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61 巻, 1 号
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田淵 正幸, 丸川 健三郎, 佐藤 博保1997 年 61 巻 1 号 p. 1-7
発行日: 1997年
公開日: 2008/04/04
ジャーナル フリーThe formation process of bainites (of 9R structure) and fcc precipitates in a quenched β1 phase of a Cu-Zn-Al alloy has been studied by electrical resistivity measurements and electron microscopy. Bainites precipitate by aging at a temperature between 423 and 623 K, and they successively transform to the fcc structure by a further aging. The process of bainite formation gives rise to an increase in electrical resistivity, while the transformation to fcc corresponds to a decrease in it. The curves of the resistivity change as a function of the aging time are compared with appropriate theoretical curves. The precipitation process of bainites fits well with the Johnson-Mehl-Avrami equation.The later process of the transformation from the 9R structure to fcc closely follows an exponential decay curve. Both processes are highly sensitive to a temperature change. The activation energy for the later process is approximately equal to that of the solute diffusion in the fcc phase, while the activation energy for the bainite formation roughly equals the corresponding energy in the matrix β1 phase. The present results of resistivity measurements, combined with electron microscope observations indicate that the transformation to fcc structure is well explained by random extinction of structural faults in the 9R structure. The process of this extinction is discussed in terms of nucleation and motion of partial dislocations.抄録全体を表示PDF形式でダウンロード (799K) -
辻 新次, 頃安 貞利1997 年 61 巻 1 号 p. 8-17
発行日: 1997年
公開日: 2008/04/04
ジャーナル フリーA general model to treat multiphase diffusions in a semi-infinite couple after impregnation, a finite/semi-infinite couple and a finite/finite couple is presented on the finite difference solutions with a variable-grid. In the model, the numerical solutions previously presented for the multiphase diffusions in a semi-infinite medium whose surface is maintained at a constant concentration, and an infinite medium are used as a means of giving the initial conditions, respectively.
Critical layer widths for the occurrence of a new phase and for the disappearance of a preexisting phase, and critical values defining whether to calculate the change in concentration for a terminal phase are introduced in this model in order to diminish the number of iterations in the calculation and successfully to apply its model to a great variety of binary alloys.
The resultant surface concentrations and layer widths of existing phases at any time, for example, may be given as part of data which have been stored in the form of concentration profiles as a function of diffusion time. Typical examples to which the model has been applied are discussed.抄録全体を表示PDF形式でダウンロード (934K) -
張 仁誠, 杜澤 達美, 加藤 一, 高山 善匡1997 年 61 巻 1 号 p. 18-24
発行日: 1997年
公開日: 2008/04/04
ジャーナル フリーThe uniformity in the microstructures of materials is one of the most important factors in the properties and behavior of materials. However, the uniformity has not been characterized well. Therefore, the uniformity evaluation is revealed at present from inspection such as sensory test performed by expert. The evaluation of the uniformity by subjective sense inspection of an expert generally includes fuzziness or ambiguity. This paper attempts to construct the objective and quantitative evaluation systems based on the technique of fuzzy reasoning for the uniformity on grain structure. The systems are modelled by the fuzzy inference rules with two input variables (Usp, Usize) and a single output variable(sensory evaluation), and are trained by the results of the expert sensory test. The results obtained by the fuzzy reasoning are in good agreement with the results of sensory test by experts. Furthermore, the avaiability of the present fuzzy reasoning system is confirmed by the comparison of the performance for training data and test data with the statistical method using linear regression analysis.抄録全体を表示PDF形式でダウンロード (658K) -
張 仁誠, 杜澤 達美, 加藤 一, 高山 善匡1997 年 61 巻 1 号 p. 25-33
発行日: 1997年
公開日: 2008/04/04
