巻号一覧
59 巻, 9 号
選択された号の論文の17件中1～17を表示しています
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森田 孝治, 連川 貞弘, 中島 英治, 吉永 日出男1995 年 59 巻 9 号 p. 881-888
発行日: 1995年
公開日: 2008/04/04
ジャーナル フリーThe high resolution TEM observation of ⟨110⟩ symmetric tilt grain boundaries in titanium carbide has shown that at a boundary near to the incoherent (11\bar2)Σ3 coincidence boundary there exists a periodic grain boundary structure consisting of two kinds of atomic arrangements. One is a mirror-symmetric atomic arrangement in the adjacent crystals to the boundary, and the other is a periodically mixed structure of mirror-symmetric and asymmetric arrangements. Two kinds of asymmetric structures are observed depending on a slight deviation from the ideal misorientation. This fact is explained by the DSC dislocation (b=a⁄6[11\bar2]) and lattice dislocation (b=a⁄2[01\bar1]) extended on their boundaries after dissociating into two partial dislocations, respectively. Further, the observed periodic structures of the boundary can well be explained by the DSC dislocations based on the CSL model and boundary dislocations predicted by the O-lattice model.抄録全体を表示PDF形式でダウンロード (1735K) -
三浦 博己, 西條 和秀, 酒井 拓1995 年 59 巻 9 号 p. 889-893
発行日: 1995年
公開日: 2008/04/04
ジャーナル フリーCu-SiO2 bicrystals having [011] twist boundaries with different misorientation angles were tensile tested at various temperatures from 473 to 1173 K. Most bicrystals fractured intergranularly. As the grain-boundary energy increases, intergranular brittle fracture tended to take place more easily at lower temperatures and the ductility of bicrystals with higher energy boundaries became lower. The elongation to fracture of the fractured bicrystals intergranularly decreased with increase in temperature monotonically. These grain boundary dependent characteristics of deformation and fracture behavior of bicrystals could be explained reasonably by considering the difference in the occurrence of grain-boundary sliding and Schmid factor.抄録全体を表示PDF形式でダウンロード (1316K) -
今清水 雄二, 渡辺 慈朗1995 年 59 巻 9 号 p. 894-901
発行日: 1995年
公開日: 2008/04/04
ジャーナル フリーSingle crystals of copper-aluminum dilute alloys containing 0.05, 0.1, 0.2, 0.5, 1, 2, and 5 at%Al were grown by pulling up from the melt with the [111] orientation at a pulling rate of 1.7×10−5 m/s and a crystal rotation rate of 1 rad/s in a stream of purified argon gas. The density and distribution of dislocations in the pulled crystals were investigated by an etching technique, and the effect of aluminum atoms on the dislocation formation in the copper-aluminum dilute alloy crystals during pulling was examined.
(1) A small addition of aluminum suppresses the formation of slip dislocations and the increase of dislocation density from the center to the periphery which occurred frequently in the pulled crystals of copper. Moreover, the mean dislocation density takes a minimum value about 5×107 m−2 at 0.1 at%Al, which is more than one order of magnitude less than that in the copper crystals.
(2) On the other hand, the subboundaries and the dislocation clusters were sometimes introduced into the crystals containing 0.05∼0.5 at%Al, which are similar to those found in the copper-aluminum dilute alloy crystals grown by the Bridgman method in the previous work.
