巻号一覧
72 巻, 9 号
選択された号の論文の23件中1～23を表示しています
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齋藤 繁, 黒川 一哉, 高島 敏行, 成田 敏夫2008 年 72 巻 9 号 p. 639-643
発行日: 2008年
公開日: 2008/09/01
ジャーナル フリーCompositions with tie-lines between the σ and (γ, γ′, β) phases in a quaternary Ni-Al-Re-Cr system were investigated by heat-treating various quaternary Ni-Al-Re-Cr alloys in vacuum at 1423 K for a variety of heating times up to 2750 h. The microstructures of the Ni-Al-Re-Cr alloys that had been water-quenched after heating were observed and their Ni, Al, Re, and Cr concentration profiles were measured using an electron probe micro-analyzer (EPMA). It was found that a very long heat treatment was required to obtain equilibrium compositions of Ar-arc-melted Ni-Al-Re-Cr alloys.
The tie-lined compositions (at%) of each phase at 1423 K were experimentally determined as follows. The σ phase tie-lined with the γ phase (73.5Ni, 14.6Al, 2.9Re, and 9.0Cr) consists of 56.7Re, 25.0Cr, 18.1Ni, and 0.2Al. The σ phase tie-lined with the γ phase (70.5Ni, 14.3Al, 2.0Re, and 13.2Cr) has 47.7Re, 36.2Cr, 15.9Ni, and 0.2Al. The σ phase tie-lined with the γ′ phase (73.6Ni, 21.0Al, 1.2Re, and 4.2Cr) consists of 58.3Re, 25.0Cr, 16.6Ni, and 0.1Al. The σ phase tie-lined with the β phase (50.2Ni, 48.7Al, 0.3Re, and 0.8Cr) consists of 61.1Re, 32.5Cr, 5.2Ni, and 1.2Al. The σ phase tie-lined with the β phase (65.1Ni, 29.5Al, 0.4Re, and 5.0Cr) consists of 45.8Re, 39.3Cr, 14.6Ni, and 0.3Al.
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坂本 有卯幾, 徳永 仁夫, 藤田 和孝, 張 偉, 木村 久道, 井上 明久2008 年 72 巻 9 号 p. 644-647
発行日: 2008年
公開日: 2008/09/01
ジャーナル フリーFracture toughness of the Cu-Zr-Ti bulk metallic glass (Former Cu-Zr BMG) under plane-strain condition could not be evaluated because the BMG with a sufficient thickness for the plane strain condition had not been fabricated. However, as the fracture morphology was similar to that in the Zr-based BMGs having the large plane-strain fracture toughness (KIC), e.g. about 50 MPa•m1/2, it was presumed that the Former Cu-Zr BMG has a large KIC. Recently, in Cu-Zr-Ag-Al BMG (New Cu-Zr BMG), a large sample of 25 mm in diameter became possible to be made. Therefore, in this study, KIC of the New Cu-Zr BMG was investigated. The New Cu-Zr BMG plate sample of Cu36Zr48Ag8Al8 was made by a copper mold casting method. Tensile strength was 1850 MPa and Young's modulus was 115 GPa. Compact type specimen with 2.3 mm in thickness and 9.2 mm in width was used. Fatigue pre-crack was induced under stress intensity factor range (ΔK) less than 6 MPa•m1/2, and the fracture toughness test was conducted at a loading rate of 1 MPa•m1/2•s-1. The new Cu-Zr BMG exhibited a KIC of 17 MPa•m1/2. The former Cu-Zr BMG that could not satisfy the plane-strain condition exhibited a fracture toughness of 62 MPa•m1/2. The stretched zone width along the inner fatigue crack front and vein pattern size on the unstable fracture surface in the new Cu-Zr BMG were smaller than those of the former Cu-Zr BMG. Therefore, it seems that the KIC of the new Cu-Zr BMG is smaller than that of the former Cu-Zr BMG.
