材料
Online ISSN : 1880-7488
Print ISSN : 0514-5163
ISSN-L : 0514-5163
50 巻 , 6 号
選択された号の論文の18件中1~18を表示しています
  • 幸島 元彦, 三浦 精
    2001 年 50 巻 6 号 p. 559-565
    発行日: 2001/06/15
    公開日: 2009/06/03
    ジャーナル フリー
    Peculiar deformation accompanied by band having 46% strain was observed in the [001] oriented Fe-30%Cr alloy single crystal. Specimen was again deformed after ageing at 473K for 30min. at the 23.5% strain. Second Luders band started from the opposite side of the chuck. From the surface observation of the side surface of the specimen, the propagation speed, width and the strain rate in the band were determined. The mobile dislocation density in the band was also estimated to be about 2×108cm/cm3. The effective and internal stress were determined during the straining in order to analyze the mechanism of deformation.
  • 山口 克彦, 高倉 章雄, 今谷 勝次, 岡本 俊明
    2001 年 50 巻 6 号 p. 566-571
    発行日: 2001/06/15
    公開日: 2009/06/03
    ジャーナル フリー
    When polycrystalline metals are subjected to inelastic deformation, inhomogeneous deformation is induced in the individual crystal grains. In the present paper, the effects of temperature and loading type on this inhomogeneous deformation with plastic strain are examined experimentally using aluminium sheet specimens with coarse crystal grains. It is shown that for the uniaxial tension at room temperature the strain at the inside of grain is slightly larger than that at the grain boundary, while for the creep test at the temperature of 175°C the strain at the grain boundary becomes dominant. The surface roughness developments for these cases are closely related to such a deformation behaviour at the grain and the grain boundary.
  • 大村 勝, 吉田 尚弘
    2001 年 50 巻 6 号 p. 572-577
    発行日: 2001/06/15
    公開日: 2009/06/03
    ジャーナル フリー
    Inhomogeneous material, tri-axial deformation of especially powder sintered materials and metal composite material was analyzed. The materials model proposed it as the materials which became the materials center from the thing which had spherical pore or the second phase. The admissible velocity fields in the matrix is assumed and the upper bound approach is attempted. The yield surfaces for various volume fraction Vf was obtained as a change of ellipsoids for increase of Vf.
    Furthermore, the strength and deformation behavior of powder sintered materials and the metallic composite materials are investigated by the upper bound approach in relation to the volume fraction Vf of the second-phase particles, and the yield strength ratio and bond strength between the constituents, and the shape of the particles and pore.
  • 陸 偉, 冨田 佳宏
    2001 年 50 巻 6 号 p. 578-584
    発行日: 2001/06/15
    公開日: 2009/06/03
    ジャーナル フリー
    To estimate the deformation behavior of rubber-blended glassy polymers, a computational method has been established with newly developed constitutive equation for glassy polymer and homogenization method. The parametric study has been performed through series of simulation of deformation behavior for the plane strain glassy polymer unit cell containing inclusion with different volume fraction, size, and different distribution pattern subjected to different directional loading. The effect of these parameters on the characteristic feature of the deformation resistance, the onset and propagation of shearband, the normal stress distribution on the interface of matrix and inclusion and the maximum mean stress inside the inclusions have been clarified. The results indicate that depending on these parameter, quite different types of shear bands appear and propogate. The decrease of the macroscopic yield stress is attributalbe to the onset of the shearband which connects the most neighboring particles. The macroscopic deformation behavior exhibits nearly isotropic for the case with different sized inclusions. The maximum normal stress appears at the position where the shear band arrived and it moves with the propagation of shear band. The maximum mean stress increases as the shearband is sharpened.
  • 沢田 和秀, 八嶋 厚, 岡 二三生
    2001 年 50 巻 6 号 p. 585-592
    発行日: 2001/06/15
    公開日: 2009/06/03
    ジャーナル フリー
    In the present paper, a Cosserat type elasto-viscoplastic Cosserat model for clay is proposed with couple stress and characteristic length scale. The model is applied to the numerical analysis of strain localization water saturated clay by FEM. In the FE analysis, Biot type of mixture theory was adopted to formulate governing equations. Two types of numerical analyses were conducted. One is the analysis of the behavior under the simple shearing and the other is analysis for the clay specimen with imperfection under the plane strain compression conditions. It was found that the strain rate and the characteristic length scale greatly affect the shear strength and stiffness. In addition, it was found that there is a critical value of characteristic length scale over which the numerical results does not depend on the length scale. The introduction of characteristic length scale into the analysis diminishes the mesh size dependency.
