日本金属学会誌
Online ISSN : 1880-6880
Print ISSN : 0021-4876
ISSN-L : 0021-4876
72 巻, 1 号
選択された号の論文の11件中1~11を表示しています
  • 中島 謙一, 大菅 広岳, 横山 一代, 長坂 徹也
    2008 年 72 巻 1 号 p. 1-7
    発行日: 2008年
    公開日: 2008/01/01
    ジャーナル フリー
      Approximately 400,000 tons per year of aluminum dross (Al dross) are generated during a melting process of aluminum metal in Japan. The Al dross and the residue, which have high concentration of metallic Al, are mostly used as an Al resource for Al production or as a deoxidizer in the steel industry. On the other hand, the residue with the Al content is less than 20%, is difficult to be recycled and is therefore land filled.
       This paper deals with (1) a material flow analysis (MFA) of the domestic Al dross in order to achieve clear targets for recycling of Al dross and residue, and (2) an environmental assessment of newly developed technologies for its recycling, such as the process of hydrogen production from residue.
       The result of material flow analysis on the domestic Al dross in 2003 shows that 2.344×105 t of aluminum is recovered and 2.150×105 t of residue is generated from the dross. The residue is mostly used in the steelmaking process, whereas 5.0×104 t of residue is landfilled in the final disposal site. As the result of the environmental assessment through the material flow, there is a possibility of reduction of CO2 emission and waste emissions by using residue (Al content: 10%) as a hydrogen resource, which is presently landfilled.
  • 鈴木 崇宣, 横川 忠晴, 小林 敏治, 小泉 裕, 原田 広史, 今井 八郎
    2008 年 72 巻 1 号 p. 8-11
    発行日: 2008年
    公開日: 2008/01/01
    ジャーナル フリー
      A second-generation Co-free Ni base single crystal superalloy, TMS-82C (Ni-0Co-4.9Cr-1.0Mo-8.7W-5.3Al-6.0Ta-2.4Re-0.1Hf, in mass%) was derived from its base alloy, TMS-82+ (Ni-7.8Co-4.9Cr-1.9Mo-8.7W-5.3Al-6.0Ta-2.4Re-0.1Hf, in mass%), which had been successfully engine tested. The absent of Co can eliminate the product of isotope 60Co from radioactive decay, and it can improve the maintainability of the gas turbine engine. However, the removal of Co had decreased the creep strength of TMS-82C. To further improve its creep strength, five additional alloys were designed with the addition of 0.5 mass% Mo, W, Ti, Ta and Re to TMS-82C, respectively. Results indicated that creep properties of all five alloys performed better than that of TMS-82C under 900°C/392 MPa and 1000°C/245 MPa conditions. W-bearing alloy exhibits similar creep property comparing to that of TMS-82+ under the 900°C/392 MPa condition.
  • 梶井 洋, 日比野 敦
    2008 年 72 巻 1 号 p. 12-20
    発行日: 2008年
    公開日: 2008/01/01
    ジャーナル フリー
      In this paper, the effects of the third element (Cr, Mo, and Mn) on the mechanical properties of TiAl intermetallic compound made by combustion synthesis were considered. The powders of Ti, Al, Co, and the third element (Cr, Mo, and Mn) were mixed. The green compact was made from the mixed powder, and was reacted in an electric vacuum furnace. The density, the microstructure, the hardness, and the compressive strength of the obtained synthesized products were investigated. The density of the synthesized products became more than 90% by Co/Al sintering additive. The grain size of them was 20 μm. The components of the synthesized products were TiAl and Ti3Al. As addition quantity of the third element increased, the hardness of them rose and the strength of them fell. The ductility of the synthesized product that added Cr 5% especially is excellent. Further the fracture surfaces of them were discussed.
  • 本郷 和弘, 熊谷 達夫, 木村 博
    2008 年 72 巻 1 号 p. 21-26
    発行日: 2008年
    公開日: 2008/01/01
    ジャーナル フリー
      A nanocrystalline Ti50Al50-20 vol%(PSZ-45 mol%Al2O3) composite is fabricated by pulse current pressure sintering of the mixed powder of mechanically milled Ti-50 mol%Al powder and amorphous PSZ-45 mol%Al2O3 powder. The mechanically milled Ti-50 mol%Al powder and amorphous PSZ-45 mol%Al2O3 powder were prepared by the rotating-arm reaction ball milling system. For the powder of the Ti50Al50 -20 vol%(PSZ-45 mol%Al2O3), we have controlled the process variables of pulse current pressure sintering system such as stress, temperature and current. Then, the lowest consolidation temperature necessary to obtain a full densification of compact under the applied stress of 150 MPa is 1405 K at the surface temperature of compact. The X-ray diffraction method confirmed that the nanocrystallization occurs in an overall cross-section of Ti50Al50-20 vol%(PSZ-45 mol%Al2O3) composite with the crystalline size of 28 nm, 16 nm and 16 nm for γ-TiAl, α-Ti and cubic zirconia solid solution respectively. The composite material shows a high 0.2% proof stress value of 2.5 GPa obtained by compression test at room temperature.