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村上 浩二, 岡野 雅子, 日野 実, 高見沢 政男, 仲井 清眞2008 年 72 巻 9 号 p. 648-656
発行日: 2008年
公開日: 2008/09/01
ジャーナル フリーGeneration and growth of whiskers and nodules from electroplated tin and tin-lead films on copper or nickel substrate were studied by scanning electron microscopy and X-ray diffraction. In the case of copper substrate, whiskers generated in 0.3 Ms on the electroplated tin film whose thickness was 1 μm. On the other hand, electroplated tin-lead film on copper substrate showed only nodules even after 13 Ms. Residual stress of electroplated tin film (1 μm) and the number of whiskers increased with the amount of copper-tin intermetallic compounds (Cu6Sn5) which developed between the plated film and the substrate of copper. Although residual stress and the amount of Cu6Sn5 also increased in the tin-lead system, the morphology of the layer of Cu6Sn5 was more uniform compared with the case of tin electroplated film on copper substrate. When the electroplated tin-lead film was subjected to the compression testing by a ball of zirconium oxide (1 mm-diameter, 2.94 N-0.605 Ms), the edge of the indentation did not show any whiskers but diffusion of lead was observed from right under the zirconium oxide ball to the fringe, as well as Ostwald growth of lead. In the case of electroplated tin film on nickel substrate, whose residual stress was weakly tensional, nickel-tin intermetallic compounds (Ni3Sn, Ni3Sn2, Ni3Sn4) uniformly developed immediately after electroplating, and no whiskers were observed even after the compression testing. While growth of whiskers is considered to be due to diffusion of tin atoms induced by inhomogeneous strain field in the electroplated film, lead atoms in tin-lead system is considered to diffuse rapidly toward the free surface to release residual stress and to generate many nodules.
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—bcc FeΣ3(111)粒界における溶質元素の偏析と脆化および強化効果—山口 正剛2008 年 72 巻 9 号 p. 657-666
発行日: 2008年
公開日: 2008/09/01
ジャーナル フリーThe microscopic mechanism of the grain boundary embrittlement in metals by solute segregation has been not well understood for many years. From first-principles calculations, we show here that the calculated cohesive energy (2γint) of bcc iron Σ3(111) symmetrical tilt grain boundary is reduced by the segregation of sulfur (S) or phosphorous (P), while it is increased by the segregation of boron (B) or carbon (C). The rate of the decrease/increase in the 2γint was excellently proportional to the experimental ductile-to-brittle transition temparature (DBTT) shift with increasing segregation; this demonstrates that the grain boundary embrittlement is governed by the change in the 2γint.
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川村 貴人, 砂田 聡, 近藤 勝義, 能登谷 久公, 真島 一彦2008 年 72 巻 9 号 p. 667-673
発行日: 2008年
公開日: 2008/09/01
ジャーナル フリーIt is well known that Mg alloys are the excellent candidates for the use in automotive, aerospace and electronic industries because of their low density and excellent strength to weight ratio. In this study, their corrosion behavior under applied stress has been investigated by the slow strain rate tensile test (SSRT) and electrochemical impedance spectroscopy test (EIS) for their practical use. AZ31B Mg alloy sample showed good mechanical properties under cathodic polarized condition. It was also confirmed that both the fracture and corrosion behavior under applied stress were closely related to the formation and destruction of the protective film.
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成田 健吾, 新家 光雄, 仲井 正昭, 赤堀 俊和, 織部 一弥, 田村 貴志, 小塚 慎治, 佐藤 静磨2008 年 72 巻 9 号 p. 674-678
発行日: 2008年
公開日: 2008/09/01
ジャーナル フリーInstalling a spinal fixture using implant rods is one of the effective operations for spinal diseases. Most of the implant rods are made of Ti-6Al-4V ELI alloy (Ti64). However, some problems regarding the Ti64 rod have been pointed out; it contains vanadium, which is considerably toxic to the human body, and exhibits a much higher Young's modulus than that of the cortical bone. Ti-29Nb-13Ta-4.6Zr alloy (TNTZ) developed by the authors exhibits good biocompatibility due to its nontoxic- and allergy-free elements, and has a lower Young's modulus than that of Ti64. In addition, the mechanical properties of TNTZ can be changed drastically according to various heat treatments. The mechanical properties of TNTZ rods subjected to various heat treatments have been investigated in this study.
