巻号一覧
54 巻, 8 号
選択された号の論文の13件中1～13を表示しています
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稲葉 輝彦, 飴山 惠, 時実 正治1990 年 54 巻 8 号 p. 853-860
発行日: 1990年
公開日: 2008/04/04
ジャーナル フリーThe effect of (1) β grain size and (2) α precipitate morphology on the mechanical properties (i.e., tensile strength, elongation) of a meta-stable β titanium alloy (Ti-15V-3Cr-3Sn-3Al) has been investigated. β single phase specimens of varying grain size (i.e., ∼15 to 200 μm) were obtained by solution heat treatment above the β transus temperatures for various periods of time, followed by water quenching. The specimens were prepared for mechanical testing by (1) isothermal aging, and (2) two-stage aging, followed by water quenching. In the case of solution treated specimens, both the tensile strength and the elongation increase with decreasing β grain size. After aging in the (α+β) two-phase region, regardless of the aging method, the specimens having the same β grain size show increasing tensile strength and decreasing elongation with α precipitate refinement. However, when the morphology of α precipitates (i.e., shape, size and distribution) is approximately the same, the tensile strength is found to be independent of the β grain size, whereas the elongation increases with decreasing β grain size. Improvements in the ductility are likely due to suppression of brittle rupture at or near the grain boundaries through the refinement of β grain size.抄録全体を表示PDF形式でダウンロード (3018K) -
渡辺 陽一, 佐分利 敏雄, 中川 豊, 稔野 宗次1990 年 54 巻 8 号 p. 861-869
発行日: 1990年
公開日: 2008/04/04
ジャーナル フリーSelf-accommodation process and the resulting structure of the orthorhombic martensite in a Ti-Ni-Cu shape memory alloy were investigated.
Observations of the self-accommodation process of habit plane variants of the orthorhombic Ti-Ni-Cu martensite were made by transmission electron microscopy, and the three-dimensional configuration of the variants resulting from self-accommodation was analyzed.
The results obtained are as follows.
(1) The fundamental unit of the self-accommodation structure in three-dimensions is cuboidal, consisting of six different variants. This structure appears to be a triangular when observed in the ⟨111⟩P direction (P: Parent).
(2) The six variants are twin related with each other and two types of twin relations exist among them. One is the (111)M[211]M type I twin and the other is the (011)M[011]M compound twin (M: Martensite).
Then, on the basis of the observed relations among the variants the deformation process of the orthorhombic martensite was discussed.抄録全体を表示PDF形式でダウンロード (2415K) -
安丸 尚樹1990 年 54 巻 8 号 p. 870-877
発行日: 1990年
公開日: 2008/04/04
ジャーナル フリーPure iron was ion-nitrided in a mixed gas (80 vol% N2+20 vol% H2) under a reduced pressure of 665 Pa at 803, 923 and 1013 K and then quenched in water for the elucidation of the ion-nitriding behaviour accompanied with phase transformations above the eutectoid transformation temperature of 863 K for the Fe-N system.
When nitrided at 803 K, the nitrided case consists of two layers as usual nitrided cases do; (i) a compound layer with a hardness of about Hv 700 which is mainly composed of γ′-Fe4N, and (ii) a diffusion layer of about Hv 250.
When nitrided at 923 K, the nitrided case consists of; (i) a compound layer of about Hv 750, mainly composed of γ′-Fe4N, under which are (ii) an inner layer of γ austenite of about Hv 400 and (iii) a diffusion layer.
When nitrided at 1013 K, the nitrided case consists of; (i) a thin compound layer, (ii) an inner hardened layer of γ and α′ martensite, of which the hardness increases from Hv 400 to Hv 700 toward the inside corresponding to the content of the α′ phase, and (iii) a diffusion layer.
