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75 巻, 4 号
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秋屋 貴博, 佐藤 文隆, 宇根 康裕, 佐川 眞人, 高橋 弘紀, 加藤 宏朗2011 年 75 巻 4 号 p. 193-197
発行日: 2011年
公開日: 2011/04/25
ジャーナル フリーEffect of magnetic-field direction applied during annealing at 800°C on the demagnetization process was investigated systematically in sintered Nd-Fe-B magnets. We observed a stepwise decrease in the demagnetization curve when the perpendicular field was applied during the 800°C annealing, which suggests an existence of soft magnetic grains. We then annealed this sample in zero field successively from Ta=400°C to 720°C with the temperature increment of 10°C, and traced a change in demagnetization curves. The volume fraction Vsoft of the soft magnetic grains was estimated from the step width of the demagnetization curves. The Vsoft value showed a maximum around Ta=500°C with Vsoft=25%, and decreased rapidly with increasing Ta. The coercivity versus Ta plot exhibited a similar tendency to that of Vsoft versus Ta plot. Origin of such soft magnetic grains is considered to be a precipitation of perpendicularly-aligned Nd2Fe14B small particles in the grain boundary, which would act as a nucleation site on the large Nd2Fe14B host matrix. These results suggest that the magnetic coupling between Nd2Fe14B grains is one of the important factors to understand the coercivity mechanism in sintered Nd-Fe-B magnets.
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成田 健吾, 新家 光雄, 仲井 正昭, 織部 一弥2011 年 75 巻 4 号 p. 198-206
発行日: 2011年
公開日: 2011/04/25
ジャーナル フリーMicrostructural evolution accompanying mechanical properties change by aging treatment at 723 K in cold-swaged Ti-29Nb-13Ta-4.6Zr were investigated in order to obtain an optimized aging condition for getting excellent mechanical properties.
The precipitate free zone exists in Ti-29Nb-13Ta-4.6Zr after aging treatment for various time periods. Such the precipitate free zone corresponds to Nb and Ta-enriched region according to the result of element-distribution analysis. With the increase in aging time, the area of the precipitate free zone decreases.
Two types of α phase, acicular and ellipsoidal ones, are observed in Ti-29Nb-13Ta-4.6Zr after aging treatment for various time periods. The acicular α phase is precipitated in the Ti- and Zr-enriched region. While the size increases, the area fraction barely changes with aging time for acicular α phase, On the other hand, the ellipsoidal α phase precipitates at β grain boundary and its subgrain boundary. Both the size and area fraction increase with the increase in aging time for the ellipsoidal α phase.
The lattice correspondence between acicular α phase and β matrix is [110]β//[121]α, (112)β//(210)α and [110]β//[001]α, (112)β//(200)α until 86.4 ks of aging time. However, the lattice correspondence of [110]β//[121]α, (112)β//(210)α disappear over 259.2 ks of aging time.
Tensile strength of Ti-29Nb-13Ta-4.6Zr subjected to aging treatment after cold swaging is around 1200 GPa, regardless of aging time. On the other hand, elongation of those are decreased by the aging treatment up to 86.4 ks, increased at ones over 259.2 ks.
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小栗 和幸, 関川 貴洋, 紙田 徹2011 年 75 巻 4 号 p. 207-212
発行日: 2011年
公開日: 2011/04/25
ジャーナル フリーOxidation behavior of ZrB2-SiC ceramics in air up to 2000°C was investigated. A thick oxidized layer forms and protects the inside of material even at 2000°C. The oxide consists of mainly ZrO2 with surface layer of SiO2 and B2O3. The bending strength of ZrB2-SiC ceramic decreased with increasing oxidizing temperature and duration.
The strength can be evaluated with the remaining un-oxidized portion of the material.
