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Volume 63, Issue 12
Displaying 1-17 of 17 articles from this issue
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Kazuhiro Okamoto, Hans-Joachim Kleebe, Ken’ichi Ota, Giuseppe Pe ...1999 Volume 63 Issue 12 Pages 1479-1484
Published: 1999
Released on J-STAGE: April 24, 2008
JOURNAL FREE ACCESSThe changes of ceramics properties are influenced by a microstructure, namely grain size and grain boundary. Available silicon nitride ceramic powder is usually covered with very thin silicon oxide layer. This silicon oxide is the origin of a glass film at grain boundaries. The purpose of this paper is to produce the new SiAlON materials (Si6−ZAlZOZN8−Z) which were controlled glass film. SiAlONs (with Z=1, 2, 3) were hot isostatically pressed (HIPed) at 2273 K under an argon-gas pressure of 180 MPa using high-purity SiAlON powders (Ube Industries). We can obtain SiAlON ceramics without glass film at grain boundary. Microscopy studies revealed the presence of a 15R SiAlON phase precipitated at the grain boundaries or triple-grain junctions of Z=2, 3 SiAlONs. Z=1 SiAlON revealed presence of glass-SiO2 grain boundary structure in which a conspicuous amount of Al was found. The viscous behavior of grain boundary at high temperature was studied by the internal friction method. Internal friction data collected up to very high temperatures showed no grain boundary relaxation peak in the Z=2, 3 SiAlON materials, and a relaxation peak centered at a rather low temperature in the Z=1 SiAlON.View full abstractDownload PDF (848K) -
Young Jo Park, Manabu Enoki, Tadatomo Suga, Teruo Kishi1999 Volume 63 Issue 12 Pages 1485-1489
Published: 1999
Released on J-STAGE: April 24, 2008
JOURNAL FREE ACCESSThe effect of plasticity of Al on the bonded area fraction of Al/Sapphire bulk joint fabricated by SAB(surface activated room temperature bonding) was investigated. It is already known that the mechanical properties of bonded materials, such as fracture behavior and fracture energy, depend on the bonded area fraction to a great extent. In this research, specimens having different bonded area fraction were made by controlling bonding pressure and time. Because plastic deformation plays a dominant role in SAB, the bonded area fraction was simulated by FEM with different material properties and surface morphology. The simulation results showed a good agreement with the measured values.View full abstractDownload PDF (624K) -
Yasunori Miyata, Takemichi Honma1999 Volume 63 Issue 12 Pages 1490-1496
Published: 1999
Released on J-STAGE: April 24, 2008
JOURNAL FREE ACCESSThe primary spacing and breakdown wavelength of the planar interface with given crystallographic orientations are studied on growth patterns in the unidirectional solidification of succinonitrile-acetone alloy. Experiment shows that the effect of the crystalline anisotropy is significant on the tip shape of the growing interface. During dendritic growth, the primary spacing is strongly dependent on the crystallographic orientation. During cellular growth, the crystal grows in a direction parallel to heat flow, and its primary spacing is dependent little on the crystallographic orientation.View full abstractDownload PDF (1244K) -
Shin-ichi Hasegawa, Takeshi Kobayashi, Koichi Sato, Shukuro Igarashi, ...1999 Volume 63 Issue 12 Pages 1497-1502
Published: 1999
Released on J-STAGE: April 24, 2008
JOURNAL FREE ACCESSA simple pretreating method, which consists of solid phase extraction using, bonded silica with benzenesulfonic acid as a solid phase sorbent was tried for the determination of trace elements in pure aluminium samples by means of graphite furnace atomic absorption spectrometry(GF-AAS). The acidic solutions were prepared by dissolving samples in sodium hydroxide, subsequently adding nitric acid. The analytes could be separated as 1-10 phenanthroline chelate from the matrix by the solid phase extraction after adjusting pH and adding 1-10 phenanthroline. The optimum condition for aluminium separation was pH 3 and 20 cm3 of 0.01 kmol/m3 1-10 phenanthroline. As the eluants 15 cm3 of 6 kmol/m3 nitric acid were used. In this method, some trace elements such as Fe, Ni, Co, Cu, and Zn were determined by GF-AAS using the eluate. The detection limits (3σ of blank value) were 0.03 ppm of Fe, Ni and Co, 0.02 ppm of Cu and 0.004 ppm of Zn when the weight of the sample was 1 g.View full abstractDownload PDF (538K) -
Takayuki Miura, Hisashi Kuwano, Kiyohiko Itoh, Yuichi Ishikawa1999 Volume 63 Issue 12 Pages 1503-1509
Published: 1999
Released on J-STAGE: April 24, 2008
