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Volume 53, Issue 9
Displaying 1-19 of 19 articles from this issue
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Yoshihiro Takahara, Hidehiko Matsuda1989 Volume 53 Issue 9 Pages 843-849
Published: 1989
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSReversible structural relaxation behavior in Fe-B-Si amorphous alloys was discussed on the basis of the structural model proposed by Dobois et al. According to the model, the structure consists of the two regions AB and AFe which are occupied by Fe atoms with and without B neighbors, respectively, in Fe-B-Si amorphous alloys (B<20 at%). The silicon atoms exist only in the region AFe.
The validity of this model was confirmed for Fe88−xB12Six amorphous alloys (2≤x≤13) through the measurements of differential scanning calorie, Mössbauer effect and Vickers hardness.
The reversible behavior in Fe78B7Si15 and Fe75B10Si15 amorphous alloys was then investigated by means of electrical resistivity and differential scanning calorie measurements and compared with each other. As a result, reversible changes were obsenved in both alloys and their quantities differed obviously. The difference was explained well by the reversible structural relaxation in the region AFe.View full abstractDownload PDF (1019K) -
Takashi Koseki, Makoto Kobayashi, Reimon Hanada, Hiroshi Kimura1989 Volume 53 Issue 9 Pages 850-857
Published: 1989
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSAn Fe-Si (6 at%) alloy single crystal has been studied by Mössbauer spectroscopy by varying the magnetization direction relative to the crystal axis ⟨100⟩. The difference spectra ⟨hkl⟩-⟨100⟩ reveal sharp downward spikes in the 1st line (−5 mm/s) and in the 5th line (+3 mm/s) at the position of the main line in the original spectra. Comparing the result with the similar measurement on a pure Fe single crystal, we find that these spikes are caused by Si atoms. The magnitude of each spike was measured as a function of the magnetization direction, and it is ascertained that Si atoms in the 2nd neighbor site play the decisive role to give rise to the spikes. The fact that the spike is present at the main line position confirms the proposal by Cranshaw that the hyperfine field at the probe atom site is not reduced by the Si atom at the second neighbor site.
These results are quantitatively analysed by dipolar as well as quadrupolar shifts of 57Fe Mössbauer transition energies.View full abstractDownload PDF (1242K) -
Ryo Shimizu, Jirou Harase1989 Volume 53 Issue 9 Pages 858-865
Published: 1989
Released on J-STAGE: April 05, 2001
JOURNAL FREE ACCESSTexture evolution by grain growth in an Fe-3%Si containing MnS as an inhibitor was investigated by SEM-ECP technique and X-ray diffraction method.
The intensity of the {335} and {334} orientation increased by grain growth from the primary texture having a rather strong {334} and {111} orientation, while the intensity of the {111} orientation decreased by grain growth. The frequency of Σ1 and Σ3 boundary increased by grain growth. The increase in the frequency of Σ1 was considered to be due to the evolution of the rather sharp texture by grain growth and the stableness of the Σ1 boundary comparing with other boundaries.
The increase in the frequency of Σ3 boundary by grain growth was considered to be due to the relatively higher frequency of orientations having Σ3 orientation relationship in the primary matrix and that these grains come in contact to form Σ3 boundaries in the course of grain growth suggesting that the Σ3 boundary is also relatively stable.
The {335} and {334} orientation had rather higher value of the product of the intensity of these orientations and the intensity of the Σ9 oriented grains in relation to these orientations in the primary recrystallized stage. The mechanism of the evolution of these texture was explained by considering the special mobility of Σ9 boundaries in precipitates.View full abstractDownload PDF (1260K) -
Naoki Yasumaru1989 Volume 53 Issue 9 Pages 866-872
Published: 1989
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe change in the surface layer of SUS304 steel exposed to d.c. glow discharge plasma in a H2-Ar mixed gas was investigated, in order to elucidate the influence of H2 plasma concerning the austenitic stainless steels.
