巻号一覧
56 巻, 9 号
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須崎 嘉文, 渡部 平司, 吹田 義一, 鹿間 共一, 芳井 熊安, 川辺 秀昭1992 年 56 巻 9 号 p. 985-990
発行日: 1992年
公開日: 2008/04/04
ジャーナル フリーThermal release of hydrogen in hydrogenated amorphous SiC(a-SiC : H) films was studied using IR spectroscopy and elastic recoil detection analysis (ERDA). The films were prepared onto Si(111) wafers at room temperature by r. f. planar magnetron sputtering at a power of 210 W in a mixture gas of argon at partial pressures of 0.33 Pa and hydrogen at 0.065 to 1.3 Pa.
Hydrogen depth profiles of as-deposited films examined by the ERDA method showed that hydrogen concentrations in the films ranged from 5.3−7.8×1027 atoms/m3. The IR measurements conducted on the films annealed at various temperatures for 1 h suggested that the hydrogen was released from Si-H and C-H bonds in the films at the temperature above about 573 and 873 K, respectively. In-situ isochronal annealing for 5 min at various temperatures from 323 to 1123 K in the ERDA system was carried out for the specimen having the hydrogen concentration of 7.1×1027 atoms/m3. The results showed that there existed three states of hydrogen in the film; hydrogen bonded to the Si atom, that to the C atom, and that free from the bonding with the concentrations of 2.8×1027, 1.9×1027 and 2.4×1027 atoms/m3, respectively. Furthermore, from the kinematical analyses of these results, the activation energies for the release process of the three states of hydrogen were determined to be 7.05×10−20 J (0.44 eV), 2.08×10−19 J (1.3 eV) and 1.27×10−20 J (0.079 eV), respectively.抄録全体を表示PDF形式でダウンロード (895K) -
関 彰1992 年 56 巻 9 号 p. 991-997
発行日: 1992年
公開日: 2008/04/04
ジャーナル フリーA mean-field approach in which the grain boundary structure, alloy effects, a surface tension term and a size effect are taken into considerations is applied to the grain boundary segregation at FCC [001] twist boundaries in a Pt-1 at.%Au, a Pt-1 at.%Ni, a Ni-1 at.%Pt, a Ni-1 at.%Cu and a Cu-1 at.%Ni alloy at 1000 K. The results from the present model are in good agreement with those of Monte Carlo simulations utilizing the embedded atom method (EAM) potentials. In a Pt-1 at.%Au alloy, the segregation of Au occurs by the alloy effect. The size mismatch between solvent and solute atoms plays a significant role in the case of Pt-Ni alloys. On the contrary, the surface tension term is important in Ni-Cu alloys. That is, in both Ni-1 at.%Cu and Cu-1 at.%Ni alloys, Cu atoms, which have lower surface tension than Ni atoms, are enriched in the boundary.抄録全体を表示PDF形式でダウンロード (816K) -
相根 博道, 桑野 範之, 沖 憲典1992 年 56 巻 9 号 p. 998-1005
発行日: 1992年
公開日: 2008/04/04
ジャーナル フリーModulated structures in Cu-(10, 15 and 20) mass%Ni-8 mass%Sn alloys have been investigated by X-ray diffraction and transmission electron microscopy. The side band profiles in X-ray powder patterns were calculated using a general diffraction theory for a one-dimensionally disordered crystal, which were compared with the experimental ones for various aging processes. A variety of modes of modulation waves were taken into account in the calculations. Although the modulation waves are different in time evolution in these alloys with 4.4 at%Sn (8 mass%Sn), they grow up to have similar profiles of the modulation waves. It is suggested that the wave profiles are asymmetric and the amplitudes increase by about 2 to 2.5 at%Sn in higher Sn regions and decrease by about 1 at%Sn in the lower Sn ones. The D022 ordered structure appearing in the modulated structures alters gradually into L12 during aging. This transition takes place earlier in the alloy with higher Ni content.抄録全体を表示PDF形式でダウンロード (2047K) -
大西 正己, 伊藤 力, 若松 良徳, 下 敏唯1992 年 56 巻 9 号 p. 1006-1012
発行日: 1992年
公開日: 2008/04/04
ジャーナル フリーFundamental research for the alloying reaction in the galvannealing process was made using the multiple marker technique which enables us to investigate atomic movement due to diffusion. 0.1 mass%Al was added to both solid and molten zinc employed. After anneal of the iron-solid zinc diffusion couples, intermetallic compounds were detected in the couple. Bends of the multiple marker arrays were observed at both iron/intermetallic compound and intermetallic compound/zinc interfaces. From these results we can deduce that iron atoms leave an iron lattice and then be included in a crystal lattice of the intermetallic compound together with zinc atoms at the iron/compound interface. At the same time vacancies are created at the interface and then move toward the compound/zinc interface by exchange of positions with zinc atoms. Consequently, growth of the compounds is controlled by the diffusion of zinc atoms.
