巻号一覧
64 巻, 12 号
選択された号の論文の19件中1～19を表示しています
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新田 紀子, 谷脇 雅文, 鈴木 朝夫, 林 禎彦, 佐藤 裕樹, 義家 敏正2000 年 64 巻 12 号 p. 1141-1147
発行日: 2000年
公開日: 2008/04/24
ジャーナル フリーDefect formation in (100) GaSb by 60 keV Sn+ ion-implantation at 150-153 K is investigated using cross-sectional TEM, SEM and EDX. An anomalous structure consisting of many cells, which looks like a honey comb, was formed on the surface implanted with 8×1018 ions/m2. The diameter and the depth of a cell were about 50 nm and 220-250 nm respectively, and the thickness of the walls partitioning the cells was about 10 nm. The upper part of the partitioning wall is amorphous and rich in Ga, while the lower part shows crystalline structure. A heavy strain region with 50 nm thickness, corresponding to the maximum depth of the projected Sn ions, was observed under the cells. This defect structure is compared with similar defects which have been observed by other researchers. The defect formation mechanism is discussed, and an explanation based on movement of the implantation induced point defects is proposed. It is assumed that hills and hollows are formed in the early stage of implantation. The point defects created on the hills do not contribute to the development of the defect structure, because they annihilate almost completely by the recombination of vacancy and interstitial and by the movement to the near surface sink. However, under the hollows, vacancies remain which escaped recombination, and the interstitial atoms, which are highly mobile at low temperatures, migrate far from there to aggregate under the hills. The hollows become deeper by the movement of the remaining vacancies to the surface, and the hills develop into the walls by the migration of the interstitial atoms from the surrounding hollows.抄録全体を表示PDF形式でダウンロード (3688K) -
樋尾 勝也, 安達 崇, 山田 隆志, 土田 豊, 中島 浩衛, 細井 祐三2000 年 64 巻 12 号 p. 1148-1155
発行日: 2000年
公開日: 2008/04/24
ジャーナル フリーA study has been made on the effects of Al, Si and Mo on anodic polarization characteristics of Fe-10Cr alloys in 0.05-1.0 kmol·m−3 H2SO4 and NaCl aqueous solutions. Potential decay curves have also been measured in order to evaluate the stability of the passive films formed on Fe-10Cr alloys containing Al, Si and Mo. The analysis of the chemical composition of the passive film has been carried out by AES and XPS.
The addition of Mo was very useful to decrease the critical passivation current density of Fe-10Cr alloys which contained Al and Si. The passive current density decreased with addition of 2 mass%Mo to an Fe-10Cr-3Si alloy, while it increased in an Fe-10Cr-3Al alloy. Pitting potential was moved toward the noble direction by the addition of Mo, except for the case of an Fe-10Cr-3Al-3Si-2Mo alloy. It seems that Laves phase (Fe2Mo) was precipitated in this alloy, and Mo-depleted zone was formed locally. The activation time was increased by the addition of Al, Si and Mo to Fe-10Cr alloys. Two step potential decay curves were obtained in Si-containing alloys, and this behavior of the decay curve was shown more clearly in an Fe-10Cr-3Si-2Mo alloy. The results of AES and XPS analysis indicated that Cr and Al concentrated in the passive film of an Fe-10Cr-Al alloy. In the case of an Fe-10Cr-Si alloy, Si concentrated in the surface region of the film and Cr did in the internal region of the film. The confirmation was not possible for the enrichment of Mo in the passive film.抄録全体を表示PDF形式でダウンロード (1637K) -
鰐川 周治, 太田口 稔, 村松 祐治2000 年 64 巻 12 号 p. 1156-1161
発行日: 2000年
公開日: 2008/04/24
ジャーナル フリーIn this study, we investigated a method for producing iron-base particle dispersion alloys of Fe-13Cr-3W-0.5Ti-(0.17∼0.83)Y2O3(mass%) using σ-phase alloy powder as a starting material for mechanical alloying(MA). The alloy powder was prepared by crushing a Fe-43Cr-10W-1.7Ti(mass%) alloy containing brittle σ-phase. The powder obtained was mixed with iron and Y2O3 powders. The mixture was then subjected to MA, and the MA powder was consolidated by hot working. In the study, we especially examined the formation of σ-phase with heat-treatment conditions and the milling characteristics of σ-phase alloys. We also examined the MA characteristics of the mixture and the mechanical properties together with microstructure of the consolidated dispersion alloys.
