巻号一覧
70 巻, 8 号
選択された号の論文の26件中1～26を表示しています
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福本 倫久, 工藤 紗織, 原 基, 成田 敏夫2006 年 70 巻 8 号 p. 607-610
発行日: 2006年
公開日: 2006/08/22
ジャーナル フリーThe formation of coating layer of a Ni aluminide containing La on a Ni-10 at%Cr-8 at%Al alloy substrate was tried by the electrodeposition of La, Ni and Al. The cyclic oxidation resistance for the alloys covered with the coating was then evaluated. Ni was deposited by aqueous solution electrolysis. La and Al were deposited by molten salt electrolysis. For the sample treated with the Ni and Al depositions, a layer consisting of Ni2Al3 was uniformly formed. On the other hand, for the sample treated with the La deposition for 0.6 ks, followed by the Ni and Al depositions, a Ni-rich layer and a Ni2Al3 layer were formed in that order from the substrate alloy. Further, when electrodeposition time of La became long to 1.2 and 1.8 ks, a La-rich layer, a Ni-rich layer and a Ni2Al3 layer were formed in that order from the substrate alloy. The cyclic oxidation test showed that for the untreated sample and the sample with Ni and Al depositions, the mass reduction due to exfoliation of a scale took place. However, for the sample treated with La deposition for 0.6 and 1.2 ks, followed by the Ni and Al depositions, mass reduction was not observed. For this sample after the cyclic oxidation test, a scale consisting of α-Al2O3 adhering to the substrate was formed. Consequently, it was found that a cyclic oxidation resistance of the alloy was improved by the La, Ni and Al electrodepositions.
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山末 英嗣, 中島 謙一, 奥村 英之, 石原 慶一2006 年 70 巻 8 号 p. 611-614
発行日: 2006年
公開日: 2006/08/22
ジャーナル フリーThe number of discarded home electric appliances CRT TV (CRT), liquid-crystal display TV (LCD), plasma display panel TV (PDP), refrigerator, air conditioner, washing machine, microwave oven, cleaner, video cassette recorder (VCR) and (DVD) has been estimated using a population balance model. For the estimations of CRT and VCR, the effects of alternative products (LCD and PDP, and DVD, respectively) were considered. The increasing rates of the estimated number of the discarded refrigerator, the washing machine and the cleaner from 2000 to 2020 were within 5%, while those of air conditioner and microwave oven were more than 30%. The estimated number of shipped CRT and VCR were in good agreement with those of statistic values, indicating the reasonability of the estimated number of discarded LCD, PDP and DVD. As an application of the estimated data, the amount of indium included in the discarded display panel of LCD and PDP was calculated.
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田中丸 天兵, 松岡 範佳, 竹内 光明, 松村 義人2006 年 70 巻 8 号 p. 615-617
発行日: 2006年
公開日: 2006/08/22
ジャーナル フリーSm-Fe thin films as giant magnetostrictive materials were prepared by d.c. magnetron sputtering process with Ar or mixed N2-Ar sputtering gas. In X-ray diffraction patterns of the film prepared by 2.3 vol% N2-Ar as sputtering gas, diffraction peaks of SmN and Fe2N where observed. With increasing N2 gas amount, saturated magnetostriction of the Sm-Fe thin films decreased from 1400 ppm to 600 ppm. The maximum value of magnetostrictive susceptibility was showed at the film prepared by 1.0 vol% of N2-Ar gas. The film prepared by pure Ar gas showed compressive stress with 0.5 GPa. Sm-Fe thin films prepared by mixed N2-Ar gas showed about 0.7 GPa of compressive stress. Increasing of magnetostrictive susceptibility of films prepared by N2-Ar gas due to reduce of perpendicular magnetic anisotropy energy.