Generally, grain boundaries are ion-etched by Ar 100% glow discharge plasma. Some surface reliefs like slip lines except for grain boundaries were formed on the plasma treated specimens in a mixed gas (80 vol%H2+20 vol%Ar) under a reduced pressure of 665 Pa at 623 K, as observed in the previously reported H2-N2 plasma treatment. By detailed observation of the microstructure, it was found that these surface reliefs were due to the growth of plate-like precipitates along {111} planes of the matrix, being similar to the morphology of ε martensite. Furthermore, we found that this surface layer contained newly formed two f.c.c. phases (a=0.367 nm, 0.363 nm) and a small amount of α phase and showed a high carbon content and a high hardness of about 500 Hv.
From these results, the following mechanism for the formation of surface reliefs was proposed: by the absorption of carbon being mixed in the plasma, new f.c.c. phases precipitated in the plate-like form along {111} planes of the matrix and surface reliefs were generated combining with the effect of ion-etching.
In austenitic stainless steels treated in the plasma using H2-mixed gas, the formation of surface reliefs is considered as a characteristic phenomenon.View full abstractDownload PDF (3005K) -
Toshiya Shibayanagi, Ichiro Minami, Shigenori Hori1989 Volume 53 Issue 9 Pages 873-879
Published: 1989
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSGrain refinement by thermal cycling in Cu-2Be and Cu-2Be-0.15Co alloys has been investigated. The thermal cycling means the alternative heat treatments for the discontinuous precipitation and the dissolution of nodules. The solution treatment was performed at 1023 K and the aging temperatures for Cu-2Be and Cu-2Be-0.15Co alloys were 673 and 773 K, respectively. Microstructures of heat treated specimens were observed by means of an O. M., SEM and TEM. Crystallographic orientation was determined by analyzing SEM-ECP (Electron Channeling Pattern) and SADP.
The fronts of the nodules without contacting each other moved back to the initial position during dissolution. Consequently the grain size did not change. The dissolution of the precipitates occurred both at the moving front and within the nodules. Meanwhile, the dissolution proceeded mainly within the nodules in the Co-added alloy an account of a low mobility of grain boundaries. Therefore, the mechanism of the dissolution is a combination of the grain boundary diffusion and the volume diffusion in the nodules.
Grain refinement was achieved for the fully precipitated specimen. The refinement was explained as a special case of the back motion of the front of nodules, that is, the case of a very low mobility of the front. Grain size reduced from 100 to 19.3 μm by the first thermal cycling in the Cu-2Be alloy. However, only a small change in grain size occurred after the 2nd thermal cycling. On the other hand, such a small change in grain size was also observed by the 1st thermal cycling from the initial grain size of 12 μm. Thus the refinement ratio depends on the initial grain size.View full abstractDownload PDF (3249K) -
Kazuo Saito, Masaya Iwaki, Yuko Hirohata, Toshiro Yamashina, Katsumasa ...1989 Volume 53 Issue 9 Pages 880-884
Published: 1989
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSIn order to examine the effect of nitrogen ion implantation prior to ceramic coating, the SUS304 substrates were implanted with nitrogen ions, and titanium carbide films were deposited on the implanted substrates by a reactive sputtering method. Hardness measurements and indentation fracture tests were made to evaluate the adhesion properties of these TiC/SUS304 specimens by using a microhardness tester. Friction coefficient measurements and scratch-tests were also carried out.
It was shown that at loads above 0.049 N (5 gf) the hardness of the TiC films deposited on the substrates increased monotonically with nitrogen dose, but for a small load below 0.0198 N (2 gf) the hardness tended to decrease significantly with an increase of nitrogen dose. At relatively high loads above 0.098 N (10 gf) irregular cracks and exfoliation of TiC films were induced on the unimplanted substrates. Such cracking or exfoliation of TiC films was hardly observed on the nitrogen implanted substrates. A significant hardness decrease of TiC films on the implanted substrate was attributed to the effect of the film replication of a plastic deformation of underlying soft material under the conditions of a sufficiently strong adhesion between the film and underlying substrate. The improved adhesion of TiC films to the substrates was considered to arise from the facts: (i) the formation of the complex transition layers at the interface region, denoted by TiC-Ti(C, N)-Ti(C, N, O). (ii) the transformation of Fe and Cr surface oxides into Fe, Cr nitrides and titanium oxides, and (iii) the removal of OH− radicals from the substrate surface by nitrogen ion irradiation.View full abstractDownload PDF (1547K) -
Eiichi Sato, Kazuhiko Kuribayashi, Ryo Horiuchi1989 Volume 53 Issue 9 Pages 885-891
Published: 1989
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe deformation and grain growth behavior during superplastic deformation was studied when the ternary element Cr was added to the microduplex superplastic Al-33%Cu eutectic alloy beyond its solubility.