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新野邊 幸市, 井土 祐希, 瀧山 直之2011 年 75 巻 4 号 p. 213-222
発行日: 2011年
公開日: 2011/04/25
ジャーナル フリーBinary Fe-Al intermetallic compounds were developed by combining a non-pressurizing cladding with a simple heat treatment. Thin plates of pure Fe and pure Al were alternately laminated, followed by heat treatment at temperatures higher than the melting point of Al ranging from 973 K to 1473 K in an Ar atmosphere. A tongue-like diffusive layer consisting of Fe2Al5 was initially formed and the melted Al was disappeared in the specimen heated for 900 s at temperatures ranging from 973 K to 1273 K. By increasing the heating time up to 10.8 ks, the layers of FeAl and α-Fe with Al were formed in the region between the tongue-like diffusive layer and the Fe substrate. In addition, the tongue-like diffusive layer changed the constituent phase from Fe2Al5 to FeAl2 because of the decrease in the Al content of the layer. By heating at more than 1373 K, the layers of FeAl and Fe with Al were only formed, resulting in the disappearance of Fe2Al5 and FeAl2. The specimen heated at 1473 K for 10.8 ks has the uniform chemical composition in whole area. However, it shows a lower Al content than the theoretical composition, since the melted Al oozed outside the specimen with increasing the heating temperature. In order to suppress the decrease in the Al content, the specimen was heated at 973 K for 3.6 ks, followed by heating at 1473 K for 10.8 ks. It was then possible to obtain the sample with the chemical composition which is approximate to the theoretical one.
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田代 優, Khyoupin Khoo, 大貫 仁2011 年 75 巻 4 号 p. 223-228
発行日: 2011年
公開日: 2011/04/25
ジャーナル フリーThe effect of the electrolyte purity on the resistivity of very narrow Cu wires has been investigated. The resistivity difference between high purity (6N) electrolyte and low purity (3N) electrolyte processes is relatively small (1.5%) when the line width is wide. However, it increases with the decrease in the line width, and it reaches about 17%, i.e., 2.9 μΩ•cm for the former and 3.5 μΩ•cm for the latter at the 50 nm line widths. A 50 nm Cu wire formed with the high purity electrolyte process had more uniform and larger grain sizes and lower impurity (oxygen) concentrations than the wire formed with the low impurity electrolyte process. The impact of the purity of electrolyte on the reduction of Cu wire resistivity is found to be much larger than that for anode plating material.
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石橋 啓祐, 奥山 勇治, 栗田 典明, 武津 典彦2011 年 75 巻 4 号 p. 229-234
発行日: 2011年
公開日: 2011/04/25
ジャーナル フリーIt has been known that hydrogen can dissolve into a crystal of LiTaO3. However, there is not much literature about the details of the hydrogen in LiTaO3. In the present work, the transport properties and the location site of hydrogen in the non-stoichiometric LiTaO3 single crystal was studied by the electrical conductivity measurement and the IR absorption analysis.
H+/D+ isotope effect on the conductivity was examined in order to verify whether proton in LiTaO3 was dominant charge carrier. The result that no isotope effect was detected showed that proton was not the main charge carrier in LiTaO3 in the measured temperature range 673-873 K.
On the displacement reaction of proton and deuteron, the annealing time dependence of IR absorbance was measured in order to estimate the self-diffusion coefficient of proton. The value was determined as DH+=5.5×10−8 cm2/s at 973 K.
For single crystal of LiTaO3, the crystal orientation dependence of IR absorbance was measured using polarized light. The analysis based on the one-dimensional model of the hydrogen bond showed that proton was locating between the O-O pairs on the basal plane.
The amount of dissolution hydrogen in LiTaO3 equilibrated with gas mixture 1%O2-3%H2O-Ar at 773-973 K was estimated to be (1.3±0.4)×10−8 mol/cm3.
