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Volume 49, Issue 9
Displaying 1-16 of 16 articles from this issue
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Isao Tanaka, Saburo Nasu, F. Eiichi Fujita1985 Volume 49 Issue 9 Pages 701-706
Published: 1985
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSMössbauer spectra of 119Sn nuclei have been measured for an Au-2.0 at%Sn alloy annealed in air at temperatures between 673 K and 1073 K. An internally oxidized phase was observed and determined to be SnO2. The internal oxidation process was discussed by the changes in Mössbauer spectra and their parameters. The results are summarized as follows:
(1) The oxide phases formed during the internal oxidation process were found to be only SnO2, in which the 119Sn isomer shift ΔSI=0.02±0.04 mm/s relative to BaSnO3, and the magnitude of quadrupole splitting ΔEQ=0.49±0.02 mm/s.
(2) By annealing in H2 gas flow for 1.8 ks at 1123 K, the oxide was completely reduced and Sn atoms dissolved into Au matrix.
(3) The oxide phase was localized near the specimen surface within the depth of 0.8 μm. No preferential oxidation along grain boundary was observed.
(4) During a short-period annealing, the formation of oxide proceeded with the internal oxidation, the rate of which was controlled by the diffusion of oxygen in Au matrix. Dependence of the oxidation process on the annealing temperature was of the Arrhenius type, and its activation energy was obtained to be 0.49±0.07 eV. After annealing at 973 K for 0.6 ks, transition from the internal to the external oxidation occurred, and the oxidation rate was sharply diminished.
(5) Using Wagner’s theory for the internal oxidation, the sum of EOS, the heat of solution for oxygen in Au and EOD, the activation energy of diffusion for oxygen in Au, were determined. The obtained value of EOS+EOD, 1.2±0.1 eV, suggests that the mechanism of diffusion of oxygen in Au is the same as in Cu and Ag.View full abstractDownload PDF (931K) -
Teruo Kishi, Shuichi Wakayama, Yasuo Shinozaki, Yutaka Kagawa, Eiichi ...1985 Volume 49 Issue 9 Pages 707-713
Published: 1985
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe fracture process in Al2O3 ceramics was studied by Acoustic Emission (AE) source characterization technique and fractography. AE source function, which estimated the size and nucleation rate of microcracking quantitatively, was obtained by deconvolution integral of detected signals with the dynamic Green’s function of elastic medium and response function of measuring system.
Three points bending tests gave the bending strength of 350 MPa and the microcracks nucleation stress of 210 MPa. On the other hand, the plane strain fracture toughness of the present material was evaluated as KIC=5.5 MPa \sqrtm by double-torsion tests.
In the fracture toughness testing of a 1 inch compact tension specimen, intergranular small microcracks, of which sizes were less than 20 μm, were detected by small amplitude AE signals at 80% of final unstable fracture load, and three large microcrackings, of which sizes of 170-190 μm were evaluated by AE source characterization, were observed at over 90% of final fracture load. These large microcrackings correspond to the coalescence of small microcracks and/or transgranular cracking of coarse grains.
It is concluded that final unstable fracture occurs when one of these large microcrackings has grown and reached to the critical size.View full abstractDownload PDF (1227K) -
Kazuwo Imai1985 Volume 49 Issue 9 Pages 714-722
Published: 1985
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSA general method of calculating the deformation gradient tensor F for deformation of single crystals along any path due to slip on N slip systems is presented, N being an arbitrary positive integer; this method enables us to obtain the value of F easily, if we know N active slip systems and the amount of glide shear of each system at every moment. Examples of the calculation are shown for several typical deformations.
A glide strain tensor G determined by the above knowledge about slip is introduced, and a differential equation relating G to F is derived. By solving the equation, F is given in a form of a tensor-valued functional defined over the function of time, G( · ); the value of F depends on the path of slip deformation in the eight-dimensional G-space. For a wide variety of paths satisfying a certain condition (piecewise-commutative paths), the functional is reduced to a product of the exponential functions of the glide strain tensor increments. In general, the functional can be represented by an infinite series and approximated by the above product. An analytical method for evaluating the exponential of an arbitrary increment of the glide strain tensor is given explicitly. Degrees of multiplicity of the slip is introduced in the evaluation.View full abstractDownload PDF (1346K) -
Ken Atagi, Fukuji Inoko, Genjiro Mima1985 Volume 49 Issue 9 Pages 723-728
Published: 1985
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSIn order to examine the initiation of fatigue cracks along grain boundaries, three kinds of aluminum bicrystals were tested by bending fatigue under a constant strain amplitude of 0.2% and a cyclic frequency of 30.4 Hz.
