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77 巻, 11 号
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中川 時子, 長澤 允彦, 金児 紘征2013 年 77 巻 11 号 p. 479-488
発行日: 2013年
公開日: 2013/11/01
ジャーナル フリーThe galvanic characteristic of a Fe-Zn couple was investigated in aerated 0.1 mol/L NaHCO3 solution at 298 K. Two galvanic couples, one external and the other internal, were used: the former was formed by connecting Fe and Zn by a wire lead external to the solution and the latter by electroplating Zn on a part of the Fe. Fe in the externally-connected Fe-Zn couple was not corroded for a short immersion period, and the galvanic potential showed a value of about −1.0 V vs. Ag•AgCl. This potential was near to the open-circuit potential of uncoupled Zn. When the galvanic potential drifted and maintained a value of about −0.75 V, Fe was corroded although Fe was still cathodic and Zn was anodic. Finally, the corrosion of Fe was slightly accelerated due to that Fe became anodic and Zn cathodic. The galvanic potential displayed almost no change for the remaining duration of the experiment.
Uncoupled Fe itself maintained the open-circuit potential of about −0.2 V and was not corroded as a result of the presence of a protective layer. On the other hand, the uncoupled Fe was corroded when cathodically pretreated followed by being under open-circuit. The open-circuit potential showed about −0.75 V. These measurements show that a protective layer on Fe of the coupled specimen is destroyed cathodically by the existence of Zn, and that Zn does not work well to prevent corrosion of Fe in NaHCO3 solution. The corrosion characteristic of the internal couple was essentially similar to that of the external one but that of the former was more complex due to inhomogeneous pH distribution on the surface, especially near the Fe/Zn boundary.
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中野 博昭, 山口 拓人, 山田 遥平, 大上 悟, 孫 仁俊, 堀田 善治, 古賀 弘毅2013 年 77 巻 11 号 p. 489-496
発行日: 2013年
公開日: 2013/11/01
ジャーナル フリーThe effects of reducing the grain size by high-pressure torsion (HPT) on the pitting corrosion resistance of Al-Fe alloys with Fe contents of 0.5, 2, and 5 mass% were investigated by means of polarization curves in solutions containing 0.1 mol•dm−3 Na2SO4 and 8.46 mmol•dm−3 NaCl (300 ppm Cl−) at 298 K and by surface analysis. The potentials for pitting corrosion of the Al-Fe alloys were clearly shifted to the noble direction by HPT, leading to an improvement in pitting corrosion resistance. This improvement was larger in the Al-0.5%Fe and Al-2%Fe alloys and smaller in the Al-5%Fe alloy. The Al-Fe alloys contained precipitates of Al-Fe intermetallic compounds, around which pitting corrosion occurred. The Al-5%Fe alloy, in particular, contained large precipitates tens of micrometers in size, and pitting corrosion was significant around these large precipitates. It is evident from the time-dependence of the corrosion potential and the polarization resistance of the corrosion reaction that the formation rate of Al oxide films increases as a result of HPT. It was therefore concluded that the improvement in pitting corrosion resistance of the Al-Fe alloys with HPT is caused by increasing the oxidation rate of Al.
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関戸 健治, 北薗 幸一2013 年 77 巻 11 号 p. 497-502
発行日: 2013年
公開日: 2013/11/01
ジャーナル フリーClosed-cell superplastic Zn-22Al eutectoid alloy foams were manufactured through the melt foaming process using titanium hydride powder as a foaming agent. Foaming tests were carried out under different foaming temperatures, times and additive amounts of foaming agent. Maximum porosity of 75% and small pore diameter were obtained during the temperature range of semi-solid condition from 738-753 K. This is because of increased melt viscosity. Though the small amount of the foaming agent is effective to decrease the pore diameter, the porosity becomes low. Cell morphology of the present Zn-22Al alloy foam is identical to conventional aluminum foams. Semi-solid condition of Zn-22Al foam has an advantage over increasing melt viscosity on manufacturing of metal foam.