JOURNAL FREE ACCESSA cast duplex stainless steel practically used in the intermediate temperature range of 280 to 330°C was investigated in terms of its aging behavior in the temperature range of 350 to 450°C for aging times up to 20000 h. A change in ferrite composition with increasing aging time was detected at room temperature by Mösbauer spectroscopy. The characteristic changes in internal magnetic field distribution and its full width at half maximum revealed that the ferrite phase decomposes by the spinodal process. The change in ferrite composition with time during aging was analyzed and the corresponding equation proposed was that of the sum of two hyperbolic tangent curves. The activation energy for the compositional change during decomposition was about 200 kJ/mol, which is comparable to that for volume diffusion of Cr or Fe in ferrite. An aging parameter p(t,T) calculated from the above activation energy was introduced to estimate the decomposition behavior at temperatures lower than 350°C. The time required for the ferrite phase to reach completion of phase decomposition was estimated to be about 1700000 h at 320°C.View full abstractDownload PDF (603K) -
Sumiko Sanuki, Motoya Nishiwaki, Hiroshi Majima1999 Volume 63 Issue 12 Pages 1510-1518
Published: 1999
Released on J-STAGE: April 24, 2008
JOURNAL FREE ACCESSHigh temperature hydrolysis of the mixed aqueous solution consisting of 5.0×10−3∼5.0×10−2 kmol·m−3 Cu(II), Zn(II), Co(II) or Ni(II) sulfate, 0∼0.5 kmol·m−3 (NH4)2SO4 and 0.1∼1.2 kmol·m−3 NH3 were studied at 373 K for 3.6 ks to examine the effects of solution composition on the shape, particle size and precipitation degree of the hydrolyzed particles. Particles precipitated were identified as spherical CuO, cylinder shape ZnO, spherical Ni(OH)2 and spherical Co3O4.
The increase in the concentration of metal ions, NH3 and (NH4)2SO4 in the high temperature hydrolyses of Cu(II) and Zn(II) results in the increase of particle size, while the precipitation degree decreases. In contrast, the increase in the concentration of Co(II) ions results in a slight increase in the particle size, but there was no significant effect on controlling particle size expected from changing NH3 and (NH4)2SO4 concentrations.
As mentioned above, the particle shape as well as the particle size can be controlled by changing the composition of ammine solution in the case of Cu(II) and Zn(II), whereas it is difficult for Co(II). The control of particle size of Cu(II) is far easier than that of Zn(II). The change in precipitation degree by changing the solution composition was the smallest with Cu(II). Controlling the particle size of Co3O4 was almost impossible by changing solution composition.View full abstractDownload PDF (1967K) -
Yonosuke Murayama, Shuji Hanada1999 Volume 63 Issue 12 Pages 1519-1526
Published: 1999
Released on J-STAGE: April 24, 2008
JOURNAL FREE ACCESSIn this study we have investigated the effect of mechanical properties of Nb solid solution (Nbss) on toughness and strength of multiphase alloys in Nb-Si-Al ternary systems. Especially, we focused on the effect of (Si+Al) content in Nbss as the constituent of the multiphase alloys. Nbss is equilibrated with Nb3Al and/or Nb5Si3 in Nb-Si-Al ternary phase diagram. Nbss in equilibrium with Nbss+Nb3Al+Nb5Si3 three-phases in the Nb-Si-Al ternary system has significantly lower solute content compared with Nbss in equilibrium with Nb3Al in Nb-Al binary system. Based on the obtained results of Nb-Si-Al phase diagram, we prepared the samples of Nbss single-phase alloys, Nbss+Nb3Al, Nbss+Nb5Si3 and Nbss+Nb3Al+Nb5Si3 multiphase alloys and investigated the toughness and the strength. The toughness was estimated by Small Punch (SP) tests and the strength was estimated by tensile tests at room temperature and compression tests at high temperature. The toughness of Nbss single-phase alloys and multiphase alloys estimated from SP energy increases with decreasing (Si+Al) content in Nbss. Nbss+Nb3Al+Nb5Si3 multiphase alloys are found to be promising because of not only high toughness (KIC) value estimated from SP tests but also high strength at elevated temperature.View full abstract -
Toshikazu Akahori, Mitsuo Niinomi, Kei-ichi Fukunaga1999 Volume 63 Issue 12 Pages 1527-1534
Published: 1999
Released on J-STAGE: April 24, 2008
JOURNAL FREE ACCESSMechanical properties, dislocation structure, fatigue strength and fatigue crack initiation characteristics were investigated at various fatigue steps in pure titanium having equiaxed α and Windmanstätten α structures. Relationship between fatigue life and the above mentioned factors was also studied.
