巻号一覧
73 巻, 4 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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今出 政明, 張 林, 飯島 高志, 福山 誠司, 横川 清志2009 年 73 巻 4 号 p. 245-250
発行日: 2009年
公開日: 2009/04/01
ジャーナル フリーThe internal reversible hydrogen embrittlement (IRHE) of the thermally hydrogen-charged iron-based superalloy of SUH660 and austenitic stainless steels of SUS 304, 316, 316L, 316LN and 310S was investigated in the temperature range from 300K to 80 K. Hydrogen showed a marked effect on the tensile properties of SUH660 and SUS 304, a minimal effect on those of SUS316 and SUS316LN, and no effect on those of SUS 310S and 316L at room temperature. Although the IRHE of SUH660 decreased with decreasing temperature, those of SUS304, 316 and 316LN increased with decreasing temperature, reached a maximum at around 200 K, and decreased rapidly with decreasing temperature down to 80 K. It was observed that hydrogen caused transgranular fracture along the slip plane in the iron-based superalloy and brittle transgranular fracture along the strain-induced martensite lath in the austenitic stainless steels, respectively. It was suggested that IRHE of the SUH660 depended on the diffusion of hydrogen, and that IRHE of the austenitic stainless steels from 300 K to the maximum IRHE temperature depended on the transformation of strain-induced martensite and the behavior below the maximum IRHE temperature depended on the diffusion of hydrogen.
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三橋 史典, 手束 展規, 杉本 諭2009 年 73 巻 4 号 p. 251-254
発行日: 2009年
公開日: 2009/04/01
ジャーナル フリーWe investigated the structure and magnetoresistance effect for the Fe/MgO/GaAs/MgO/Fe junctions. The junctions were deposited on MgO(001) single crystal substrate by Molecular Beam Epitaxy. RHEED patterns and XRD pole profiles reveal that bottom electrodes, Fe, and inter layers, n-GaAs, grow epitaxially. While RHEED patterns reveal that upper electrodes, Fe, grow in a polycrystal form. The junctions exhibit magnetoresistance ratio of 3.2% at room temperature. The magnetoresistance curves correspond to the magnetization alignment between the bottom and the upper Fe electrodes. These results indicate that the magnetoresistance effect originates from spin injection from Fe to GaAs through MgO barriers.
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有川 秀一, 宗木 政一, 大久保 弘, 阿部 冨士雄, 佐々木 朋裕, 八高 隆雄2009 年 73 巻 4 号 p. 255-261
発行日: 2009年
公開日: 2009/04/01
ジャーナル フリーThe effect of an aluminizing treatment on the oxidation behavior of carbon-nitrogen free Fe-12Ni-9Co-10W alloy has been investigated in steam at 973 K for 28 Ms. An FeAl layer with a thickness of 70 μm was observed to form on the alloy surface during aluminizing treatment, which consisted of hot pressing of pure Al foil of 50 μm thickness on to the sheet specimens at 523 K, and subsequent diffusion annealing at 1373 K for 3.6 ks in vacuum of 10-4 Pa. The sheet specimens subjected to the aluminizing treatment exhibit excellent oxidation resistance in steam at 973 K, resulting from the formation of very thin Al2O3 scale. Oxidation tests were carried out using specimens with a thin layer of FeAl, and specimens with no FeAl layer but different Al concentrations at the alloy surface. Excellent oxidation resistance was observed due to Al2O3 scale formation when the FeAl layer was present or the Al concentration at the alloy surface with no FeAl layer was higher than 11%. When the Al concentration at the alloy surface with no FeAl layer decreased below 11%, thick scale of Fe3O4 and Fe2O3 formed during oxidation.
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室田 忠俊, 曽川 幸助, 松尾 伸也, 小俣 孝久2009 年 73 巻 4 号 p. 262-267
発行日: 2009年
公開日: 2009/04/01
ジャーナル フリーOxide materials with high oxygen storage capacity (OSC) at low temperatures, possessing high thermal stability at high temperatures are indispensable for advanced automotive exhaust catalyst. We have recently discovered a single CaF2-type phase of λ-(Zr1/4Pr3/4)O2-y with wide oxygen nonstoichiometry, which can release oxygen at a low temperature as 573 K in Ar. In the present study, various (Zr2/8Cex/8Pr(6-x))O2-y(x=0~6) compositions were prepared by a coprecipitation method. The samples were first oxidized at 1473 K in air, reduced in H2 at 1373 K, and then oxidized again at 973 K in air. The oxide samples obtained in each situation were subjected to XRD, OSC analysis and TPD oxygen gas analysis by means of TG/DTA in Ar+5%H2. The single λ-phase with CaF2 structure appeared for x=0.5 and 1. The Ce addition stabilized the λ-phase, while a single C-phase with CaF2 structure appeared in the composition range of x=5 and 6. Two-phases region of the λ- and C-phases existed for the composition of 1<x<5, where the amount of oxygen released with fast rate decreased monotonously with decreasing the Pr composition. The oxygen release and OSC properties have been discussed in terms of phase relationship and Ce/Pr composition.
