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58 巻, 2 号
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山本 悟, 若林 利幸, 小林 久芳1994 年 58 巻 2 号 p. 117-123
発行日: 1994年
公開日: 2008/04/04
ジャーナル フリーIn the present work, the characteristics of complete solid solution systems with respect to the change of cohesive energy and the nature of chemical bonds have been examined by the calculation of energy and Mulliken’s population of cluster models by the extended Hückel method.
The results of the present work are as follows:
(1) The stability of solid solution systems and the nature of chemical bonds can be estimated on the basis of cohesive energy, atomic bond populations and atomic populations.
(2) The nature of chemical bonds of two elements which make a continuous series of solid solution is mutually similar, resulting in the similarities in both the cohesive energy and Mulliken’s populations, and the chemical bond is the metallic or covalent one. The cohesive energy changes linearly with the composition of the systems.抄録全体を表示PDF形式でダウンロード (1798K) -
青木 法智嘉, 吉田 英一, 和田 雄作1994 年 58 巻 2 号 p. 124-131
発行日: 1994年
公開日: 2008/04/04
ジャーナル フリーIt is known that the mechanical properties of a 2\frac14Cr-1Mo steel deteriorated due to the decarburization during immersion in the melt sodium at high temperatures. In low-alloy steel as well as a 2\frac14Cr-1Mo steel, precipitation reactions of carbides are known to be accelerated by cold working and aging. Thus, it may be expected that cold working and aging effectively suppress the decarburization of the mechanical properties of a 2\frac14Cr-1Mo steel because the decarburization will be restrained owing to fixation of carbon as precipitates of the carbides. In the present article, effects of cold-working and heat treatments on the kinetics of the decarburization of a 2\frac14Cr-1Mo steel has been studied experimentally. The annealed, cold-rolled, and normalized and tempered specimens were immersed in the melt of sodium at 500, 600 and 700°C for 425, 437 and 432 h, respectively. On the basis of the observations obtained from these specimens, the experiment was also carried out at 450, 500 and 550°C for 2270 and 5465 h. The microstructures before and after the immersion were observed with optical and scanning electron microscopes. An average concentration of carbon in each specimen was analyzed by an inert gas fusion method. The carbides extracted from the specimens were identified by X-ray diffraction. At immersion temperatures of 450 and 500°C, a 10% reduction of the decarburization in thickness by cold-working is sufficiently effective for retardation of the decarburization at both 2270 and 5465 h. Whereas, at 550°C, more than 30% reduction in thickness by cold-working is needed for it at 2270 h but even 80% reduction in thickness by cold-working causes merely slight retardation of the decarburization at 5465 h.抄録全体を表示PDF形式でダウンロード (1207K) -
渡辺 徹, 金山 孝範1994 年 58 巻 2 号 p. 132-137
発行日: 1994年
公開日: 2008/04/04
ジャーナル フリーThe cross-sectional microstructure of the Ni film electroplated from a Watts type bath was observed by transmission electron microscopy in detail and the formation process of a layered structure which had been observed sometimes in the cross-section of the film was discussed. It was found that the layered structure is the alternate structure of large crystal layers and small crystal layers. The reason for the formation of the layered structure is related to the bubbles of hydrogen evoluted at higher current density plating. Namely, when the evoluted hydrogen bubbles rise along the cathode surface, a diffusion layer on the cathode surface is agitated by the bubbles, and then the Ni atoms are deposited and plating is carried out without existence of a diffusion layer. At this time, the large crystal layer is formed. But, after a short time, the diffusion layer is formed again and the deposition of atoms takes place through the diffusion layer. At this time the small crystal layer is formed. The formation of the layered structure observed in the cross-section of the Ni plating film results from alternate occurrence of this behavior in accordance with the chemical reaction change on the Ni plating.