It has been found that the initiation of fatigue cracks along the boundaries occurs under the following conditions: (a) {111} in at least one component crystal is parallel to the boundary plane (it is not always necessary for {111} in the other component crystal to be parallel to the boundary plane) and (b) the slip system parallel to the boundary plane is remarkably activated in the vicinity of the boundary.View full abstractDownload PDF (1571K) -
Kazuhisa Azumi, Toshiaki Ohtsuka, Norio Sato1985 Volume 49 Issue 9 Pages 729-736
Published: 1985
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSIn order to characterize the semiconductive properties of the passivation film on iron, the impedance of iron electrode was investigated in borate and phosphate solutions at various pH values. The results were discussed as compared with thickness data previously obtained from 3-parameter reflectometry.
From the effect of frequency and potential on the impedance an equivalent circuit is postulated for a passivated iron electrode, which consists of a series conection of two parallel RC circuits. One component RLCL of the two parallel circuits which is predominantly responsible for frequencies lower than 100 Hz, characterizes the dielectric property of the passive film, whereas the other component RHCH which appeares at higher frequencies corresponds to the oxide/solution interface.
From comparison CL with the film thickness, the passive film is found to consist of an inner electron-conductive layer where no potential drop occurs and an outer carrier depleted layer where the electric field is of the order of 1×108 Vm−1. The dielectric constant of the outer layer is also evaluated at about 40. The component RHCH is found to be sensitive to the anionic species present in the solution and is thus likely to be assosiated with an ionic adsorption-desorption process taking place across the electric double layer at the oxide/solution interface.View full abstractDownload PDF (1212K) -
Shigeru Ando, Norio Kurose, Toshio Shimoo, Hiroshi Kimura1985 Volume 49 Issue 9 Pages 737-745
Published: 1985
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe carbon depositing behavior on iron in CO-H2 mixtures at 773 to 1273 K has been studied by means of metallography and thermogravimetry. Two types of carbon, laminar carbon and filamentous carbon, are observed to deposit on iron. The deposition of laminar carbon is predominant early in the reactions at all temperatures. The outward growth reaction of laminar carbon and the depositing behavior of filamentous carbon change definitely near A1 transformation temperature. These may be caused by the facts that CO gas is thermodynamically more unstable and easier to decompose with decreasing temperature, and that laminar carbon changes from turbostratic carbon towards graphitic carbon with increasing temperature and particularly at temperatures above A1 point it becomes a dense and filmy carbon which has almost the same crystallinity as natural graphite. Mechanisms are suggested for the deposition of these two types of carbon at temperatures below and above A1 point.View full abstractDownload PDF (2885K) -
Shigeo Oya, Mitsuhiro Ohtaki, Masao Kobayashi, Keiichi Kobayashi1985 Volume 49 Issue 9 Pages 746-752
Published: 1985
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSTensile strength and apparent deformation of solidifying binary Cu-Zn alloy castings were studied at various fractions of solid by use of a tensile test apparatus newly designed. The alloys complete solidification through four stages with increasing fraction of solid. The alloys in stage I with fraction of solid up to fa have significant deformation and negligible strength. Those in stage II with fraction of solid fa to fb rapidly lower the deformation. Those in stage III with fraction of solid fb to fc minimize the deformation and have noticeable strength. Those in stage IV with fraction of solid fc or more show rapid increase in both of deformation and strength (fa<fb<fc). The α-phase alloys containing Zn up to 30 mass% have less apparent deformation in the extended brittle stage III than the β-phase alloys. The peritectic alloy has the maximum apparent deformation. Interdendritic fluid flow plays a significant role in the embrittlement during solidification. Changes in the tensile properties with increase of fraction of solid are explainable by the solid forming process and interdendritic fluid behavior.View full abstractDownload PDF (1586K) -
Yasunori Miyata, Toshio Suzuki, Noboru Nagata1985 Volume 49 Issue 9 Pages 753-758
Published: 1985
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSAn Al-1.0 mass%Si alloy was unidirectionally solidified under the gravity force alone and under 5 G, that is, the centrifugal acceleration force together with the gravity force. The dendrite tip radius, ρ, the primary arm spacing, λ1, the core diameter of primary arm, d0, the first secondary arm spacing, λ2, and the tip concentration, Ctip, were measured as functions of growth rate for each series of experiments.
