-wetting behavior of pure water and the surface composition of SUS304 steel are discussed.
The results obtained from XPS shows that considerable organic contamination is present on each surface, and oxides and hydroxides of iron, chromium and nickel formed on the specimen surfaces after wet polishing. The amount of oxide and hydroxide of chromium in the oxide (hydroxide) layer increased, while those of iron and nickel decreased after 1.8×106 s immersion in NaCl aqueous solution. The specimen surface became rougher after immersion, due to corrosion pitting. SVE measurements revealed that the ratio of anodic to cathodic area changed with immersion time, which indicates that oxides and hydroxides were resolved or formed, and local corrosion occurred. The AFM observation and evaluation showed that the wettability of SUS304 steel was reduced after immersion in NaCl solution.抄録全体を表示PDF形式でダウンロード (1170K) -
福本 倫久, 林 重成, 前田 滋, 成田 敏夫2002 年 66 巻 5 号 p. 513-520
発行日: 2002年
公開日: 2008/04/24
ジャーナル フリーOxidation behavior of Fe-0.5 and 5 mass%Ni alloys(0.5Ni, 5Ni) as well as Fe for comparison, was investigated at 1273 K for up to 7.2 ks in air and air containing 10.5 vol%H2O(air-10.5H2O). In the air-10.5H2O, the 0.5Ni and 5Ni were oxidized faster than in air. The scale was composed of a duplex structure, an outer Fe-oxides layer and an inner FeO+Ni layer containing voids. Marker experiments with a small Pt wire were carried out for the 5Ni oxidized in air and the Pt-marker was located between the inner and outer layers, suggesting that the inner layer grows due to inward migration of oxygen and the outer layer due to outward iron diffusion. A similar scale structure was observed for the 5Ni oxidized in air but the inner layer thickness of the 5Ni oxidized in air-10.5H2O was thicker than in air. Oxygen in the inner FeO+Ni layer formed in air was supplied by the dissociation of outer Fe-oxides, leaving voids there, probably by the perforating dissociation mechanism. Both oxygen and water molecules could be diffusing species through the void in the atmosphere containing water vapor. Concentration profiles of each element indicated that concentration of Ni was increased at the scale/alloy interface. The Ni-concentration of the 0.5Ni oxidized in air was lower than that in air-10.5H2O, but the Ni-concentration of the 5Ni oxidized in air was higher than that in air-10.5H2O.抄録全体を表示PDF形式でダウンロード (1600K) -
小野寺 龍太, 祝 桂合, 森田 泉2002 年 66 巻 5 号 p. 521-527
発行日: 2002年
公開日: 2008/04/24
ジャーナル フリーWe examined the effect of grain size on flow stress and yield-point phenomena in variously heat-treated low-carbon steel specimens. We found that the experimental results are easily understood if the flow stress consists of two internal stresses, Yint and Yir. Yint is a common internal stress that is work hardened; Yir is the cause of yield-point phenomena, and its value is supposed to be rapidly decreased (work-softened) to zero with strain. Both Yint and Yir were affected by grain size. Furthermore, the effect of heat treatment was strong on Yint but weak on Yir. The Hall-Petch coefficient k was appreciably larger at lower yield points than in the large strain region. This comparison supports the hypothesis of the existence of two internal stresses because the grain size dependence of flow stress at lower yield points has two origins, Yint and Yir, whereas the latter case has only one origin, Yint. In the strain region exceeding yield-point elongation, the stress-strain curves of specimens with various grain sizes were perfectly superposed on each other by parallel translation, which means that if Yint is expressed as Yint(ε)=f(ε) for a specimen with a certain grain size, it is expressed as Yint(ε)=f(ε+Δε)−Δσ for arbitrary grain size specimens, where Δε and Δσ are the amounts of translation in strain and stress, respectively.抄録全体を表示PDF形式でダウンロード (579K) -
飯島 康裕, 柿本 一臣, 斉藤 隆, 加藤 丈晴, 平山 司2002 年 66 巻 5 号 p. 528-536
発行日: 2002年
公開日: 2008/04/24
ジャーナル フリーIn recent years, worldwide research efforts have been made to develop Y-123 coated conductors. Ion-Beam-Assisted Deposition (IBAD) is the method that presents quite reliable superconducting properties, by using highly aligned buffer layers on non-textured substrate tapes. In this work biaxially aligned growth was studied for ZrO2-RE2O3 oxide films on polycrystalline Ni-based alloy substrates. Several pyrochlore type oxides (RE2Zr2O7) were found to have sharp textures and RE element was optimized to be Gd, or Eu. The origin of texture enhancement was discussed based on the variation of radiation damage come from lattice bonding energies including the stability of ordered structure for pyrochlore. The time constant of texture evolution for Gd2Zr2O7 was about half compared to YSZ. The growth structures were observed by transmission electron microscope (TEM), which have columnar-like colony of small size crystallites nearly equal to YSZ. Continuous depositions were performed on 10-mm width Ni-alloy tapes by a large-area reel-to-reel IBAD system with the production speed of 1.0 m/h. A uniform Gd2Zr2O7 film of 60-m length was obtained with the in-plane mosaic spread (Δφ) of 16-18 degrees. Y-123 films were deposited by Pulsed Laser Deposition (PLD) with tape speed of 1.0 m/h. Ic of 50.0 A and Jc of 4.2×109 A/m2 were obtained at the length of 9.6 m, with Δφ for the Y-123 film were 9-12 degrees. Ic of 150.0 A and Jc of 1.0×1010 A/m2 were obtained on a shorter sample at the length of 8 cm.抄録全体を表示PDF形式でダウンロード (846K) -
大参 達也, 室田 康宏, 工藤 昌行2002 年 66 巻 5 号 p. 537-542
発行日: 2002年
公開日: 2008/04/24
ジャーナル フリーThe solidification structure, hardness and wear resistance of surface composite castings of an Al-Cr-Cu alloy produced by a two-step process of stir-mix-quenching and centrifugal casting have been investigated. In this process, two kinds of molten metals with different compositions are mixed with agitation in a mixing vessel to produce semi-solid slurry containing fine intermetallic crystals, and then the slurry is centrifugally cast. In the stir-mix-quenching experiments, a hypoeutectic Al-Cu alloy melt was used for “the first melt” which acts as a coolant, and a hyperperitectic Al-Cr alloy melt with a higher liquidus temperature was used for “the second melt,” which is rapidly quenched to precipitate numerous primary intermetallic crystals when it is brought into contact with the first melt.
The structure, hardness and wear resistance of the specimen vary with the mass fraction of α-phase (aluminum solid solution) in the slurry. As the fraction of α-phase increases, the volume of macroscopic pores and hardness of the composite layer decrease. On the other hand, the composite layer has good wear resistance when the slurry with proper amount of α-phase was used. In such case, θ-phase (Al2Cu) acts as an bonding material for the primary intermetallic crystals to form rigid network of hard phases.抄録全体を表示PDF形式でダウンロード (997K)
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