The as-solutionized TNTZ rod consists of a single β phase. Isothermal ω phase and α phase precipitate in the β phase of the TNTZ rod aged at 673 K for 259.2 ks. Only α phase precipitates in the β phase of the TNTZ rod aged at 723 K for 259.2 ks. Tensile strength and 0.2% proof stress become larger in order of as-solutionized TNTZ rod, TNTZ rod aged at 723 K for 259.2 ks and TNTZ rod aged at 673 K for 259.2 ks, while elongation is smaller in order of as-solutionized TNTZ rod, TNTZ rod aged at 723 K for 259.2 ks and TNTZ rod aged at 673 K for 259.2 ks. Young's modulus become larger in order of as-solutionized TNTZ rod, TNTZ rod aged at 723 K for 259.2 ks and TNTZ rod aged at 673 K for 259.2 ks.
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國則 正弘, 菊川 久夫, 淺香 隆, 粕谷 平和2008 年 72 巻 9 号 p. 679-685
発行日: 2008年
公開日: 2008/09/01
ジャーナル フリーBone specimens used for evaluating the mechanical properties of bone have not necessarily been preserved by the same method before they become available. However, the mechanical properties of bone may be influenced by freezing, a common preservation method, as well as by formalin and other preservation solutions. In this study, bone specimens were preserved by different methods (freezing, physiological saline solution, ethanol, formalin and neutral buffered formalin) to examine the effects of preservation method on the fracture characteristics of bovine femoral cortical bone. Regarding the crack extension behavior in the fracture toughness test, microcracks accumulated at the top of the slit in the low load region before the maximum load was reached. When such accumulated microcracks grew to a visible size, a crack was formed from the top of the slit, and then grew with subsequent expansion of the processing zone. The fracture toughness values of the groups preserved in formalin and neutral buffered formalin were significantly lower than those of other preservation groups. As the fracture surface by SEM observations was smoother with a loading rate of 20 mm/min than 1 mm/min, cracks were considered to develop easily, resulting in a lower fracture toughness value. SEM observations of a test section subjected to a low loading rate showed that the fracture surface of the groups preserved in formalin or neutral buffered formalin was flat and smooth. In the other preservation groups, the lamellae adjacent to the top of the slit had undulating fracture surface, with plastic deformation produced.
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吉年 規治, 三浦 彩子, 董 偉, 川崎 亮2008 年 72 巻 9 号 p. 686-692
発行日: 2008年
公開日: 2008/09/01
ジャーナル フリーMetallic glasses are potentially applied for accurate micro parts because of their good formability and transferability as well as high mechanical properties and excellent magnetic properties. So the raw materials that the volume is precisely controlled are needed for a highly accurate processing. In this study, mono-sized spherical particles of Fe-Co-based metallic glass were prepared by Pulsated Orifice Ejection Method (POEM) and the capabilities of their micro-forming process in the glass transition temperature were investigated.
Mono-sized spherical particles of Fe-Co-based metallic glass particles with 200-500 μm of diameter have been obtained by Pulsated Orifice Ejection Method (POEM). The XRD pattern of the particles shows only broad peaks without any crystalline peak. A bright field TEM image of the particles and the selected area diffraction patterns shows only halo patterns that indicate fully amorphous phase. DSC curve shows that supercooled liquid region was ΔT=48 K and a TTT curve can be constructed by isothermal DSC.
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丹羽 陽亮, 戸高 義一, 梅本 実, 山名 啓太, 木下 恭一, 谷澤 元治2008 年 72 巻 9 号 p. 693-697
発行日: 2008年
公開日: 2008/09/01
ジャーナル フリーFirst-principles calculation revealed that Na atoms were expected to be primarily located Mg sites in Mg2Si. Densities of electronic states of the Na-doped Mg2Si showed p-type. To obtain a good p-type thermoelectric material, Na-doped Mg2Si (Mg66.7-xSi33.3Nax) were fabricated by solid-liquid reaction using spark plasma sintering. The X-ray diffraction experiments showed that the prepared samples were composed of a single Mg2Si phase. Electrical resistivity, ρ, and Seebeck coefficient, α, were measured in the temperature range from room temperature to around 600 K for samples with various Na contents. The α of samples in the Na composition range of x≥0.5 were positive values (p-type). The results of first-principles calculation and experiment showed that Na was employed as acceptor in Mg2Si system. The maximum power factor of 0.44×10-3 W•m-1•K-2 was obtained at 313 K for the Mg65.7Si33.3Na1.0 sample.