ジャーナル フリーThe uniformity of a microstructure is one of the most important factors which govern the properties of materials. The evaluation of microstructures is generally performed by experts based on sensory tests because the uniformity of a microstructure has not been well defined. Therefore, it is important to understand how the subjective evaluation is carried out by experts. The aim of the present paper is to characterize the uniformity evaluation on grain structures, based on the results obtained by the sensory test of 83 panelists for uniformity of 42 grain structures. First, we asked panelists questionnaires about the uniformity of each grain structure evaluated based on his or her subjectivity. This is designated as the questionnaire test 1. Next, three items for the uniformity evaluation were established; i.e. size uniformity, spatial uniformity and a total evaluation which describe the uniformity of grain structures. Then the sensory tests by questionnaires of these evaluation items were carried out. This is designated as the questionnaire test 2. The total evaluation obtained by the questionnaire test 2 was quite similar to that of the questionnaire test 1. Using the results obtained by the sensory tests, we analyzed the relationship and/or interaction between the size uniformity and spatial uniformity as well as the influence of the standard length on the uniformity evaluation.抄録全体を表示PDF形式でダウンロード (1153K) -
中山 栄浩, 鷹合 徹也, 金 大洲, 山田 雄司1997 年 61 巻 1 号 p. 34-40
発行日: 1997年
公開日: 2008/04/04
ジャーナル フリーAluminum-magnesium alloys containing 5 and 10 mass%Mg were aged at temperatures between 373 and 573 K for a prolonged time in order to investigate the precipitation process of the β-phase and the variation in solute Mg concentration in the matrix. The precipitates were examined by means of X-ray diffraction, EPMA and differential scanning calorimetry. The Mg concentration in the matrix was estimated using the electrical resistivities measured at 77 and 300 K. The obtained results are summarized as follows. (1) Based on the variation in the solute Mg concentration of the matrix, the nose temperatures for the precipitations of β and/or β′-phases were estimated to be about 453 and 493 K for 5%Mg and 10%Mg alloys. (2) The particle like precipitate was suggested to be the stable precipitate β-phase(Al3Mg2) from both X-ray diffraction and EPMA analyses. (3) In the Al-10%Mg alloy aged at 453 K, rod-like precipitates were found to have a coherent strain field caused by the partially coherent interface with the matrix in the early stage of aging.抄録全体を表示PDF形式でダウンロード (916K) -
峯 洋二, 安藤 新二, 高島 和希, 頓田 英機, 肥後 矢吉1997 年 61 巻 1 号 p. 41-48
発行日: 1997年
公開日: 2008/04/04
ジャーナル フリーThe fatigue crack growth behavior of α-titanium single crystals has been investigated in laboratory air at room temperature. SEN specimens A, B and C with different notch orientations were prepared by a strain-annealing technique. The notch plane and direction in the A-specimen were close to (1\bar210) and [10\bar10], those in the B-specimen were (01\bar10) and [2\bar1\bar10], and those in the C-specimen were close to (10\bar10) and [0001], respectively. A definite dependence of crystallographic orientation on fatigue crack growth behavior was obtained. The crack in the A-specimen propagated parallel to (01\bar10) [2\bar1\bar10] and two sets of prismatic slip traces ((1\bar100) [11\bar20] and (10\bar10) [1\bar210]) were found near the crack tip. The crack in the B-specimen propagated parallel to the [2\bar1\bar10] notch direction. Therefore, the cracks in both the A- and the B-specimens are deduced to extend by alternating shear on two intersecting prismatic slip systems ((1\bar100) [11\bar20] and (10\bar10) [1\bar210]). The fatigue crack propagated along the [0001] direction in the C-specimen. Although very fine traces due to twinning were observed near the crack surface, large slip bands were not found. Ridges and valleys which are deduced to be associated with twin interfaces were observed on the fatigue surface. This suggests that the crack may grow by the separation of twin interfaces.抄録全体を表示PDF形式でダウンロード (1948K) -
新井 甲一, 小村 一成, 鬼頭 秀明, 前 健彦1997 年 61 巻 1 号 p. 49-55
発行日: 1997年
公開日: 2008/04/04
ジャーナル フリーThe electrochemical characteristics of Al-Al3Ni eutectic alloys were investigated by polarization tests and potentiostatic dissolution tests. EDAX analysis of various phases in the alloys and scanning electron microscopic observation of the surface of the alloys corroded in a dilute HClO4 solution were also performed.
The results obtained are summarized as follows:
(1) The anodic dissolution rates of Al-Al3Ni eutectic alloys in a dilute HClO4 solution increase with increasing HClO4 concentration and solution temperature. However, the rates are decreased in the order of Al-5.65 mass%Ni alloy>Al-29.8 mass%Ni alloy>Al-42.57 mass%Ni alloy. The anodic dissolution rates increase with increasing surface area rations of eutectic stracture in the alloys.
(2) The apparent activation energies of anodic dissolution are 30.6 kJ/mol for the Al-5.65 mass%Ni alloy, 33.4 kJ/mol for the Al-29.8 mass%Ni alloy and 44.6 kJ/mol for the Al-42.57 mass%Ni alloy, respectively.