The reaction of a solid iron specimen with molten zinc in the high temperature range of more than about 780 K yields thin coherent compound layers over the iron substrate. The outer compound, δ1, layer, however, is disrupted by attack of the molten zinc, in place of a coherent layer. The marker experiment also shows that iron and zinc atoms are included in the intermetallic compound at the iron/compound interface. Hence, a cause for rapid proceeding of the alloying reaction in the galvannealing can be ascribed to the short distance pass for zinc atom diffusion.抄録全体を表示PDF形式でダウンロード (2210K) -
富田 友樹, 高谷 泰之, 橋詰 源蔵, 原田 良夫1992 年 56 巻 9 号 p. 1013-1019
発行日: 1992年
公開日: 2008/04/04
ジャーナル フリーIsothermal aging at 773∼1023 K has been carried out to investigate precipitation in low Fe, high Cr, Ni-base overlay weld alloys which were formed on a mild steel by plasma powder welding process. In this work, effects of NbC addition on precipitation process were studied by hardness measurements, X-ray diffraction and metallographic methods.
It was found that the NbC dispersed alloy was higher in age-hradenability than the NbC-free alloy in the as-welded condition and both alloys had a peak hardness followed by slowly softening during aging. In the NbC-free alloy, nodular precipitates appeared at grain boundaries and then continuous precipitation of α′-phase occurred within the matrix (γ-phase). However, in the NbC dispersed alloy, any precipitaion has not occurred except for continuous precipitation of α′ in the matrix. It was considered that such different precipitation phenomena have been caused by niobium atoms dissolved in the matrix. Age hardening observed is due to the continuous precipitation of α′ particles and the softening is caused by their coarsening.抄録全体を表示PDF形式でダウンロード (2741K) -
古原 忠, 中森 英行, 牧 正志1992 年 56 巻 9 号 p. 1020-1029
発行日: 1992年
公開日: 2008/04/04
ジャーナル フリーCrystallographic orientation relationships of α phases precipitated on dislocations and deformation twin boundaries in the β matrix have been investigated in a Ti-15V-3Cr-3Sn-3Al alloy, by means of transmission electron microscopy (TEM).
Planar and widely spaced, {112}⟨111⟩β slip bands are formed by weak rolling at room temperature after solution treatment. By subsequent aging at 933 K, α plates precipitate preferentially on the dislocations in the slip bands. In the same slip band, α plates select the particular variant of the Burgers orientation relationship. The selection rule of variant was discussed in terms of the effective relaxation of the transformation strain by the stress field associated with the dislocation.
By subzero rolling at 77 K, {332}⟨113⟩β deformation twins are produced. By subsequent aging at 933 K, α phases precipitate on the twin boundaries, following the Burgers orientation relationship with respect to both of the β matrix and the twin. It is considered that α nucleus forms coherently with both of the β phases to reduce the energy of the α/β interface formed newly.抄録全体を表示PDF形式でダウンロード (2164K) -
下尾 聰夫, 森内 恭彦, 岡村 清人1992 年 56 巻 9 号 p. 1030-1036
発行日: 1992年
公開日: 2008/04/04
ジャーナル フリーThe kinetics and mechanism of the reaction of Si3N4 with Fe were investigated. Using powdered Si3N4-Fe mixture, the reaction rates were measured by means of a thermobalance at temperatures from 1373 to 1673 K in Ar or N2 gas stream. The reaction products were examined by X-ray diffraction.
The reaction of Si3N4 with Fe was initiated after heating to about 1350 K. The reaction product changed from Fe-Si solid solution to Fe silicide Fe3Si, as the reaction proceeded. The reaction rates and the reaction products were independent on the atmosphere. The kinetics obeyed the nearly parabolic rate law. The formation of Fe3Si increased the rate constant abruptly. The apparent activation energy was 533 kJ/mol in the region of Fe-Si solid solution. The reaction rates of Si3N4 with Fe are probably mixed-controlled by both the interfacial reaction and the diffusion through the reaction layer.抄録全体を表示PDF形式でダウンロード (909K) -
姜 祥春, 吉村 敏彦, 石川 雄一1992 年 56 巻 9 号 p. 1037-1042
発行日: 1992年
公開日: 2008/04/04
ジャーナル フリーCyclic polarization curves were measured for aged Fe-25Cr-6Ni-3Mo duplex stainless steel in xMH2SO4+0.01MKSCN(x=0.5, 0.1) solution to investigate the electrochemical behaviour during the formation of Cr-rich phase (α′). The results are discussed in relation to the microvickers hardness and atom probe analysis.