  • 小寺 秀俊, 島 進, 北原 治倫
    2001 年 50 巻 6 号 p. 593-597
    発行日: 2001/06/15
    公開日: 2009/06/03
    ジャーナル フリー
    The effect of the relative density of magnetic powder on particles' rotation in an applied magnetic field during compaction is studied. For producing permanent magnets, magnetic powder is compressed in a magnetic field to impart a high residual strength for magnetization. The magnetic particles are aligned in the magnetic field, and the magnetic powder is subjected to plastic deformation during compression. The magnetic particles are forced to rotate and transform both by the mechanical force and magnetic force. Although it is commonly known that the relative density of the powder affects the rotation and deformation of the constituent particles, a quantitative study of the effect of powder density on the particles' alignment has not been undertaken with a view to application for designing the compaction process in magnetic field. In this study, we carry out magnetic powder compaction in magnetic field after pre-compression without a magnetic field. We also calculate the particles' alignment by the magnetic Cosserat continuum theory. Both the calculated and experimental results show the dependency of the particles' alignment on the relative density at which the magnetic field is applied.
  • 福本 学, 吉崎 正敏, 今高 秀樹, 岡村 一男, 山本 憲司
    2001 年 50 巻 6 号 p. 598-605
    発行日: 2001/06/15
    公開日: 2009/06/03
    ジャーナル フリー
    The simulation system to evaluate the deformation during the carburized quenching process is developed, using the commercial FEM code “ABAQUS”. In this system, carburizing process and phase transformation kinetics are introduced by coding the constitutive relations into user subroutines available in ABAQUS, so as to simulate coupling effects of temperature, stress and metallic structure during the quenching process. And also, transformation plasticity and incomplete transformation of bainite are taken into account. For calculating phase transformations during continuous cooling, the additivity rule based on the isothermal transformation (IT) data is employed. If IT diagrams are not available enough to calculate transformation kinetics appropriately at any location of carburized work, they can be estimated from CCT diagram by a simple treatment proposed in this paper. The quenching process of Cr-Mo steel and Boron steel helical gear is studied with this system. The gear is partially modeled applying the cyclic symmetry constraint (MPC type CYCLSYM) in order to reduce the calculation time and to improve the accuracy. Calculated results are compared with the experimental measurements.
  • 若杉 隆, 門口 卓矢, 大田 陸夫
    2001 年 50 巻 6 号 p. 608-612
    発行日: 2001/06/15
    公開日: 2009/06/03
    ジャーナル フリー
    Li2O-SiO2 glasses were heat-treated under various conditions for nucleation and were employed for DTA measurement to evaluate their nucleation behavior. Crystallization peak temperature, TC of 33Li2O-67SiO2 and 30Li2O-70SiO2 glasses showed a minimum at 460°C and it is found that TC is a good measure for the number density of nuclei. On the other hand, TC of 40Li2O·60SiO2 and 36Li2O·64SiO2 glasses did not show a minimum because the growth rate of crystal during the heat-treatment was so large at temperatures above 460°C that TC tended to decrease. In order to evaluate the nucleation behavior quantitatively from TC, the relationship between TC and the number density of nuclei in 33Li2O·67SiO2 glass which had been heat-treated for various lengths of time at different temperatures was obtained. A single correlation curve was obtained between TC and the number density of nuclei. Using this relationship, variation of the number density of nuclei for 33Li2O-67SiO2 glass with heat-treatment time at a given temperature (460°C) can be evaluated.
  • 坂本 清子, 水口 和野, 山口 俊郎, 中平 敦
    2001 年 50 巻 6 号 p. 613-618
    発行日: 2001/06/15
    公開日: 2009/06/03
    ジャーナル フリー
    The thermoluminescence characteristics of fluoridated hydroxyapatite (FHAp) having various fluoride contents have been investigated. The FHAp samples were prepared from reaction of α or β-tricalcium Bis (orthophosphate) (α-TCP or β-TCP) with NH4F. TL peaks of FHAp heated at 700°C were observed at 90°C and 190°C, and the 90°C peak was higher than the 190°C peak. The TL peak intensity increased with the fluoride contents in FHAp. The TL peak intensity of FHAp from α-TCP was higher than that from β-TCP. The intensity of TL peak increased linearly up to about 1.8C/kg for X-ray irradiation.
  • 桑原 彰秀, 幾原 雄一, 佐久間 健人
    2001 年 50 巻 6 号 p. 619-624
    発行日: 2001/06/15
    公開日: 2009/06/03
    ジャーナル フリー
    The electronic structure of various kinds of c-ZrO2 solid solutions is calculated by a first principles molecular orbital method. It is found that the calculated partial density of states agrees well with the ELNES obtained from ZrO2-8mol%Y2O3. From the calculation for ZrO2-R2O3 system in which the effect of stabilization on c-ZrO2 is high, the addition of R2O3 was found to remarkably decrease the repulsive Coulomb force between neighboring oxygen ions. In contrast, the addition of TiO2, which has no effect to stabilize c-ZrO2, increases the repulsive interaction between oxygen ions. It was concluded that the instability of c-ZrO2 solid solution depends on the repulsive interaction between neighboring oxygen ions.