Scaling laws were shown to exist between λ2, d0 and λ0, and ρ, which were given by equations λ2=1.0ρ, d0=3.3ρ and λ0=2.3ρ, respectively. Characteristic dimensions of dendrite decreased by the addition of acceleration force. Under 5 G the values of ρ, λ1, d0, λ0 and λ2 decreased by about 30, 20, 30, 25 and 30%, respectively, from those under 1 G. The tip concentration was little affected by the accelerational force in the dendrite growth, and the gravity segregation was not confirmed. Planar interface under 5 G was also more unstable than that under 1 G. The increase of its instability was comparable to the decrease of the dendrite tip radius under 5 G.View full abstractDownload PDF (1370K) -
Yonosuke Murayama, Kazuo Obara, Eihachiro Tanaka1985 Volume 49 Issue 9 Pages 759-764
Published: 1985
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSIn this experiment, the procedure to form oriented etch pits on a commercially pure titanium sheet was presented, and the feature of the orientation distribution of grains, containing the orientation relation between neighboring grains, was analyzed by the etch pit method. The shape of the etch pit is coincident with that introduced from the rotation of the 14-hedral model formed by the {0001} planes and the {10\bar11} planes. Shape parameters Rc, Rp and Ra, have the following relation. Rc:Rp=1:1.4 (Ra=Rp⁄sin(61.4π⁄180)=1.6).
Using such oriented etch pits, the feature of the orientation distribution in two differently textured titanium sheets were examined. In the sheets cross rolled at 873 K, 61% of the grains have the c-axis normal to the sheet plane. The preferred orientation is (0001)[10\bar10] and the number of grains with such an orientation are 23.1%. The frequency of the orientation difference of the c-axis between neighboring grains with angles between 0 and π⁄18 is over 80%. In the sheets rolled unidirectionally at 1173 K, the grains with the c-axis parallel to the sheet plane are 50%. The grains with the orientation in the range from (10\bar10)[11\bar25] to (10\bar10)[11\bar2 17] are 12.5% in number. The preffered orientation is from (10\bar10)[11\bar25] to (10\bar10)[11\bar2 17]. The orientation difference of the c-axis between neighboring grains is distributed uniformly in the whole range from 0 to π⁄2, so that this distribution is extremely different from that of the sheets cross rolled at 873 K.View full abstractDownload PDF (1332K) -
Yonosuke Murayama, Kazuo Obara, Eihachiro Tanaka1985 Volume 49 Issue 9 Pages 765-772
Published: 1985
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSUniaxial tensile tests and hydraulic bulge tests were carried out for two differently textured sheets of pure titanium. The sheets were previously examined for the orientation distribution of grains, containing the orientation relation between neighboring grains. The deformation behaviour of the titanium sheets were examined in connection with the effect of the orientation difference between neighboring grains on the deformation mechanism of grains.
In the case of the uniaxial tensile test, the correlation in the 0.2% proof stress among the differently textured sheets and the different test directions can be explained by the preffered orientation of the sheets. However, the stress-strain curves are influenced by the orientation difference between neighboring grains. In the sheets rolled unidirectionally at 1173 K, the orientation difference of the c-axis between neighboring grains is distributed uniformly in the whole range from 0 to π⁄2. The anisotropy of the flow stress is smaller than that of the 0.2% proof stress, and the slope of the stress to the strain is larger than that of the sheets cross rolled at 873 K.
