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Volume 57, Issue 9
Displaying 1-21 of 21 articles from this issue
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Yoshio Kawamura, Toshio Saburi, Tetsuo Yashiki, Tetsuo Nakai, Shuji Ya ...1993 Volume 57 Issue 9 Pages 975-982
Published: 1993
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe structure of diamond films grown from a methane and hydrogen gas mixture by chemical vapor deposition (microwave plasma and hot-filament methods) has been studied with particular attention to the structure of substrate-interface. By examining the diamond films deposited on either Si or Mo by scanning and transmission electron microscopies, electron diffraction, and energy dispersive X-ray (EDX) micro-analysis (in-situ), it was found that there is an intermediate layer composed of amorphous carbon and fine particles of face-centered cubic (fcc) carbon between the employed substrate and the deposited diamond film in both cases of Si and Mo. The fine particles of carbon give rise to electron diffraction rings which satisfy the extinction rule of fcc. The obtained lattice constant is very close to that of SiC which has a similar extinction rule. However, the fcc carbon and SiC are discernible by examining the intensities of their 200 rings of electron diffraction. It appears that the fcc carbon plays an important role in the diamond nucleation.View full abstractDownload PDF (2266K) -
Motonobu Onoda, Kazuo Shimizu, Takeshi Tsuchiya, Tohru Watanabe1993 Volume 57 Issue 9 Pages 983-989
Published: 1993
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThis study relates to electrodeposition of amorphous Ni-Co-B alloy films by the rotated electrode and to their structure. The conclusions are as follows:
The electrode rotation process provides an amorphous film deposition range approximately 10 times wider than that by the existing static bath process. The practical peripheral speed of the rotating electrode is 70 cm/s or more. Hydrogen contained in amorphous Ni-Co-B alloy films by the electrode rotation process is more than that by the static bath process. We consider that the hydrogen alloyed in these plating films may be related to the formation of the amorphous structure or refining of crystal grains. The CoB intermetallic compound was formed in boundaries between substrates and amorphous plating films.View full abstractDownload PDF (1586K) -
Yan-Sheng Kang, Hideki Araki, Yoritoshi Minamino, Toshimi Yamane, Sige ...1993 Volume 57 Issue 9 Pages 990-997
Published: 1993
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSAl-Zn binary phase diagrams under pressures of 0.1 MPa and 2.1 GPa were experimentally determined mainly with the method of diffusion couple and the method of two-phase observation and analyses. The phase diagrams at 0.1 MPa and 2.1 GPa were also calculated with volumetric and thermodynamic data at 0.1 MPa. The results obtained from the calculations were compared with the experimental data.
Solidus of the α phase and the β phase were observed to shift to the higher temperature range when the high pressure of 2.1 GPa is applied, and the solid solubility of the α phase decreases simultaneously. According to the values evaluated from the intersection point formed by the α phase solidus and the α/(α+β) phase solubility line, the maximum solubility of Zn in Al at 2.1 GPa is 68.1 at%Zn and the eutectic temperature is 750 K. These values are by 1.1 at%Zn and 96 K higher than those at 0.1 MPa, respectively. Based on the experimental results, it is proved that the top of the miscibility gap at 2.1 GPa rose to 702 K. This is 78 K higher than that at the 0.1 MPa. The calculated miscibility gap rises with the pressure and it exhibits the same trend as the experimental results.View full abstractDownload PDF (1603K) -
Byung-Nam Kim, Teruo Kishi1993 Volume 57 Issue 9 Pages 998-1005
Published: 1993
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSA crack deflection model was constructed to explain the fracture behavior in polycrystalline ceramics consisting of isotropic ideal grains. From the considerations of the competition criterion between penetration and deflection of crack at grain boundaries, a 3-dimensional fracture process was modelled where the crack path is affected by adjacent crack planes. Cracks in polycrystals were divided into 3 types, that is, transgranular, intergranular and a mixture of the two. The macroscopic fracture toughness, Kca, and the transgranular fracture ratio, Tf, were calculated as a function of the grain boundary toughness, Kcb. The maximum Kca of polycrystals is about 3 times that of single crystals, Kct, at Kcb=0.9Kct, and the crack path restriction at triple or quadruple points indicating a forced fracture in the connecting plane was found to be the primary reason for the increased fracture toughness of polycrystals over that of single crystals. In this analysis, the theoretical relationships between Kca and Tf were also obtained where the maximum Kca is at Tf=75%. On the other hand, the calculations on both the plane strain and plane stress states showed that the fracture toughness of ceramics is not dependent on stress states.View full abstractDownload PDF (1177K) -
Masako Morita, Shigeru Asano1993 Volume 57 Issue 9 Pages 1006-1011
Published: 1993
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSMechanical hysteresis was observed at room temperature for polycrystalline Al-Mg dilute alloys by the three-point bending method. The form of hysteresis loops was not a breakaway type but a friction type, when the observation was done in the steady-state deformation of loading-unloading cycles. The results suggest that the amplitude dependence of internal friction is caused by dislocations moving across the field of dispersed solute atoms, and it should not be deduced from the Granato-Lücke theory based on a breakaway model of dislocations.