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室田 忠俊, 曽川 幸助, 松尾 伸也, 小俣 孝久2009 年 73 巻 4 号 p. 268-274
発行日: 2009年
公開日: 2009/04/01
ジャーナル フリーOxide materials with high oxygen storage capacity (OSC) at low temperatures, possessing high thermal stability at high temperatures are indispensable for advanced automotive exhaust catalyst. A candidate for the high efficient OSC materials must lie in the composition of (Zr2/8Cex/8Pr(6-x)/8)O2-y (x=0~6), because the small amount of Ce addition stabilizes a single phase of λ-(Zr0.25Pr0.75)O2-y with wide oxygen nonstoichiometry. In addition, noble catalytic metal, e.g., copper must be investigated instead of platinum. In the present work, the (Zr2/8Cex/8Pr(6-x)/8)O2-y compositions (x=0~6) with the addition of Cu have been investigated for the phase relationship and OSC behavior. The samples were first oxidized at 1473 K in air, reduced in H2 at 1373 K, and then oxidized again at 973 K in air. The oxide samples obtained in each situation were subjected to XRD, OSC analysis and TPD oxygen gas analysis by means of TG/DTA in the Ar+5% H2.
When oxidized at 1473 K in air, the two-phases region between the λ-and C-phases, observed for (Zr2/8Cex/8Pr(6-x)/8)O2-y, disappeared and a pyrochlore-like phase appeared with the addition of Cu. That is, the addition of Cu led to the mutual solid solution of λ- and C-phases. When the samples (Zr2/8Cex/8Pr(6-x)/8)Cu0.5/8O2-y (x<3) were reduced at 1373 K in H2, C-rare earths-like phase appeared on (Zr2/8Cex/8Pr(6-x)/8)Cu0.5/8O2-y (x<3). With increasing the Ce content, the lattice parameter of the CaF2 unit varied continuously to those of λ- and C-phases. For the samples (Zr2/8Cex/8Pr(6-x)/8)Cu0.5/8O2-y (x=0∼6), the oxygen storage capacity was greatly improved at low temperatures as 573 K, probably due to the oxygen defect of pyrochlore-like phase.
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廣崎 龍児, 小澤 孝好, 上田 豊甫, 篠田 哲守, 清宮 義博2009 年 73 巻 4 号 p. 275-282
発行日: 2009年
公開日: 2009/04/01
ジャーナル フリーThe present study aims to confirm whether the AlN/Al composite can be synthesized or not by infiltrating molten Al into Al powder compact under N2 gas atmosphere. Firstly some amount of Al is melted in a crucible and then the same mass of Al powder with the cast Al is filled on it. The crucible has been heated at a temperature between 700 to 1150°C under the N2 gas flowing. At heating temperatures above 950°C, almost molten Al at the bottom is sucked up to the Al powder compact side forming an AlN/Al composite. The volume fraction of AlN, VfAlN, in the composite increases as an increase in heating temperature and the level of VfAlN attains to 50% at most. However, below 850°C, the power of infiltration of molten Al is not so strong that VfAlN ends in the level less than 20% but a trace of AlN formation is observed even at 700°C. The experiment indicates that a large scale contact of Al powder surface with molten Al under the nitrogen gas flow is necessary to synthesize the AlN/Al composite of a high volume fraction of AlN.
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小島 真由美, 足立 吉隆, 友田 陽, 池田 圭太, 片田 康行2009 年 73 巻 4 号 p. 283-289
発行日: 2009年
公開日: 2009/04/01
ジャーナル フリーThe fracture behavior of a high nitrogen bearing austenitic stainless steel (Fe-23Cr-4Ni-2Mo-1N(mass%)) at cryogenic temperature was investigated by 3DSEM-EBSD method, electron microscopy, X-ray diffraction and thermodynamic evaluation of phase stability. Ductile-to-Brittle Transition (DBT) was found to occur as a result of brittle fracture in the present steel. The brittle fracture took place on {111} with a high Schmid factor, which likely proceeded in the slipping-off mechanism on the most active {111}. Although the stress-induced martensitic transformation occurs, its contribution seems to be negligible.