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針替 伸拓, 西 義武2011 年 75 巻 4 号 p. 235-242
発行日: 2011年
公開日: 2011/04/25
ジャーナル フリーProduction process of titanium and aluminum joint reinforced by nickel coated carbon fiber (Ti/NiCF/Al) has been successfully developed. Although the discontinuous stress relaxation always occurred at 100±20 MPa in the stress-strain curves of fiber free Ti/Al joints, a smooth stress-strain curve was observed in the aluminum rod of the Ti/NiCF/Al joint. The fracture toughness, which was evaluated by the integrated area of the stress-strain curve of the Ti/NiCF/Al joint which underwent ductile fracture at the Al side rod, was more than two times larger than that of the fiber free joint which fractured near the joint interface. Since the nickel coated layer prevented the reaction between carbon fiber and molten metals, it mainly prevented generation of fracture near the Ti/Al joint interface. The Ti/NiCF/Al joint exhibited the high values of stiffness (dσ/dε), fracture strain and strain at tensile strength. These improvements were explained by both fining the metallic compounds and solution hardening by nickel addition, as well as the broad interface area of fine carbon fibers.
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中島 基樹, 細川 将之, 駒崎 慎一, 庄子 哲雄2011 年 75 巻 4 号 p. 243-247
発行日: 2011年
公開日: 2011/04/25
ジャーナル フリーThe influence of hydrogen content in steel on atmospheric oxidation behavior of low carbon austenitic stainless steel SUSF316L was investigated for clarifying the mechanism of SCC initiation in a boiling water reactor environment, which is closely associated with the localized oxidation and its acceleration. The stainless steel was charged with hydrogen by the means of cathodic electrolysis followed by subjecting the hydrogen-charged steels to the atmospheric oxidation test at 300°C for 10 h. The oxide films that formed on the non-charged and hydrogen-charged specimens were analyzed by optical microscopy, scanning electron microscopy, laser Raman spectroscopy and glow discharge optical emission spectroscopy. Experimental results revealed that relatively thick oxide films were formed on the hydrogen-charged specimen resulting in the hydrogen accelerated oxidation (HAO), when the hydrogen content was 35 mass ppm. However, there was almost no difference between the non-charged and the hydrogen-charged from the viewpoint of oxidation behavior when the hydrogen content was 24 mass ppm. The spinel-type oxides such as Fe3O4 and FeCr2O4 were identified by laser Raman spectroscopy only on the specimen surface where the HAO occurred. In addition, the Cr concentration in the inner oxide layer of the oxidation-accelerated specimen was around 20% and was lower than that of the non-charged (30-35%). The HAO seemed to be closely associated with this decrease in Cr concentration in the inner oxide layer.
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—研磨面方位および調製雰囲気による磁気特性への影響—中村 通秀, 早川 一生, 小林 久理眞, 増田 宏2011 年 75 巻 4 号 p. 248-253
発行日: 2011年
公開日: 2011/04/25
ジャーナル フリーThe magnetic properties of the Nd-Fe-B magnet fine particles with diameters of 20 μm-5.5 mm were investigated using the magneto-meters of Vibrating Sample Magnetometer (VSM) and of a high sensitivity Resonating Sample Magnetometer (RSM) (max. 10−6-10−7 emu). The coercivities disappeared in the finest 20 μm samples, but the saturated magnetizations kept 60-70% mass of the bulk sample. The deteriorations should come from the oxidation and the formation of lattice defects by mechanical polishing. The effects of polishing both in the c-plane, in the perpendicular planes along the c-axis, on the shape of the demagnetization curves, and on the coercivity were investigated.
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高橋 裕, 清 弘文, 平田 知大, 氏原 祐貴2011 年 75 巻 4 号 p. 254-258
発行日: 2011年
公開日: 2011/04/25
ジャーナル フリーC60-C70 solids were prepared via volatilization of solutions of C60 and C70 in toluene as the solvent. During volatilization of the toluene, saturated fullerene molecules did not precipitate as a C60-C70 solid, but formed a single phase (C60)1−x(C70)x•C6H5CH3 solvate. The solvate was unstable in air when x was small and naturally decomposed into a C60-C70 solid. With heat-treatment in a vacuum, the solvate could also be converted into the C60-C70 solid even when x was large. The single solvate phase produced two phases of C60-C70 solids, indicating that the C60-C70 system possesses a miscibility gap.