In the superplastic region called region II, Cr bearing had no effect on flow stress, though in the lower strain rate region called region I, it made the flow stress large, the strain rate sensitivity small and the characteristics of region I distinct.
The deformation induced component of grain growth during deformation was independent of strain rate, initial grain size and static component of grain growth, and was proportional to the given strain. It was not affected by Cr bearing. On the other hand, the static grain growth was retarded by Cr bearing. The apparent flow hardening on the stress-strain curves was explained by the whole grain growth and the dependence of the flow stress on grain size.View full abstractDownload PDF (890K) -
Eiichi Sato, Kazuhiko Kuribayashi, Ryo Horiuchi1989 Volume 53 Issue 9 Pages 892-897
Published: 1989
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe numerical simulation was examined in superplastic deformation of an Al-33%Cu eutectic alloy in order to show the neck shape change. The simulation was based on the experimental constitutive equations in consideration of the strain rate sensitivity m and the flow hardening parameter γ distributions as well as the strain rate distribution in the specimen. The simulated results were compared with experimental results of the same shape specimen.
In regions I and II, where the deformation induced grain growth was independent of strain rate, the simulated results showed that I≡(γ−1)⁄m>−2 in any part of the specimen and the neck became broadened and diffuse. In these regions the simulated results were well coincide with the experimental results.
On the other hand, in region III it was simulated that the instability and strain rate would become larger rapidly at the narrowest part of the specimen, and that the specimen would become constricted sharply.View full abstractDownload PDF (801K) -
Toshio Shimoo, Yasushi Sakai1989 Volume 53 Issue 9 Pages 898-905
Published: 1989
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSIn relation to the smelting reduction of chromite ore, the mechanism of dissolution of Cr2O3 particles in silicate slags and subsequent reduction by solid carbon was studied. The reduction rate of Cr2O3 particles melted in a graphite crucible with the slag was measured by means of thermogravimetry under an argon atmosphere, and the dissolution of Cr2O3 was examined by microscopic observation and chemical analysis. The dependence of the reduction rates on flux/Cr2O3 ratio, particle size of Cr2O3, temperature and slag composition were investigated. The rate was markedly affected by the wettability of the slag to the graphite. In early stage of the reduction, Cr2O3 particles were attacked by the slag and were broken into smaller ones. Thereafter, they dissolved in the slag from their surface. Carbide was mainly formed on the graphite, but the fine particles of carbide also was observed inside Cr2O3 melted with some silicate slag containing Al2O3 and MgO. The rate determining step was not a single process but varied with the conditions of the reduction.View full abstractDownload PDF (1866K) -
Li Wei Zhang, Kazuhiro Silvester Goto1989 Volume 53 Issue 9 Pages 906-913
Published: 1989
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSIn 1969 Deb suggested that the color of amorphous thin film of WO3 changes to blue by simultaneous injection of cations and electrons, according to the reaction
(This article is not displayable. Please see full text pdf.)