In pure titanium with both structures, long fatigue crack propagation life strongly affects fatigue strength and this life occupies total fatigue life as compared with small fatigue crack initiation and propagation life. The mechanical properties, that is, 0.2% proof stress and hardness tend to increase obviously according to the fatigue steps particularly at the early stage of the low cycle fatigue (LCF) region, whereas elongation shows the reverse trend. The hardness far from the specimen surface is smaller than that near the specimen surface at the early stage. Hardness of both areas becomes however nearly equal each other at the later stage. The reason why those phenomena occurred would be that increment of dislocation density near the specimen surface is larger than that far from the specimen surface at early stage and the dislocation density of both areas saturates at later stage, becoming similar. Dislocations in pure titanium with both structures form equiaxial dislocation cell structure. The dislocation structure at each fatigue step has a correlation with the fatigue life under constant maximum cyclic stress.View full abstractDownload PDF (1125K) -
Takefumi Sugiyama, Hideki Hosoda, Shuji Hanada1999 Volume 63 Issue 12 Pages 1535-1544
Published: 1999
Released on J-STAGE: April 24, 2008
JOURNAL FREE ACCESSFor further understanding of hydrogen pulverization in intermetallic alloys, the effects of volume fraction of constituent phases, lattice strain, and mechanical property on hydrogen pulverization were investigated using 10 mol%Ti-added Nb-solid-solution (Nbss)/Cr2(Nb, Ti) two-phase alloys. ICP-OES chemical analysis, XRD, EPMA and SEM were performed for alloy characterization. Bend tests were conducted at room temperature in air to evaluate fracture strength and to observe the fracture surface. Hydrogenation was carried out at room temperature under a hydrogen atmosphere of 0.1 MPa for 10.8 ks after arc-melting in Ar atmosphere without exposure to air. Hydrogen pulverization occurred for all the alloys investigated. After hydrogenation, volume expansions and NbH2 formation occurred. The expansion rates depend on constituent phases, which must cause the pulverization. The bend strength simply increased with increasing volume fraction of Nbss. The distribution of powder size does not depend on the bend strength, but it seems to depend on the product of volume fractions of Nbss and Cr2(Nb, Ti). SEM fractography revealed that “river” patterns, which were clearly seen at the fracture surface after the bend tests in air, were not clear on the powder surface after the hydrogenation. These results indicate that hydrogen pulverization is attributed to not only the difference in volume expansion of constituent phases but also hydrogen embrittlement of constituent phases.View full abstractDownload PDF (2055K) -
Tomohiro Uno, Kohei Tatsumi1999 Volume 63 Issue 12 Pages 1545-1554
Published: 1999
Released on J-STAGE: April 24, 2008
JOURNAL FREE ACCESSThe replacement of conventional pure Au bonding wires by highly-alloyed Au-Ag ones in LSI semiconductors can reduce significantly material cost. However, Au-Ag wires have not yet been used due to a failure problem at the bonding points between the Au-Ag balls and Al thin film pads. Therefore, to apply Au-Ag wires to LSI products, the improvement of the thermal reliability at the bonding points between Au-Ag/Al is very important.
The thermal reliability of the Au-Ag/Al bonds depends on the Ag concentration (CAg) in Au wires. A certain range of CAg showing good bond reliability was found. Ball bonds of Au-14 at%Ag produced a significant degradation after annealing. On the contrary, bonds of Au-24 at%Ag provided as good a reliability as the commercial pure Au wire after annealing at 473 K for 1000 hr. Thus, the optimization of the Ag concentration in the Au-Ag alloy wires was significantly effective in improving the bond reliability.
Diffusion behavior at the bond interface of the Au-Ag/Al was different from that of pure Au/Al. It was characteristic that AuAl2 grew predominantly in the interface of the Au-Ag/Al. The formation of intermetallic compounds varies with CAg. The dependence of the intermetallic compounds (Au5Al2, AuAl2, Ag2Al) on the Ag concentration dominated the bond reliability.View full abstractDownload PDF (1611K) -
Satoshi Nagashima, Tomohiro Akiyama, Jun-ichiro Yagi1999 Volume 63 Issue 12 Pages 1555-1560
Published: 1999
Released on J-STAGE: April 24, 2008
JOURNAL FREE ACCESSThe combustion synthesis of magnesium-nickel alloys in a hydrogen atmosphere is attractive for direct synthesis of Mg2NiH4. However, control of the hydrogen storage capacity by changing the mixing ratio of magnesium and nickel has not been reported. In this study, compressed magnesium-nickel powders with different atomic ratios, 1 to 55% in nickel, was combustion-synthesized in hydrogen, in which the hydrogen storage capacity and the hydriding rate were examined.