Internal friction in the same alloys was measured at 190-370 K by the free decay method of flexual vibration. The amplitude-dependent internal friction was found to decrease with increasing Mg content and decreasing temperature. The data were analyzed on the basis of the microplastic theory, assuming a friction-type hysteresis, and converted into the microplastic strain expressed as a function of stress. The stress-strain responses showed that the flow stress increased more rapidly with alloying in the microplastic strain range than in the range of usual tensile tests.View full abstractDownload PDF (632K) -
Yuji Imashimizu, Jirô Watanabé1993 Volume 57 Issue 9 Pages 1012-1017
Published: 1993
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSCzochralski-grown Cu-0.1 at%Ni alloy crystals were annealed in a stream of purified argon gas under thermal cycle conditions by varying the heating temperature sinusoidally between 1123 K and 1323 K with a period of 1.8 ks. Changes in dislocation distribution and density as a function of annealing time were investigated by an etch pit technique with two specimen crystals which had different initial dislocation structures.
Many subboundaries, mostly of the ⟨211⟩ type, were formed at the beginning of cyclic annealing, though they vanished during an early stage of annealing. Overall dislocation densities of 5×109 m−2∼8×109 m−2 in as-grown crystals decreased to 2×107 m−2∼3×107 m−2 after cyclic annealing for 172.8∼345.6 ks. It was observed that an elimination of edge dislocations was more remerkable than that of screw dislocations, especially in the early annealing stage. The decrement in dislocation density in Cu-0.1 at%Ni alloy crystal with an increase of annealing time was found to be comparable to that in pure copper crystal reported so far, showing that a small addition of Ni in Cu has little effect on the annihilation process of dislocations.View full abstractDownload PDF (1130K) -
Koji Ikeda, Teruo Kishi1993 Volume 57 Issue 9 Pages 1018-1026
Published: 1993
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThis study was carried out to investigate multitoughening effect by reinforcements of μm size. Five different SiC-reinforced Al2O3-matrix composites were fabricated in the same procedure as model materials, which were reinforced with SiC-whisker and SiC-platelet. Those reinforcements were expected as the bridging generator and the crack-deflection generator, respectively. Bending strength and fracture toughness were measured, as the mechanical properties. These experimental data were discussed in comparison with theoretical toughening mechanisms. The experimental results showed that the bending strength for the whisker reinforced composites has no strong dependence on the matrix grain size. On the other hand, the platelet reinforced composites showed very low strength, which was concluded as the intergranular fracture of the coarse matrix and the interfacial glass layer. Fracture toughness was enhanced to 7.1 MPa \sqrtm by cooperation of SiC-whisker and SiC-platelet from 3.8 MPa \sqrtm for monolithic Al2O3. This enhancement was concluded as the results of effective cooperation between crack deflection and bridging.View full abstractDownload PDF (1060K) -
Norio Matsuda, Fuyuki Yoshida, Keisuke Matsuura1993 Volume 57 Issue 9 Pages 1027-1034
Published: 1993
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSStress relaxation tests were carried out for a P/M Al-8 mass%Fe alloy using a lever type creep machine at temperatures from 573 to 673 K. The way to estimate the strain rate just after the start of stress relaxation, \dotεr0, was discussed. The values of \dotεr0 were compared with the strain rate just before the relaxation test(steady-state creep rate), \dotεs, and the work hardening rate, h, and the recovery rate, r, were determined.
The relation between the strain rate, \dotεr, and the actual stress of the specimen, (σ−σr), during the stress relaxation test, was almostly linear in a log-log plot except the early stage after the start of stress relaxation. The \dotεr0 was estimated by extrapolating the linear relation to the initial creep stress. The \dotεr0 was usually smaller than the \dotεs, which showed that the contribution of the effective stress to high temperature deformation could be neglected in the present alloy. The h did not depend on temperature and slightly or scarcely decreased with the increase in stress, while it tended to decrease rapidly in the high stress range above a critical stress, that is the Orowan stress. The r, on the other hand, largely depended on stress and temperature, and the activation energy for it was close to that determined from the temperature dependence of the steady state creep rate, \dotεs.