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田代 優, 門田 裕行, 伊藤 雅彦, 村中 誠志, 大貫 仁2013 年 77 巻 11 号 p. 503-508
発行日: 2013年
公開日: 2013/11/01
ジャーナル フリーIn order to apply high-purity plating process using high purity plating materials (anode and electrolyte) to practical use, the influence of phosphorus impregnated ultra-high purity Cu anode on the particle pollution and Cu wiring resistivity in the 8 inch wafer processes has been investigated. Black film formed on the phosphorus impregnated ultra-high purity 99.999999 mass% (8 N) anode prevents the emission of fine particles from anode to electrolyte, resulting in the formation of low resistivity narrow Cu wires.
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石山 新太郎, 馬場 祐治, 藤井 亮, 中村 勝, 今堀 良夫2013 年 77 巻 11 号 p. 509-513
発行日: 2013年
公開日: 2013/11/01
ジャーナル フリーTo testify thermal stability of the BNCT neutron target synthesized by in-situ lithium deposition and ion implantation, laser heating test of the Li3N/Li/Cu tri-layered target was conducted in high vacuum chamber of 10−6 Pa and thermal stability of the tri-layered target was characterized by X-ray photoelectron spectroscopy. Following conclusions were derived; (1) The Li3N/Li/Cu tri-layered target with very low oxide and carbon contamination was synthesized by in-situ lithium deposition and ion implantation techniques without H2O and O2 additions, (2) The starting temperature of evaporation of the Li3N/Li/Cu tri-layered target increased by 120 K compared to that of the Li/Cu target, and (3) Frequent repair synthesis of the damaged Li3N/Li/Cu tri-layered target caused by evaporation is possible.
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玉木 裕和, 北澤 留弥, 吉田 誠, 堀部 進2013 年 77 巻 11 号 p. 514-521
発行日: 2013年
公開日: 2013/11/01
ジャーナル フリーFor S45C carbon steel with three heat treatments, pulsating tension tests were carried out under controlled stress condition. The effect of compressive pre-strain, Bauschinger effect and controlling factors on fatigue life were examined. The following results were obtained. The decrease of pulsating fatigue life was caused by three factors, i.e. increase of the total plastic strain amplitude, cyclic plastic strain amplitude and cyclic creep rate. The increase of Bauschinger strain led to the increase of the value of the three factors. Then it resulted in shorter fatigue life. In order to examine the cyclic stress conditions to the fatigue life, the stress ratio was defined as the ratio of maximum cyclic stress to yield stress of each material. Bauschinger strain was occurred when the stress ratio was under the threshold for each material. As the result, cyclic plastic strain amplitude and cyclic creep rate were increased and then pulsating fatigue life was reduced.
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藤原 弘, 川畑 健志, 宮本 博之, 飴山 惠2013 年 77 巻 11 号 p. 522-526
発行日: 2013年
公開日: 2013/11/01
ジャーナル フリーTi-Al alloy demonstrates high strength in high-temperature environments. Thus, the Ti-Al alloys are expected in an application as high temperature materials. However, the Ti-Al alloys demonstrate limited ductility at room temperature. Harmonic-structured materials with a network fine grain structure and a dispersed coarse grain structure show high strength and sufficient ductility at room temperature. In addition, a composite of different materials is also effective in improving both strength and ductility. Therefore, the harmonic-structured composite with pure titanium (Ti) and Ti-48 mol%Al alloy (Ti-48Al) were fabricated by the combination of the mechanical milling (MM) and the spark plasma sintering (SPS) process. The harmonic-structured composite consists of a fine grained network Ti-Al alloy and a dispersed coarse grain Ti region. The XRD result reveals that the harmonic-structured composite is composed of Ti, TiAl, and Ti3Al phases. The harmonic-structured composite demonstrates high strength and sufficient ductility compared with the conventional compact consisting of only Ti-48Al. Advanced ductility of the harmonic-structured composite is attributed to an obstruction of the crack propagation by the dispersed coarse grain region. After heat treating the Ti/Ti-48Al harmonic-structured composite, its hardness decreased to much lesser than that of the pure Ti compact.