  • 孫 仁俊, 中野 博昭, 大上 悟, 小林 繁夫, 福島 久哲, 堀田 善治
    2008 年 72 巻 1 号 p. 27-34
    発行日: 2008年
    公開日: 2008/01/01
    ジャーナル フリー
      The effect of annealing on the pitting corrosion resistance of anodized Al-Mg alloy processed by equal-channel angular pressing (ECAP) was investigated by electrochemical techniques in a solution containing 0.2 mol/L of AlCl3 and also by surface analysis. The degree of internal stress generated in anodic oxide films during anodization was evaluated with a strain gauge. The ECAP decreased the pitting corrosion resistance of anodized Al-Mg alloy. However, the pitting corrosion resistance was improved by annealing after the ECAP. The internal stress present in the anodic oxide films was compressive, and the stress was higher in the alloys with ECAP than without. The compressive internal stress gradually decreased with increasing annealing temperature. Cracks occurred in the anodic oxide film on Al-Mg alloy during initial corrosion. The ECAP produces high internal stresses in the Al-Mg alloy; the stresses remain in the anodic oxide films, increasing the likelihood of cracks. It is assumed that the pitting corrosion is promoted by these cracks as a result of the higher internal stress resulting from the ECAP. The improvement in the pitting corrosion resistance of anodized Al-Mg alloy by annealing appears to be attributable to a decrease in the internal stresses in anodic oxide films.
  • 末永 竜一, 神田 昌枝, 広中 直人, 岩田 圭祐, 利根川 昭, 西 義武
    2008 年 72 巻 1 号 p. 35-38
    発行日: 2008年
    公開日: 2008/01/01
    ジャーナル フリー
      In order to evaluate the influence of sheet electron beam irradiation (SEBI) with low potential on water absorption in nylon6, the mass of water absorption in nylon6 has been measured. The SEBI decreases the saturated mass of water absorption in nylon6 and also decreases the initial absorption rate of water, as well as the mass of absorbed water in nylon6 for each treatment time. Based on the results of ESR and XPS, the SEBI forms dangling bonds and then decreases the electrical polarization of nylon6 molecules, resulting in decreasing the mass of absorbed water in nylon6.
  • 楠 克之, 田淵 正明
    2008 年 72 巻 1 号 p. 39-42
    発行日: 2008年
    公開日: 2008/01/01
    ジャーナル フリー
      Self-interstitial diffusion in alpha-iron is investigated using an embedded-atom-method potential and molecular dynamics simulations. Curved Arrhenius plot is obtained for the temperature dependence of diffusion coefficients, which is well explained by the superposition of two transition processes among the two allotropic states of self-interstitial defects, the reformation of <110> dumbbell into another <110> configuration and one-dimensional solitonic propagation of a crowdion on <111> axis.
  • 本田 和彦, 潮田 浩作, 山田 亘, 田中 幸基, 畑中 英利
    2008 年 72 巻 1 号 p. 43-50
    発行日: 2008年
    公開日: 2008/01/01
    ジャーナル フリー
      The solidification structure of a hot-dip Zn-11%Al-3%Mg-0.2%Si coated steel sheet with a slight Ti addition was investigated by EBSD. In every center of the primary Al phase of the alloy-coating layer, TiAl3 was observed by a scanning electron microscope, which suggests that TiAl3 acts as a heterogeneous nucleation site of the primary Al phase. The latter was revealed to have perfect lattice coherency with the nucleus TiAl3 phase. The crystal orientation relationships between TiAl3 and the primary Al are {001}TiAl3//{001}Al and <100>TiAl3//<001>Al, {100}TiAl3//{001}Al and <001>TiAl3//<001>Al, {102}TiAl3//{110}Al and <201>TiAl3//<110>Al, {110}TiAl3//{110}Al and <110>TiAl3//<110>Al, indicating that the primary Al phase grows in an epitaxial manner from the nucleus TiAl3 phase. The planar disregistry δ between the two phases was calculated to be less than 5%, owing to this good lattice coherency. The TiAl3 phase is considered to decrease the degree of undercooling necessary for the nucleation of the primary Al phase.