Relation between \dotεr and actual stress (σ−σr) during the relaxation tests in the low stress region below the critical stress was very close to one between steady-state creep rate \dotεs and creep stress σc obtained by creep tests at each temperature. It is thought that the internal structure during the stress relaxation is close to one in the steady state creep deformation.View full abstractDownload PDF (1078K) -
Kenji Matsunaga, Shojiro Ochiai, Kozo Osamura, Yoshiharu Waku, Takemi ...1993 Volume 57 Issue 9 Pages 1035-1040
Published: 1993
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe Young’s modulus, tensile strength, fracture morphology and microstructure of the unidirectional Si-Ti-C-O fiber (Tyranno Fiber®)-reinforced aluminum (99.7%) matrix composite heat-treated in vaccum at 673 K for 3.6-10800 ks and 773 K for 0.3-3600 ks were investigated. The longitudinal and transverse Young’s moduli and the transverse strength after heat-treatment were nearly equal to those before heat-treatment. While the longitudinal strength was 1.1 GPa on the average before heat-treatment, it decreased with increasing heat-treating time and then remained to be 0.6-0.7 GPa. Al-Fe-Si compound layers were observed at the interface between the matrix and the fibers by means of a transmission electron microscopy and energy dispersive X-ray spectroscopy. The reduction in longitudinal strength of the composite due to heat-treatment could not be attributed to the degradation of fiber itself or damage of fiber surface but to the premature fracture of the compound layers, resulting in formation of cracks on the fiber surface.View full abstractDownload PDF (2011K) -
Tetsu Go, Nobuyoshi Hara, Katsuhisa Sugimoto1993 Volume 57 Issue 9 Pages 1041-1046
Published: 1993
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe formation process of Al2O3 films in low-pressure CVD using aluminum-tri-isopropoxide (ATI) has been examined by in-situ ellipsometry as functions of substrate temperature, carrier gas flow rate, ATI temperature, and the existence of O2 as the reactant gas. The formation process can be divided into two regions, that is, the initial growth region in which the increase rate of thickness is changing with time and the linear growth region in which the increase rate of thickness is constant. The growth behavior was different in the initial growth region, corresponding to the substrate temperature and the ATI concentration. At the substrate temperature of 535 K, the increase rate of thickness increased with time in the low ATI concentration and decreased in the high ATI concentration. The increase rate of thickness, however, increased in the high ATI concentration at the substrate temperature of 695 K. This suggests that the growth behavior in the initial growth region changes with the difference in the rate-determining step. The growth rate of Al2O3 films was calculated from the product of increase rate of thickness in the linear growth region and the film density estimated from the refractive index. At the substrate temperatures in the range of 535-634 K, Arrhenius’ relation was observed. The apparent activation energies were 97.98 kJ mol−1 and 113.66 kJ mol−1 with and without O2 gas, respectively. At the substrate temperature of 695 K, the growth rate increased with increasing carrier gas flow rate and ATI temperature.View full abstractDownload PDF (802K) -
Satoshi Sunada, Nobuyuki Nakamura, Takehiko Mae, Hisakimi Notoya, Sumi ...1993 Volume 57 Issue 9 Pages 1047-1053
Published: 1993
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe effect of the deformation-induced martensite (α′) on stress corrosion cracking (SCC) for SUS304 austenitic stainless steel was investigated by measurements of the time to failure of stress corrosion cracking for the specimens which contains (α′) martensite under a loaded stress of 0.2% proof stress and the creep strain during the SCC test in 1×10−2 kmol⁄m3HCl+35 mass%MgCl2 solution at 358 K.
The main results obtained from the experiments are summarized as follows:
(1) The time to failure of stress corrosion cracking of the specimens are decreased with increasing volume fraction of martensite below 57%. However, there is no effect on the time to failure of stress corrosion cracking of the specimens at the volume fraction of martensite higher than 57%.
(2) The effects HCl concentration and loaded stress on the time to failure are little for the specimens martensite contained.