\ oindentThe rate-controlling step of this electrochromic reaction is the slow diffusion of cations in the tungsten oxide film. In the present study, the conditions of formation of oxygen deficient thin films of tungsten oxide WO3−δ by RF sputtering were systematically changed and the properties of the formed thin films were measured. Also, the interdiffusivity of Li+ ions in the thin films was measured as a function of oxygen deficiency δ and of the content of lithium ions in the thin films. The diffusivity was about 10−15 m2/s at 296 K. The diffusivity increased with the increase of the δ value and slightly decreased with the increase of the lithium content.View full abstractDownload PDF (997K) -
Shinya Yao, Hirokazu Tanaka, Zensaku Kozuka1989 Volume 53 Issue 9 Pages 914-920
Published: 1989
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe activity coefficients of oxygen γO in Sn-Te melts in the dilute region of oxygen have been measured at 1123 and 1223 K utilizing the modified coulometric titration technique with the electrochemical cell: O in Sn-Te melts/ZrO2(+CaO)/air, Pt. The measured lnγO values decrease gradually with the addition of tellurium to tin, and increase rapidly in the vicinity of NTe=0.50. The enthalpy and entropy values for the oxygen dissolution also increase rapidly around this composition. The variation of lnγO reasonably agrees with that predicted from Otsuka’s PCC model. Since the saturation solubility of oxygen is expected to be a maximum around NTe=0.40∼0.50, the variation of γO values in the high oxygen concentratin range for NTe=0.40 was measured. The melt-oxide equilibrium was examined by electrochemically pumping oxygen into the melt until a constant emf was observed. The phase precipitated was found to be SnO2. Combining the both data, the saturation solubility of oxygen in Sn-Te melt of NTe=0.40 was determined to be 1.3 mol% at 1123 K. This experimental value is approximately 10 times larger than that in liquid Sn. When referring to the data for γO in other metal-chalcogen melts, it is quite feasible that there are metal-chalcogen melts whose saturation solubility of oxygen is more than ten times larger than that in the liquid metal solvent. The melts having high satuation solubility of oxygen and possessing electronic conduction may be useful as electrode materials for oxygen-related reaction.View full abstractDownload PDF (1040K) -
Yasunori Harada, Masanobu Ohmori, Fusahito Yoshida, Misao Itoh1989 Volume 53 Issue 9 Pages 921-926
Published: 1989
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe enhancement in rolling workability of a sintered powder chromium (Cr 1, 99.9 mass%) by CIP and HIP processes was made at elevated temperatures by means of a sandwich rolling, in which the workpiece sandwiched in between two mild steel sheets was rolled. The behavior of ductile-to-brittle transition and recrystallization was also examined in the rolled specimens of 99.99 mass% purity sintered powder (Cr 2) and the above specimen Cr 1, respectively. The results are summarized as follows.
The sandwich rolling was very efficient to prevent the crack generation during rolling of the workpiece at elevated temperatures, especially at the temperatures ranging from 1173 to 1373 K, at which the workability was extremely poor in a conventional rolling.
The ductile-to-brittle transition temperature (DBTT) was lowered by a high rolling reduction given to the specimen. Namely, the DBTT of the specimen rolled to 85% at 973 K and annealed at 1473 K was 510 K which was about 200 K lower than that of the specimens as sintered and/or rolled to 50% after annealing at the same temperature.
Room temperature hardness of the specimen rolled to a given reduction at 973 K, the temperature at which the dynamic strain ageing occurred, was considerably larger than the hardness measured in the specimen rolled to the same amount at 773 K at which the strain ageing did not occur. The recrystallization temperature of the present sintered powder was similar to that of a cast material. The recrystallization during the sandwich rolling at the temperatures beyond the recrystallization temperature occurred evenly on the surface and in the inside of the workpiece, while it occurred only in the inside during the conventional rolling.View full abstractDownload PDF (1330K) -
Kiyoshi Nogi, Hiroyuki Takeda, Kazumi Ogino1989 Volume 53 Issue 9 Pages 927-935
Published: 1989
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSBy using an oxygen ionic conductivity of stabilized zirconia, the effect of applied DC voltage on the wettability of zirconia by liquid copper was investigated. It has been clarified that the wettability of zirconia by liquid copper was improved by migration of oxygen forced by applying a DC voltage between liquid copper and zirconia. Main results are as follows:
(1) Application of a DC voltage to eliminate oxygen from the copper-zirconia interface can deoxidize zirconia to zirconium at the copper-zirconia interface. This is the chief mechanism of the decrease of the contact angle between liquid copper and zirconia.