  • 本田 和彦, 山田 亘, 潮田 浩作
    2008 年 72 巻 1 号 p. 51-56
    発行日: 2008年
    公開日: 2008/01/01
    ジャーナル フリー
      The solidification structure of the coating layer in hot-dip Zn-11%Al-3%Mg-0.2%Si coated steel sheet was studied via metallographic examinations together with the calculation of a phase diagram based on Thermo-Calc. The solidification structure observed, which exhibited a combination of the Zn/Al/MgZn2 ternary eutectic structure, the primary Al phase and the MgZn2 phase, turned out to be different from the predicted one under an equilibrium state in the sense that MgZn2 instead of Mg2Zn11 was observed under the present condition. Excluding the Mg2Zn11 phase from the equilibrium phase diagram, the metastable phase diagram was calculated and excellent agreement obtained between the calculation and the experiment in terms of the solidification structure of the coating layer. Consequently MgZn2 is considered to form easily as the metastable structure known as the Laves phase, because the high cooling rate associated with the present experiment does not provide any potential for peritectic-eutectic reactions, which usually occur in the equilibrium state. Furthermore, MgZn2, which has a C14 type Laves structure and a high rate of nucleation in the liquid phase, is considered to cause the preferential Zn/Al/MgZn2 ternary eutectic reactions.
  • 宮部 さやか, 中野 貴由, 石本 卓也, 高野 直樹, 安達 泰治, 岩城 啓好, 小林 章郎, 高岡 邦夫, 馬越 佑吉
    2008 年 72 巻 1 号 p. 57-62
    発行日: 2008年
    公開日: 2008/01/01
    ジャーナル フリー
      Two-dimensional quantitative analysis of microbeam X-ray diffraction (XRD) was performed using a transmission optical system to examine biological apatite (BAp) orientation in an isolated trabecula of a human fourth lumber vertebral body. The incident X-ray beam is 20 μm in diameter, which is small enough for the isolated trabecula despite a slight beam divergence of 0.2°. Integrated intensities of (002) and (310) are obtained separately by different incident angles and detector positions. Distribution of the preferential orientation of the BAp c-axis is finally calculated quantitatively as an integrated intensity ratio of (002)/(310) in a plane containing the trabecular direction.
       Preferential alignment of the BAp c-axis was finally determined to be perfectly parallel to the fiber direction in a rod-shaped trabecula, since accurate one-dimensional alignment is different from the alignment in the femoral cortical bone as a long bone that shows the local maximum of preferential alignment perpendicular to the longitudinal bone axis. For example, the integrated intensity ratio of (002)/(310) has a maximum value of 16 along the trabecular fiber and a minimum value of 0.09 in the perpendicular direction.
       Using this method, the anisotropy of BAp orientation in the trabecular bone can be quantitatively evaluated in the plane including the trabecular fiber. Thus, we successfully obtained a methodology that two-dimensionally analyzes the distribution of the BAp c-axis along all axes within a plane in a bone specimen.
  • 赤堀 俊和, 新家 光雄, 仲井 正昭, 川岸 航, 福井 壽男
    2008 年 72 巻 1 号 p. 63-71
    発行日: 2008年
    公開日: 2008/01/01
    ジャーナル フリー
      Dental Ag-Pd-Cu-Au-Zn system alloy, which is a semi-precious alloy, is one of the most widely used metallic dental materials in Japan due to its excellent mechanical properties and corrosion resistance and applicability to health insurance. Dental products, e.g., inlays and crowns, fabricated from this alloy are used under cyclic loading conditions including frictional wear, when it comes in contact with the same or other dental materials in the oral cavity or an opposing tooth during mastication. The effects of microstructures of Ag-20 mass%Pd-14.5 mass%Cu-12 mass%Au-2 mass%Zn alloy on the fretting-fatigue properties are, therefore, investigated in this study.
       The fretting-fatigue strength of the Ag-20 mass%Pd-14.5 mass%Cu-12 mass%Au-2 mass%Zn alloy subjected to solution treatment (ST) and aging treatment (AT) decreases significantly as compared to the fatigue strength without fretting (plain-fatigue strength). Moreover, the fretting-fatigue strength after the AT decreases by approximately 60% as compared to that after the ST, especially in the high-cycle fatigue life region. Several traces of fretting wear are observed to be distributed in the slip region of both materials. These wear traces are generated due to the accumulation of wear debris on the fretting pad or the fretting fatigue specimen. These traces of fretting wear are distributed more closely in the slip region of the AT material. Therefore, the fatigue life decreases significantly because the fretting fatigue crack initiation life and the propagation life decrease in the AT material.
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