To explain the formation of the relatively thick hardened layers of austenite at 923 K and martensite at 1013 K, the nitrogen concentration at each temperature and the degree of the stability of the γ phase when quenched in water after nitriding were examined.抄録全体を表示PDF形式でダウンロード (1928K) -
津 兼彰, 松山 博久, 長尾 護, 牧 正志1990 年 54 巻 8 号 p. 878-887
発行日: 1990年
公開日: 2008/04/04
ジャーナル フリーSuperplasticity and microstructural change during deformation of a 25Cr-7Ni-3Mo α⁄γ duplex stainless steel having a microduplex structure have been studied. The specimen of microduplex structure with fine α and γ grain sizes (∼1 μm) showed high strain rate superplasticity at 1273 K. Elongation over 1700% was obtained at a strain rate of 1.7×10−2 s−1. Even at 1.7×10−1 s−1 elongation was near 1000%. α⁄α boundaries were low angle ones before the superplastic deformation and were changed to high angle ones by dynamic recrystallization in the early stage of deformation. During deformation up to 1300% elongation after the recrystallization of the α phase, dislocations were scarcely observed in the whole of the specimen. It was concluded that the grain boundary sliding is a predominant deformation mode during superplastic flow in the present steel and the role of dynamic recrystallization is to make the structure suitable for the grain boundary sliding in the early stage of deformation. The mechanism of dynaimic recrystallization was briefly discussed.抄録全体を表示PDF形式でダウンロード (3765K) -
連川 貞弘, 松原 正吾, 栗下 裕明, 吉永 日出男1990 年 54 巻 8 号 p. 888-894
発行日: 1990年
公開日: 2008/04/04
ジャーナル フリーIn order to clarify the high-temperature deformation mechanism in titanium carbide during steady state deformation, specimens prepared by r. f. zone melting technique were deformed by compression at temperatures from 1745 to 2270 K and at strain rates from 2×10−5 to 5×10−3 s−1, and the dislocation structure
\ oindentafter deformation was observed by transmission electron microscopy.
It is found that the activation energy for steady state deformation is 560 kJ/mol which is about 3/4 of that for lattice self-diffusion of Ti in TiC, and the stress exponent, ms, for steady state strain rate is about 7 in a temperature range of 1745 to 2125 K and about 5 at 2270 K. The dislocation structure consists of subboundaries and networks in subgrains.
The rate-controlling mechanism in the steady state deformation was discussed on the basis of the dislocation network model and it is suggested that the network growth should be controlled by the pipe diffusion of Ti along dislocations in the lower temperature range where ms is 7, while the growth should be controlled by the lattice self-diffusion of Ti in the higher temperature range where ms is 5.抄録全体を表示PDF形式でダウンロード (1459K) -
阿部 俊一, 佐治 重興, 堀 茂徳1990 年 54 巻 8 号 p. 895-902
発行日: 1990年
公開日: 2008/04/04
ジャーナル フリーAlloying processes, formation of amorphous phase and hardening of Al-20 mass% (12.4 at%)Ti mixed powders during mechanical alloying with an Attritor type of ball mill, have been investigated by means of optical, scanning and transmission electron microscopy, X ray analysis and hardness measurements.
The mechanical alloying (MA) process detected consists of flake-forming, cold welding of the flaked powders, fracturing of the composite powders, formation of solid solution and amorphous phase. The amount of solute titanium in the composite powder after 493.2 ks MA was estimated to be about 17 mass% from the lattice parameter measurement and grain sizes of the matrix aluminum were in the range from about 20 to 60 nm. The amount of oxygen in mechanically alloyed powders increased with milling time, and dispersions of Al2O3 particles were observed by TEM. The spherorized composite powders with the average particle size of 0.6 μm after 2200 ks MA were amorphous. The amorphous particles showed halo patterns in electron diffraction and showed no grain boundary, no dislocation and few Al2O3 particles in TEM. A remarkable increase in hardness of the composite powders was explained in terms of solid solution hardening of titanium in aluminum, dispersion hardening of Al2O3 particles, work-hardening and hardening by grain refinement.抄録全体を表示PDF形式でダウンロード (3198K) -
新井 甲一, 佐貫 須美子, 板倉 浩二, 三賀 朋尚, 砂田 聡1990 年 54 巻 8 号 p. 903-910
発行日: 1990年
公開日: 2008/04/04
ジャーナル フリーThe feasibility of an electro-winning process of Ag for lead anode slime was investigated from the electrochemical and kinetic points of view based on the experimental results of nitric acid leaching of lead anode slime, the stoichiometry of electro-winning of Ag recovery, the determination of cathodic polarization curves of the Pt electrode in the thiocyanate solution containing complex ions of metal-thiocyanate, the selective separation of AgX from the leach solution and thiocyanate leach of AgX.
The experimental results are summarized as follows:
(1) The leaching rate of Ag component from the lead anode slime in a nitric acid solution is fast, and the leaching degree of Ag reaches about 100% for the retention time of 10.8 ks at 323 K. However, the dissolution of precious metals such as Au and Pt are not detected in the leach solution.
(2) The selective separation of AgX from the leach solution is easily, and the recovery of AgX from the leach solution reaches 100% for the retention time of 3.6 ks at ambient temperature.