The crystallographic relationship between the deposited Ni film and the Cu substrate is also discussed.抄録全体を表示PDF形式でダウンロード (2061K) -
渡辺 徹, 金山 孝範1994 年 58 巻 2 号 p. 138-145
発行日: 1994年
公開日: 2008/04/04
ジャーナル フリーThe cross-sectional structure of electroplated Ni-P film was observed by transmission electron microscopy in detail. The Ni-P films with some kinds of P concentration were obtained by changing the quantity of addition of phosphorous acid and current density. The size of the Ni crystals which construct the plating film decreased with the increase of the concentration of P in the plated film, and when the concentration of P in the film arrives at about 25 at%, the structure of the plated film becomes amorphous. This concentration of 25 at%P agrees with the P concentration that of a Ni3P intermetallic compound.抄録全体を表示PDF形式でダウンロード (2540K) -
武藤 侃, 後藤 正治, 田上 道弘, 麻生 節夫1994 年 58 巻 2 号 p. 146-153
発行日: 1994年
公開日: 2008/04/04
ジャーナル フリーFor a further understanding of intermediate temperature embrittlement of α brass, the ductility of a Cu-30 mass%Zn binary alloy was investigated in detail at elevated temperatures up to 803 K under three strain rates of 6.7×10−4, 2.0×10−2, 2.0×10−1s−1 using specimens with six grain sizes ranging from 0.009 to 0.209 mm diameter. The coarse-grained specimens show a markedly poor ductility near 673 K accompanied with intergranular fracture, i.e., intermediate temperature embrittlement, while fine-grained specimens show an excellent ductility together with the formation of fine recrystallized structures due to dynamic recrystallization. In the necked regions near the fractured portion, many cavities are present in the fine-grained material. The shape and number of cavities are significantly changed with decreasing grain size. Small round holes are observed at the grain boundaries of the fine-grained specimens. As the grain size decreases, small isolated cavities are frequently observed. In the fine-grained specimens, grain refinement by dynamic recrystallization leads to high ductilitily, although cavities are introduced.抄録全体を表示PDF形式でダウンロード (3017K) -
東樹, 宮原 一哉1994 年 58 巻 2 号 p. 154-161
発行日: 1994年
公開日: 2008/04/04
ジャーナル フリーThe objective of the present study is to investigate the effects of fine precipitates of vanadium nitride on the creep deformation behaviors of 12%Cr-15%Mn austenitic steels through the measurement of internal stress and effective stress. These stresses were obtained by strain dip tests. The internal stress of VN free materials was determined as a unique function of applied stress. On the other hand, that of VN containing materials was not obtained uniquely as a function of applied stress. This indicates that fine precipitates of VN with high number density are strong barriers for the dislocation motion in spite of wide range variation of stress applied on the dislocations. At lower applied stress, the change of deformation rate during the strain dip test of the VN containing materials was very small and could not be detected with the increase of deloaded stress. Consequently this means that the forward or backward motion of almost all dislocations were inhibited by the precipitates. At higher applied stress, the VN containing materials showed the decrease of deformation rate with the slight deloading during strain dip test. This means that there exist movable dislocations which can glide without being blocked by the precipitates. The difference of stress dependence of minimum creep rate between at lower applied stress and at higher one was considered to be caused by such interaction of the fine precipitates with dislocation motion.抄録全体を表示PDF形式でダウンロード (2205K) -
山田 葉子, 川崎 亮, 田谷 稔, 渡辺 龍三1994 年 58 巻 2 号 p. 162-168
発行日: 1994年
公開日: 2008/04/04
ジャーナル フリーA theoretical estimation has been made on the effect of debonding at the phase interface on Young’s modulus in the sintered PSZ/stainless steel composite, where an abnormal deterioration of Young’s modulus has been observed. The present analysis is based on Eshelby’s equivalent inclusion method and on a debonding model. The comparison is made between the theoretically predicted Young’s modulus and experimental data for the composites having three different combinations of original powder sizes.