The effect of the mixing ratio on the storage capacity was significant, in which Mg-1 mass%Ni showed the highest capacity, 7.20 mass%H2. Moreover, all of the product reached 85 to 95% of the theoretical capacity. The reaction rate increased with nickel addition. These results could promote the practical use of hydriding combustion synthesis.View full abstractDownload PDF (444K) -
Tetsuo Toge, Mineo Muraki, Takashi Obara1999 Volume 63 Issue 12 Pages 1561-1566
Published: 1999
Released on J-STAGE: April 24, 2008
JOURNAL FREE ACCESSA 3%Si-Fe (100)[011] single crystal was investigated to analyze its texture evolution during rolling and recrystallization. Cold rolled (100)[011] could be fully recrystallized by utilizing dynamic strain aging, and a sharp recrystallized texture was obtained.
Rolled texture maintained the initial orientation (100)[011] with TD rotational dispersion. The recrystallized texture was composed of eight orientations rotated about 30 degrees around eight ⟨112⟩ axes from the initial orientation (100)[011], which is the central orientation of cold rolled matrix. On the assumption that single slip operates locally, recrystallized texture formation is explained by eight kinds of {110}⟨111⟩ slip cause crystal rotations around eight kinds of ⟨112⟩, which are perpendicular to both slip plane normal and slip direction. The sense of the crystal rotation is always towards the direction which makes the angles between slip plane and rolling plane increase, which is consistent with Furubayashi’s Hard Model.
It was found, furthermore, that the intensity of each component of recrystallized texture corresponds to the Schmid factor of the slip system to which recrystallized orientation is attributable. Such correspondence between the intensity of each recrystallized orientation and Schmid factor was clearly verified by an experiment using single crystal whose initial orientation deviates ten degrees deviated from (100)[011] around ND axis.View full abstractDownload PDF (538K) -
Shojiro Ochiai, Takayuki Fujita, Mototsugu Tanaka, Masaki Hojo, Ryohei ...1999 Volume 63 Issue 12 Pages 1567-1575
Published: 1999
Released on J-STAGE: April 24, 2008
JOURNAL FREE ACCESSTensile behavior of SiC/TiAl composite was investigated. Main results are:
(1) The interface of the composite was weak. The fracture of the composite was accompanied by the fracture of matrix, fracture and pull-out of fibers, and interfacial debonding along the whole length between grips.
(2) Under the condition that strength of individual fiber is determined by the largest defect, the extreme value distribution function was applied for description of the distribution of the size of the maximum defect of fibers, and the strength of the composite at room temperature based on the fiber bundle strength was calculated. The experimentally measured strength could be accounted for by this calcuation.
(3) From the results of a Monte Carlo simulation, it was suggested that the improvement of frature strain of the matrix and minimization of the residual stresses are needed to achieve high strength.View full abstractDownload PDF (1509K) -
Yukio Ide, Katsuhiko Kishitake, Takashi Nakamura1999 Volume 63 Issue 12 Pages 1576-1583
Published: 1999
Released on J-STAGE: April 24, 2008
JOURNAL FREE ACCESSIt is expected that an Al-Cr-N composite nitride film may have a higher resistance to oxidation at elevated temperatures than the well-known Ti-Al-N films because both AlN and CrN possess good oxidative resistance. Al-Cr-N films were formed by a dc reactive sputtering process, while the plasma condition being monitored with an optical emission spectroscope and a mass spectrometer. The effect of the sputtering power and applied probe current on the emission intensity and ion current of reacting species in the plasma were investigated by using the monitors. The formed films were characterized by X-ray diffraction, electron microprobe analysis and auger electron spectroscopy. The results are summarized as follows.
(1) AlN+ and CrN+ were observed in the plasma by mass spectroscopy, suggesting that nitrides formed partly in the plasma before depositing on a substrate.
(2) The emission intensity of reacting species increases with increasing sputtering power and applied probe current.
(3) The atomic ratio of Al/Cr in the Al-Cr-N films is found to be proportional to the ratio of the emission intensities of aluminum and chromium measured by optical emission spectroscopy.
(4) The crystal structure of Al-Cr-N films is B1(NaCl) type in the range up to 50 at% of aluminum and B4(Wurtzite) type over 75 at% of aluminum.