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永井 傑朗, 赤羽 智明, 篠嶋 妥, 大貫 仁2008 年 72 巻 9 号 p. 698-702
発行日: 2008年
公開日: 2008/09/01
ジャーナル フリーCu is now commonly used for wires in LSI because of high conductivity and EM resistance. However, voids are frequently produced at the bottom of the Cu wire during heat treatment process and wire breaking occurs. To clarify the origin of the defect production process at the atomistic level, we have performed molecular dynamics simulation. The focus of the present study is how the difference of crystal orientation affects on the stability of Cu ultra-fine-wire structure. Cu atoms with fcc structure were placed in the wire form surrounded by rigid Ti walls. Three different orientations of Cu wire were examined: (111) stacked on the bottom, on the side wall and parallel to the wiring direction. The isothermal annealing was at 300-900 K and the compression strain of the buried wire was 0-4%. It was found that the wire structure with (111) stacked parallel to the front of the drain is most unstable. Therefore the controlling crystal orientation is shown to be one of the key technologies for the next generation wiring process.
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藤田 晋伍, 加藤 量裕, 高山 新司2008 年 72 巻 9 号 p. 703-707
発行日: 2008年
公開日: 2008/09/01
ジャーナル フリーDilute Cu-TM alloy films (TM=Ni, Ti, Mn, Zn, Mg) were investigated in order to develop interconnect lines with low resistivity, high thermal stability and high adhesion to a glass substrate for the installation of an advanced thin film transistor (TFT)-liquid crystal display (LCD). We found that among these added impurities, Zn showed the lowest resistivity 2.8 μΩcm by adding less than 1 at% on annealing above 350°C. Most of these dilute Cu alloy films except for Cu-Zn and Cu-Mn alloys show the formation of thermally grown hillocks on annealing above 300°C. It was also found that the dilute Cu-Zn alloy films showed the highest adhesion to a glass substrate among present alloy systems. The high resolution EDS analysis of the cross section of the films after the 400°C anneal shows not only a large segregation of Zn atoms at the interface between film and glass substrate, but also a relatively high concentration of Zn atoms at both free surface and grain boundaries. However, any precipitation of oxides, such as ZnO was not observed at the interface between film and glass substrate by using a high resolution cross-section TEM analysis. We conclude from these results that the segregation of Zn atoms in Cu alloy systems plays a large role not only to increase an adhesion to a glass substrate, but also suppress the formation of hillocks at elevated temperatures.
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諸星 圭祐, 小澤 俊平, 田川 俊夫, 日比谷 孟俊2008 年 72 巻 9 号 p. 708-713
発行日: 2008年
公開日: 2008/09/01
ジャーナル フリーSurface tension of molten silver was measured by oscillating droplet method using an electromagnetic levitation under Ar/He gas atmosphere with oxygen partial pressure PO2 of 1×102 Pa and Ar-5%H2/He-5%H2 gas atmosphere with the H2O content of 2.6 ppm. We succeeded in the measurement at a wide temperature range of 500 K including undercooling condition of the melt. The surface tension of molten silver can be described by the following equations; σ=984-0.298(T-1234) [mN/m] under Ar-5%H2/He-5%H2 atmosphere and σ=698+0.546(T-1234) at PO2 of 1×102 Pa. Influence of oxygen partial pressure on surface tension of high temperature melt was theoretically discussed.
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蒔田 晃司, 田中丸 天兵, 竹内 光明, 内田 裕久, 松村 義人2008 年 72 巻 9 号 p. 714-718
発行日: 2008年
公開日: 2008/09/01
ジャーナル フリーSm27Fe73 films fabricated by a magnetron sputtering were studied with respect to magnetism and plasma physics. A new parameter ‘Pi’ was proposed to evaluate effects of ion bombardment for a magnetostriction. The Pi is represented as Pi=(i/a)•(2mi Ei)1/2, here i is ion flux, a is material flux, mi is the ion mass and Ei is the ion energy. The plasma parameter was determined by Langmuir probes. As a result, the inplane magnetic anisotropy was enhanced by increasing of the Pi. Increase of the Pi induced an increase of magnetostrictive susceptibility and a decrease of saturated magnetstriction. This is probably caused by a change of internal stress accompanied with the Pi.
