日本金属学会誌
Online ISSN : 1880-6880
Print ISSN : 0021-4876
ISSN-L : 0021-4876
60 巻, 7 号
選択された号の論文の11件中1~11を表示しています
  • 楊 続躍, 三浦 博己, 酒井 拓
    1996 年 60 巻 7 号 p. 625-632
    発行日: 1996年
    公開日: 2008/04/04
    ジャーナル フリー
    Hot deformation of prior warm-worked 7075 aluminum alloy was studied by means of 2-step tensile tests at temperatures ranging from 673 to 798 K and at various strain rates from 10−5 s−1 to 10−1 s−1. Deformation behavior and structural development change at a critical temperature Tc around 730 K. In the region below Tc, a power law relationship with n\simeq3.3 is established between strain rate and flow stress, which suggests the deformation is controlled by the dragging motion of dislocations. In the region over Tc, the strain rate dependence of flow stress changes clearly in three regions of strain rate, \dotε. Typical superplasticity taking place in the medium region of \dotε results from the evolution of fine gained structure based on continuous dynamic recrystallization. It is concluded that hot deformation of the warm-worked 7075 aluminum alloy is affected by the changes in microstructure with temperature and straining, and can be controlled by dislocation motion in grains in the region of high \dotε or by grain boundary sliding in the regions of medium and low \dotε.
  • 洪 性吉, 手塚 裕康, 神尾 彰彦, 崔 政喆 , 黄 善孝
    1996 年 60 巻 7 号 p. 633-639
    発行日: 1996年
    公開日: 2008/04/04
    ジャーナル フリー
    The effect of thermal residual stress on the age hardening behavior of the extruded SiC whisker reinforced Al-4 mass%Cu and Al-4 mass%Cu-1.5 mass%Mg alloys composites is investigated with micro-Vickers hardness, X-ray diffraction, differential scanning calorimetry and transmission electron microscopy. To control the thermal residual stress induced during heat treatment before isothermal ageing at 373, 423 and 473 K, two kinds of heat treatments are carried out for the composites. One is water quenching from solution temperature to R.T. (W.Q. composite) directly, the other is heating of the W.Q. composite to R.T. after holding for 3.6 ks at liquid nitrogen temperature (L.N. composite). Tensile residual stresses in the matrix of the whisker axis (σ11) and the perpendicular direction (σ22, σ33) of the L.N. composite are markedly reduced compared with those of the W.Q. composite. In the SiCw/Al-Cu system, both the W.Q. and L.N. composites show the suppression of the G.P. zone formation and the acceleration of the θ(Al2Cu) precipitation compared with the unreinforced matrix alloy. Also, the precipitation of the G.P. 1 zone and θ(Al2Cu) in the L.N. composite is more accelerated than in the W.Q. composite. In SiCw/Al-Cu-Mg system, both the W.Q. and L.N. composites show more remarkable age hardening due to the precipitation of the G.P.B. 1 zone and S(Al2CuMg) phase than the unreinforced matrix alloy. Compared with the W.Q. composite, especially the precipitation of metastable S phase is much more accelerated in the L.N. composite.
  • 磯貝 宏道, 秋山 友宏, 八木 順一郎
    1996 年 60 巻 7 号 p. 640-646
    発行日: 1996年
    公開日: 2008/04/04
    ジャーナル フリー
    In this paper, reaction kinetics in the combustion synthesis of Mg2Ni was discussed, in which physical and chemical changes of the samples during combustion synthesis were observed and identified by Scanning Electron Microscope (SEM), Electron Probe X-ray Microanalyzer (EPMA) and X-ray diffraction, and a rate equation of solid phase reaction was derived, based on the data measured by Differential Scanning Calorimeter (DSC). The SEM observation demonstrated that the synthesis reaction of Mg2Ni proceeds uniformly rather than topochemically, and an intermediate phase dose not exist during combustion synthesis. The synthesis reaction was accelerated by liquid generation of eutectic-composition. As a result, the rate equation of the sample was expressed by the form of a second-order irreversible equation, k(1−f)2, with the change of the frequency factor, and then it simulated reasonably the DSC curves of combustion synthesis.