(3) The dislocation density increases with an increase in aluminum concentration more than 0.5 at%Al. The frequency for the formation of subboundaries and dislocation clusters also increase when the crystals contain more than 1 at%Al. In the 5 at%Al alloy crystals, the dislocation clusters surrounded with a ringed subboundary are frequently formed together with subboundaries. It is inferred that the dislocation substructures might arise from the segregation of aluminum atoms occurred at the labilized solid-liquid interface due to constitutional supercooling.抄録全体を表示PDF形式でダウンロード (1565K) -
渡辺 徹, 保科 宏行1995 年 59 巻 9 号 p. 902-909
発行日: 1995年
公開日: 2008/04/04
ジャーナル フリーThere are five kinds of structures in binary alloys: two-phase structure, solid solution, metastable crystal, amorphous structure, and intermetallic compound. In this study, a Monte Carlo simulation was attempted for the formation of these structures. The main parameter in the algorithm of this simulation is the probability of the arrangement of different kinds of atoms neighboring each other during crystal growth. This parameter is closely related to the difference in the affinity between the same and different kinds of atoms. The high value of this parameter means that the affinity between two different kinds of atoms is higher than that between the same kind of atoms. In this situation, the formed solid has a long-range ordered structure. In contrast, when the value of this parameter is low, namely when the affinity between two different kinds of atoms is low, atoms of the same kind agglomerate and the formed solid has a phase separated structure. Other parameters are the size of each deposited atom, and the rate of nucleation. By combination of these parameters, all of the five kinds of structures mentioned above could be formed. From the results of this simulation, it is found that the affinity (chemical interaction) between atoms is the most important factor in the structure formation.抄録全体を表示PDF形式でダウンロード (1144K) -
斎藤 秀雄, 森 実, 石田 洋一1995 年 59 巻 9 号 p. 910-916
発行日: 1995年
公開日: 2008/04/04
ジャーナル フリーBehavior of hydrogen in an austenitic stainless steel SUS316L was investigated by tritium transmission electron microscopic autoradiography exposed at liquid nitrogen temperature. In this case, the size of blackened silver particles was about 0.04 μm, that was one third of the particles size when exposed at 253 K.
Blackened silver particles at liquid nitrogen temperature were observed at precipitates of the grain boundaries, in the vicinity of triple points, along coherent twin boundary, at facet corners of twins, dislocations and interfaces between precipitates and the matrix phase.抄録全体を表示PDF形式でダウンロード (2618K) -
原勢 二郎, 黒沢 文夫, 牛神 義行, 吉富 康成, 中島 正三郎1995 年 59 巻 9 号 p. 917-924
発行日: 1995年
公開日: 2008/04/04
ジャーナル フリー87.4% cold rolled and primary recrystallized Fe-3%Si specimens containing Al were nitrided after primary recrystallization. They were then annealed intermittently with the heating rate of 15°C/hr in a infrared radiation furnace in 100%N2 atmosphere. Magnetic induction B8 were measured after each annealing. The onset of secondary recrystallization was detected by the rapid rise of B8 value. The secondary recrystallization temperatures were higher when the initial grain sizes were larger or the nitrogen contents after nitriding treatment were higher. The secondary recrystallization with a sharp (110)[001] orientation took place at temperatures between 1070 and 1085°C in the specimens with different nitrogen contents and different initial grain sizes.
The existence of an optimum temperature range for the selective growth of the (110)[001] oriented grain in secondary recrystallization suggests that the Σ9 boundary becomes most mobile in the temperature range under the given inhibitor intensity.抄録全体を表示PDF形式でダウンロード (786K) -
戸田 裕之, 井上 直也, 新村 良子, 小林 俊郎1995 年 59 巻 9 号 p. 925-932
発行日: 1995年
公開日: 2008/04/04
ジャーナル フリーRecently, the existence of PFZ layers in the vicinity of the reinforcement with a width of several ten nm have been reported in the aluminum alloy matrix composite. Solute atom segregation due to the non-equilibrium mechanisms has been observed simultaneously in this region.
Elastic-plastic finite element analyses have been performed to evaluate the effects of these locally-inhomogeneous matrix on the tensile mechanical properties of a 6061Al alloy matrix composite reinforced with aligned 22 vol%SiC whiskers. The reinforcement is assumed to be surrounded by the PFZ layers of 0, 44 and 88 nm widths in which the mechanical properties of the matrix are substituted by those of the Al-6%Mg alloy without precipitation.