(3) The electrochemical reaction for Ag deposit starts at about 0.05 volt and the reaction rate increases with an increase in the concentration of Ag(SCN)nn−1 ions in the solution. The reaction rate is controlled by the rate of Ag(SCN)nn−1 ions from the bulk solution to the solid interface, and the metallic Ag of more than 99.5% purity can be recovered from the thiocyanate electrolyte.
(4) The electrochemical consideration and other observations have proved the effectiveness of the above electro-winning process of Ag from the lead anode slime.抄録全体を表示PDF形式でダウンロード (1123K) -
下尾 聰夫1990 年 54 巻 8 号 p. 911-918
発行日: 1990年
公開日: 2008/04/04
ジャーナル フリーThe mechanism of reduction of synthetic complex chromite (FexMg1−x)Cr2O4 with solid carbon was studied at high temperatures from 1673 to 1973 K under an argon atmosphere. The rate of reduction was measured by means of thermogravimetry, and the reduction behavior was investigated by microscopic observation and chemical analysis.
The reduction of the FeCr2O4 component preceded that of MgCr2O4, although both components was reduced simultaneously in the transient period. During the reduction of the FeCr2O4 component, FeO was preferentially reduced.
In the case of the reduction of the powdered chromite, the molten Fe-Cr-C alloy was finely dispersed except at 1673 K. The temperature dependence of the reduction rate at lower temperatures was significantly larger than that at higher temperatures. The reduction at 1973 K was slower than at 1873 K. These results showed the difference in the reaction mechanism or the rate determining step for the different temperature range.
The reduction of the coarse particles proceeded topochemically and was controlled by the gas diffusion through the porous product layer. The different reaction mechanism of the chromite with a lower ratio of Cr/Fe was due to the meltdown of the alloy layer from the oxide particles.抄録全体を表示PDF形式でダウンロード (1493K) -
大橋 重雄, 石原 只雄1990 年 54 巻 8 号 p. 919-924
発行日: 1990年
公開日: 2008/04/04
ジャーナル フリーIntergranular stress corrosion cracking (IGSCC) of sensitized Type 304 stainless steel in high temperature water was investigated in relation to the nature of oxide film. SCC tests were conducted in 0.2 to 32 ppm oxygen water at temperatures of 523 and 563 K, under two-step loading conditions; a slow strain rate technique (SSRT) up to a stress level of 275 MPa and followed by a constant loading test.
IGSCC failure time was decreased with increasing dissolved oxygen (DO) concentration from 0.2 to 8 ppm oxygen, and lengthened at 16 ppm oxygen and again shortened at 32 ppm oxygen. Auger electron spectroscopic analysis indicated that a chromium-rich oxide was formed in an inner oxide film on the specimen surface exposed to water containing 0.2 ppm oxygen, and no chromium-rich oxide was formed on the specimen surface exposed to water containing above 2 ppm oxygen.
The low susceptibility to IGSCC of sensitized Type 304 stainless steel in water containing 0.2 ppm oxygen may be correlated with the formation of chromium-rich oxide film. It was confirmed that crack initiation is stifled by the formation of chromium-rich oxide film on the specimen surface. Furthermore, the role of oxide film in IGSCC is discussed in relation to the anodic dissolution behavior and physical properties such as electric resistance, structure and porosity of oxide film.抄録全体を表示PDF形式でダウンロード (1138K) -
豊田 正道, 杉本 克久1990 年 54 巻 8 号 p. 925-932
発行日: 1990年
公開日: 2008/04/04
ジャーナル フリーThe growth rates of TiO2 films in the MOCVD process using tetraisopropyl titanate (TPT) and O2 have been measured at temperatures between 373 K and 573 K by in-situ ellipsometry. Growth rate vs. time curves can be divided into three stages, that is, the induction, the transition and the linear growth stages. The apparent activation energies for the linear growth stage were 24.7 and 22.7 kJ·mol−1 for Pt and Si(100) substrate, respectively. All films obtained at temperatures less than 573 K had amorphous structures as far as their thickness was less than 200 nm. However, when the film grew up to 600 nm in thickness at 573 K, it crystallized into anatase. The refractive index and extinction coefficient of the films increased with increasing deposition temperature. The corrosion resistance of the films in 2 kmol·m−3 HCl also increased, corresponding to the increase in the refractive index.抄録全体を表示PDF形式でダウンロード (1378K) -
小橋 真, 長 隆郎, 堀部 泰隆1990 年 54 巻 8 号 p. 933-940
発行日: 1990年
公開日: 2008/04/04
ジャーナル フリーSiC particules are mainly used as reinforcement of metal matrix composites. However, it is impossible to incorporate SiC particles with small size (<1 μm) into molten aluminum and difficult to get a good distribution of particles. ZrC is more suitable as reinforcement than SiC, because of its thermal stability and low surface energy, so the effect of alloying elements on dispersion of ZrC particles into molten aluminum was investigated. Good wettability between ZrC particle and molten aluminum is essential for particulate incorporation. A number of reports have shown the dependence of wettability between ceramics and metals upon chemical reactions. ZrAl3 was detected in the matrix of ZrC/pure Al composite by using EPMA. The time required for incorporation of ZrC particles into molten aluminum was defined as an incorporation time. The incorporation time of ZrC was shortened by alloying Si, Ti or Bi which has strong affinity for ZrC. In this case, metallic compounds including these alloying elements were detected in the matrix. On the other hand, the incorporation time was not so influenced by adding Pb, Cu or Zn which has weak affinity for ZrC and it was prolonged by adding Zr, a constituent of ZrC particle.