(2) Application of a DC voltage to migrate oxygen to the copper-zirconia interface can oxidize copper at the copper-zirconia interface and the reaction between copper oxide and zirconia may occur. This is the chief mechanism of the decrease of the contact angle between liquid copper and zirconia.View full abstractDownload PDF (2752K) -
Satoru Ohno, Kazuhiro Honma, Hideo Okuyama, Masaya Ozawa1989 Volume 53 Issue 9 Pages 936-945
Published: 1989
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSIn order to create the composite ultrafine particles of metal and ceramics, ultrafine particles (UFP) of Fe-TiN, Ni-TiN and Co-TiN systems were prepared by arc melting, vaporization and deposition of binary Fe-Ti, Ni-Ti and Co-Ti alloys in an atmosphere of a nitrogen-hydrogen mixed gas (“reactive plasma-metal” reaction) at 0.1 MPa pressure. The crystal structure, the chemical composition, the morphology and the specific surface area of obtained UFP were determined by X-ray diffractometry, energ dispersion analysis for X-ray, transmission electron microscopy and the BET method, respectively.
Crystal structures of UFP obtained from Me (Fe, Ni or Co)-Ti parent alloys containing less than about 40-50 at%Ti were found to be a single phase of Me (α-Fe, Ni or β-Co), but in the case of titanium contents higher than about 40-50 at%, the TiN phase (NaCl type structure) was found in UFP. The TiN concentration of the obtained UFP remarkably deviated negatively compared with titanium concentration of the Me-Ti parent alloys over the entire composition range. It agreed very closely with the apparent vapor composition of Me-Ti parent alloys measured by “hydrogen plasma-metal” reaction.
The composite UFP consisting of TiN and Me particles, whose morphlogy were dumbell-like or dice-like particles was found in UFP obtained from the parent alloys containing more than 50 at%Ti. The formation mechanism (LS mechanism) of the composite UFP was presumed as follows: (i) vaporization of Me and Ti into the nitrogen atmosphere, (ii) nucleation of TiN owing to the reaction of Ti vapor with nitrogen, (iii) deposition of a Me-Ti-N melt on the TiN nucleus, (iv) crystallization of TiN on the TiN nucleus from the Me-Ti-N melt, (v) solidification of residual Me-rich melt (composite UFP is formed).View full abstractDownload PDF (1900K) -
Satoru Ohno, Masahiro Uda1989 Volume 53 Issue 9 Pages 946-952
Published: 1989
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSUltrafine particles (UFP) of Fe-Ni, Fe-Cu and Fe-Si alloys were produced by arc melting, vaporization and deposition of iron alloys in 50%H2-50%Ar atmosphere (“hydrogen plasma-metal” reaction) at 0.1 MPa pressure. The morphology, chemical composition and crystal structure of particles obtained were determined by TEM observation, energy dispersion analysis for X-ray and X-ray powder diffraction.
It was recognized that the chemical composition of Fe-Ni UFP was nearly identical with bulk composition. The composition of Cu in Fe-Cu UFP and Si in Fe-Si UFP remarkably deviated positively and negatively from the bulk composition, respectively. It was found that the deviation tendency of composition between UFP and bulk of alloys can be assessed by using an activity curve of alloys at the high temperature range of above 2000-2500 K.View full abstractDownload PDF (1173K) -
Minoru Nobuki, Ei-ichi Furubayashi, Tokuzou Tsujimoto1989 Volume 53 Issue 9 Pages 953-957
Published: 1989
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe purpose of the study is to develop a new simulation testing machine for hot working brittle materials such as intermetallic compounds.
Various factors which are the requisites for hot working these materials have been argued, and a new simulator which satisfies these requirements has been developed.
