巻号一覧
78 巻, 1 号
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依頼解説論文
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坂口 紀史2014 年 78 巻 1 号 p. 1-6
発行日: 2014年
公開日: 2014/01/01
ジャーナル フリーΣ3 CSL grain boundaries in poly-crystalline silicon were investigated by high-resolution transmission electron microscopy (HRTEM), electron energy-loss spectroscopy (EELS) and ab initio calculations. A {112} Σ3 CSL boundary consisted of two segments which differed in atomic structure. The segment near the corner and connected to {111} Σ3 CSL boundary showed symmetric structure while the other long segment, which was the distant one and away from the corner, showed asymmetric structure. Ab initio calculations revealed that the asymmetric structure is more stable than the symmetric one. A pronounced pre-edge shoulder was detected only in Si-L23 electron energy-loss near-edge structure (ELNES) acquired from the symmetric segment of the {112} and {111}Σ3 CSL boundaries. It was indicated that the shoulder in the ELNES acquired from the CSL junction resulted from the formation of the deep gap state originated by the 5-fold-coordinated silicon atom.
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論文
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田中 慎二, 水澤 護, 三浦 博樹, 萩沢 武仁2014 年 78 巻 1 号 p. 7-15
発行日: 2014年
公開日: 2014/01/01
ジャーナル フリーThe influence of Zr and P additions on the microstructure and tensile ductility at room temperature of a Cu-4.2 mass%Ni-1.0 mass%Si forged alloy was investigated. The discontinuous precipitation and age hardening due to Ni2Si in the alloy was delayed by Zr and P additions. The activation energies for discontinuous precipitation were 124 kJ/mol for the Cu-Ni-Si alloy, 134 kJ/mol for the Zr-added alloy and 139 kJ/mol for P-added alloy. The tensile ductility of the Zr- and P-added alloys was drastically improved by decreasing dimpled fractures at the grain boundaries. These drastic increases in tensile ductility of the Zr- and P-added alloys was correlates with the delay of intergranular precipitation due to grain boundary segregation and dissolution of Zr and P in the Cu matrix.
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井岡 郁夫, 木内 清, 滝沢 真之, 伊藤 剛士2014 年 78 巻 1 号 p. 16-22
発行日: 2014年
公開日: 2014/01/01
ジャーナル フリーA multi-axis stress field is indispensable for quick and quantitative evaluation of stress corrosion cracking for constructional materials and weld joints of existing industrial plants. The applicability of multi-axis residual stress field formed by pushing of a hard sphere ball made of WC into stress corrosion cracking tests was evaluated.
The Brinell type hard sphere ball was stuffed into small flat-plate of type 304SS. The residual stress and displacement around the indentation were measured using an X-ray diffraction method and a displacement meter. Numerical analysis by the finite element method was conducted in order to compare with the experimental results. The numerical analysis was comparatively in agreement with the experimental results. A hard sphere ball diameter, a specimen holder hole diameter, specimen thickness, and an indentation depth were selected by numerical analysis to optimize the residual stress of specimen. The stress corrosion cracking test in chloride solution was performed using the specimen with optical residual stress condition. It is confirmed that the multi-axis residual stress field was useful in quick and quantitative stress corrosion cracking test by comparing the initiation of cracks with the distribution of residual stress obtained by numerical analysis.
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—その(2) 84% 圧延まで—山本 厚之, 大森 裕之, 梶浦 拓也, 塚本 雅章, 岡井 大祐2014 年 78 巻 1 号 p. 23-30
発行日: 2014年
公開日: 2014/01/01
ジャーナル フリーLattice rotations due to cold-rolling on polycrystalline commercial 1050 aluminum were investigated on individual grains with the same area observation technique using scanning electron microscope (SEM)-electron backscatter diffraction (EBSD) system. After annealing at 803 K for 3.6 ks, a specimen was cold-rolled up to 84% with multi-pass rolling at about 30% reduction for each pass. Electropolishing of the specimen surface and EBSD observation were carried out after each rolling. Lattice rotation towards the rolling direction occurred at the early stage of multi-pass rolling, while the rotation towards the opposite rolling direction also occurred at the latter stage. To-and-fro motion in rotation would be repeated during multi-pass rolling. The rotation would be interpreted with slip system analyses assuming that stresses due to rolling are applied along the rolling direction and the surface normal direction. Primary and conjugate slips operated in the grains initially having orientations in the cold-rolled pure metal texture, which caused splitting orientations into near rotated cube orientation and near {111}〈110〉 orientation. In the case of the grains initially having near cube orientations, rotations toward two or three directions occurred at the early stage of multi-pass rolling, which caused the lattice rotation toward the rotated cube orientations and caused the orientation splitting into the above mentioned two orientations at the latter stage. These orientations, however, would not be stable for further cold-rolling but split into other orientations belonging to the surface rolling texture through the to-and-fro motion.