The theoretical calculation shows that the Young’s modulus decreases with increasing fraction of debonding. The fraction of debonding can be, in turn, predicted by comparing the theoretical calculation with the experimental data, which has been found to depend on the composition of PSZ and original particle size. The particle size dependence on debonding has been discussed on the basis of the Weibull theory, which shows that the coarser dispersoids have more debonded interfaces. The composition dependence has been explained by the variation in interface residual stress with composition, which is generated by the mismatch of thermal expansion coefficient between the matrix and the dispersed particles, and the residual stress is compressive at the metal-rich side and tensile at the ceramic-rich side. The tensile stress at the interface enhances the debonding, however, the compressive stress defend it and improve the Young’s modulus. The dependence of abnormal deterioration of Young’s modulus on the composition and particle size has been well accounted for.抄録全体を表示PDF形式でダウンロード (1085K) -
岡林 久喜1994 年 58 巻 2 号 p. 169-175
発行日: 1994年
公開日: 2008/04/04
ジャーナル フリーThe fracture toughness tests have been performed in the temperature range of 4.2 K to brittle-ductile transition for 34 kinds of polycrystalline iron alloys. Based on the test results, the critical strain-energy release rate Gic of crack extension is expressed as follows:
(This article is not displayable. Please see full text pdf.)
\ oindentwhere, T is the testing temperature, d is the grain size in mm, and G0, 1⁄T0 and 1⁄T0.1 are material constants, which show the Gic value extrapolated to 0 K, the dependence coefficient of ln Gic upon temperature and 1⁄T0 value in case of d=0.1 mm respectively.
The G0 depends upon solute carbon and nitrogen contents as an increasing function of ([C]+4[N]) at.%. The 1⁄T0.1 depends upon chemical compositions as a function of (−[C]−4[N]−0.2[Si]−1.2[P]−1.2[S]+0.2[Mn]+0.2[Ni]) at.% under quenched condition, but not influenced by solute Al, Ti, V, Cr, Mo and B micro-alloying.
Mechanism of the effect of these elements on Gicis discussed.抄録全体を表示PDF形式でダウンロード (727K) -
福山 博之, 和田 英作, 藤澤 敏治, 山内 睦文1994 年 58 巻 2 号 p. 176-181
発行日: 1994年
公開日: 2008/04/04
ジャーナル フリーFor the application of Na2CO3 slag to the elimination of iron from molten copper, the thermodynamic properties of the Cu-O-Fe system and the distribution behavior of iron between NaO0.5-CO2-FeO1.5 slag and molten copper have been inverstigated at 1523 K. The first order interaction parameter was determined as:
(This article is not displayable. Please see full text pdf.)
\ oindentby the equilibrium distribution experiments between the NaFeO2-saturated slag and molten copper. By a combination of the value obtained above with the activity of FeO1.5 determined as a function of the slag composition reported in the previous paper, the distribution ratios of iron between the slag and molten copper can be estimated over the composition range of 0.5<N<1{N=nNa⁄(nNa+nFe), n: the number of moles} under the partial pressure of CO2 of 0.01∼0.08 MPa.
The lower CO2 partial pressure and the higher oxygen partial pressure are more preferable for the removal of iron from molten copper. However, due to the strong affinity between oxygen and iron in molten copper, the ratios have a maximum value when oxygen partial pressure is 0.5 Pa. The ratios decrease with decreasing the FeO1.5 content in the NaFeO2-saturated slag. From the dependence of the ratio on the oxygen partial pressure in the homogeneous liquid slag, it was considered that iron exists as a trivalent form in the slag.抄録全体を表示PDF形式でダウンロード (651K) -
田辺 晃生, 高橋 啓二, 吉田 秀紀, 朝木 善次郎1994 年 58 巻 2 号 p. 182-187
発行日: 1994年
公開日: 2008/04/04
ジャーナル フリーTo clarify the formation mechanism of La-Ni compounds by the reduction-diffusion (R-D) process, the reduction of La2O3 by CaH2 and the R-D reaction to form La-Ni compounds were carried out at 1200, 1300 and 1400 K. In the reduction experiment, pellets of mixed powders of La2O3 and CaH2 were heated in a deoxygenated Ar gas stream and the reduction rate was estimated from the intensity measurement with XRD. In the R-D experiment, La2O3 and CaH2 were mixed with Ni powder or Ni wires and pressed into pellets, and the reacted samples were examined with XRD, SEM and EPMA.