The formation of α′ phase is found to begin after 1000 h. The reactivation current peak is also abserved. This results from the Cr-depleted Fe-rich region formed with the formation of α′ phase. For the specimens aged for less than 340 h, both the hardness and the passivation current increase with aging time, while no reactivation current peak is observed. This behavior together with a significant increase in the hardness may reflect the development of the fluctuation of the Cr concentration in the ferrite phase by spinodal decomposition. Separation of active dissolution and reactivation peaks into several distinct peaks indicates the presence of Cr-depleted Fe-rich regions of different Cr concentrations.抄録全体を表示PDF形式でダウンロード (2603K) -
泰松 斉, 和田 慶司, 金児 紘征1992 年 56 巻 9 号 p. 1043-1049
発行日: 1992年
公開日: 2008/04/04
ジャーナル フリーThe couples Ti/CoO and Ti/NiO were allowed to react at 1273 K. In the couples Ti/CoO and Ti/NiO, the reaction zones consisted of Co+TiO2 and Ni+TiO2 two-phase aggregate layers, respectively; in a TiO2 matrix, Co or Ni phases were three-dimensionally entangled with each other. No lower oxides of Ti were found in the product layers. The growth of the product layers obeyed the parabolic rate law. In these systems, cermets with structures mixed in micron size could be easily made by using the solid-state displacement reaction between powders.抄録全体を表示PDF形式でダウンロード (2615K) -
加藤 雅敏, 榊 孝1992 年 56 巻 9 号 p. 1050-1055
発行日: 1992年
公開日: 2008/04/04
ジャーナル フリーCorrosion behaviours of 99.83%Cr, Fe-Cr alloys and Ti were investigated by measuring polarization curves and corrosion rates in the solutions of various HNO3 concentrations.
Ti and the Fe-30Cr alloy were severely corroded by less than 60%HNO3 solutions above 400 K. On the other hand, Cr had much better corrosion resistance than Ti and the Fe-30Cr alloy in these conditions. It is because the corrosion potential of Cr is kept in the passive and the surface film of Cr in the passive state is very stable. However, with increasing concentration of HNO3, the corrosion potential of Cr sifted in a much more noble direction by the cathodic reaction of NO−3, and then the trans-passive dissolution reaction as Cr6+ occurred. Therefore intergranular corrosion of Cr occurs in more than 65%HNO3 solutions above 400 K. As the formation reaction of Cr3+ from Cr6+ is also included in the corrosion reaction of Cr in HNO3, the corrosion of Cr in HNO3 is accelerated by this cathodic reaction.抄録全体を表示PDF形式でダウンロード (1002K) -
宮原 広郁, 大谷 潤, 森 信幸, 大城 桂作1992 年 56 巻 9 号 p. 1056-1063
発行日: 1992年
公開日: 2008/04/04
ジャーナル フリーThe wettability and the reaction between molten Al and Al2O3-SiO2 substrates were measured by the sessile drop method in a vacuum of 2×10−3 Pa at temperatures from 973 to 1173 K. The contact angles of molten Al to Al2O3 and Al2O3-SiO2 substrates decreased from about 110° to 90° as the temperature rose from 973 to 1173 K. The reaction between molten Al and NC mullite, which consisted of mullite and vitreous SiO2, produced a mixed layer of Al2O3 and mullite. The reaction layer grew in proportion to the holding time at 973 K. The linear growth was also recognized until 300 s at 1073 K, and the growth rate was controlled by the chemical reactions:
3SiO2+4Al=3Si+2Al2O3
3(3Al2O3·2SiO2)+8Al=6Si+13Al2O3
On the contrary, at 1173 K or after 300 s at 1073 K, the reaction layer grew parabolically with the increase in time. The growth rate was controlled by the diffusion of Al and Si through the reaction layer.
The uniform Al2O3 layer formed between molten Al and mullite substrate at 1173 K after an incubation period. The growth rate was also governed by the diffusion of Al and Si.