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日野 実, 村上 浩二, 村岡 賢, 永田 教人, 金谷 輝人2014 年 78 巻 1 号 p. 31-36
発行日: 2014年
公開日: 2014/01/01
ジャーナル フリーZinc-nickel-SiO2 electrodeposits have been produced from an acid sulphate bath. The co-deposition behavior of SiO2 and the macrothrowing power of platings were examined. The presence of SiO2 nanoparticles in the plating bath appears to change the alloy deposition behavior. The rate of nickel deposition was considerably decreased with SiO2 nanoparticles in the bath. The macrothrowing power of plating was improved by adding the SiO2 nanoparticles in the bath. At an early stage of electrodeposition, it seems that the SiO2 nanoparticle acts as a nucleus of the precipitation. The SiO2 nanoparticles did not disperse uniformly in a plating film, but distributed only in the SiO2 rich layer with about 50 nm in thickness formed beneath the surface. In addition, this SiO2 rich layer can improve the anticorrosive performance. Therefore, the zincic use can be suppressed, because the film thickness can be more thinned, compared with zinc and zinc-nickel alloy electroplating.
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中間 一夫, 龍谿 翔, 杉田 一樹, 白井 泰治2014 年 78 巻 1 号 p. 37-44
発行日: 2014年
公開日: 2014/01/01
ジャーナル フリーFe-36mass%Ni alloy is well known as invar alloy for its low thermal expansion (LTE) near room temperature. Since its strength is relatively low and thus its application is limited, strengthening of LTE alloy has been a matter of concern for industrial use. It has been reported that the combined additions of V and C are effective for enhancing age hardness of Fe-36mass%Ni alloy without remarkable increase in thermal expansion. However, since worldwide depletion of rare metals such as V has been making it difficult to purchase and pushing their prices up, saving these elements is an urgent issue for steel industry. In addition, more strengthened LTE alloy is still in demand. From these aspects, the effect of substitution of V by Ti and Cr on strength of Fe-0.2mass%C-36mass%Ni-0.8mass%V alloy is investigated in this paper. As a result, age hardness reached its maximum when a quarter of V was replaced by Ti. Substitution by Cr by about up to a half of V had little effect on age hardness. Based on these results, an LTE alloy, Fe-0.3mass%C-36mass%Ni-0.6mass%V-0.2mass%Ti-0.6mass%Cr, was prepared and its properties were measured. Consequently, the alloy had 70 MPa higher tensile strength than the previously reported for Fe-0.2mass%C-36%massNi-0.8mass%V alloy. In the viewpoint of saving rare metals, influence of reducing nickel on thermal expansion is also discussed.
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都留 智仁, 青柳 吉輝, 加治 芳行, 下川 智嗣2014 年 78 巻 1 号 p. 45-51
発行日: 2014年
公開日: 2014/01/01
ジャーナル フリーHuge-scale atomistic simulations of shear deformation tests to the aluminum polycrystalline thin film containing the Frank-Read source are performed to elucidate the relationship between the inter- and intragranular plastic deformation processes and the mechanical properties of ultrafine-grained metals. Two-types of polycrystalline models, which consist of several grain boundaries reproducing easy and hard slip transfer, respectively, are prepared to investigate the effect of grain boundary on flow stress. While the first plastic deformation occurs by the dislocation bow-out motion within the grain region for both models, the subsequent plastic deformation is strongly influenced by the resistance of the slip transfer by dislocation transmission through grain boundaries. The influence of the competition between the intragranular dislocation nucleation and intergranular slip transfer on the material strength is considered. The nanostructured material's strength depending on local defect structures associated with grain size and dislocation source length is assessed quantitatively.
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大谷 良行, 兒島 洋一, 原 信義2014 年 78 巻 1 号 p. 52-59
発行日: 2014年
公開日: 2014/01/01
ジャーナル フリーIn an effort to improve the tensile strength of aluminum-silicon (Al-Si) alloys used in heat exchangers, we investigated the influence of Si concentration and heat treatment at 453 K on the susceptibility of Al-Si alloys to intergranular corrosion. It was found that the susceptibility to intergranular corrosion increased with an increase in Si concentration. It also initially increased with heat treatment at 453 K, but then decreased with long-term heat treatment at 453 K. The addition of Mg and Mn, which affect the precipitation of Si, promoted precipitation and reduced the susceptibility of the Al-Si alloys to intergranular corrosion. With longer heat treatment at 453 K, large Si precipitates were observed in the grains and at the grain boundaries, which reduced the susceptibility to intergranular corrosion. Short term heat treatment at 453 K formed a continuous Si-depleted layer along the grain boundaries, which increased the susceptibility to intergranular corrosion. It is suggested that the susceptibility to intergranular corrosion was dependent on the addition of Mg and Mn.
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