(3) The crack propagation of stress corrosion of the specimens proceeds at two stages. The crack propagation rates at the first stage and the second stage increase with increasing volume fraction of martensite in SUS304 stainless steel under the same experimental condition. However, the rate is almost constant at the volume fraction of martensite higher than 33%.View full abstractDownload PDF (1813K) -
Kazumitsu Shinohara, Toshihiro Seo, Takashi Naohara, Noriaki Sugamoto, ...1993 Volume 57 Issue 9 Pages 1054-1063
Published: 1993
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSEutectic phases of binary alloys can often be morphologically lamellar. Referring to λ and V as an interlamellar spacing and solidification rate, respectively, the Jackson-Hunt’s relationship where λ2V is constant(1) has been obtained on minimizing the supercooling during solidification. Prigogzine(2) has proposed that the morphology is determined so as to minimize the entropy production in irreversible thermodynamics. This investigation has been undertaken to find the ranges of λ as resultant lamellae in several Al-base eutectic alloys and the results are interpreted in terms of the perturbation theory originally developed by Mullins and Sekerka(3). It is found that the interlamellar spacing is determined either by the criterion of minimum supercooling or minimum entropy production depending upon the latent heat of fusion of the eutectics.View full abstractDownload PDF (3249K) -
Isamu Yamauchi, Itsuo Ohnaka, Yuji Ohashi1993 Volume 57 Issue 9 Pages 1064-1071
Published: 1993
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSCu-70 at%Al alloys with various amount of Pd were solidified at different cooling rates and structures of the as-solidified alloys and catalysts made by leaching Al from them were examined by SEM, DSC and X-ray diffraction as a basic study for improvement of the catalytic activity of Raney copper catalysts for the hydration reaction of acrylonitrile which is important for production acrylamide. The specific surface area of the catalysts were measured by the BET Ar-absorption technique. The activity of the catalysts was evaluated by the conversion ratio from acrylonitrile to acrylamide by the hydration reaction. The results are as follows.
(1)In the conventional slowly solidified alloys, most of the added Pd was distributed in primary ε phase and its solubility in the θ phase was quite few. On the other hand, in the rapidly solidified alloys, the formation of the primary ε phase was almost suppressed and Pd was supersaturated in the θ phase.
(2)Raney copper with soluted Pd was newly obtained by leaching the θ phase with Pd. This suggests that the rapid solidification process is an effective process to get new catalysts.
(3)Specific surface area of Raney copper produced by leaching rapidly solidified alloys increased with Pd content. It was about 3 times higher in the 1.5 at%Pd alloy than that in the Pd-free alloy.
(4)The catalytic activity of 1.5 at%Pd catalysts showed a maximum, but its value per unit specific surface area decreased with Pd content.View full abstractDownload PDF (2415K) -
Koichi Tada, Atsumi Ohno1993 Volume 57 Issue 9 Pages 1072-1077
Published: 1993
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSIt has been demonstrated that aluminum strips with a unidirectionally solidified structure can be produced by the OSC (Ohno Strip Casting) process. This new process employs an open type horizontal heated mold. In this process, the mold temperature is maintained above the solidification temperature of the metal to be cast. The cooling water is applied only to the top surface of the solidified strip on the mold. An apparatus for casting of aluminum strip was constructed, and strips of 99.7 and 99.9 mass% pure aluminum were produced under several casting conditions. The casting speed ranged from 4 to 16.7 mm/s. The influence of the casting speed on the surface condition and macrostructure of the strip was examined. The surface of the strip is smooth and flat irrespective of the casting speed, when the mold temperature is higher than the melting point of aluminum. At a high casting speed (13 mm/s), the strip exhibits a unidirectionally solidified structure with the sub-boundary extended fanwise and the boundary extended parallel to the casting direction. The position and shape of the solid-liquid interface are important factors in the formation of the macrostructures of the strip.View full abstractDownload PDF (1014K) -
Masahiro Fukumoto, Hirokazu Tsunekawa, Minoru Umemoto, Isao Okane1993 Volume 57 Issue 9 Pages 1078-1082
Published: 1993
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSThe separation phenomena of ceramic phase from metal phase have been often recognized in the DC plasma spraying of uniformely mixed mechanically alloyed(MA) metal-ceramic powders. The separation mechanism of the MA composite powder materials during plasma spraying was mainly investigated in this work. Some methods for restrain the separation were also applied.
The results obtained are summarized as follows.
(1)The wettability between metal and ceramic material, surface tension of each material melted as well as the accelaration force of the plasma to the molten particles have affected this separation phenomena.
(2)Separation was recognized even in the Cu/TiC MA powder material system, which had good wettability between metal and ceramic materials.