  • 西川 直宏, 中嶋 篤久, 本多 沢雄, 淡路 英夫
    2001 年 50 巻 6 号 p. 625-629
    発行日: 2001/06/15
    公開日: 2009/06/03
    ジャーナル フリー
    Porous alumina samples were prepared with a fine alumina powder containing glass balloon or polyvinyl alcohol (PVA) as pore-former. After calcination, alumina samples with different porosities and pore morphologies were synthesized at 1623K by pressureless sintering. Referential porous alumina samples without the pore-former was obtained by reducing the sintering temperatures. Density, porosity and microstructure of porous alumina samples thus obtained were characterized. Young's modulus and Poisson's ratio were estimated by the linear strain under compressive stress and fracture strength was measured by three-point bending test. With adding the pore-former, the spherical pores with 10-20μm in diameter were observed uniformly in alumina matrix. Closed pores were pre-dominant for porous alumina samples prepared with glass balloon, and open or continuous pores were for porous alumina samples with PVA. Continuous but small pores were mainly observed in alumina samples sintered at lower temperatures. Young's modulus of porous alumina decreased with increasing porosity, independent of pore shape and size. A slight decrease in Poisson's ratio was observed for porous alumina samples prepared with glass balloon and PVA, and a clear decrease for referential porous alumina samples sintered incompletely. The fracture strength also decreased with an increase in porosity. Especially, the continuous and large pores accompanied with sharp and large flaws were found to cause strength reduction. These mechanical properties of porous alumina were discussed in terms of power law based on the minimum solid segment or area model.
  • 林 卓, 谷村 明宏, 篠崎 裕志, 高梨 一也, 青木 秀行, 佐々木 〓一
    2001 年 50 巻 6 号 p. 630-633
    発行日: 2001/06/15
    公開日: 2009/06/03
    ジャーナル フリー
    Chemical processing of ZrO2-coated BaTiO3 composites was investigated with the surface modification through the hydrolysis of zirconium alkoxide on the surfaces of BaTiO3 particles. It was clarified from the BET measurement and the SEM observation that original BaTiO3 particles were homogeneously coated with zirconium hydroxide fine particles.
    2mass%ZrO2-coated BaTiO3 (BT-05) bodies sintered at 1275°C exhibited a flattened dielectric temperature dependence (dielectric constants of 3600 to 4700) with lower loss (tanδ of<5% in the temperature range of -30 to 110°C), indicating a relaxor characteristics. The microstructure of ZrO2-added BaTiO3 (BT-05) sintered bodies consisted of grains of several 0.9μm which are much smaller than ones of non-added BaTiO3 sintered bodies, suggesting that the grain growth of BaTiO3 was suppressed by zirconia existing at the grain boundaries.
  • 塩見 治久, 小川 乾吾, 岡本 謙一, 塩野 剛司, 奥村 真也, 神谷 昌岳, 北村 真
    2001 年 50 巻 6 号 p. 634-638
    発行日: 2001/06/15
    公開日: 2009/06/03
    ジャーナル フリー
    Aluminium hydroxide (Al(OH)3) was mechanically activated in a dry condition using high energy media agitating mill. The reaction between the activated Al(OH)3 and Mg(OH)2 in aqueous solutions of various pHs was investigated, and the effectiveness of the use of the activated Al(OH)3 was discussed for the synthesis of spinel (MgAl2O4) powder. Milling up to 1h apparently reduced grain size and promoted amorphization. Milling longer than 2h, however, did not give further physical changes. Al(OH)3 milled for 2h showed almost 1000 times higher solubility than as-received Al(OH)3 and easily reacted with Mg(OH)2 to form a complex hydroxide (Mg4Al2(OH)14·3H2O). Especially, the formation of the complex hydroxide was remarkably promoted in acidic and basic solution. The complex hydroxide decomposed to MgAl2O4 and MgO at about 400°C. MgO, which decomposed from the complex hydroxide, reacted with Al2O3, which was converted from Al(OH)3, to form a spinel phase at lower temperature than that of an ordinary solid-state reaction between MgO and Al2O3. Accordingly, the use of the activated Al(OH)3 was effective for low temperature synthesis of spinel powder. Furthermore, it was found that mixing of Al(OH)3 and Mg(OH)2 with a ball mill remarkably enhanced the formation of the complex hydroxide. Consequently, almost monolithic spinel powder was obtained at heat-treatment temperature as low as 1000°C when the activated Al(OH)3 was mixed with Mg(OH)2 using a ball mill.