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中島 謙一, 中村 愼一郎2006 年 70 巻 8 号 p. 618-621
発行日: 2006年
公開日: 2006/08/22
ジャーナル フリーMaterial Flow Analysis (MFA) has been widely used to identify and trace the flow of materials and substances. Within the frame work of the Waste Input Output (WIO) model (Nakamura and Kondo, JIE, 2002), we have developed a new methodology of MFA, the Waste Input-Output Material Flow Analysis, reported elsewhere (WIO-MFA) (Nakamura and Nakajima, Materials Trans., 2005). In this study, the methodology is applied for the purpose of analyzing the material cycle of iron and steel in Japan. First, we discuss issues of data that we developed for estimating the WIO-MFA table with 395 sectors, and then proceed to the estimation of the metal composition of specific products. Our major concern is the composition of recycled Fe components in the products.
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森田 真英, 松岡 範佳, 村松 幸之助, 竹内 光明, 松村 義人2006 年 70 巻 8 号 p. 622-625
発行日: 2006年
公開日: 2006/08/22
ジャーナル フリーThe magnetostrictive characteristics of Fe-Al alloy thin films formed by an ion plating process were evaluated. An Fe-40 at%Al film showed α-Fe(b.c.c.) structure, although the Al content exceeded the solubility limit. Those results may be caused by a non-equilibrium condition with rapidly quenching of metal plasma gas phase to solid phase peculiar to ion plating process. The thin film of Fe-40 at%Al alloy prepared by ion plating showed higher magnetostriction than a film of pure Fe.
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菊川 久夫, 淺香 隆, 三宅 真人2006 年 70 巻 8 号 p. 626-629
発行日: 2006年
公開日: 2006/08/22
ジャーナル フリーTo precisely determine the mechanical properties of bone, the effects of preservation on these properties need to be minimized. It seems probable that prolonged exposure to formalin or saline will have some effect on the mechanical properties of bone. This study investigated the effects of formalin preservation on the fracture toughness of bovine femoral cortical bone (Haversian bone and plexiform bone) including the eluted bone mineral concentrations in the preservative solution. The periods of formalin preservation were 30 and 150 days. To confirm anisotropic properties, two different specimens were used: circumferential and radial specimens with initial fissures in the lateral cross section were examined. The fracture toughness tests were performed using three point bending specimens at a crosshead speed of 1 or 20 mm/min. It was confirmed that the fracture toughness of the bone decreased, with the highest figure showing a 30% reduction in fracture toughness when formalin preservation was employed. The fracture toughness reduction rate was higher in the plexiform bone sample at a crosshead speed of 20 mm/min. The eluted Ca concentration from the specimen in saline was higher than that in formalin. Thus, preservative aqueous solutions such as saline were shown to significantly dissolve bone mineral.
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山中 俊佑, 川崎 亮, 坂元 宏規, 馬久地 裕, 久野 昌樹, 塚田 高行2006 年 70 巻 8 号 p. 630-633
発行日: 2006年
公開日: 2006/08/22
ジャーナル フリーCarbon nanotube (CNT) has excellent feature like low density, high strength, and high thermal conductivity. The metal-based CNT composite is expected as a light and high strength material or the heat radiation material for the application to automobile and aircraft parts, etc. Such that the development of CNT-metal matrix composite is gaining wide research attention. Since CNTs are easy to agglomerate, however, it is difficult to disperse them into a metal matrix homogeneously. To overcome these problems, in this study, CNT-Nickel matrix composite was fabricated by using hetero aggregation and spark plasma sintering method.
Slurry precursors with homogeneously dispersed CNT were obtained, with optimum in amount of ethanol. The composites were densified up to more than 99% of relative density by sintering these precursors. Additionally, dispersion and orientation of CNTs were verified by FE-SEM observation of microstructure. The thermal conductivity of the composite was increased by about 10% or less at room temperature. Thermal anisotropy were indicated.