The reduction with CaH2 1.7 times as much as the chemical equivalent for the reduction of La2O3 revealed that the reduction rate was considerably high and the reaction was completed in 0.5 to 1.0 ks from the start of the reaction at 1300 or 1400 K. In the R-D reaction for the samples containing Ni powder, LaNi5, La2Ni7 and CaNi5 were formed, and the CaNi5 at 1300 and 1400 K was diminished as the reaction proceeded. It was also proved in the R-D reaction for the pellets containing Ni wires that a double-layer of CaNi5 and LaNi5 was formed on the surface of each Ni wire and that La diffused in the CaNi5 layer to form LaNi5. When the amount of CaH2 mixed in a pellet was 3 times as much as the chemical equivalent for reduction, Ni wires in the pellet were dissolved in Ca melt and their original shapes was not retained. In the case of the amount of CaH2 just as much as the chemical equivalent for reduction, on the other hand, the reaction rate was lowered and the reaction products were LaNi5 and La7Ni16, though the formation of CaNi5 was not observed.抄録全体を表示PDF形式でダウンロード (1178K) -
斎藤 守正1994 年 58 巻 2 号 p. 188-193
発行日: 1994年
公開日: 2008/04/04
ジャーナル フリーFor the determination of trace and ultra-trace amounts of impurities in high-purity molybdenum, spark source mass spectrometry and glow discharge mass spectrometry were studied. In spark source mass spectrometry using the metal probe method, the liquid-helium cryogenic pump was used in order to protect the surface of the samples from oxidation. The theoretical relative sensitivity factors (Mo=1) calculated from physical properties were used. the analytical results obtained for molybdenum tablet and high-purity molybdenum were in good agreement with those obtained by other methods (atomic absorption spectrometry and others).
In glow discharge mass spectrometry, the relative sensitivity factors were calculated by using the results obtained by spark source mass spectrometry and atomic absorption spectrometry, and this method was applied to the determination of ultra-trace amounts of impurities in ultra high-purity molybdenum and gave the satisfactory results. The detection limits (2σ, n=10) in the integration time of 600 s for U and Th were 0.6 ppb and 0.3 ppb, and the values for Al, Si, Cr, Mn and Cu were in the range of 10 ppb to 0.5 ppb.抄録全体を表示PDF形式でダウンロード (704K) -
井上 尚三, 内田 仁, 徳永 洋一, 竹下 和義, 小寺澤 啓司1994 年 58 巻 2 号 p. 194-200
発行日: 1994年
公開日: 2008/04/04
ジャーナル フリーThe rf reactive sputtering of Al target in Ar+N2 mixed gas was applied to fabricate the compositionally gradient films consisting of Al and AlN phases. In this paper, two methods are presented to form the compositionally gradient Al-AlN films. The first is the N2 partial pressure-to-total pressure ratio (PN2⁄Ptotal) control method, and the other is the rf power control method. The compositionally gradient Al-AlN films were deposited onto slide glasses, and the substrate temperature were room temperature and 200°C. The crystallographic structure, the composition and the morphology of deposited films were characterized by X-ray diffractometry, Auger electron spectroscopy and scanning electron microscopy, respectively.
Both the PN2⁄Ptotal and rf power control methods can be used to grow the compositionally gradient films. It is demonstrated that the deposited film has the structure with a c-axis perpendicular AlN layer on a non-oriented Al layer. The morphology of the films is greatly dependent on the substrate temperature, independently of the deposition method. It is also shown that the optical emission spectroscopy and the mass spectroscopy are useful tools to monitor the growth of these films.抄録全体を表示PDF形式でダウンロード (1348K) -
木村 博, 小林 信一1994 年 58 巻 2 号 p. 201-207
発行日: 1994年
公開日: 2008/04/04
ジャーナル フリーInstrumented pulse electro-discharge consolidation of mechanically alloyed amorphous TiAl powder is proposed as a method for synthesizing a high-strength titanium aluminide compact composed of fully densified nano-scaled structure by controlling the process variables of temperature, stress and pulse electric current.
We obtained a fully densified compact consisting of titanium aluminide{γ(TiAl)+α2(Ti3Al)} with the dispersion of an island-shaped α (Ti) phase and Al3Ti particles using a relatively low stress of 29 MPa with an electro-discharge consolidating time less than 600 s. The consolidating temperature necessary to obtain a fully densified TiAl compact decreases from 1312 to 1051 K with increasing applied stress from 29 to 147 MPa. Such a decrease is conducive to the great decreases in size of titanium aluminide grains and Al3Ti second phase particles. Moreover, we found that the fully densified compact of titanium aluminide has an increasing Vickers hardness up to 1050 DPN at 1100 K, following a decrease with decreasing consolidating temperature.