(3) The main anodic dissolution reaction of all the alloys in the dilute HClO4 solution is the selective dissolution of the Al(α) phase from the Al(α)+Al3Ni(β) eutectic structure. However, on the Al-42.57 mass%Ni alloy, the dissolution of Al from Al3Ni(β) occurs as a side reaction.抄録全体を表示PDF形式でダウンロード (1067K) -
佐藤 芳幸, 原 基, 品田 豊, 成田 敏夫1997 年 61 巻 1 号 p. 56-63
発行日: 1997年
公開日: 2008/04/04
ジャーナル フリーHigh temperature oxidation behavior of Ni-5, 10 and 20%Cr alloys in a 1%HCl-50%O2-N2 atmosphere was examined at 973-1273 K by thermogravimetry. Mass gains of the Ni-5 and 10%Cr alloys in the 1%HCl-50%O2-N2 atmosphere increased with time in the early stage of the reaction and then decreased to show negative values. On the other hand, mass gain of Ni-20%Cr alloy decreased with time from the early stage. Total metal consumptions of these alloys showed a simple increase with time and with oxidation temperature. To investigate the mechanism of the reaction taken place at the stated conditions, the metal consumptions were divided into two kinds of consumption, i.e. consumptions for oxidation and chlorination. The metal consumption for oxidation increased with time in the earlier stage, and then showed a nearly constant value. In another hand, the metal consumption for chlorination appeared very small values at first, and then showed a constant rate at the later stage. Scales formed on the specimens had a layered construction. The inner scale around the metal/scale interface was porous. Scales formed on Ni-5 and 10%Cr alloys consisted of NiO, and an elemental Cr was detected in them. In the scales formed on Ni-20%Cr alloys, Cr2O3 was identified. From all the results and a thermodynamical equilibrium discussion, it was revealed that oxidation and chlorination reactions took place simultaneously in the 1%HCl-50%O2-N2 atmosphere at high temperatures. It was also found that the addition of 20%Cr effectively reduced oxidation and chlorination in the HCl-bearing atmosphere.抄録全体を表示PDF形式でダウンロード (992K) -
石田 央, 赤尾 昇, 原 信義, 杉本 克久, 藤井 重男1997 年 61 巻 1 号 p. 64-70
発行日: 1997年
公開日: 2008/04/04
ジャーナル フリーMagnetoresistive heads (MR heads), which utilize the magnetoresistive effect of ferromagnetic films, are consisted of metal multilayer films. The metal multilayers of the MR heads should cause galvanic corrosion in the water environment. The aim of this study is to make clear the corrosion behavior of the metal multilayers used for MR heads.
To investigate the corrosion of real MR heads, the corrosion test of simulated MR head samples having the structure of Au/Fe-Mn/Ni-Fe/Ta/Ni-Fe-Cr was performed in 0.1 kmol·m−3 NaCl and 0.1 kmol·m−3 Na2SO4. Corrosion and electrochemical behavior of each metal film was examined in pH 8.45 boric-borate buffer, 0.1 kmol·m−3 NaCl and 0.1 kmol·m−3 Na2SO4. Galvanic current measurement was performed in the same solutions on galvanic couples of Au and Fe-Mn films or Fe-Mn and Ni-Fe films.
It has been found that Fe-Mn films do not suffer from corrosion in pH 8.45 boric-borate buffer owing to the formation of passive films. In 0.1 kmol·m−3 NaCl and 0.1 kmol·m−3 Na2SO4, however, the films suffer from serious pitting corrosion. Moreover, couples of Au and Fe-Mn films or those of Ni-Fe and Fe-Mn films cause galvanic corrosion in the same solutions and the corrosion rate increases with increasing area ratio of Au or the Ni-Fe film to the Fe-Mn film.抄録全体を表示PDF形式でダウンロード (807K) -
矢野 哲夫, 大家 利彦, 米田 理史, 勝村 宗英, 日野 孝紀, 荒木 孝雄1997 年 61 巻 1 号 p. 71-76
発行日: 1997年
公開日: 2008/04/04
ジャーナル フリーThe Effect of oxygen pressure was investigated on the composition of TaOx thin films deposited by a laser ablation method. A Ta target was ablated under various oxygen pressures and TaOx films were formed on room temperature substrates. The deposition process was discussed with respect to the reaction of ablated Ta particles and atmospheric O2 molecules. The main results obtained were as follows.
(1) The films deposited under vacuum (1 mPa) had an oriented fine polycrystal structure of Ta. (2) The deposition rate increased with increasing pressure. (3) The film deposited at an oxygen pressure of 10 Pa was amorphous and its composition was nearly stoichiometry. (4) By annealing this film at 973 K for 3.6 ks under vacuum, a Ta2O5 polycrystal was formed. (5) At the pressure of lager than 50 Pa, the deposition rate was very large, but the films were porous and had a lower density.