  • 円管の変形が接合界面へ及ぼす影響
    伊達 秀文
    2001 年 50 巻 6 号 p. 639-644
    発行日: 2001/06/15
    公開日: 2009/06/03
    ジャーナル フリー
    A tubular aluminum projectile, subjected to a longitudinal impact, was impact-welded onto a stainless steel target using a gas gun at impact velocities of 200m/s or more. The bonding area was estimated using scanning acoustic tomograph. The microstructures and element distribution in the joint were analyzed by means of SEM and Energy dispersive X-ray spectroscopy. The bonding strength was measured by a tension test. Additionally, the experimental results were compared with the numerical one obtained using the finite element method. It appeared that the aluminum projectile was bonded to stainless steel target at the impact velocity from 200 to 300m/s. The bonding strength of aluminum/stainless steel joint showed the maximum of 190MPa at 230m/s and decreases with impact velocity. The bonding strength at the impact velocities of 220-240m/s was stronger than that of aluminum. The numerical results clearly showed that the temperature rise due to the conversion of the plastic work has influence on the profile of the projectile after deformation.
  • 佐久間 淳, 徳永 行伸, 山西 建樹, 香川 誠
    2001 年 50 巻 6 号 p. 645-650
    発行日: 2001/06/15
    公開日: 2009/06/03
    ジャーナル フリー
    Partial quenching technique on the surface of the ultra-thin steel wire by using YAG laser system is developed to modify the mechanical properties of the materials. The proper condition of the quenching is examined by the simulation technique for continuous process of heating and cooling. Here, the formal description of the transformation kinetics is evaluated on the reverse transformation in the heating process since the quenched region corresponds to the austenite-formed region in the process. The calculated conditions of the quenching are also examined by the experiments for the thin steel wire produced by drawing process because surface modification is expected to reinforce the mechanical properties. The laser power and the wire-feeding rate are found to alter the quenched region, and it is also examined by comparison with some experimental studies.
  • 荒井 正行, 佐久間 俊雄, 岩田 宇一, 斎藤 正弘
    2001 年 50 巻 6 号 p. 651-656
    発行日: 2001/06/15
    公開日: 2009/06/03
    ジャーナル フリー
    In this study, thermal cycle tests for thermal barrier coating, which is constructed by 8wt%Y2O3-ZrO2 as top coating material and NiCrAlY as bond coating, were conducted. It was found that (1) number of cycles to delamination were reduced with the increase of hold time at the maximum temperature in the thermal cycle, (2) debonding was occurred at side of the top coating layer near the interface between the top coating layer and the bond coating layer, and (3) a thermally growth oxidation layer was formed at the interface. The delamination model of thermal barrier coating layer under thermal cycle condition was proposed based on the some life properties of the coating delamination and microstructure observations of cross section of test specimen used in this study. The model is that radial thermal stress at the interface during heating up and down in thermal cycle test and then stress relaxation due to accumulation of creep deformation in the coating layer during holding temperature was cyclically acted at the interface. The delamination damage progresses as the interface crack propagation due to cyclic thermal stress and the acceleration of the crack propagation due to the effect of the thermally growth oxidation layer. The delamination life prediction method of thermal barrier coating was proposed based on the damage model. The proposed method could estimate actual delamination life of thermal barrier coating layer with a good accuracy.
  • 杉本 公一, 宋 星武, 井上 一也, 小林 光征, 増田 雪也
    2001 年 50 巻 6 号 p. 657-664
    発行日: 2001/06/15
    公開日: 2009/06/03
    ジャーナル フリー
    The effects of prestraining on cyclic hardening-softening behavior of low alloy TRIP steels such as “TRIP-aided dual-phase (TDP) steel” and “TRIP-aided bainitic (TB) steel” were examined. In addition, cyclic hardening mechanism of the prestrained TRIP steels was investigated through the variations in an internal stress, dislocation structure and strain-induced martensite content. The TRIP steels exhibited cyclic hardening with extreme unsymmetrical hysteresis curves, even if prestrained up to 10% in tension or 5% in compression. However, the TRIP steels prestrained in compression possessed the same low tensile stress amplitude as unprestrained ones although an increment of cyclic hardening was far larger than the steels prestrained in tension. It was suggested that cyclic hardening of the TDP steel and TB steel are mainly associated with the internal stress and severely developed cell structure, respectively. Also, the prestraining was expected to decrease the contribution of the internal stress and strain-induced transformation to cyclic hardening, differing from the contribution of cell structure. Unsymmetry of the hysteresis curves in prestrained TRIP steels was qualitatively related with the internal stress.
  • 6. 火力発電機器・プラントの予防保全への適用
    桜井 茂雄, 藤山 一成
    2001 年 50 巻 6 号 p. 665-670
    発行日: 2001/06/15
    公開日: 2009/06/03
    ジャーナル フリー
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