The process viscosity(η) for pulse electro-discharge consolidation of amorphous TiAl is fairly well expressed by an Arrhenius-type equation of η=ηoexp(HV⁄kT) with 87-115 kJ mol−1 for activation energy(HV), which is smaller than 339 kJ mol−1 for specimen viscosity, and a significantly decreasing ηo with increasing applied current. These results indicate that pulse electro-discharging strongly accelerates the rate of the densification via viscous flow in an amorphous TiAl powder compact.抄録全体を表示PDF形式でダウンロード (934K) -
朴 相俊, 藤井 英俊, 中江 秀雄1994 年 58 巻 2 号 p. 208-214
発行日: 1994年
公開日: 2008/04/04
ジャーナル フリーAn improved sessile drop method which prevents aluminum from oxidizing, was used in order to obtain accurate values for the contact angles between boron nitride and aluminum or alminum-silicon alloys. The experimental temperature and atmosphere were 1373 K and an purified He+3%H2 mixed gas respectively. The contact angle of each system changed with time through the four phases (I, II, III, IV) similar to other typical ceramic/metal systems. As the quantity of Si increases, the original contact angle (Phase II) decreases. When more than about 11 mass%Si is added, the original contact angle is smaller than 90°. The equilibrium contact angle (Phase IV) increases as the quantity of Si increases. However, it has become clear that the increase in the observed equilibrium contact angle was apparently caused by the crystallization of Si at the solid/liquid/vapor interface and that the true equilibrium contact angle is equal to or around 0 degrees. Therefore, it is concluded from the viewpoint of wetting that the BN/Al-Si system is a suitable combination for fabricating a composite material. Furthermore, the results indicate, when a sessile drop method is used to measure contact angles, the evaporation of the liquid and/or the change in the composition of the liquid can apparently change the contact angles under the conditions where the true contact angles are constant.抄録全体を表示PDF形式でダウンロード (911K) -
宮下 卓也, 日野 春樹1994 年 58 巻 2 号 p. 215-220
発行日: 1994年
公開日: 2008/04/04
ジャーナル フリーTiAl is one of the most promising materials with low density and high specific strength in the forthcoming age. For structural applications of TiAl, its joining process requires much improvements. Friction welding, brazing, diffusion bonding and so on are the candidates for the joining process. Among them, friction welding is promising in view of its reliability, quality assurance and productivity.
This paper describes the results of a basic research for examining the capability of friction welding of TiAl compounds with a nearly equiatomic composition. The friction welding tests of TiAl to TiAl were carried out in air, using a brake-type friction welding machine. Diameters of TiAl specimens to be welded are 6 and 12 mm. The friction welding conditions for obtaining reproducible joints with high strength were investigated.
The main results are as follows.
(1) In the case of joints with a diameter of 12 mm, all of the tensile specimens were fractured at the base metal part. In the case of joints with a diameter of 6 mm, fracture occurred at the base metal part in tensile tests when the friction welding conditions are optimized. As the diameter of specimens becomes small, the appropriate range of the friction welding conditions trends to be narrow.
(2) In the case of joints with a diameter of 6 mm, the maximum temperature of the weld interface reached during friction welding was about 50°C higher than that for joints with weld diameter of 12 mm. Accordingly, in the case of joints with a weld diameter of 6 mm, the amount of plastic deformation became larger. Thus, the region of the recrystallized and fibrous fine structure near by the weld interface became narrower and the plastically deformed region became wider. Furthermore, the hardness of the plastically deformed region became lower.