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篠辺 潔, 森田 真英, 中村 翔, 松村 義人2008 年 72 巻 9 号 p. 719-721
発行日: 2008年
公開日: 2008/09/01
ジャーナル フリーIon-plating (IP) process is a kind of vacuum evaporation process. In this study, Bunshah's triode type ion plating system was used for the film preparation. In this process dense plasma flux (~2.5 A) of ionized source materials can be dosed and deposited on a substrate. The flux of the source vapor is ionized by thermal electrons accelerated from melted evaporant to a positive electrode so called “probe”. Excess energy of vapor particles is able to control by applied bias voltage of “probe”. Fe has no Mg solid solution phase in equilibrium phase diagrams. In this study, Fe-Mg thin films were prepared by an IP process. Investigated the relation between crystal structure and excess energy of particles with bias voltage. In all samples, α-Fe body-centered cubic structure was observed by X-ray diffraction patterns. The lattice distortion changed with a change in applied bias voltage. These results were suggested that the excess energy of vapor particles was inputted more than the mixing enthalpy of Fe and Mg. At the same time lattice distortion energy in Fe increased with increasing Mg content. Film structures of samples were dependent on the kinetic energy of evaporated vapor particles changed by bias voltage.
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城田 明典, 徳永 仁夫, 藤田 和孝, 横山 嘉彦, 木村 久道, 井上 明久2008 年 72 巻 9 号 p. 722-727
発行日: 2008年
公開日: 2008/09/01
ジャーナル フリーBulk metallic glasses (BMGs) have many unique mechanical properties, e.g. extremely high strength and bending ductility. However, very limited data are reported on tensile ductility on BMGs. Recently there has been interest in strain rate dependence of fracture behavior in BMGs, such as fracture strength, plastic deformation and shear band formation. Meanwhile, we indicated that a hypoeutectic Zr-Cu-Al BMG shows longer and many shear bands and higher fracture toughness than a eutectic Zr-Cu-Al BMG. In this study, tensile test on a hypoeutectic Zr-Cu-Al BMG is performed under several different strain rates. Effect of strain rate on the mechanical properties such as tensile strength and Young's modulus are investigated. Also, it is ascertained whether the tensile plastic elongation in the hypoeutectic Zr-Cu-Al BMG occur or not. The hypoeutectic Zr-Cu-Al BMG is fabricated by an arc-tilt casting method. Chemical composition is Zr60Cu30Al10 at%. Tensile test is carried out under several strain rates. As a result, it was found that Young's modulus, tensile strength and elastic strain are about 90 GPa, 1700 MPa and 2%, respectively. Also the tensile specimen fractured with the shear plane inclined 52-55 degree for the loading axis. All these values were independent on the strain rate. Under any strain rate, the tensile plastic elongation did not occur and the multiple shear bands were not observed in the specimen surface.
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泉 岳志, 吉岡 隆幸, 成田 敏夫2008 年 72 巻 9 号 p. 728-732
発行日: 2008年
公開日: 2008/09/01
ジャーナル フリーThe oxidation behavior of a fourth generation Ni-based single crystal superalloy with diffusion barrier coating system was investigated under thermal cycling conditions at 1100°C. The coating consisted of outer Pt-modified β-NiAl with and without inner σ- Re-W-Cr-Ni diffusion barrier. After 100 one-hour oxidation cycles β-NiAl was retained on the diffusion barrier coated sample. However, in the non-barrier Pt-modified β-NiAl sample the Al reservoir changed to γ′-Ni3Al. Also without the diffusion barrier a secondary reaction zone (SRZ) formed extensively. The σ- Re-W-Cr-Ni diffusion barrier proposed in this study effectively suppressed Al and Pt diffusion toward the substrate, and also reduced diffusion of alloying elements into the Al reservoir.