Stress-strain curves and effective stress-effective strain curves of the two differently textured titanium sheets, which were estimated from the hydraulic bulge test using the Hill’s theory for the anisotropy, were examined. In the case of the sheets cross rolled at 873 K, since the preferred orientation is (0001)[10\bar10] and the orientation difference of the c-axis between neighboring grains is small, the deformation mechanism of grains is extremely different between the uniaxial tensile test and the biaxial tensile test. Therefore, as pointed out previously, the over estimation of the anisotropy by the r value takes place. In the case of the sheets rolled unidirectionally at 1173 K, though the r values are high (from 2 to 5), the difference in the deformation mechanism of grains between different loading conditions is small because of the plastic constraint among neighboring grains. As a result, the estimation of the anisotropy by the r value is not so irrelevant.View full abstractDownload PDF (3053K) -
Hisashi Suzuki, Hideaki Matsubara, Akira Matsuo, Kunio Shibuki1985 Volume 49 Issue 9 Pages 773-778
Published: 1985
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe residual stresses produced in a titanium carbonitride (C⁄N\simeq4⁄6, called Ti(C, N)) layer deposited on a WC-10%Co substrate by the PVD process were studied by using 2θ−sin2ψ method as a function of PVD conditions such as temperature, bias voltage of substrate and thickness of layer, as compared with those produced in titanium carbide (TiC), titanium nitride (TiN) and titanium layers. Changes in residual stresses due to annealing after PVD were also studied.
The residual stresses (σr), being compressive, were always detected in TiC and TiN layers as well as in Ti(C, N) layer, and the |σr| increased with decreasing PVD temperature, bias voltage (up to −20 V) and thickness of layers. It was noted that none of residual compressive stresses were found in the titanium layer. The |σr| produced in three sorts of hard layers had a tendency to decrease by annealing treatments. However, the thermal stability of residual stresses was the highest for Ti(C, N) layer. It was suggested that the origin of σr was in the interstitial atoms of carbon and/or nitrogen introduced during PVD in each crystal lattice. Annealing effects on σr would be described in view of recovery of the interstitial atoms. The excellent strength of PVD coated specimen would be understood, based on the compressive stresses in the hard layers.View full abstractDownload PDF (852K) -
Jun-ichi Echigoya, Yuichi Takabayashi, Ko Sasaki, Shigeyuki Hayashi, H ...1985 Volume 49 Issue 9 Pages 779-783
Published: 1985
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe microstructure of the Al2O3-ZrO2 eutectic with addition of a small amount of Y2O3 has been studied. The eutectic composition was determined as 59 mol%Al2O3-36.8 mol%ZrO2-4.2 mol%Y2O3. The added Y2O3 (1-5.2 mol%) dissolved only in the ZrO2 phase and changed the crystal structure of this phase from monoclinic to cubic through a tetragonal+cubic mixture with increasing addition of Y2O3. Several orientation relationships were found between the ZrO2 and Al2O3 phases. The Al2O3-ZrO2 eutectic contained twins in the ZrO2 phase. The orientation relationship between monoclinic ZrO2 and Al2O3 can be interpreted to be affected by the thermal expansion coefficient of ZrO2 and Al2O3.View full abstractDownload PDF (1764K) -
Takao Takeuchi, Yasuo Iijima, Kiyoshi Inoue, Kyoji Tachikawa1985 Volume 49 Issue 9 Pages 784-791
Published: 1985
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSEffects of the heat treatment on the high-field performance in the diffusion-processed superconducting V3Ga have been investigated. Vanadium, V-5 at%Al, V-6 at%Ga and V-0.2 at%Zr substrate tapes were coated with gallium, electrically plated with copper, and finally heat-treated to form V3Ga layers. Ic’s at fields near Hc2 have been found to depend mainly on the layer thickness and Hc2 of V3Ga. The two-stage reaction process, which consists of a first reaction at a higher temperature to form enough thick V3Ga layers and a subsequent second reaction at a lower temperature to achieve high values of Tc and Hc2, has been found to improve the Ic in high magnetic fields. The second reaction leads to the increases in Tc by 0.4 K and in Hc2 by 1 T. The Hc2 enhancement can be interpreted only by the increase in Tc, since −[dHc2⁄dT]Tc remains unchanged through the second reaction. The increase in Tc has been discussed in relation to the long range order parameter. Generally, the variation in Hc2 with fabrication conditions such as substrate composition, gallium coating, copper plating and heat treatment seems to depend directly on the variation in Tc. This is due probably to the fact that Hc2 of V3Ga is strongly limited by the paramagnetic effect. Aluminum and gallium alloying to the substrate tape effectively enhances the growth rate of V3Ga layer. An overall Jc of 1.7×108 A/m2 has been obtained at 4.2 K and 20 T for the aluminum alloyed specimen treated at 973 K for 180 ks and subsequently at 873 K for more than 360 ks.View full abstractDownload PDF (1508K) -