TiAl intermetallic compound has been used to verify the ability of the simulator. It was found in this test that the stress-strain curve of TiAl single phase mateials is quite different from that of TiAl+Ti3Al two phase materials at high temperatures.View full abstractDownload PDF (1376K) -
Hiromasa Kaibe, Makoto Sakata, Yukihiro Isoda, Isao Nishida1989 Volume 53 Issue 9 Pages 958-963
Published: 1989
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe n-type sintered Bi2Te2.85Se0.15, which is a composition of the practical thermoelectric material, were prepared by a hot pressing technique. The resistivity ρ, the Hall coefficient R, the thermoelectric power Q and the thermal conductivity κ were measured over the temperature range from 77 to 300 K. The range of the starting powder particle size was between 37 and 74 μm for the sintered specimen with the large values of the figure of merit Z=Q2⁄(ρκ). The values of Z were 1.60×10−3 and 2.24×10−3 K−1 for the specimens doped with HgBr2 and SbI3, respectively. During the heat treatment process in a hydrogen atmosphere, the amount of oxygen which acted as a donor in the sintered Bi2Te2.85Se0.15 was reduced and then the electron concentration was decreased. However, the increase in electron mobility resulted in improvement in Z. In the case of the sintered specimens doped with HgBr2, a large value of Z was obtained for the specimens prepared form the deoxidized powder compared with those deoxidized after sintering. The value of Z was 2.56×10−3 K−1 which was equal to the utilized unidirectional solidified material. At 240 K, a remarkably large value of Z=3.70×10−3 K−1 was obtained for the specimen doped with SbI3 due to the high electron mobility and the low lattice thermal conductivity.View full abstractDownload PDF (898K) -
Hiroshi Araki, Fujio Abe, Tetsuji Noda1989 Volume 53 Issue 9 Pages 964-971
Published: 1989
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSIn order to clarify the effect of carbide precipitation on the embrittlement of reduced-activation high-Mn austenitic steels suitable for fusion reactors, Charpy impact testing was carried out for 10%Cr-30%Mn steels with 0.07, 0.11, 0.26 and 0.55%C after aging at temperatures between 823 and 973 K for the periods from 3.6 to 10800 ks.
The embrittlement due to the aging increased with increasing carbon content, aging temperature and time. The solution-annealed specimens exhited a mode of ductile fracture with dimple pattern. The percentage of brittle grain boundary fracture in the fractured surface increased with aging time. The M23C6 carbide precipitated during aging preferentially along grain boundaries and the major component of the carbide was Cr. Therefore, the embrittlement resulted from the grain boundary precipitation of M23C6 which promoted grain boundary fracture. The activation energy for the embrittlement was evaluated to be 233-237 kJ/mol which correspond to that for diffusion of Cr in γ-iron. It was concluded that the rate-determining process of the transition from ductile to embrittlement was diffusion of Cr in the γ-matrix of the alloys for the grain boundary precipitation of the M23C6 carbide. The carbon content in the steels was recommended to be below 0.1% for preventing the grain boundary embrittlement.View full abstractDownload PDF (2195K) -
Taketo Sakuma, Hideo Hata1989 Volume 53 Issue 9 Pages 972-979
Published: 1989
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe diffusionless cubic-to-tetragonal (c-t) transformation was examined in ZrO2-Y2O3 alloys prepared by arc-melting. The alloys with 3∼7 mol% Y2O3 rapidly-cooled from high-temperature cubic phase (c-ZrO2) region were of single tetragonal phase (t-ZrO2) at room temperature, while those containing 8 mol%Y2O3 were fully cubic. The two-phase structure consisting of t-ZrO2 and c-ZrO2 was not found in the rapidly-cooled alloys. The diffusionless c-t transformation accompanied two types of microstructures; the domain structure and the thin plate or lenticular microstructure. The former was initially developed by this transformation in the whole region of samples, and the latter was formed by subsequent cooling for accommodating the strain induced in t-ZrO2. The diffusionless c-t transformation took place above T0 temperature and was always completed. The nature of this transformation is different from that of martensitic transformation as has generally been accepted, and is of the second-order phase transformation.View full abstractDownload PDF (2273K)
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