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谷田 芳夫, 松井 大治, 西山 文隆, 福島 博, 杉尾 健次郎, 佐々木 元2013 年 77 巻 11 号 p. 527-536
発行日: 2013年
公開日: 2013/11/01
ジャーナル フリーChromium molybdenum (Cr-Mo) layers electrodeposited with organic sulphonic acid as catalyst have lower friction coefficient. The purpose of this report is to understand the low friction mechanism focusing on both nano-structures and hydrogen configuration in electrodeposited layer. The Cr-Mo plated layers were characterized by XRD, TEM, PALS and ERDA. The TEM observations revealed that nano-voids were dispersed in crystal grains of chromium and the size of nano-voids was in the same order with that predicted by PALS. The study on interaction between void and hydrogen by first-principles showed that voids containing hydrogen shorten positron lifetime. These results suggest that hydrogen does not exist in nano-voids. However existence of hydrogen was confirmed in electrodeposited layer by analysis of ERDA. This should probably show the state of hydrogen atoms trapped by vacancies existing stably in electrodeposited layer. During electrodeposition, two hydrogen atoms trapped by mono vacancy diffuse in crystal grain and gather together to form clusters on (110) plane in Cr-Mo layers, which have the ability to weaken interaction force between (110) planes. As a result, sliding along (110) planes was considered to take place easily, lowering the friction coefficient of Cr-Mo layers.
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中間 一夫, 龍谿 翔, 杉田 一樹, 白井 泰治2013 年 77 巻 11 号 p. 537-542
発行日: 2013年
公開日: 2013/11/01
ジャーナル フリーFe-36 mass%Ni alloy, also known as invar alloy, is widely used for precision parts where dimensional change with temperature elevation needs to be minimized. Thermal expansion behavior of the alloy differs by annealing conditions after plastic forming processes; thermal expansion coefficient (TEC) below TC anomalously increases with annealing temperature and reaches a maximum when annealed at 500℃, followed by a decrease to TEC in solution-treated condition when annealed at over 650℃. Neither crystallographic anisotropy nor lattice defects, both of which are introduced by cold deformation, affects the anomalous increase of TEC, since the recrystallization temperature does not coincide with 500℃ and positron lifetime measurement for the sample annealed at the temperature after solution-treatment does not show any emergence of defects. Considering an increase in TC of the sample annealed at 500℃ and a resemblance to the behavior of higher Ni-containing Fe-Ni alloy, this phenomenon might derive from inhomogeneous distribution of Ni atoms resulting in an increase in Fe-Ni pairs by annealing in the temperature range.
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赤堀 俊和, 大口 友里恵, 服部 友一, 安井 利明, 福本 昌宏, 福井 壽男, 新家 光雄2013 年 77 巻 11 号 p. 543-549
発行日: 2013年
公開日: 2013/11/01
ジャーナル フリーThis study investigated the effect of the friction stir process (FSP) on the mechanical properties and microstructure of biomedical beta-type titanium alloy, Ti-29Nb-13Ta-4.6Zr (TNTZ), and Ti-6Al-4V ELI (Ti64), which is one of representative biomedical alpha/beta type titanium alloy used in practical applications.
The surface layer of TNTZ subjected to FSP was composed of severely deformed and heat-affected zones with a large amount of precipitated fine alpha phases or relatively coarse beta phases. On the other hand, the surface layer of Ti64 was comprises almost entirely of a heat-affected zone with relatively small acicular alpha and beta phases in the prior beta phase. Vickers hardness of TNTZ and Ti64 subjected to FSP showed the highest value at the very edge of the specimen surface and decreased significantly with increasing depth from the surface. The trend in the change of Young's modulus of TNTZ and Ti64 subjected to FSP was approximately the same as the change in the Vickers hardness. The tensile strength of TNTZ subjected to FSP increased by around 100 MPa when compared to that of as-solutionized TNTZ. The elongation, however, showed a reverse trend. The change in the tensile properties of Ti64 subjected to FPS was small.
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