  • 磯貝 宏道, 秋山 友宏, 八木 順一郎
    1996 年 60 巻 7 号 p. 647-652
    発行日: 1996年
    公開日: 2008/04/04
    ジャーナル フリー
    A mathematical model of the combustion synthesis process is quite effective for its process design because the synthesis reaction occurs instantaneously in general. However, an experimentally-verified mathematical model of the combustion synthesis using practical properties and a reliable rate-equation has not been reported as yet. Very recently, a new energy-saving production process of Mg2Ni through the combustion synthesis is attracting attention. The mathematical modeling of Mg2Ni combustion synthesis has been proposed in this paper. First, the thermal diffusivity and the reaction rate of a sample to use in the mathematical model were measured by the method of laser flash and differential scanning calorimetry (DSC), respectively, and then correlated with the temperature and reaction degree. Secondy, an unsteady, two-dimensional mathematical model of heat transfer of a cylindrical sample was constructed, in which independently-measured properties and reaction rate equations were introduced. Finally, simulated data based on the mathematical model were compared with experimental data during the combustion synthesis of Mg2Ni. As a result, their agreement was good enough for confirming the model. The feature of this model was to have a general rate equation with solid combustion and liquid-trigger combustion at a eutectic temperature, and to consider the influence of latent heat due to melt of a eutectic composition. Thus, the results also show the applicability of the mathematical model to other system of combustion synthesis.
  • 毛利 猛, 小橋 真, 金武 直幸, 長 隆郎
    1996 年 60 巻 7 号 p. 653-659
    発行日: 1996年
    公開日: 2008/04/04
    ジャーナル フリー
    The titanium aluminide intermetallic matrix composites are synthesized by the spontaneous infiltration of a raw powder phase containing Ti powder with molten pure Al. This paper deals with (i) the effect of adding Al2O3 and Al to Ti powder on the spontaneous infiltration and (ii) the result of the compressive test. In the case of using only Ti powder as a raw powder phase, the crucible is destroyed by the rapid increase in temperature due to the exothermic reaction between Ti powder and pure Al melt. However, it was found that the addition of Al2O3 particles to Ti powder allows the spontaneous infiltration without the crucible fracture. Excess additions of Al2O3 particles prevent the spontaneous infiltration of the mixed powder with molten pure Al. This is because the excess amount of Al2O3 particles acts as an obstacle between Ti and Al, and as a result, molten pure Al cannot contact with Ti powder effectively. The result of the XRD analysis suggests the formation of Al3Ti by spontaneous infiltration. In the case of adding pure Al powder to the raw powder phase, molten pure Al can infiltrate without the addition of Al2O3 particles, and the infiltration occurs more thoroughly and the microstructure becomes more homogeneous. The compressive strength of the Al2O3 dispersed Al3Ti is 592 MPa, which is 100 MPa higher than that of the Al3Ti made by this infiltration process.
  • 田中 智雄, 見山 克己, 伊藤 正也
    1996 年 60 巻 7 号 p. 660-666
    発行日: 1996年
    公開日: 2008/04/04
    ジャーナル フリー
    In this study, fatigue properties and initial strengths of ceramic/metal joints under cyclic rotary bending stress were investigated using the Ono’s rotary bending fatigue test machine. The initial strengths measured using this machine were compared to the 4-point bending strengths. The relationship between the applied stress and the fatigue life was discussed in terms of the S-N curve. Furthermore, SEM and EPMA observations of the fracture surfaces and the cross sections made the mechanism of fatigue fracture clear. The main results obtained are summarized as follows. (1) The initial strengths measured using the Ono’s rotary bending fatigue test machine were lower than the 4-point bending strengths. (2) From the S-N curve of ceramic/metal joints in this study, the fatigue limit was estimated to be approximately 280 MPa. (3) From SEM and EPMA observations, the first stage of fatigue fracture was caused at the Ti-rich layer existing next to the ceramic/braze layer interface.
  • 菊池 章弘, 中村 敬, 太刀川 恭治
    1996 年 60 巻 7 号 p. 667-673
    発行日: 1996年
    公開日: 2008/04/04
    ジャーナル フリー
    The Tl-2223 phase, about 150 μm in thickness, is synthesized through a diffusion process in a short reaction time. The scanning electron microscope observation reveals the existence of an appreciable amount of a second phase and voids in the 2223 phase. The fluorine (F) added to the coating layer of the diffusion composite acts like an effective flux to transform the 2223 phase into the 1223 phase, and the resulting 1223 phase shows a dense and homogeneous structure. The c-axis lattice parameter of the 1223 phase formed in the specimen with F addition reaches a slightly shorter value than the reported one after the reaction.