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水野 愛, 廣崎 龍児, 篠田 哲守, 大塚 寛治, 清宮 義博2008 年 72 巻 9 号 p. 733-738
発行日: 2008年
公開日: 2008/09/01
ジャーナル フリーElastic and mechanical properties have been measured on an in-situ type AlN/Al composite which is synthesized by the “solid-liquid reaction method”, developed by the present authors. The 0.2% offset proof stress and Young's modulus of the composite increases with increasing volume faction of AlN. The 0.2% offset proof stress of this composite is considerably larger than that of commercial aluminum alloy A7075 in the temperature range from R.T. to 700°C. The existence of aluminum boride in the composite, if its quantity attains to several tens of vol%, probably works to lower Young's modulus of the composite, while small amounts of void in the composite, if it is as small as a few vol%, does not influence so badly.
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大上 悟, 中野 博昭, 倉井 大輔, 福島 久哲, 中村 克昭, 増田 正孝2008 年 72 巻 9 号 p. 739-744
発行日: 2008年
公開日: 2008/09/01
ジャーナル フリーAl-Mg alloys treated by continuous rotation evolutional control (CREO) were anodized and colored by means of AC electrolysis at 10 V in sulfate solutions of 303 K containing Cu, Sn, Ni or Co. The anodized Al-Mg alloys were colored rufous (Cu), yellow to gold (Sn), or red brown (Ni and Co) by the electrolysis. The lightness of the colored Al-Mg alloys was significantly enhanced by CREO, regardless of the metals deposited. The gloss of the Al-Mg alloys decreased-probably due to an increase in surface waviness resulting from CREO. The enhancement of the lightness of colored Al-Mg alloys treated by CREO is attributed to the decrease in the glossiness. SEM images showed that the density of the micro-pores in anodic oxide films on Al-Mg alloys decreased as a result of CREO. The decrease in the density of the micro-pores may be assumed to have enhanced the lightness of the colored Al-Mg alloys treated by CREO.
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平本 貴則, 杉山 真悟, 石森 康浩, 不破 章雄2008 年 72 巻 9 号 p. 745-750
発行日: 2008年
公開日: 2008/09/01
ジャーナル フリーUsing the basic solution made of Bi(NO3)3•5H2O(4.0×10-3, 4.5×10-3, 5.0×10-3, 6.0×10-3, 7.0×10-3 kmol•m-3), TeO2: (3.0×10-3 kmol•m-3) and nitrilotriacetic acid (NTA: 0.1 kmol•m-3) at pH 9.5, electrochemical deposition of stoichiometric, crystalline Bi2Te3 film was carried out at various potential of -0.6, -0.7 and -0.8 V. The experimental results obtained are as follows;
(1) Electrochemical experimental condition for crystalline Bi2Te3 film deposition is as follows: the basic solution containing Bi(NO3)3•5H2O(5.0×10-3 kmol•m-3), TeO2(3.0×10-3 kmol•m-3) and NTA(0.1 kmol•m-3) at pH 9.5 and deposition potential of -0.6 V.
(2) Various thermoelectric power properties such as semi-conductor type, electro-conductivity, Seebeck factor and power factor have been measured and evaluated for the crystalline Bi2Te3 and other Bi-Te deposited films, as deposited and after heat-treated. It has been shown those properties of the heat-treated crystalline Bi2Te3 film has similar or superior thermo-electric properties with those made by MOCVD or a acidic solution process.
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山田 勝利, 井島 清, 篠原 嘉一, 原田 幸明2008 年 72 巻 9 号 p. 751-757
発行日: 2008年
公開日: 2008/09/01
ジャーナル フリーThe research was made on how ecomaterials have been developed and are used currently in Japan. All the information was obtained from the web-sites 2001-2005 year version environmental reports of over two hundred and sixty companies mainly with more than 5000 employees and listed on Japanese stock markets. The researched ecomaterials were classified into the six categories proposed by Japanese “Ecomaterials Forum”. The number of ecomaterials nearly doubled between 2001 and 2003, and has been on the yearly increase ever since. Each industry is considered to have its individual problems to tackle and has developed its peculiar ecomaterials in response to such problems and requirements year by year. Moreover, many remarkable achievements in eco-products, eco-systems and ecological techniques utilizing ecomaterials are proudly shown in the environmental reports. The spread of these ecomaterials and eco-products will be quite effective for the saving of energy and also contribute greatly to the improvement of environment. Meanwhile, given the use of a large quantity of resources in these days, it is necessary for us to pay attention to and conduct researches into environmental problems including preventive measures against exhaustion of rare resources from a broader perspective and a bird's-eye view approaches.