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柴田 曉伸, 村上 俊夫, 森戸 茂一, 古原 忠, 牧 正志2009 年 73 巻 4 号 p. 290-298
発行日: 2009年
公開日: 2009/04/01
ジャーナル フリーIn the present paper, the origin of midrib in lenticular martensite is clarified by examining the similarity between midrib and thin plate martensite in detail and studying the stress-induced growth behavior of thin plate martensite at various temperatures. Although lenticular martensite, especially midrib, exhibits a zigzag array in general, some martensite plates which are branched or kinked were also observed as thin plate martensite. The substructure of midrib is completely twinned and the orientation relationship of midrib with respect to austenite is close to Greninger-Troiano relationship. The morphology, substructure and crystallographic features of midrib in lenticular martensite are quite similar to those of thin plate martensite. Furthermore, stress-induced growth behavior of thin plate martensite changes with deformation temperature. Thermally-transformed thin plate martensite grows keeping a thin plate shape when deformed at temperature close to the Ms temperature. However, it grows into a lenticular shape accompanied by a substructure with a high density of dislocations after deformation at temperature much higher than Ms temperature. Therefore, it is concluded that midrib in lenticular martensite is thin plate martensite itself. The difference between lenticular martensite and thin plate martensite is only in their growth behaviors.
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山田 類, 吉年 規治, 川崎 亮, 渡辺 龍三2009 年 73 巻 4 号 p. 299-305
発行日: 2009年
公開日: 2009/04/01
ジャーナル フリーMetallic glasses have been reported to exhibit excellent properties such as high strength, high corrosion resistance, high wear resistance, resulting from their random structure. In addition, metallic glasses usually exhibit a drastic reduction in viscosity in the supercooled liquid region. Therefore, metallic glasses have excellent workability in this temperature range and it has already been reported that large size of bulk metallic glasses are successfully fabricated in several Zr-, Pd-based metallic glasses.
In recent years, Fe-based metallic glasses have been intensively studied because of their excellent mechanical performance, excellent magnetic properties and rich resources. However, due to their poor glass forming ability, the size of bulk metallic glasses is limited using a copper mold casting technique.
In the present study, [(Fe0.5Co0.5)0.75Si0.05B0.2]96Nb4 bulk metallic glasses are fabricated by spark plasma sintering (SPS) of amorphous powders which have been prepared by a gas atomization. To find optimum conditions in the SPS process, Time-Temperature-Transformation diagram (TTT diagram) is also constructed by isothermal differential scanning calorimetry. After consolidation of metallic glassy powders, mechanical properties of consolidated glassy specimens are measured by compressive tests.
As a result, the TTT diagram can be constructed and maximum incubation time can be predicted at any holding temperature. Using SPS method, large size and nearly 100% relative dense glassy compacts are obtained with a loading pressure of 75 MPa and 400 MPa, comprising full amorphous in the case within incubation time. Compressive tests indicate that mechanical properties of consolidated specimens are still low, and one of the reasons may be the formation of approximately 50 nanometer crystalline phases between each particle observed by Transmission Electron Microscope (TEM).
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服部 智哉, 兼子 佳久, 橋本 敏2009 年 73 巻 4 号 p. 306-311
発行日: 2009年
公開日: 2009/04/01
ジャーナル フリーWear processes of Co/Cu multilayers whose component layer thickness h ranged from 10 nm to 250 nm have been investigated. The Co/Cu multilayers were fabricated on polycrystalline copper substrates using electrodeposition method. Sliding wear tests on the Co/Cu multilayers were carried out in a ball-on-disk type machine in air at room temperature. Wear resistance of the multilayers depended strongly on component layer thickness h: a lost thickness of the multilayer of h=10 nm was shorter than that of h=250 nm by a factor of 5. From surface observation of the worn multilayer of h=100 nm, surface cracks were detected along lines corresponding to grain boundaries of the copper substrate. The wear process of the multilayers having thicker layers was certainly promoted by these surface cracks. On the other hand, in the worn multilayer of h=20 nm, the crack formation was almost suppressed. Accordingly, the layer thickness dependence of the wear resistance could be related to the resistance to surface cracking.
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—鋼スクラップ中の不純物元素活用—小林 能直, 劉 中柱, 桑原 守, 長井 寿2009 年 73 巻 4 号 p. 312-321
発行日: 2009年
公開日: 2009/04/01
ジャーナル フリーCopper is one of the main residual elements in steel, especially in recycled scrap steel. Sulfur and phosphorus are two of the main impurities in steel, and it may result in a large emission of slag and CO2 to remove them from steel. Utilization of these elements has been an important and difficult matter for metallurgist. In the present paper, the as-cast steels containing different concentrations of copper, sulfur and phosphorus are prepared by strip casting process or laboratory rapid solidification process. The effect of phosphorus addition on sulfide precipitation is investigated and discussed with respect to the morphology, size, and composition of sulfide. Both experimental results and mathematical calculation showed that the addition of phosphorus retards the sulfide precipitation at high temperature, promotes more copper bearings and smaller sulfides precipitation at low temperature. On the other hand, sulfide precipitates are shown to reduce the micro-segregation degree of phosphorus in steel, which may be because some phosphorus dissolves in sulfide and sulfide particles provide more interfaces for phosphorus to distribute.
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