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安藤 新二, 池尻 幸繁, 飯田 直美, 津志田 雅之, 頓田 英機2006 年 70 巻 8 号 p. 634-637
発行日: 2006年
公開日: 2006/08/22
ジャーナル フリーThe fatigue crack propagation behavior of pure magnesium single crystals has been investigated in laboratory air at room temperature. Two types of CT specimens with different notch orientations were prepared from the magnesium single crystal made by the Bridgeman technique. Fatigue crack propagation behaviors of each specimen were different related to notch orientation. In the case of C-specimen with (1010)[0001] notch, a crack was inclined to (0001) gradually at low ΔK. To investigate crack propagation behavior along [0001], a tri-crystal specimen in which has (1010)[0001] notch was prepared. A crack propagated to [0001] in this specimen and the fatigue surface shows striation-like pattern. In the case of E-specimen with (0001)[1010] notch, a crack propagates parallel to basal plane. {1012} twin occurred in front the crack at higher ΔK level. A fatigue surface of the E-specimen was changed by {1012} twin formation.
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森 久史, 伊藤 暁, 辻村 太郎2006 年 70 巻 8 号 p. 638-641
発行日: 2006年
公開日: 2006/08/22
ジャーナル フリーThis paper presented the results of application of super hydrophilicity TiO2 coating on Shinkansen vehicle. Also effect of metalic powder on hydrophilicity of TiO2 coatings was investigated. It was found that durability of protection from dirt adhesion was less than five months in real vehicle tests. The reason of degradation on protection was due to the contamination of metal powders produced by abrasive wear on the coating surface. Accordingly, it was considered that the degradation of hydrophilicity was attributed to the metal powder on the interface between TiO2 and water.
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中田 隼矢, 駒崎 慎一, 中島 基樹, 幸野 豊, 谷川 博康, 芝 清之, 香山 晃2006 年 70 巻 8 号 p. 642-645
発行日: 2006年
公開日: 2006/08/22
ジャーナル フリーReduced activation ferritic/martensitic steels (RAFs) are one of the leading candidates for structural materials of fusion reactors. Since there are severe limitations on specimen capacity at material irradiation testing facilities, it is required to use miniaturized specimens. In the previous study, it was revealed that the small punch (SP) creep test was useful technique for evaluating the creep rupture strength of RAFs. If this SP test technique was applicable to the measurement of not only the creep properties but also the high-temperature tensile properties, it would have an important meaning from the standpoints of designing and developing more superior fusion reactor materials. In this study, the SP test were carried out at 823~923 K to investigate the applicability using two representative RAFs, JLF-1 and F82H. The experimental results revealed that the load at initial localized plastic straining, Fy, and the maximum load, Fmax, determined by the SP test were well correlated with the yield strength, σy, and the ultimate tensile strength, σB, respectively. The empirical linear correlation between the Fy and the σy was expressed by σy=1.5Fy+19. Similarly, there was an almost linear correlation between the Fmax and the σB represented by σB=0.37Fmax+86. Consequently, the high-temperature tensile properties of the RAFs can be also estimated by the SP test and the above empirical equations.
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及川 奨, 増田 進吾, 松村 義人, 西 義武2006 年 70 巻 8 号 p. 646-649
発行日: 2006年
公開日: 2006/08/22
ジャーナル フリーA three-layered composite mover device constructed with both hydrogen storage La-Ni and compressive magnetostrictive Sm-Fe alloy thin films on each side surface of polyimide substrate has been prepared by using a flash vacuum evaporation and a direct current magnetron sputtering, respectively. When the motion strain is about -750 ppm at ±400 kA/m of magnetic field before hydrogenation, it is about -1150 ppm after hydrogenation. The hydrogenation of the La-Ni alloy film in the three-layered composite mover device enhances the magnetostriction.
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増田 進吾, 松村 義人, 西 義武2006 年 70 巻 8 号 p. 650-653
発行日: 2006年
公開日: 2006/08/22
ジャーナル フリーFe2.4Sm alloy thin films have been prepared by using a direct current magnetron sputtering process at different substrate temperatures from 323 K to 523 K under 0.5 Pa-argon gas pressures. All films prepared shows above 800 ppm. A magnetostriction and its magnetostrictive susceptibility have been strongly affected by the morphology change of the thin film. The giant magnetostriction values above 1000 ppm and high magnetostrictive susceptibility are obtained in homogeneous Fe2.45Sm amorphous alloy film deposited on a silicon substrate of 323 and from 403 to 473 K.