The initial strain hardening rate decreases with increasing PFZ width, while the Young’s modulus is almost independent of PFZ width. These results are primarily attributed to the plastic deformation near the corner of the reinforcement due to the considerably low elastic limit in the PFZ layer. The numerical results also provide a mechanistic rationale for experimentally-observed efficiency of the microstructural control in which the PFZ layer have been successfully vanished utilizing the gradient of the solute atom concentration near the interface.抄録全体を表示PDF形式でダウンロード (701K) -
白砂 洋志夫, 野末 章, 大久保 忠恒1995 年 59 巻 9 号 p. 933-938
発行日: 1995年
公開日: 2008/04/04
ジャーナル フリーWeld joint is locally deformed plastically and simultaneously restored at a high temperature after welding, and subsequently cooled to room temperature. Its singular thermomechanical hysteresis of the weld joint may affect aging behavior. Ti-15V-3Cr-3Sn-3Al alloys have showed aging enhancement in the weld joint. In the present study, we clarify the aging enhancement mechansim of this alloy on the base of the thermomechanical processing. A distinctive microstructure has existed in the weld joint after the welding and the subsequent cooling. Fringe-type microstructures of plate and bulk configuration may be created by local plastic deformation due to thermal stress after welding and by freezing of a solute atom atmosphere in the vicinity of edge dislocation component on cooling. Its distinctive microstructures have promoted the aging because of preferential sites for α precipitation. From the present results, a thermomechanical treatment has been proposed to obtain a high strength of this alloy by more short aging time.抄録全体を表示PDF形式でダウンロード (1240K) -
本郷 和弘, 赤池 淳, 松田 則男, 松浦 圭助1995 年 59 巻 9 号 p. 939-946
発行日: 1995年
公開日: 2008/04/04
ジャーナル フリーCreep tests were carried out at temperatures from 573 to 773 K on the 6061Al matrix composites reinforced with 11 vol% and 18 vol% alumina short fibers to examine the effect of short fibers reinforcement on the creep rate and the creep curve shape, and their stress and temperature dependences. Furthermore, the density change by creep deformation was measured to examine the formation of cavities during creep of the short fiber reinforced composites.
Creep curve shape changed with stress as follows: In the low stress range, the tertiary creep occurred after small extent of the primary stage, so that the creep curve was dominated by the tertiary creep without being related to the occurrence of necking in the specimen. With increasing the stress, the extent of primary and secondary stages became large and occupied a large part of the creep curve in the high stress range at low temperature.
The higher the creep temperature and the lower the creep stress, the larger was the density change by creep deformation. It showed that the tertiary creep was associated with the formation of cavities, especially at the fiber/matrix interface and at the grain boundaries at high temperature (773 K).
The θ-projection method was useful in describing the creep curve shape of the short fiber reinforced composites and it’s variation with stress and temperature. It was found that rate parameters θ2 and θ4 describing the primary and tertiary creep were about equal, at least at 573 and 673 K, as proposed by Maruyama et al.
These results were compared with the creep behaviour of Al matrix composite reinforced with the same short alumina fibers as the present composites and the effect of matrix alloy on creep was discussed.抄録全体を表示PDF形式でダウンロード (978K) -
嶋影 和宜, 佐藤 忠夫, 平井 伸治, 戸田 茂雄, 高橋 徹, 作田 庸一1995 年 59 巻 9 号 p. 947-952
発行日: 1995年
公開日: 2008/04/04
ジャーナル フリーCrude niobium has been purified by a refining process consisting of molten salt electrolysis and electron beam melting. The molten salt electrorefining was carried out galvanostatically using a FLINAK bath (26.3 mass%LiF-10.5 mass%NaF-47.0 mass%KF-16.2 mass%K2NbF7) at 963 K under Ar atmosphere. After the molten salt electrorefining and the electron beam melting, the contents of metallic impurity components in the purified niobium were determined by ICP emission spectrography analysis. Refractory metals such as tantalum, tungsten and molybdenum in crude niobium could be eliminated by means of molten salt electrorefining. Especially, the molten salt electrorefining method using fluoride bath was remarkably effective for the removal of metallic tantalum in crude niobium. Nonmetallic impurity components such as oxygen and nitrogen could be also removed by electron beam melting.