Hiroaki Kumakura, Kyoji Tachikawa, C. Lew , Jr. Snead, Masak ...1985 Volume 49 Issue 9 Pages 792-800
Published: 1985
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSEffects of ternary additions to the bronze-processed Nb3Sn on its superconducting properties and martensitic transformation have been investigated. The samples were single-core Nb3Sn composite wires prepared using 0-10 at%Ti, Ta, Zr and Hf added Nb cores. Ternary additions increase Hc2 of Nb3Sn composites, which have no bronze matrices, by 0.7-3.5 T. Young’s modulus and internal friction were measured at temperatures from 6 to 300 K using a vibrating-reed technique for the observation of the martensitic transformation in the Nb3Sn compound layers. In the pure Nb3Sn, softening of Young’s modulus occurred with decreasing temperature, and drastic increase in internal friction below the martensitic transformation temperature Tm was observed. The internal friction below Tm is thought to be associated with a stress-induced motion of martensitic domain wall. By the ternary additions, softening of Young’s modulus and the occurrence of the martensitic transformation are strongly affected. Addition of Ti or Ta reduces softening of the Young’s modulus at low temperatures and decreases Tm, and the transformation is suppressed for sufficient amounts of the alloying addition. Addition of Zr or Hf, on the other hand, doesn’t change Tm and is not effective in suppressing the transformation, although it reduces softening of the Young’s modulus at low temperatures. The results mentioned above suggests that the suppression of the martensitic transformation is not a dominant factor of the improvement in Hc2 by the ternary additions. The improvement in Hc2 is thought to be attributed to the increase in ρn.View full abstractDownload PDF (1359K) -
Osamu Odawara, Jun Ikeuchi1985 Volume 49 Issue 9 Pages 801-805
Published: 1985
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSA “centrifugal-thermit process” is mainly characterized by a large amount of the reaction heat and the centrifugal force applied to the reaction products. Therefore, it is important to investigate the influence of these effects on the production of composite pipes and to assess the potential and limitation of the centrifugal-thermit process.
In the present work, the effect of centrifugal force is investigated in order to determine optimum conditions for producing good metal-ceramic composite pipes. Production tests under various values of centrifugal force are performed with a thermit mixture of Fe3O4 and Al system. The producd composite pipes are evaluated by measuring mechanical properties through a squeezing test, a compression-shear test, a thermal shock test etc.
With the increase of the centrifugal force, the compressive strength and the density of the products are improved. The compression-shear stress and thermal shock resistance are not necessarily improved. The metal and ceramic layers are uniformly partitioned, and a dense ceramic layer is obtained under the centrifugal force of 208 G. However, small cracks are observed in the ceramic layer.
As a result of the present work, it is confirmed that the optimum effect of centrifugal force would be exhibited in the region from 55 G to 208 G.View full abstractDownload PDF (1300K) -
Osamu Odawara, Masao Shiraishi, Jun Ikeuchi, Yasumasa Ishii, Hiroshi Y ...1985 Volume 49 Issue 9 Pages 806-810
Published: 1985
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSResearches on a “Centrifugal-Thermit Process” are extended to the development of 5.5 m long metal-ceramic composite pipes. In the process of the development, it is confirmed that the thermit reaction proceeds rapidly to produce the composite pipes of homogeneous quality in the direction of pipe length by igniting only a part of reactant under the conditions of proper amount of thermit powders and proper centrifugal force. This fact is a great advantage in the production of long composite pipes. For producing the composite pipe of much higher quality, the propagation mechanism of thermit reaction should be investigated in more detail from the fundamental point of view.
In the present work, the characteristics of thermit reaction are investigated by measuring propagation patterns of reaction in the pipes with various powder densities and shapes. The propagation patterns of reaction in a Centrifugal-Thermit Process are also measured by means of a radio (FM)-telemeter technique.
The propagation rate of the thermit reaction is inversely proportional to the thermit powder density. If the reaction is applied to a hollow body, it propagates along the inner surface first and into the layer of the reactant subsequently. It is concluded that the Centrifugal-Thermit Process proceeds along the inner surface of the hollow body first and then into the layer in the radial direction resulting in producing the composite pipes of homogeneous quality.View full abstractDownload PDF (743K)
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