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高橋 啓介, 松村 義人, 西 義武2006 年 70 巻 8 号 p. 654-657
発行日: 2006年
公開日: 2006/08/22
ジャーナル フリーComposite mover device constructed with both positive and negative magnetostrictive thin films on each side surface of copper substrate are prepared by direct current magnetron sputtering process. The magnetic field induced the mover strain (apparent magnetostriction) of composite mover film at 1200 kA/m of magnetic field is 1800 ppm and is two times larger than the sum of magnetostriction values of Fe-Pd positive and Fe-Sm negative magnetostrictive thin films.
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常木 達也, 白崎 義則, 安田 勇2006 年 70 巻 8 号 p. 658-661
発行日: 2006年
公開日: 2006/08/22
ジャーナル フリーWe are developing hydrogen permeable membranes for application to a membrane reformer. In this study, we have studied hydrogen permeability of palladium-copper (Pd-Cu) alloys that show β-phase in certain composition and temperature ranges in the binary phase diagram. Three compositions of Pd-Cu alloys were prepared: Pd-30 mass%Cu, Pd-40 mass%Cu and Pd-45 mass%Cu. All these alloys were rolled to foils of 100 microns thickness, and only the Pd-40 mass%Cu alloy was re-rolled to 20 microns thick. As a result of X-ray diffraction analyses, the Pd-30 mass%Cu and Pd-40 mass%Cu membranes showed mostly α-phase, while the Pd-45 mass%Cu showed β-phase mixed with minor α-phase at room temperature. Hydrogen permeability of the membrane samples was measured in the temperature range of 350-600°C with 0.1-0.3 MPa hydrogen pressure difference. The permeability of both Pd-30 mass%Cu and Pd-45 mass%Cu were about one order of magnitude lower than that of Pd-23 mass%Ag, and it was found to monotonously increase with increasing temperature. The permeability of Pd-40 mass%Cu also increased with temperature to 1.2×10-8 mol•m-1•s-1•Pa-1/2 at 450°C, but it drastically decreased over 500°C. And different permeability was obtained at the same temperature of 450 °C after different treatments: hydrogen introduction at 450°C and hydrogen introduction at 350°C followed by heating to 450°C. This suggests that crystal structure and condition of phase transition change by the presence of hydrogen in the crystal or solid solubility of hydrogen in this alloy. It was also found that the existence of β-phase was important to give the highest hydrogen permeability of Pd-Cu alloy.
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堀田 英樹, 千葉 雅史, 久慈 俊郎, 内田 裕久2006 年 70 巻 8 号 p. 662-665
発行日: 2006年
公開日: 2006/08/22
ジャーナル フリーMg-Fe bcc alloys were synthesized by mechanical alloying under argon atmosphere. The bcc lattice parameters of synthesized alloys with composition less than 15 mol% of Mg were expanded. It suggests that larger Mg atoms were dissolved into the Fe bcc lattice. Lattice parameter of bcc decreased with higher Mg composition, from 20 mol% to 50 mol%. The results from SEM and TEM images implied that Mg and Fe were separated when increasing Mg concentration. As the result, the bcc lattice parameter relaxed to nearly that of pure iron.
P-C isotherms of MgxFe1-x(x=0-0.5) were determined at 523 K. It was found that plateau pressures decreased with the increasing Mg composition. In this study, the Mg-Fe alloys with different compositions were synthesized and their hydrides stability was discussed from viewpoints of both “interstitial size effect” and “metal-hydrogen inter-atomic bonding”.