Crude niobium of 99.8 mass% purity was found to be purified to 99.99 mass% by this refining process.抄録全体を表示PDF形式でダウンロード (600K) -
原 基, 中川 時子, 佐藤 芳幸, 山口 邦彦, 品田 豊1995 年 59 巻 9 号 p. 953-959
発行日: 1995年
公開日: 2008/04/04
ジャーナル フリーThe effect of hydrogen reduction on photo-anodic polarization behavior for TiO2 films formed by high temperature oxidation was investigated in Na2SO4 solution. The hydrogen reduction was conducted at 773∼1173 K for 1.8 ks in 2.9 vol.%H2-Ar atmosphere. The rate of increase in anodic photocurrent with an increase in polarization potential grew as reduction temperature increased. In order to explain this increase of photo-anodic reaction rate for the TiO2 films, the changes in limiting wavelength for the generation of photocurrent, surface morphology, crystal structure, and chemical composition of the films were examined as a function of reduction temperature. The limiting wavelength for the generation of photocurrent was almost independent of the reduction temperature. The rutile structure of the TiO2 films was not changed by the hydrogen reduction. On the contrary, the concentration of titanium in the films increased consistently with the reduction temperature. Therefore, it was thought that the increase in photo-anodic reaction rate for the TiO2 films with rising reduction temperature was attributable to an increase in concentration of excessive titanium ions, which may become the sites for the formation of the surface state on the oxide film.抄録全体を表示PDF形式でダウンロード (938K) -
原 基, 永原 敏行, 佐藤 芳幸, 中川 時子1995 年 59 巻 9 号 p. 960-966
発行日: 1995年
公開日: 2008/04/04
ジャーナル フリーThe corrosion behavior of pure chromium in molten NaNO3 has been examined by the measurement of corrosion loss and the electrochemical measurement. Particular attention was given to the influence of melt temperature. Corrosion losses of pure chromium in the temperature range lower than 723 K were small, whereas those in the temperature range higher than 823 K were extremely large. It was found that a surface oxide consisting of Cr2O3 was formed on the chromium after the corrosion test in the low temperature range. In the high temperature range, on the contrary, the formation of the surface oxide was not found, and the specimen surface showed a feature of vigorous dissolution. Such a temperature dependence of the corrosion behavior corresponded to that of the electrochemical behavior. That is to say, the anodic polarization curves measured at the low temperatures showed the spontaneous passivation behavior, while those at the high temperatures showed a large rise in anodic current density from the low corrosion potential. As the result of the corrosion test of oxides in molten NaNO3, it was found that Cr2O3 dissolved vigorously in the high temperature range. Consequently, it was thought that the high corrosion rate of chromium in molten NaNO3 at high temperature was attributed to a dissolution of the surface oxide consisting of Cr2O3 and a consequent electrochemical corrosion reaction of chromium.抄録全体を表示PDF形式でダウンロード (565K) -
公門 武, 鈴木 亮輔, 小野 勝敏1995 年 59 巻 9 号 p. 967-972
発行日: 1995年
公開日: 2008/04/04
ジャーナル フリーThe combination of hot dipping in molten aluminum and the subsequent anodic oxidation to dense Al2O3 films was studied to prepare an oxidation-resistant coating on niobium surface. By immersing Nb into a molten Al bath, granular NbAl3 was precipitated and improved the coherency of the film to the substrate. Amorphous Al2O3 was formed by anodic oxidation of the Al layer and crystallized to corrosion resistant α-Al2O3 by the subsequent heat treatment. The Nb substrate after this combined treatment did not form any niobium oxides even after heating in air for 64.8 ks at 1073 K, and the oxygen increment in the Nb bulk was suppressed below 400 mass ppm.抄録全体を表示PDF形式でダウンロード (875K) -
竹下 博之, 冨井 洋一, 鈴木 亮輔, 小野 勝敏1995 年 59 巻 9 号 p. 973-977
発行日: 1995年
公開日: 2008/04/04
ジャーナル フリーLocal quantitaive analysis of small amounts of oxygen in titanium was studied using the secondary ion mass spectrometry (SIMS). Cs+ ion was used for the primary ion beam, and 16O−, 64TiO− and 96Ti2− for the secondary ones. The intensity profiles of the secondary ions against energy at sputtering (energy profile) showed a good similarity between the cluster ions, i.e., TiO− and Ti2−. The precision of oxygen analysis was improved due to the similar energy profiles of the two analytical ions. Using the high energy resolution of mass spectrometer and the stable extraction voltage of secondary ions, the effect by mismatching in the energy profiles was reduced. The relative standard deviation of the ion intensity ratio I[64TiO−]⁄I[96TiO2−] was suppressed less than 10% over the oxygen concentration of 23 to 1540 mass ppm.抄録全体を表示PDF形式でダウンロード (476K) -