The formation of the σ-phase varied with heat-treatment temperature and time. Alloys containing more than 75 vol% of σ-phase could be easily pulverized by stamping and milling. The powder mixture consisting of iron, σ-phase alloy and Y2O3 powders exhibited excellent MA characteristics, and its MA was accomplished within 72 ks. Y2O3 particle addition inhibited recrystallization and resulted in the refinement of structure. TEM observation and EDS analysis revealed that dispersoids in the alloy consolidated at 1203 K were mainly composed of titanium and oxygen, but yttrium content was small. This fact was considered to cause the solid solution of Y2O3 particles into iron-base alloy during the MA process. The tensile strength of dispersion alloys increased markedly with increasing Y2O3 content, and their elongation decreased with an increase of the strength. The results of tensile tests carried out at 923 K were comparable or superior to those reported by other authors.抄録全体を表示PDF形式でダウンロード (1670K) -
小野寺 龍太, 野々村 実奈展, 荒牧 正俊2000 年 64 巻 12 号 p. 1162-1171
発行日: 2000年
公開日: 2008/04/24
ジャーナル フリーLoad and strain were recorded at every 1 ms interval during the serrated flow in annealed Al-4Cu-0.5Mg-0.5Mn alloy. The strain was measured by four minute strain gauges (0.15 mm length) stuck on the specimen at 0.5 mm intervals. The Luders strain was 0.3%-1% and the Luders strain rate (maximum value) was 0.1-0.6 s−1 for average strain rates between 6×10−5 and 3×10−2 s−1. The Luders band length was about 2-3 mm. In the test with the average strain rate of 3×10−3 s−1 two staged Luders deformation occurred, that is, a fast deformation (0.1 s−1) was followed by a slow one (0.01 s−1). The current theory, which is based on the concept of the negative strain rate sensitivity of the flow stress, could not explain the experimental results mentioned above.抄録全体を表示PDF形式でダウンロード (1504K) -
小野寺 龍太, 森川 龍哉2000 年 64 巻 12 号 p. 1172-1180
発行日: 2000年
公開日: 2008/04/24
ジャーナル フリーA new constitutive equation for the Portevin-LeChatelier effect has been proposed. A main feature of the equation is the introduction of an internal stress Yir which is supposed to be decreased with strain (work softening) and increased with time (age hardening). Yir is introduced in order to explain the negative rate sensitivity (n.r.s) of the flow stress. Another feature of the theory is that all the parameters used in the equation can be obtained by macroscopic experiments. The results of computer simulation based on the theory showed that the simulated values of the Luders strain, the strain rate, the stress drop and its rate agree quantitatively with the experimental data. Moreover, the simulation could explain the peculiar behavior of Luders deformation, namely, the fast and slow deformation, which was observed in the tensile test carried out at the moderate tensile speed of 3×10−3 s−1.抄録全体を表示PDF形式でダウンロード (1490K) -
朴 仁徳, 増山 不二光, 遠藤 孝雄2000 年 64 巻 12 号 p. 1181-1188
発行日: 2000年
公開日: 2008/04/24
ジャーナル フリーFor two kinds of 25Cr-20Ni stainless steels, A and B with and without a small amount of Nb and N, creep behavior has been studied in a stress and temperature range from 141 to 343 MPa and from 923 to 973 K with a special reference to tertiary creep. The average creep life of the A steel was about 100 times longer than that of the B steel. The logarithm of strain rate (\dotε) in a tertiary stage was well expressed by the following equation:
ln\dotε=ln\dotε0+Ω·ε,
\ oindentwhere \dotε0 is the imaginary initial strain rate, ε is the true strain and Ω is the strain rate acceleration factor.