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佐藤 彰洋, 葉 安洲, 小林 敏治, 原田 広史2006 年 70 巻 8 号 p. 666-669
発行日: 2006年
公開日: 2006/08/22
ジャーナル フリーAdvanced Ni-base single crystal superalloys for turbine blade applications are precipitation strengthened by coherent γ′ phase; the particle size and the evolution of its morphology during creep can depict deformation behaviours. A primary ageing is often applied to the alloy after the solution heat treatment to control the γ′ size and refine the precipitates into regular/cuboidal shape for optimal mechanical properties. During turbine blade manufacturing, the primary ageing is combined with coating cycles. The present article examines the effects of primary ageing on a 4th and a 5th generation superalloys, TMS138A and TMS-196, respectively. Experimental observations indicated that alloys treated with 1100°C/4 hours condition could retain the coherency between the precipitates and the matrix, while 1150°C or above would result semi-coherent microstructures. During creep at 1000°C/245 MPa, pre-crept coherent microstructures led to formations of fine/continuous raft for best creep resistance; by contrast, pre-crept partially-coherent microstructures evolved into coarse/discontinuous raft. The effect of pre-crept coherency appeared to be less significant for both alloys during creep at 900°C/392 MPa, when the driving force of microstructural evolution would be lower.
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横川 忠晴, 小泉 裕, 小林 敏治, 原田 広史2006 年 70 巻 8 号 p. 670-673
発行日: 2006年
公開日: 2006/08/22
ジャーナル フリーTo improve the creep strength of Ni-base superalloys, Re and Ru additions were investigated with using 2nd generation single crystal superalloy TMS-82+ which contains 2.4 mass%Re, as the base alloy.
When Re and Ru were added at the same time, creep strength was improved at lower and higher temperature. We suppose that these were caused by the solution strengthening due to Re at lower temperature, and the stabilization of γ/γ′ structure at higher temperature by Ru addition. Further more, in the case of Re addition, creep strength at lower temperature was improved, and creep strength at higher temperature became worse due to the TCP phase formation. Also, in the case of Ru addition, creep strength at lower and higher temperature became worse, although TCP phase formation was completely suppressed. This is because Ru is not an effective element for the solution strengthening at high temperature.
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伊津野 仁史, 横川 忠晴, 原田 広史2006 年 70 巻 8 号 p. 674-677
発行日: 2006年
公開日: 2006/08/22
ジャーナル フリーWe have proposed a new creep constitutive equation of Ni-base superalloys with good reproductibility and predictivity under the conditions of high temperature-low stress and intermediate temperature-intermediate stress. In this paper, an application of the creep constitutive equation for low temperature-high stress condition (800°C/735 MPa) is discussed. It is said that at low temperature-high stress condition, a Ni-base superalloy has different deformation mechanism from the condition of higher temperature-lower stress. A good reproducivility for each creep curve with applying the creep constitutive equation has achieved. Although this good reproducivility, the result of multi regression analysis for each parameter of the creep constitutive equation with composition and strucutural parameters point out that it is different tendency from higher temperature-lower stress conditions.
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北嶋 具教, 原田 広史, 村雲 岳郎, 川岸 京子2006 年 70 巻 8 号 p. 678-681
発行日: 2006年
公開日: 2006/08/22
ジャーナル フリーIn order to develop new superalloy which can reach higher temperature capabilities beyond Ni-base superalloys, Ni-Al and Ni-Al-Ta superalloys were mixed with a Rh-Nb refractory superalloy which has a higher γ/γ′ eutectic of about 1900°C, and the phase relationships of the Ni-base and Rh-Nb superalloy mixtures were investigated. Three phases of fcc, L12-Ni3Al and B2-AlRh were determined in the alloys of (Rh-17 at%Nb alloy) : (Ni-15.8 at%Al-6.5 at%Ta alloy)=20 : 80 molar proportion at 1300°C. Four phases of fcc, L12-Ni3Al, L12-Rh3Nb and B2-AlRh were confirmed in the alloys of (Rh-17 at%Nb alloy) : (Ni-15.8 at%Al-6.5 at%Ta alloy)=20 : 80 molar proportion at 1100°C. The detected phases of (Rh-17 at%Nb alloy) : (Ni-22 at%Al alloy)=50 : 50 molar proportion both at 1100°C and 1300°C are fcc, L12-Rh3Nb, D022-((Ni, Rh)3Nb) and B2-AlRh. The above three-phase equilibrium system of fcc, L12-Ni3Al and B2 may be applicable to EQ (Equilibrium) bond coat system, since Al in B2 phase has a good oxidation resistance.