(3) In the friction process, microcracks were initiated along the lamellar structure in the plastically deformed region. Such microcracks should be eliminated to avoid fracture at the welded interface or along the regions.抄録全体を表示PDF形式でダウンロード (1373K) -
中田 博道, 長 隆郎, 金武 直幸1994 年 58 巻 2 号 p. 221-228
発行日: 1994年
公開日: 2008/04/04
ジャーナル フリーThe reaction between Al4C3 particles and liquid aluminum alloy containing a carbide forming element is utilized for the fabrication of in situ formed particulate aluminum composites. At first, the effects of processing variables, such as the processing temperature, the size of raw carbide Al4C3 and the kind of carbide forming element, on the mechanical properties and the resultant microstructure of in situ composites are discussed taking in situ reaction kinetics into account. TiCp/Al-Mg alloy composites fabricated by the present in situ process indicate higher strengthening efficiency than those made by the conventional melt stirring method. Scanning electron microscopic observation on the fractured surface of a conventional composite has shown this to be due to some agglomerates consisting of TiC particles. The extruded and T6 heat treated in situ TiCp/Al-Cu alloy composites exhibited a much finer microstructure compared with the monolithic matrix in the same conditions. Hence, the presence of in situ formed TiC particles leads to the refining of the grain size in the solidification of melt and prohibits the recrystallization apparently during the T6 heat treatment. Additionally, the aging response determined by the hardness of the in situ TiCp/Al-Cu alloy composite containing 10 vol% reinforcement is found to be slightly faster than that of the unreinforced matrix.抄録全体を表示PDF形式でダウンロード (2264K) -
柿本 健一, 下尾 聰夫, 岡村 清人, 瀬口 忠男, 佐藤 光彦, 熊川 潔, 山村 武民1994 年 58 巻 2 号 p. 229-234
発行日: 1994年
公開日: 2008/04/04
ジャーナル フリーThe crystallization at high temperatures based on the pyrolysis of commercial Si-Ti-C-O fibers with 18%O and 13%O is considered to be related to the oxygen content introduced by the thermal oxidation curing process. In order to improve heat-resistance of Si-Ti-C-O fiber, the fiber with lower oxygen content than that of commercial kinds has been developed using the electron irradiation curing process. The Si-Ti-C-O fiber with 6%O has been synthesized, and the crystal structure was amorphous containing microcrystallines. The pyrolysis rate of the fiber was measured with a thermobalance at temperatures from 1573 to 1973 K in an argon stream. The pyrolysis products were investigated by X-ray diffraction, SEM and TEM observation. Results are compared with that of commercial Si-Ti-C-O fibers with 18%O and 13%O.
The amorphous Si-Ti-C-O fiber crystallized to β-SiC and TiC, with evolution of SiO and CO. The activation energy was 357 kJ/mol for fiber with 6%O, and the crystallization was determined by the crystal growth of SiC controlled by the diffusion of carbon in the fiber. Lowering of oxygen content in Si-Ti-C-O fiber by the electron irradiation curing process was found to effective for the suppression of pyrolysis.抄録全体を表示PDF形式でダウンロード (1002K) -
佐藤 充典, 沼澤 健則, 木村 秀夫, 木村 隆, 深町 正利1994 年 58 巻 2 号 p. 235-241
発行日: 1994年
公開日: 2008/04/04
ジャーナル フリーThree kinds of silver based alloys containing a component of Y1Ba2Cu3, Bi2Sr2Ca1Cu2 or Bi1.8Pb0.3Sr2Ca2Cu3 were internally oxidized and then heat treated. The oxide phase of Y1Ba2Cu3Ox, Bi2Sr2Ca1Cu2Oy or Bi2Sr2Ca2Cu3Oz was precipitated in the silver matrix. For the Ag-Y1Ba2Cu3 the critical temperatures, Tc(onset) is 94 K and Tc(offset) 88 K. For the Ag-Bi2Sr2Ca1Cu2 Tc(onset) is 96 K and Tc(offset) 74 K, and the overall Jc at 4.2 K is ∼ 103 A. For the Ag-Bi1.8Pb0.3Sr2Ca2Cu3 Tc(onset) is 112 K, Tc(middle) 83 K and Tc(offset) 70 K. The composition and distribution of the precipitated oxides analysed by means of the X-ray image of EPMA are shown in cross-sectional maps.抄録全体を表示PDF形式でダウンロード (641K) -
新開 康弘, 大西 忠一, 西山 正敏1994 年 58 巻 2 号 p. 242-243
発行日: 1994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 (349K) -
1994 年 58 巻 2 号 p. 244
発行日: 1994年
公開日: 2008/04/04
ジャーナル フリー
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