The apparent activation energy for the initial creep rate was 330 kJ/mol in the A steel, while that of the B steel was 274 kJ/mol in a power law creep region and 478 kJ/mol in a region of power law breakdown (PLB). The activation energy for the B steel below PLB is close to the that for self-diffusion. When compensating for the temperature dependence of the Young’s modulus and the omega value, it was found that the apparent activation energy for the A steel was reduced to the activation energy for diffusion of chromium atom in a gamma steel. The stress exponent of the B steel was about 12 above PLB and 5.1 in a power law creep region. Notwithstanding that the creep condition for the A steel was in a power law creep region, its stress exponent was 8.3 larger than that of the B steel corresponding to the same creep conditions. This was ascribed to the presence of fine precipitates in the A steel. When stress was increased abruptly during deformation, instantaneous plastic strain was observed in the B steel but not in the A steel. These results as well as TEM observation suggest that dislocations in the A steel drag the atmosphere composed of Cr-N clusters behind them.抄録全体を表示PDF形式でダウンロード (1826K) -
朴 仁徳, 遠藤 孝雄2000 年 64 巻 12 号 p. 1189-1195
発行日: 2000年
公開日: 2008/04/24
ジャーナル フリーTo understand the effect of combined addition of Nb and N on the creep behavior of a 25Cr-20NiNbN stainless steel, strain response to abrupt stress loading and stress relaxation behavior were examined. An analysis of the strain response revealed that the threshold stress was about 190 MPa. The apparent stress exponent of creep was 8.3. However, the true stress exponent for creep of the matrix was between 2.1 and 3.7 when the effect of threshold stress on the magnitude of apparent stress exponent was taken into account. This suggests that the creep behavior of matrix is similar to that of class A alloys. The effective stress estimated from stress relaxation curve analysis was about 16% of total applied stress. Two kinds of interaction of substitutional chromium atoms with nitrogen atmospheres around moving dislocations were discussed as an origin of effective stress.抄録全体を表示PDF形式でダウンロード (1255K) -
原 基, 三川 馨, 北川 善朗2000 年 64 巻 12 号 p. 1196-1205
発行日: 2000年
公開日: 2008/04/24
ジャーナル フリーThe effect of pre-oxidation in O2 containing trace amounts of NaCl vapor on high-temperature oxidation of TiAl was examined by thermogravimetry, and analyses of the pre-oxidation scale and the scale formed on the pre-oxidized specimen after the oxidation test. Particular attention was given to the influence of NaCl vapor concentration on the structure of the pre-oxidation scale. The pre-oxidation at 1173 and 1273 K in O2 containing 1.4∼32.2 vol ppm NaCl vapor largely decreased the oxidation rate of the TiAl specimen in pure O2 at 1273 K. The magnitude of the decrease in the oxidation rate increased with increasing NaCl vapor concentration. For the specimens pre-oxidized in O2 containing 1.4 and 7.2 vol ppm NaCl vapor, a new scale formed on the pre-oxidation scale and internal oxidation in the metal below the pre-oxidation scale were observed, whereas for the specimen pre-oxidized in O2 containing 32.2 vol ppm NaCl vapor a slight growth of the pre-oxidation scale without forming a new scale was observed. The scale formed by pre-oxidation in O2 containing 32.2 vol ppm NaCl vapor was dense and adhesive to underlying metal, consisting mainly of Al2O3. Consequently, the inhibition effect of pre-oxidation in O2 containing trace amounts of NaCl vapor on high-temperature oxidation of TiAl resulted from the fact that pre-oxidation scale acted as a barrier against the outward diffusion of metal ions.抄録全体を表示PDF形式でダウンロード (3454K) -
江阪 久雄, 藤田 香奈, 大門 博康, 田村 学, 篠塚 計2000 年 64 巻 12 号 p. 1206-1211
発行日: 2000年
公開日: 2008/04/24
ジャーナル フリーGrain selection during solidification is of importance to the processing of solidified structure. It plays an important role in unidirectionally solidified products such as turbine blade. In order to understand the effect of the interfacial morphology on grain selection in unidirectional solidification, an experimental work using transparent material and a mathematical modeling has been carried out.
The number of grains (n) was found to decrease with increasing growth distance by the grain selection, depending upon the solid/liquid interfacial morphology. When the solid/liquid interface is dendritic, n rapidly decreases, on the other hand, when the solid/liquid interface is cellular, n slowly decreases. The reason for this may be that the growth direction of the cell is affected by heat flow and is closer to the heat flow direction than that of the dendrite.