馮 吉才, 奈賀 正明, Schuster J. C.1995 年 59 巻 9 号 p. 978-983
発行日: 1995年
公開日: 2008/04/04
ジャーナル フリーThe solid state bonding of pressureless-sintered (PLS) SiC to SiC using Ti-foils (50 μm, 20 μm and 8 μm) were conducted at the bonding temperatures ranging from 1373 to 1673 K for 0.3 to 144 ks in vacuum. The total diffusion path, formation process of reaction phases and the reaction mechanism were examined. At a bonding temperature of 1673 K for 0.3 ks, granular TiC next to Ti and a mixture of Ti5Si3Cx+TiC phases next to SiC were formed. Further, the Ti5Si3Cx single phase appeared between SiC and the mixture of Ti5Si3Cx+TiC at the bonding time of 0.9 ks. Upon the formation of Ti3SiC2 (T phase) after the bonding time of 3.6 ks, the complete diffusion path was observed as follows: SiC/Ti3SiC2/Ti5Si3Cx/Ti5Si3Cx+TiC/TiC/Ti. At a longer bonding time, TiC and Ti5Si3Cx were consumed and only the Ti3SiC2 and TiSi2 phases were detected in the reaction zone.抄録全体を表示PDF形式でダウンロード (721K) -
柳井 知宏, 石崎 幸三1995 年 59 巻 9 号 p. 984-989
発行日: 1995年
公開日: 2008/04/04
ジャーナル フリーSi3N4 ceramics have strong covalent bonding, which makes them difficult to sinter. Highly densified Si3N4 ceramics are normally obtained through liquid phase sintering. As the liquid phase consists of sintering additives and surface impurity phase on the raw Si3N4 powder, the quantity of grain boundary phase depends on surface impurity oxygen phase and additives content. The effects of surface impurity oxygen content on mechanical properties, microstructures and sintering behavior are investigated. In this work, the surface oxygen contents is controlled by an oxidation or washing treatment. Assuming that all the oxygen atmos form SiO2, the SiO2 content ranges from 1.07 to 9.20 mass%. The sintering additives used were 3 mol% each of Al2O3 and Y2O3. The sintered bodies are obtained by hot-pressing at 1800°C for 60 min under 30 MPa in N2 atmosphere.
The grain boundary crystalline phases were not found from 2.68 mass% to 4.68 mass%SiO2 content by X-ray diffraction analysis. While, sintered bodies from 1.07 mass% and above 6.39 mass%SiO2 powder, the grain boundary phases include crystalline phases. The fracture toughness increases with decreasing surface oxygen content. While, the bending strength decreases below 2.0 mass% and above 6.5 mass%SiO2 contents. The maximum values of fracture toughness and bending strength indicate 5.4 MN/m3⁄2 and 980 MPa, respectively. The grain shape changes from elongated to equiaxed with increasing surface oxygen content. This results in the decrease in fracture toughness and critical flaw size. The number of nuclei depends on the surface oxygen content in the raw Si3N4 powders. When the liquid phase content is low, e.g., using low surface oxygen content powder, the liquid phase content decreases, which leads the decrease in nucleation sites. Therefore, the grain shape changes from equiaxed to elongated grains with decreasing the number of nuclei. If the full dense sintered bodies can be obtained by less surface oxygen content Si3N4 powder, the β-Si3N4 grains should have a high aspect ratio. The high fracture toughness Si3N4 ceramics can be obtained by washing treatment.抄録全体を表示PDF形式でダウンロード (983K) -
麻生 節夫, 石井 雄三, 後藤 正治, 田上 道弘, 武藤 侃1995 年 59 巻 9 号 p. 990-996
発行日: 1995年
公開日: 2008/04/04
ジャーナル フリーThe γ+M2B, γ+M23(C, B)6 and γ+M7(C, B)3 eutectics solidify by itself or jointly at compositions along the pseudo-binary eutectic line in a Fe-25%Cr-C-B system. Due to this, various eutectic alloys with some kinds of eutectic structures were obtained by changing the combination of carbon and boron content. Sand-erosion tests were carried out in two kinds of slurries with tap water or seawater, in order to examine the effect of corrosion resistance on six kinds of Fe-25%Cr-C-B eutectic alloys. The sand-erosion rate (Wk) was shown by the formula, Wk=Kexp(−Q⁄RT) where K: constant, Q: apparent activation energy, R: gas constant and T: slurry temperature. The Q value obtained from this formula for each specimen ranged from 3 to 20 kJ/mol in the tap water solvent slurry and from 4 to 40 kJ/mol in the seawater solvent slurry. The variation in Q due to the difference of the slurry solvents can tentatively be arranged into three types; (I) constant, (II) increase and (III) decrease. The Q value and the Wk level were found to be a useful criteria for sand-erosion resistance. The change in Wk in the tap water solvent slurry was estimated to be little in each alloy, whereas in the seawater solvent slurry the Wk values of the alloys containing 2%B were 1⁄15∼1⁄30 of the SUS430-type stainless steel and boron free alloys.抄録全体を表示PDF形式でダウンロード (885K)
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