(3)Separation was well restrained by both the application of the CuO/alumina power materials system and spraying in the low power plasma conditions.View full abstractDownload PDF (1621K) -
Kiyoshi Mizuuchi, Yoshihira Okanda, Itsuo Ohnaka1993 Volume 57 Issue 9 Pages 1083-1088
Published: 1993
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSRapidly solidified Fe-30Cr-5Al alloy powder was sheath-rolled. With increasing reduction in cross-sectional area, oxide films of the powder particle surface were broken or divided to some pieces and the shape of oxide film was changed from plate to granular from. In this result, bonding of the powder particles were improved. The tensile strength of sheath-rolled alloy powder without Ce increased linearly with increasing reduction in cross-sectional area from 45 to 75%. The sheath-rolled alloy powder with the addition of Ce showed low tensile strength in the low reduction. However, The sheath-rolled Fe-30Cr-5Al-0.69Ce alloy powder showed almost the same tensile strength as the Ce-free compacts in the high reduction more than 60%. The tensile strength of the sheath-rolled alloy powders with or without Ce were over 700 MPa for the range of reduction in cross-sectional area more than 70%. The fracture pattern of the sheath-rolled Fe-30Cr-5Al-0.69Ce alloy powder changed from intergranular fracture at the boundaries of primary particles to trans-granular fracture with increasing reduction in cross-sectional area.View full abstractDownload PDF (1467K) -
Kohji Kawahara, Nobuo Sakuma, Yasushi Nishizaki1993 Volume 57 Issue 9 Pages 1089-1096
Published: 1993
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSAn attempt has been made to develop the manganese-based and workable damping alloys containing 20 at% copper, together with 2 or 5 at% additive elements, such as nickel, iron, cobalt, vanadium, chromium, zirconium, titanium, aluminum, zinc and tin.
Nickel was the most effective element for increasing damping capacity of a Mn-20Cu alloy. The second ranking elements were followed by iron, cobalt, aluminium, and zinc. A group of additive elements consisting of vanadium, zirconium, titanium, and chromium, showed some effect with the addition of 2%, but not with that of 5%. Tin was ineffective even with addition of 2% and 5%. We have discussed a correlation between additive elements and the effectiveness, on the basis of the following two viewpoints: (1) the solubility of additive elements in manganese or copper and (2) the possibility of the precipitation or the primary crystallization during solidification. We found that the damping capacity may increase proportionaly with the increased solubility of additive elements in manganese or copper. This effect of nickel addition may be related to formation of a complete solid solution for manganese and copper. Little effectiveness of the additive elements, such as chromium, titanium, zirconium, and tin, may be associated with little solubility for parent phase and with the possibility of the precipitation and the primary crystallization. The elements, showing a large solubility for one side and little for other side, such as iron, vanadium, cobalt, aluminum, and zinc, may yield the medium effect, depending on the additive quantity. We concluded that in manganese-based alloys the improvement of the damping characteristics may be obtained by the additive elements that have a large solubility without forming second phases during heat treatment or solidification. An alloy, Mn-20Cu-5Ni, showed a value of 0.28 in logarithmic decrement (a value of 43% in specific damping capacity), 370 MPa in tensile strength, and 27% elongation.View full abstractDownload PDF (1408K) -
Kohji Kawahara, Nobuo Sakuma, Yasushi Nishizaki1993 Volume 57 Issue 9 Pages 1097-1100
Published: 1993
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSAn attempt has been made to develop manganese-based and workable damping alloys containing 20 at% copper and 5 at% nickel, together with 2 or 5 at% additive elements, such as iron, aluminum, chromium, cobalt, and vanadium.
Furnace cooling was effective for increasing the damping characteristics in most alloys tested. Aging treatment at 698 K after annealing showed a minor increase in damping characteristics as compared with cooling rate. The alloy, Mn-20Cu-5Ni-2Fe, showed a value of 0.32 in logarithmic decrement (a value of 47% in specific damping capacity) after furnace cooling from the annealing temperature of 1173 K. The decrement in this alloy was superior to that of the Mn-20Cu-5Ni alloy reported in the previous paper. In Mn-20Cu-5Ni-2Fe-2Al and Mn-20Cu-5Ni-2Fe-5Al alloys an equivalent decrement was obtained.
It was deemed necessary for improvement of the damping capacity to add elements which have large solubility with regard to manganese and copper without precipitation or primary crystallization.View full abstractDownload PDF (495K) -
Takeo Katoh, Kazutomo Suenaga, Yoshiyuki Takayama, Kunio Ito, Yoichi I ...1993 Volume 57 Issue 9 Pages 1101-1102
Published: 1993
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSDownload PDF (756K) -
Kazutomo Suenaga, Masahito Tanaka, Takeo Katoh, Yoshiyuki Takayama, Ku ...1993 Volume 57 Issue 9 Pages 1103-1104
Published: 1993
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSDownload PDF (366K) -
1993 Volume 57 Issue 9 Pages 1105
Published: 1993
Released on J-STAGE: April 04, 2008
JOURNAL FREE ACCESSPlease see pdf. Wrong:ΔW/kg·m-2 Right:ΔW/10-2 kg·m-2View full abstractDownload PDF (20K)
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