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北嶋 具教, Jincheng Wang, 原田 広史2006 年 70 巻 8 号 p. 682-685
発行日: 2006年
公開日: 2006/08/22
ジャーナル フリーThe size, morphology and dispersion of γ′ precipitates affect the creep behaviors of Ni-base single-crystal superalloys. Phase-field modeling is powerful tool to predict such microstructure evolution. In this research, the Gibbs-free-energy function of γ and γ′ phases in the ternary Ni-Al-Cr system with a four-sublattice model was introduced to extend the phase-filed simulation of γ/γ′-microstructure-evolution to the ternary system. The values of γ/γ′-phase-compositions were in good agreements with the estimation of Dupin's CALPHAD method.
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川岸 京子, 佐藤 彰洋, 小林 敏治, 原田 広史2006 年 70 巻 8 号 p. 686-689
発行日: 2006年
公開日: 2006/08/22
ジャーナル フリーThe oxidation properties of the 5th generation Ni-base Superalloys, TMS-173 and TMS-196 were investigated comparing with 2nd generation superalloy, PWA-1484. Isothermal oxidation examination was performed at the temperatures from 1023 K to 1373 K in air for up to 3.6×106 s, and the oxides formed on the specimen surface during oxidation tests were identified by using XRD analysis and SEM cross section observation.
TMS-173 formed thick NiO layer on the surface caused by the outward diffusion of Ni at 1023 K and showed poor oxidation resistance at 1173 K and 1373 K due to the spinel formation. TMS-196 and the 2nd generation superalloy PWA-1484 show protective Al2O3 layer formation and excellent oxidation resistance at all temperatures examined in this study. This favorable result was caused by their high Cr content.
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川岸 京子, 佐藤 彰洋, 小林 敏治, 原田 広史2006 年 70 巻 8 号 p. 690-693
発行日: 2006年
公開日: 2006/08/22
ジャーナル フリーA new and stable bond coat system, EQ coating, which is in equilibrium thermodynamically with γ/γ′ substrate, suppresses the diffusion of alloying elements between the substrate and coating, and the formation of secondary reaction zone(SRZ). In this study, β phase is proposed as the candidate for oxidation-resistant EQ coating material based on its high Al content. γ/γ′ superalloy for the substrate material and γ, γ′ and β phase alloys for the coating materials which are in equilibrium were designed by using thermodynamic calculation and EDX technique in Ni-Co-Cr-Al-Hf-Mo-Ta-W system. Cyclic oxidation examination and diffusion experiment for the alloys developed were performed and the suitability of the β phase coating for EQ bond coat is discussed. Creep strength property was examined for the developed γ/γ′ single-crystal superalloy.
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加古 謙司, 太田 丈児, 黛 正己2006 年 70 巻 8 号 p. 694-699
発行日: 2006年
公開日: 2006/08/22
ジャーナル フリーThe mechanism of material hardening in the heat affected zone (HAZ) induced by TIG welding was investigated by performing tensile tests at elevated temperature and by performing Vickers hardness tests in the HAZ of high-purity Fe-18Cr-16Ni alloys and SUS316L. The results show that dynamic strain aging appears in SUS316L and Mo/P/C-doped high-purity Fe-18Cr-16Ni alloys at 773 K, that the plastic strain with dynamic strain aging at 773 K hardens materials much more than the plastic strain at 293 K, and that the dynamic strain aging is one factor that affects material hardening in HAZ.