The mathematical model using Monte Carlo simulation for the grain selection has been developed. The change in growth direction with solid/liquid interfacial morphology has been first taken into account. Introducing the dimensionless growth direction (π′), which is the ratio between growth direction and preferred growth direction, ⟨100⟩, it is found that the mathematical model agrees well with the experimental results.抄録全体を表示PDF形式でダウンロード (1446K) -
長谷川 信一, 佐藤 幸一, 井出 邦和, 小林 剛, 五十嵐 淑郎, 内藤 久仁茂2000 年 64 巻 12 号 p. 1212-1217
発行日: 2000年
公開日: 2008/04/24
ジャーナル フリーWe attempted a simple pretreating method consisting of solid-phase extraction using bonded silica with octadecyl (C18) as the solid-phase sorbent to determine trace elements in pure iron samples by means of inductively coupled plasma mass spectrometry (ICP-MS). The isotope dilution method was used along with the method mentioned above to ensure precise determination of Ni. We dissolved the sample of 1.00 g by nitric and hydrochloric acid, subsequently adding tartaric acid as a masking agent. The analytes could be separated by sodium diethyldithiocarbonate (DDTC) as chelate from the matrix by solid-phase extraction after adjusting the pH and adding DDTC. The optimum condition was 0.1 kmol/m3 DDTC, 4 cm3; tartaric acid, 15 g as the masking reagent; pH, 10.6; C18, 0.5 g as the solid-phase solvent; and 6 kmol/m3 nitric acid, 5 cm3 as eluate including 1% hydrogen peroxide. In this method, some trace elements, such as Bi, Pb, Ni, Co, Cu, Cd and In, were determined by ICP-MS using the eluate. The limits of detection in ng/g were Co 0.38, Ni 0.43, Cu 2.90, Cd 0.93, In 0.23, Pb 0.23 and Bi 0.42. The RSD was 2% or less for each element. We precisely determined the Ni content by jointly using the isotope dilution method.抄録全体を表示PDF形式でダウンロード (1032K) -
井上 尚三, 佐伯 俊明, 小寺澤 啓司, 内田 仁, 岩佐 美喜男2000 年 64 巻 12 号 p. 1218-1223
発行日: 2000年
公開日: 2008/04/24
ジャーナル フリーWe have deposited stainless steel films onto glass slides under various ion bombardment conditions by dc unbalanced magnetron sputtering. The apparatus was equipped with an external coil around the magnetron cathode which allows us to alter the ion flux to the substrate.
A commercial SUS304 steel disk (φ50 mm×2 mm) was used as a target. The sputtering gas was Ar (99.999%) and its pressure ranged from 0.2 to 1.0 Pa. The applied dc power and external coil current were also varied in the range Pdc=100∼220 W and Ic=−3∼4 A, respectively. The crystal structure, composition, internal stress, corrosion resistance and hardness of deposited films were examined.
The deposited films showed bcc structure with strong (110) preferred orientation. The film surface looks like martensite with very fine grain. The Cr composition in deposited films appeared to decrease about 2 mass% compared to target material. The ion bombardment showed very small effect on the structure and the composition of deposited films. The corrosion resistance and the hardness of the films seemed to be much better than bulk material.抄録全体を表示PDF形式でダウンロード (1581K) -
西田 義則, 有馬 弘晃, 金 鎭千, 安藤 禎一2000 年 64 巻 12 号 p. 1224-1229
発行日: 2000年
公開日: 2008/04/24
ジャーナル フリーA method for equal-channel angular pressing (ECAP) that uses a rotary die was applied to SiC whisker reinforced 7075 alloy composites to produce a fine-grained microstructure suitable to attain superplasticity in the composites. Despite the low ductility of the composites, the rotary die permitted up to 10 passes of ECAP.