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栗田 大樹, Hansang Kwon, 川崎 亮2011 年 75 巻 4 号 p. 259-264
発行日: 2011年
公開日: 2011/04/25
ジャーナル フリーCarbon nanotubes (CNTs) with their outstanding properties are expected as reinforcement for conventional materials, though they are required to be uniformly dispersed with the host matrix. However, uniform dispersion of CNTs within metal and ceramic-based materials is highly challenging to achieve due to strong van der Waal's forces between the neighboring CNTs leading to strong CNT agglomeration. We fabricated fully dense, uniformly dispersed 1.0 and 5.0 vol% CNT-aluminum matrix composite by combination of hetero agglomeration method and spark plasma sintering (SPS) followed by hot extrusion process. Tensile response and microstructure of the composites were studied by the universal Instron tester and transmission electron microscope, respectively. We realized a considerable enhancement in tensile strength of the composites while reaching the same rapture elongation for the 1.0 vol% CNT composite as the cast pure aluminum, however, the rupture elongation for the 5.0 vol% CNT composite was reduced. Although the aluminum was infiltrated into the surface defects of CNTs after the SPS, however, no Al4C3 phase was observed at the CNT/aluminum interface.
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長谷部 優作, 橋本 清, 竹山 雅夫2011 年 75 巻 4 号 p. 265-273
発行日: 2011年
公開日: 2011/04/25
ジャーナル フリーPhase equilibria among γ-Fe, TCP (Fe2Nb-ε), GCP (Ni3Nb-δ, hP24) and liquid phases in Fe-Ni-Nb ternary system at 1473 K and 1373 K were experimentally examined. At 1473 K, a ternary compound hP24 phase exists in the composition range of Fe-21.5Nb-(56.8~59.8) Ni. Liquid phase also exists around the composition of Fe-17Nb-50Ni. At 1373 K, the hP24 phase remains stable, whereas the liquid phase disappears due to a temperature invariant reaction (L→γ+ε+hP24), resulting in the three three-phase coexisting region around the hP24 phase: γ+hP24+ε, γ+hP24+δ, ε+hP24+δ. The interaction parameters for thermodynamic calculation to reproduce the experimental phase diagrams at both temperatures were successfully evaluated. The calculated isothermal section at 973 K using the parameters revealed the ternary eutectoid decomposition of the hP24 phase, leaving a γ+ε+δ three-phase coexisting region extended toward Fe-rich side. The results suggest a possibility to design austenitic heat resistant steels strengthened by both TCP and GCP phases.
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澤田 俊之, 柳谷 彰彦2011 年 75 巻 4 号 p. 274-281
発行日: 2011年
公開日: 2011/04/25
ジャーナル フリーIn order to obtain a high hardness shot peening media, the properties of Fe-8%Cr-6.5%B media (Base media) with several additive elements were investigated. Fe-8%Cr-6.5%B-X%M media (X%M=2%Zr, 2%Nb and 2~16%W; Denoted hereafter as X%M media) were produced by gas atomization. Vickers hardness, density and ductility of these media were examined.
The properties of Base, 2%Zr, 2%Nb and 2%W media were examined. Vickers hardness of 2%W media was high, but those of 2%Zr and 2%Nb media were low compared to that of Base media. Then, the properties of Base and 2∼16%W media were examined. Vickers hardness of 4%W showed the first peak, then decreased until 8%W. Furthermore, in the range of W addition amount beyond 8% Vickers hardness increased again. 4%W media with the combination of high hardness of 1300 HV, high density of 7.6 Mg/m3 and high ductility exhibited the best performance as shot peening media in this study.
From the results of X-ray diffraction, transmission electron microscope (TEM) observations and the evaluations of Vickers hardness after heat treatment at 973 K, it was inferred that 0∼4%W media were strengthened by 250∼300 HV due to supersaturated solid solution of B element with αFe phase. In addition, all media with W addition were strengthened due to solid solution of W element with αFe phase.
According to the simulation from the theoretical formula proposed by Ogawa and Asano, it was estimated that the maximum compressive residual stress at carburized steel surface shot peened by 4%W media was approximately 20 MPa higher than that by Base media.
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