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松岡 三郎, 長島 伸夫2006 年 70 巻 8 号 p. 700-708
発行日: 2006年
公開日: 2006/08/22
ジャーナル フリーThe nano-meso-macro strength analysis of fine- and coarse-grain low-carbon steels fatigued at the total strain amplitudes between 0.4 and 2% was conducted using an ultra-micro, micro and Vickers hardness testers and TEM. The coarse-grain steel cyclically hardened, while the fine-grain steel was cyclically stable. The fatigue strength for the fine-grain steel was superior to that for the coarse-grain steel. TEM observations showed that the dislocation cell was formed in the coarse-grain steel. The cell size decreased from 1.1 to 0.75 μm with increasing the total strain amplitude from 0.4 to 2%. On the other hand, the fine-grain steel showed the new dislocation structure. The 1 μm-fine ferrite grain was maintained under cyclic straining. Hardness measurements showed that the virgin and fatigued coarse-grain steels had the different indent-size dependence of the hardness and that the virgin and fatigued fine-grain steels had the unique indent-size dependence of the hardness. The results of TEM observations and hardness measurements explained that the coarse-grain steel cyclically hardened and the fine-grain steel was cyclically stable. Furthermore, the high hardness value, derived from grain-size strengthening in the ferritic steel, explained the superior fatigue strength in the fine-grain steel. The fine grain strengthening hardness due to the ferrite with the size of 1 μm in the fine-grain steel was higher than that due to the dislocation cell with the size of about 1 μm in the coarse-grain steel. The higher hardness in the fine-grain steel was due to the fact that the resistance against the dislocation motion is stronger for ferrite grain boundaries than for dislocation cell boundaries, resulting in the higher fatigue strength.
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荒島 裕信, 橋 邦彦, 久保 和也, 伊藤 秀明, 兜森 俊樹, 大西 敬三2006 年 70 巻 8 号 p. 709-714
発行日: 2006年
公開日: 2006/08/22
ジャーナル フリーThe purpose of this study is to increase the rechargeable hydrogen storage capacity of Titanium-Chromium-Vanadium (Ti-Cr-V) body-centered cubic (BCC) solid solution alloy by making a uniform alloy with high crystallinity and homogeneity on the nano-scale. The samples were prepared by a melt-quenching method, and the effects of this method on the BCC alloy were investigated using X-ray diffraction, optical and electron microscopies, and a pressure-composition-temperature (P-C-T) analyzer. It was found that the quenched alloy had highly crystalline, sub-micron scale crystals and a high dislocation density compared with the arc-melted alloy. As a result, the plateau in the P-C-T characteristics became a steep slope with large hysterisis. The quenched alloy was heat-treated to improve this plateau. This caused an increase in the grain size and a decrease in the dislocation density of the alloy; however, its high crystallinity was retained. The heat-treated alloys had a high maximum and rechargeable hydrogen storage capacity and a flat plateau in their P-C-T characteristics. As a result, the rechargeable hydrogen storage capacity reached 2.56 mass% in the pressure region of 0.1-4.5 MPa at 293 K.
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福井 紘一郎, 竹田 真帆人, 遠藤 孝雄2006 年 70 巻 8 号 p. 715-719
発行日: 2006年
公開日: 2006/08/22
ジャーナル フリーThe influence of excess Si on the precipitation behaviour in an Al-Mg-Si alloy was studied by means of Vickers microhardness tests, high-resolution transmission electron microscopy (HRTEM) and differential scanning calorimetry (DSC). The metastable-phase precipitates formed during isothermal ageing up to the time to peak hardness were investigated from the viewpoints of the morphology, the density of precipitates and the change in the exothermic heat caused by the formation of precipitates in the DSC measurements. The changes in the density of precipitates and the exothermic heat with excess Si at peak ageing time showed a similar tendency to that of the peak hardness curves. Before the formation of the β′, three exothermic peaks of the metastable-phase precipitates appeared in the DSC curves of the alloy specimens isothermally aged for a short time. It was revealed that the formation of precipitates, which were named as Type-1, -2 and -3 in this work, corresponded to the three exothermic peaks.
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