The Si pickup by Al drop was estimated by the thickness of the reaction layer between molten Al and NC mullite or mullite substrate.抄録全体を表示PDF形式でダウンロード (2354K) -
大参 達也, 工藤 昌行, 大笹 憲一1992 年 56 巻 9 号 p. 1064-1071
発行日: 1992年
公開日: 2008/04/04
ジャーナル フリーThe primary silicon crystals of hypereutectic Al-Si alloy are refined by the Duplex Casting process. In this process, two kinds of alloy melts, i.e. “the first alloy” with a relatively low liquidus temperature and “the second alloy” with a relatively high liquidus temperature, are cast in a mold in sequence at a given time interval. Concerning the refining mechanism, the authors have explained that the second alloy melt is rapidly cooled during mixing with the first alloy which acts as a coolant.
In this study, the influences of alloy composition and mold properties on the refinement of the primary silicon crystals in the Duplex Casting process were examined. As a result, it was shown that the grain size of primary silicon varied intricately depending on these conditions. The decantation technique showed that a considerable amount of solidified shell had formed in the first alloy before the pouring of the second alloy melt. Several comparative experiments were carried out in order to examine the effect of heat extraction by the solidified shell, which is to be remelted during the mixing with the second alloy melt, on the refinement of primary silicon crystals. In those experiments, the second alloy melt was mixed with the first alloy which was in the liquid or solid state. As a result, it was proved that the solidified shell contributes greatly to the refinement of the primary silicon crystals through the remarkable enhancement of the cooling capacity of the first alloy. Considering this effect, the influences of alloy composition and mold properties on the primary silicon size can be explained.抄録全体を表示PDF形式でダウンロード (1444K) -
京極 秀樹, 篠原 和充, 瀬尾 俊弘, 今村 拓夫, 津田 正夫1992 年 56 巻 9 号 p. 1072-1077
発行日: 1992年
公開日: 2008/04/04
ジャーナル フリーAustenitic stainless steel powder with an average particle diameter of 9 μm was injection molded together with a given content of binder and sintered after debinding treatment at temperatures ranging from 1573 to 1673 K for periods from 1.8 ks to 14.4 ks in an atmosphere of reduced pressure at 1 Pa. The changes in the porosities and the grain size were measured by means of the image analyzer. It was found that the changes of pores were on the transient stage from shrinking to coarsening and the coefficient of pinning force was inversely dependent on the grain size. Grain growth was found to be governed by the cubic law. Tensile strength of the sintered compact was approximately linear to the porosities. The proof stress followed the Hall-Petch relationship.抄録全体を表示PDF形式でダウンロード (1898K) -
山田 葉子, 川崎 亮, 李 敬鋒, 田谷 稔, 渡辺 龍三1992 年 56 巻 9 号 p. 1078-1086
発行日: 1992年
公開日: 2008/04/04
ジャーナル フリーThe Young’s modulus and fracture toughness of sintered ceramic composites of the SiC-AlN system, which has a limited composition range of solid solution, were evaluated by a micromechanical analysis based on a microstructural modeling which took into account the microstructural features and solid solutioning.
The Young’s modulus of the composite, which depends on the volume fraction of dispersoids, Young’s moduli and Poisson’s ratios of the matrix and the dispersoids, was evaluated by Eshelby’s method; a micromechanical approach to solve three-dimensional elasticity problems in which spherical dispersoids are embedded in a infinite elastic matrix. The fracture toughness of the composite was estimated by the Evans’ formula which considered the thermal residual stress introduced during cooling from a sintering temperature, due to the difference in coefficient of thermal expansion (CTE) between the matrix and dispersoids. The thermal residual stresses of both for the dispersoids and the matrix were analyzed by Eshelby’s method using the volume fraction of dispersoids, and Young’s moduli and Poisson’s ratios of the matrix and dispersoids. It was predicted that the thermal residual stress around dispersoids, which was introduced during processing, remarkably enhance the fracture toughness. Both of the predicted Young’s modulus and the fracture toughness of the composite, particularly in the SiC-rich composition range, were in good agreement with the experimental values.抄録全体を表示PDF形式でダウンロード (1911K) -
趙 源丞, 林 宏爾1992 年 56 巻 9 号 p. 1087-1092
発行日: 1992年
公開日: 2008/04/04
ジャーナル フリーEffects of uni-directional orientation of SiC whisker (SiC(W)) on the transverse-rupture strength (TRS) and fracture toughness (KIC) of SiC(W)/Si3N4 composite ceramics were mainly investigated. Two kinds of specimens (WL, WT) were prepared by powder extrusion and hot-pressing; The longer axes of SiC(W) in WL and WT specimens are aligned longitudinally or transversely to the specimen axis, respectively. The results were compared with those on the monolith and WR specimen in which the longer axes of SiC(W) are aligned randomly to the specimen axis, but vertically to the tensile surface.