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鈴木 良祐, 北薗 幸一2008 年 72 巻 9 号 p. 758-762
発行日: 2008年
公開日: 2008/09/01
ジャーナル フリーMetal foams are attractive materials for thermal insulators because of their low thermal conductivity. Coefficient of thermal expansion (CTE) of metal foams is the same as that of cell wall materials. Therefore, the effect of thermal stress induced by a change in CTE, which is severe in the thermal barrier coating by ceramics, becomes negligible. In this study, we focus on designing metal foams as thermal insulators. The effect of porosity and pore shape on the thermal conductivity was calculated by micromechanical analysis. It was revealed that oblate spheroidal pores are effective to decrease the thermal conductivity. Micromechanical analysis also revealed that the thermal conductivity can be controlled by pore distribution of the metal foam. That is, metal foam with graded porosity has low thermal conductivity compared to uniform porosity. A diffusion-bonding process enabled to manufacture 5083 aluminum alloy preforms containing TiH2 particles as a foaming agent. Foaming test by directional heating enabled to manufacture closed-cell 5083 aluminum alloy foams having both oblate spheroidal pores and graded pore distribution.
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小林 純一, 伊藤 聰2008 年 72 巻 9 号 p. 763-768
発行日: 2008年
公開日: 2008/09/01
ジャーナル フリーPhase equilibria and the activities of the components in indium-antimony-oxygen ternary system have been investigated at temperature of 1173 K to discuss the recovery of indium and antimony from used InSb compound semiconductors. Using the activities of indium and antimony in the indium-antimony binary system reported in literature, the equilibrium partial pressures of oxygen were calculated by applying the Gibbs-Duhem equations to the phase relation of metal-oxide equilibrium. The vapor pressures of indium, antimony and antimony oxide, Sb4O6, were then calculated. It was found that the vapor pressure of antimony was much larger than the values of indium and antimony oxide except in the vicinity of pure antimony composition, indicating that antimony might preferentially vaporize in remelting of used InSb compound semiconductors for recycling. This suggests that change in InSb composition may occur. However, the equilibrium partial pressure of oxygen calculated indicates that the indium oxide is stable compared to antimony oxide, Sb2O3. Then the melting experiment of InSb compound was conducted under the condition of simulated air atmosphere. The indium oxide film formed was observed on the metal surface and it prevented vaporization of antimony. Consequently, the recycling of InSb compound semiconductor can be expected by remelting in an oxidation atmosphere like air without a change in InSb composition.
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土田 紀之, 守本 芳樹, 岡本 尚士, 深浦 健三, 原田 泰典, 上路 林太郎2008 年 72 巻 9 号 p. 769-775
発行日: 2008年
公開日: 2008/09/01
ジャーナル フリーTo investigate the role of stress-induced martensitic transformations in the TRIP effect, stress-strain curves and TRIP effects in two types of metastable austenite steel (JIS-SUS304 and JIS-SUS301L) were compared. In static tensile tests, the tensile strength (TS) of SUS301L steel was larger than that of SUS304, and the 0.2% proof stress and uniform elongation (U.El) were both similar for the two steels. The transformation rate and strength of martensite in the stress-induced martensitic transformation were compared by X-ray diffraction and Vickers hardness tests. At the same strain, SUS301L contained a larger volume fraction of martensite than did SUS304. Both steels showed similar values of the Vickers hardness. The difference between SUS301L and SUS304 is mainly due to the transformation rate of stress-induced martensite. The effects of the transformation rate and martensite strength on the TS/U.El balance in metastable austenite steels were demonstrated by means of the Weng secant method, based on a micromechanical model.
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