The maximum stress during ECAP decreased with increasing the number of passes, and finally became constant at and beyond 4-8 passes. Optical microscopy indicated that the whisker distribution was sufficiently uniform after 10 passes. Transmission electron microscopy (TEM) revealed that the matrix grain sizes were as fine as 1.5-2 μm after 10 passes at 573 K. This composite exhibited high strain-rate superplasticity with elongations reaching 165% over strain rates between 6×10−2 to 6×10−1 s−1. The strain rate sensitivity coefficient (m-value) at these strain rates was estimated to be 0.67.抄録全体を表示PDF形式でダウンロード (1894K) -
遊佐 覚, 原 徹, 津 兼彰2000 年 64 巻 12 号 p. 1230-1238
発行日: 2000年
公開日: 2008/04/24
ジャーナル フリーAn Fe-2%Mn-0.36%C martensite with serrated prior-austenite grain boundaries was derived from work hardened austenite deformed at 1023 K. The martensite was tempered and microstructure of grain boundary carbide was observed by scanning electron microscopy and transmission electron microscopy, and compared with a conventional quench-tempered martensite. Coarse carbide films formed along flat prior-austenite grain boundaries in the conventional quench-tempered martensite. These carbide films disappeared, and the fine and uniform carbide structure was obtained in the tempered martensite derived from the work hardened austenite. On a serrated prior-austenite grain boundary, carbide particles had various sizes and shapes, and some parts of the boundary were free from carbide precipitation. Although carbide particles with various orientations were observed on one serrated prior-grain boundary, almost identically oriented carbide particles existed at a locally flat region of the grain boundary. These changes of carbide structure can be accounted for by the fluctuation of orientation on the serrated prior-austenite grain boundary.抄録全体を表示PDF形式でダウンロード (5766K) -
金子 純一, 朝比奈 敏勝, 菅又 信, 西川 泰久, 高田 秀男2000 年 64 巻 12 号 p. 1239-1244
発行日: 2000年
公開日: 2008/04/24
ジャーナル フリーExtruded plates of pure magnesium and AZ31 magnesium alloy were welded by TIG without using the filler metal and sound joints free from weld defects were obtained. Tensile strength of the welded joints were compared with that of the base metals at room and elevated temperatures and the results were discussed in relation to the crystallographic textures of the base and weld metals. It has been confirmed by XRD and EBSD analyses that the base metals show strong basal plane textures, whereas the weld metals have more random orientation distribution. At room temperature, the TIG welded joints of wrought magnesium materials show appreciably lower tensile strength than that of the base metals. However, tensile strength of the welded joints becomes nearly the same as that of the base metals at elevated temperatures. The low joint efficiency at room temperature observed in the weld joints can be attributed to the difference in the Taylor factor between the weld and base metals. The base metals with a strong basal plane texture have higher values of Taylor factor, and hence have higher yield and tensile strength than the weld metals. At elevated temperature, plastic anisotropy of magnesium decreases to such an extent that the effect of texture on the tensile strength disappears, and thus the joint efficiency increases to about 100%.抄録全体を表示PDF形式でダウンロード (2285K) -
李 常〓, 佐々木 元, 福永 秀春2000 年 64 巻 12 号 p. 1245-1251
発行日: 2000年
公開日: 2008/04/24
ジャーナル フリーNb/MoSi2-ZrO2 laminate composites have been successfully fabricated by alternately stacking MoSi2-ZrO2 powder layer and Nb sheet, followed by hot pressing in a graphite mould. The selected fabricating parameters were hot press temperature and volume fraction of Nb sheet. The instrumented Charpy impact test was carried out at the room temperature in order to investigate the relationship between impact properties and fabricating conditions. The interfacial shear strength between MoSi2-ZrO2 and Nb, which is associated with the fabricating temperature and the growth of interfacial reaction layer, is also discussed. The plastic deformation of Nb sheet and the interfacial delamination were macroscopically observed. The Nb/MoSi2-ZrO2 laminate composites had the maximum impact value when fabricated at 1623 K, accompanying the increase of fracture displacement and crack propagation energy. The impact value of Nb/MoSi2-ZrO2 laminate composites dramatically increased with increasing the volume fraction of Nb sheet and showed 64.9 kJ/m2 for Nb content of 15 vol%. The interfacial shear strength of Nb/MoSi2-ZrO2 laminate composites increased with the growth of interfacial reaction layer, which resulted from the increase of fabricating temperature. It is useful to promote an appropriate interfacial shear strength for the enhancement of impact value of Nb/MoSi2-ZrO2 laminate composites. A large increase of interfacial shear strength restrains the plastic deformation of Nb sheet.抄録全体を表示PDF形式でダウンロード (2152K) -