    The F addition significantly increases the transport Ic at 77 K, and reduces its degradation under magnetic field. Furthermore, the slow cooling after the reaction improves the Ic-B performance in the specimen with F addition. The resistive superconducting transition under magnetic field in the specimen with F addition is much less broad than that in the specimen without F addition. The irreversibility field is apparently shifted to higher temperatures by the F addition, which may originate from the phase transformation mentioned above. The annealing in O2 after the reaction increases the Ic and reduces the normal state resistivity of specimens. A Jc at 77 K of about 1.5×108 A/m2 has been obtained in the Tl-1223 diffusion layer of about 150 μm in thickness through the F addition.
  • 井口 征夫, 鈴木 一弘, 小林 康宏
    1996 年 60 巻 7 号 p. 674-678
    発行日: 1996年
    公開日: 2008/04/04
    ジャーナル フリー
    In order to clarify the mechanism by which the iron loss in TiN-coated grain oriented silicon steel sheet was improved dramatically, the relations between the tension and improvement of iron loss were investigated.
    For magnetic properties in tension from 0 to 30 MPa of the polished silicon steel sheets, the magnetic flux density B8(T) showed a moderate increase of 0.008-0.013 T and the iron loss W17⁄50(W/kg) showed a dramatical improvement of 0.15-0.20 W/kg. This improvement in iron loss was more marked in the silicon steel sheet with a higher magnetic flux density, and was remarkable with slight tensions from 2 to 5 MPa.
    With increasing tension after TiN coating, B8(T) also showed a slight increase of 0.006-0.011 T and W17⁄50(W/kg) showed a moderate improvement of 0.05-0.07 W/kg. Moreover, the improvement of iron loss of twice TiN coatings with a thickness of 0.5 μm was similar to one-time TiN coating with a thickness of 1 μm.
    From the relationship between iron loss and tension in the polished steel sheet, it was estimated that the tension of about 6.5-10 MPa was added to the TiN-coated silicon steel sheet. This value was consistent with the previous results (8 MPa) obtained from the compressive stress dependence of magnetostriction.
  • 太田 弘道, 友田 陽, 渡辺 龍三, 早稲田 嘉夫
    1996 年 60 巻 7 号 p. 679-684
    発行日: 1996年
    公開日: 2008/04/04
    ジャーナル フリー
    Effective thermal conductivity of composite materials is known to heavily depend upon the structure and distribution of dispersed phases in the matrix. Although the equivalent inclusion method has frequently been used for estimating the thermal conductivities of composite materials, the results include some reservation for the case where the percolation behavior of some phases is suggested by finding direct contact of some dispersed phases. With this fact in mind, a new method has been developed for estimating the effective thermal conductivity of composite materials directly from its optical micrograph data by applying an image analysis of 400×640 digitized elements at the micro-computer level. The capability of this new method has been clearly demonstrated by reproducing the effective thermal conductivity values of SUS304/PSZ composite materials with a wide composition range and thermal anisotropy.
  • 折茂 慎一, 藤井 博信, 池田 一貴, 北野 保行
    1996 年 60 巻 7 号 p. 685-692
    発行日: 1996年
    公開日: 2008/04/04
    ジャーナル フリー
    Hydriding and structural properties of a nanostructured Mg2Ni-H system synthesized by reactive mechanical grinding were investigated. The dissolved hydrogen content of the system reached up to 1.6 mass% (Mg2NiH1.8) without changing the crystal structure of an intra-grain region composed of the Mg2NiH0.3 crystallites, and the dehydriding reaction occurred even at 413 K. To clarify an origin of the notable hydriding properties, structural characterizations of the system were carried out. In Mg2Ni-H mechanically ground for 60 min under a hydrogen atmosphere, the HRTEM observation revealed that the sample consists of the equiaxed crystallites with an average size of 15 nm. Moreover, each crystallite is found to be surrounded by the heavily deformed and disordered region nearly 1.5 nm in width. As was evident from the thermal and magnetical analyses, a volume fraction and its hydrogen content of the inter-grain region were around 0.30 and 4.0 mass%, respectively, by the grinding only for 60 min. These results were also supported by the small angle neutron scattering measurements of the nanostructured Mg2Ni-D system. It was concluded that a large amount of hydrogen was dissolved into the disordered inter-grain region. In addition, a cooperative dehydriding reaction between both the intra- and inter-grain regions were discussed as one of the origin for the low-temperature dehydriding around 413 K.
  • 田中 孝治, 林 利生, 春田 正毅
    1996 年 60 巻 7 号 p. 693-694
    発行日: 1996年
    公開日: 2008/04/04
    ジャーナル フリー
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