The incorporation time was shortened by alloying Mg, Ca and Li, although no metallic compound including these elements was detected in the matrix,
The microstructure of the composite shows the particulate concentration along grain boundaries of matrix, because of its slow solidification rate. However, under the condition of rapid solidification rate by casting, the uniform particulate distribution was obtained.抄録全体を表示PDF形式でダウンロード (1715K) -
穴田 博之, 志田 善明, 小玉 強1990 年 54 巻 8 号 p. 941-947
発行日: 1990年
公開日: 2008/04/04
ジャーナル フリーThe effect of various heat treating conditions on the nodular corrosion behavior of Zircaloy-2 and -4 was studied with particular interest in obtaining a quantitative relationship between the condition for the prevention of nodular corrosion and the role of intermetallic compounds. As a result, it was understood that fast cooling during solution heat treatment greater than 5 K/s may be necessary for the prevention of nodular corrosion of Zircaloy-2, the size of intermetallic compounds being smaller than 0.5 μm under the condition. Degradation in corrosion resistance by alpha temperature heating was observed to be easier for Zircaloy-4 in comparison with Zircaloy-2. The importance of the size of intermetallic compounds on the corrosion behavior was discussed and the following mechanistic model was proposed. The incorporation of intermetallic compounds in the oxide scale may cause non-uniformity in the growth rate or/and stress state of the surrounding oxide, the non-uniformity being probably large enough to deteriorate the originally uniform scale when the inter-spacing between the intermetallic compounds is greater than approximately 6 μm.抄録全体を表示PDF形式でダウンロード (1576K) -
笠原 和男, 橋本 健紀, 土肥 春夫, 辻本 得蔵1990 年 54 巻 8 号 p. 948-954
発行日: 1990年
公開日: 2008/04/04
ジャーナル フリーThe oxidation behavior of the intermetallic compound TiAl with additions of Cr, Y, Mn and Si as the third elements has been investigated in a temperature range between 1123 and 1223 K under the atmospheric environment. The oxidation products have been examined by X-ray diffraction, scanning electron microscopy, and electron probe microanalysis.
The mass gain by oxidation increased with small additions of Cr or Y and decreased with their additions above 1 at%. The oxidation rates of those alloys were always larger than those without the third elements. Thus, it was concluded that the addition of Cr or Y does not improve the oxidation resistance. The oxidation resistance of the alloy containing Mn was not good. The addition of Si decreased the mass gain with increasing Si content up to 0.5 mass%. However, no further increase in oxidation resistance was observed by adding more than 0.5 mass%Si.
The surface oxides were composed predominatly of three layers, i.e., TiO2, Al2O3 and TiO2+Al2O3 from the outer side. Only in the alloys containing Mn and Si, other oxides, i.e., MnTiO3 and SiO2, were detected. A continuous film of SiO2 was formed at the alloy/oxide interface in the alloys containing more than 0.5 mass%Si. It was concluded that the formation of the continuous SiO2 film assisted the protective ability of the Al2O3 layer against oxidation by decreasing the diffusion rates of the alloy elements and oxygen ions.
The weight of the oxide spalled on cooling decreased considerably in the alloys containing Y as compared with those of the other alloys. This result indicates that the addition of Y improves the adherence of the surface oxide.抄録全体を表示PDF形式でダウンロード (3724K)
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