張 国鋒, 森下 政夫, 香山 滉一郎2000 年 64 巻 12 号 p. 1252-1256
発行日: 2000年
公開日: 2008/04/24
ジャーナル フリーThe effects of addition of Cr and Cu on the corrosion resistance of a Ni-NiMo2B2 two-phase alloy in a mixture of hydrochloric acid and nitric acid were examined by measuring the mass loss and the corrosion potential, and also by metallography. When 15 mass%Cr was independently added to the alloy, the passive state of the Ni-matrix was destroyed by Cl− ion and then the corrosion proceeded by a mechanism in which the Ni-matrix worked as the anode while the boride worked as the cathode. On the other hand, when 15 mass%Cr and 2 mass%Cu were simultaneously added to the alloy, the corrosion potential of the Ni-matrix shifted to the noble side, and consequently the difference in the corrosion potential between the Ni-matrix and the boride became small. As a result, the preferential corrosion of the Ni-matrix was extremely retarded, and the corrosion resistance of the alloy was remarkably improved.抄録全体を表示PDF形式でダウンロード (2434K) -
中山 栄浩2000 年 64 巻 12 号 p. 1257-1262
発行日: 2000年
公開日: 2008/04/24
ジャーナル フリーWe experimentally investigated the effects of Mg concentration, test temperature and strain rate on the generation of serrations for Al-Mg system alloys and proposed simple models for generating the serrations. The validity of the generation models was discussed using the values of activation energies derived from the temperature dependence of a critical strain. The critical strain of the A-type serration decreased and that of the B-type increased with rising temperature or decreasing strain rate. The measured activation energies for generating A- and B-type serrations were consistent with that for the diffusion of a vacancy, suggesting that A- and B-type serrations are generated by diffusion of Mg atoms through the migration of the vacancy. Furthermore, the onset of A-type serration was considered to result from dynamic strain aging (Cottrell model), and that of B-type, from the decrease in velocity of mobile dislocation due to the rapid increase in dislocation density (Johnston-Gilmam model).抄録全体を表示PDF形式でダウンロード (1120K) -
和久 芳春, 坂田 信一, 三谷 敦志, 清水 和敏2000 年 64 巻 12 号 p. 1263-1268
発行日: 2000年
公開日: 2008/04/24
ジャーナル フリーAl2O3/EAG/ZrO2 ternary MGCs (Melt Growth Composites) with a new microstructure have been fabricated by unidirectional solidification. The superior high-temperature strength of Al2O3/EAG/ZrO2 ternary MGCs over Al2O3/EAG binary MGCs was obtained by the following means: a new combination of single-crystal Al2O3 with a hexagonal structure, single-crystal EAG with a garnet structure and Zr0.8Er0.2O1.9 phases with a cubic structure; a microstructure consisting of three-dimensionally continuous and complexly entangled single-crystal Al2O3, single-crystal YAG and Zr0.8Er0.2O1.9 phases; characteristic dimension of the microstructure around 2∼4 μm (this dimension is defined as the typical length of the short axis of each domain seen in the cross-section perpendicular to the solidification direction) for EAG phases, around 2∼4 μm for Al2O3 phases reinforced with around 0.4∼0.8 μm Zr0.8Er0.2O1.9 phases. These features are finer than that for the Al2O3/EAG binary MGC. No amorphous phases are formed at interfaces between phases in the ternary MGC.抄録全体を表示PDF形式でダウンロード (2292K) -
新井 将彦, 青野 泰久, 蔵元 英一, 栗下 裕明, 堀 史説2000 年 64 巻 12 号 p. 1269-1274
発行日: 2000年
公開日: 2008/04/24
ジャーナル フリーLife of Nuclear Reactor Pressure Vessel Steels (RPVS) is restricted by reduction of toughness resulting from radiation hardening. Radiation hardening of RPVS is mainly due to interactions of irradiation defects and impurities, especially copper, included in the steels. It is very important for the RPVS life assessment to clarify the mechanism of radiation hardening and toughness recovery by annealing.
Fe, Cu ions and neutrons were used to irradiate high purity Fe-Cu model alloys, and the correlation between microstructure and mechanical property was examined. The results are summarized as follows.
(1) After ion irradiation copper precipitates, which have FCC structure and size of 4-12 nm in diameter, were observed. (2) The degree of radiation hardening depended on copper concentration. The more copper content, the higher yield strength. (3) After annealing above 873 K, yield strength of the neutron-irradiated specimens recovered to the pre-irradiation value.抄録全体を表示PDF形式でダウンロード (2228K)
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