We concluded that at the pressure lower than 0.25 Pa, TaOx films were formed by the reaction of O2 with Ta on the substrate, where the sticking coefficient of O2 to Ta was smaller than 0.1. It was also suggested that at the pressure larger than 0.25, TaOx films were formed by the reaction in the volume as well as on the substrate.抄録全体を表示PDF形式でダウンロード (765K) -
田口 正美, 平沢 今吉1997 年 61 巻 1 号 p. 77-82
発行日: 1997年
公開日: 2008/04/04
ジャーナル フリーThe negative electrode in the lead-acid battery contains a spongy Pb as the active material and a natural polymer, lignin. During repeated charge-discharge cycling in a sulfuric acid solution without lignin, an anomalous growth of acicular precipitate is observed on the negative electrode. The growth is depressed by addition of lignin to the electrolyte. AES and XPS of the electrode after charge-discharge cycling show that the surface is made up of PbSO4 single phase in the lignin-containing electrolyte, whereas the formation of metallic Pb occurs in the electrolyte without lignin. The lignin has both a water-repellent carbon chain and several water-acid functional groups, such as sulfonic acid. It absorbs the negative electrode; the carbon chain is directed at the surface to be coated. The adsorbate depresses the redeposition of metallic Pb from Pb2+ ions on the surface which can take place locally as a side reaction in charging. Consequently, the depressing of the anomalous growth can be explained by the hindrance to the redeposition.抄録全体を表示PDF形式でダウンロード (579K) -
吉村 博文, 藤井 祐三, 和田 真一郎, 村上 敦則, 木村 欽一1997 年 61 巻 1 号 p. 83-89
発行日: 1997年
公開日: 2008/04/04
ジャーナル フリーRecently, the refinement into ultra-fine grains in the field of metallic materials has been attracting a great deal of attention. One of the few methods available for creating ultra-fine grains is the hydrogen treatment, which easily produces grain sizes of 1 to 3 μm in titanium materials. This paper describes the characteristics of mechanical properties, such as tensile strength and elongation, of ultra-fine grained α+β type titanium alloys utilizing this method. Several test specimens having grain size varing between ultra-fine (1 to 3 μm) and coarse (approximately 20 μm) were prepared and subjected to tensile, impact and fatigue tests. The results are as follows.
It was found that the yield strength of materials with a grain size of 1-3 μm increased linearly in proportion to the grain size to the −1⁄2 power. The ultra-fine grained materials show higher elongation considering their high strength. In particular, it showed extremely large uniform elongation. Even for the fatigue strength which is similar to the tensile strength, a high value is shown. The impact test indicated that the ultra-fine grained materials had slightly low toughness.
The high strength of ultra-fine grained materials can be explained by the Hall-Petch relationship. The high uniform elongation is considered to be produced by dispersion of the highly deformable β phase throughout the materials, which creates uniform deformation, and thereby prevents stress from concentrating locally when tension is applied.抄録全体を表示PDF形式でダウンロード (1726K) -
桐野 文良, 大友 茂一, 小礒 良嗣1997 年 61 巻 1 号 p. 90-97
発行日: 1997年
公開日: 2008/04/04
ジャーナル フリーEffects of Al addition, kinds of substrate material and underlayer on the crystal structure of Fe-Ta-C magnetic thin films were studied. As-deposited Fe-Ta-C films sputtered on a single crystal Mn-Zn ferrite substrate were amorphous. On the contrary the crystal stracture of as-deposited Al doped Fe-Ta-C film sputtered on the Mn-Zn ferrite substrate, which had high corrosion resistance, was crystalline. After thermal treatment of these films at 863 K for 1800 s, the magnetic thin films showed a strong Fe(100) face orientation. At the same time, the coercive force, Hc, of this film was larger than 224 A/m. An as-deposited Al doped Fe-Ta-C film, which was formed on a crystalline glass substrate, was in the amorphous state. Even after annealing, this film formed on the glass substrate showed excellent soft magnetic characteristics. Use of an under-layer consisting of Cr or SiO2 on the ferrite substrate surface, was effective in controlling the crystal structure of Al doped Fe-Ta-C magnetic thin films on single crystal Mn·Zn ferrite substrates. With a SiO2 film of 25 nm thickness, the as-deposited Al doped Fe-Ta-C film on the ferrite substrate became amorphous.抄録全体を表示PDF形式でダウンロード (742K)
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