(5) The distribution of aluminum, chromium and nitrogen is very uniform in the films compared with the film formed by an activated reactive evaporation process.View full abstractDownload PDF (594K) -
Hiroyuki Kawaura, Kazuaki Nishino, Takashi Saito1999 Volume 63 Issue 12 Pages 1584-1590
Published: 1999
Released on J-STAGE: April 24, 2008
JOURNAL FREE ACCESSTiAl-base alloys are expected to substitute conventional materials for exhaust parts of automobile engines, because they have lower density and higher specific strength at elevated temperatures than heat resistant steels and Ni-base superalloys. The major key to successful application of TiAl alloys is improvement of oxidation resistance at high temperature.
A new surface treatment using a fluidized bed with WO3 powder has been developed. The reagent used was a mixture of 40 mass%WO3 powder (100-200 mesh) with 60 mass%Al2O3 powder (80 mesh). The bed was fluidized by an argon gas flow. Specimens were treated in the bed at 1273 K for 7.2 ks. The oxidation tests were carried out at 1173 K and 1223 K for 720 ks in air and in a typical exhaust gas atmosphere. The mass changes were examined, in addition to the characterization of treated and oxidized surface using Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD), and Auger Electron Spectroscopy (AES).
The cyclic oxidation resistance of TiAl-base alloys in air and exhaust gas up to 1223 K was significantly improved. The excellent oxidation resistance obtained is attributable to a continuous and sound Al2O3 surface layer formed during the treatment. This protective layer acts as a barrier against the formation of a complex oxide scale consisting of a TiO2 layer and a porous inner layer of TiO2 and Al2O3. The new surface treatment gives an oxidation resistance superior to that of the Ni-base superalloy Inconel 713C up to 1223 K.View full abstractDownload PDF (1423K) -
Kazutaka Okamoto, Akira Yoshinari, Yasuhisa Aono, Takahiko Kato1999 Volume 63 Issue 12 Pages 1591-1599
Published: 1999
Released on J-STAGE: April 24, 2008
JOURNAL FREE ACCESSIt has been attempted to improve the resistance to stress corrosion cracking by manufacturing single crystalline austenitic stainless steels. However, single crystal growth was observed to depend on alloying elements of steels. In this paper, relations among single crystal growth, alloying elements and microstructure were studied. Casting experiments were carried out for 26 kinds of steels which contained 10.5-20.5 mass% chromium, 8.4-20.9 mass% nickel and 0-4.7 mass% molybdenum all with carbon contents below 0.03 mass%. Single crystals were manufactured by using the mold withdrawal unidirectional solidification method which provided large size single crystals. Growth of single crystals and their microstructures were closely depended on the (Creq/Nieq) ratio. Single crystal casting were obtained for steels with (Creq/Nieq) less than 1.83. These single crystals were fully austenitic for (Creq/Nieq) less than 1.5 while contained mixtures of the continuous austenitic single crystal matrix and ferrite phases for (Creq/Nieq) between 1.5 and 1.83. Furthermore, for Mo added steels, phases enriched with the element were observed at γ⁄δ grain boundaries by TEM. On the other hand, single crystal growth was not observed for steels with (Creq/Nieq) higher than 1.87 because their microstructures were not dendritic, but rather of the lathy structure type.View full abstractDownload PDF (2360K) -
Kozo Nakazawa, Masae Sumita, Norio Maruyama1999 Volume 63 Issue 12 Pages 1600-1608
Published: 1999
Released on J-STAGE: April 24, 2008
JOURNAL FREE ACCESSFatigue and fretting fatigue of austenitic 316L and ferritic 430 and 447J1 stainless steels in pseudo-body fluid (PBS(−)) were studied. Plain fatigue strengths at 107 cycles in PBS(−) were approximately equal to those in air irrespective of the kind of stainless steel. Fretting fatigue strengths at 107 cycles in air were 1/2 to 2/3 of the plain fatigue strengths in air for the three steels. In 316L steel, fretting fatigue strength at 107 cycles in PBS(−) was lower than that in air; whereas, in 430 and 447J1 steels, fretting fatigue strengths in PBS(−) were squal to those in air. It was found that ferritic steels were superior in fretting fatigue strength in PBS(−) to 316L steel. Initiation sites of the main cracks responsible for the failure were confined to fretted areas for all the specimens except some 316L steel specimens. In 316L steel specimens tested at a certain stress amplitude range in PBS(−), the main crack initiation occurred at random places of the specimen surface other than fretted areas. It was suggested that hydrogen embrittlement due to fretting was involved in the phenomenon since intergranular fracture was observed at the initiation site of the main crack.View full abstractDownload PDF (1647K)
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