The results obtained are as follows: (1) The TRS was increased from 1000 MPa (WR specimen) to about 1150 MPa (WL specimen) by the uni-directional orientation of SiC(W), although TRS of the WT specimen was as low as 780 MPa. The KIC was also increased from 6.0 MPam1⁄2 up to 9.4 MPam1⁄2 (about 57% increase) by the uni-directional orientation, although it was decreased to 5.1 MPam1⁄2 in the WT specimen. The KIC of the WL specimen was 95% larger than the monolith. (2) The degree of crack deflection in the WL and WT specimens were small, compared with that in the WR specimen; there was no correlation between the degree of crack deflection and the KIC value, indicating that the high KIC of the WL specimen could be ascribed to the increase of the load transfer effect by the uni-directional orientation of SiC(W), etc. (3) The effect of the uni-directional orientation of SiC(W) was presumed to be promoted by the preferential orientation of acicular β-Si3N4 grains which were induced by the uni-directional orientation of SiC(W).抄録全体を表示PDF形式でダウンロード (2078K) -
真島 一彦, 中村 剛, 横田 勝, 三島 信, 永井 宏1992 年 56 巻 9 号 p. 1093-1100
発行日: 1992年
公開日: 2008/04/04
ジャーナル フリーEffects of the addition of SiO2-CaO and the partial pressure of oxygen in the sintering process on the grain growth and magnetic properties of Mn-Zn ferrite were studied to obtain a fine grain structure as well as superior magnetic properties. The results obtained are summarized as follows.
(1) With the addition of SiO2-CaO up to 0.05 mass%, the density of Mn-Zn ferrite decreased, beyond which it increased inversely up to 0.2 mass% of SiO2-CaO.
(2) After a significant increase with the addition of 0.02 mass% of SiO2-CaO, the electrical resistivity showed a rapid decrease at 0.05 mass% addition and then an increase up to the addition of 0.20 mass% of SiO2-CaO.
(3) Fine grains were observed in the specimen without the addition of SiO2-CaO. In the specimen with the addition of SiO2-CaO, its grains became coarsened with the addition up to 0.05 mass%, while they
showed a tendency to become finer with the addition of more than 0.05 mass%.
(4) The Q values at the frequencies from 0.1 to 5.0 MHz varied in a similar way to the resistivity when the addition of SiO2-CaO increased. However, the μ values varied in a different way from the resistivity, and μ with the addition of 0.05 mass%SiO2-CaO showed a maximum at 0.1 MHz, and this maximum decreased and changed to a minimum when the frequency increased up to 5.0 MHz.
(5) Grains of the specimen with the addition of 0.05 mass%SiO2-CaO became coarsened with increasing O2 partial pressure up to 1.0%, while they became finer with the values more than 1.0%. Corresponding to this tendency of grain size, the density decreased with the increase of O2 partial pressure up to 100%. On the other hand, the resistivity was very low at 0.01% of O2 partial pressure and showed a remarkable increase at 0.05%. Beyond this point, the resistivity decreased with the increase of O2 partial pressure up to 1.0%, and then it increased up to 100%.抄録全体を表示PDF形式でダウンロード (2504K) -
林 爽原, 長 隆郎1992 年 56 巻 9 号 p. 1101-1107
発行日: 1992年
公開日: 2008/04/04
ジャーナル フリーSiC particulate reinforced magnesium matrix composites were fabricated by melt strirring method. The effect of several factors on mechanical properties and the efficiency of melt stirring method from the viewpoint of these properties were investigated.
The tensile strength increased and the elongation decreased with decrease of the particle size or the increase of the particulate volume fraction for pure magnesium matrix and Mg-5%Zn alloy matrix composites. A longer stirring time improved the tensile strength of these composites. The tensile strength of Mg-5%Ca alloy matrix composites which shows no uniform particulate distribution was a little lower than that of matrix alloy. Rapid solidification rate is preferred for the improved tensile strength of these composites. The pure magnesium matrix and Mg-5%Zn alloy matrix composites have tensile strength of about 400 MPa. This value agrees with the tensile strength of some magnesium matrix composites fabricated by liquid infiltration method or powder metallurgy method at the same volume fraction of reinforcements of whisker or particle.
Therefore, the melt stirring method which has the advantages of simple process is considered to be efficient in fabricating magnesium matrix composites.抄録全体を表示PDF形式でダウンロード (2339K) -
山中 淳二, 入戸野 修1992 年 56 巻 9 号 p. 1108-1109
発行日: 1992年
公開日: 2008/04/04
ジャーナル フリーPDF形式でダウンロード (467K)
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