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Volume 73, Issue 2
Displaying 1-10 of 10 articles from this issue
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Invited Review
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—One Dimensional Motion of Point Defect Clusters and Void Growth—Toshimasa Yoshiie2009 Volume 73 Issue 2 Pages 65-73
Published: 2009
Released on J-STAGE: February 01, 2009
JOURNAL FREE ACCESSThe generation and accumulation of point defects and their interaction with pre-existing defects in crystalline solids under energetic particle bombardment are important subjects for nuclear materials developments and also in the field of crystalline lattice defects. This review gives recent results obtained in the study of radiation damage of metallic crystals, mainly concerning movements of point defect clusters and void growth.
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Regular Articles
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Takuma Otomo, Hiroaki Matsumoto, Naoyuki Nomura, Akihiko Chiba2009 Volume 73 Issue 2 Pages 74-80
Published: 2009
Released on J-STAGE: February 01, 2009
JOURNAL FREE ACCESSChanges in Young's modulus of the Co-31 mass%Ni-19 mass%Cr-10 mass%Mo alloy (Co-Ni based alloy) with cold-swaging, combined with heat-treatment at temperatures from 673 to 1323 K, was investigated to enhance the Young's modulus of Co-Ni based alloy. After cold-swaging, the Co-Ni based alloy, forming <111> fiber deformation texture, shows the Young's modulus of 220 GPa. Furthermore, after ageing the cold-swaged alloy at temperatures from 673 to 1323 K, the Young's modulus increased to 230 GPa, accompanied by a decrease in the internal fiction and an increase in the tensile strength. This suggests that the increment in Young's modulus is caused by a moving of the vacancies to the dislocation cores and a continuous locking of the dislocations along their entire length with solute atoms (trough model). By annealing at 1323 K after cold swaging, Young's modulus slightly increased to 236 GPa. On the other hand, the tensile strength decreases to almost the same value as that before cold swaging due to recrystallization. These results suggest that the Young's modulus and the strength in the present alloy are simultaneously enhanced by the continuous dislocation locking during aging as well as the formation of <111> fiber deformation texture.
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Toshiyasu Nishimura2009 Volume 73 Issue 2 Pages 81-87
Published: 2009
Released on J-STAGE: February 01, 2009
JOURNAL FREE ACCESSThe structure of the rust formed on silicon (Si) bearing steel was analyzed by EPMA and FIB-TEM, and the electrochemical behavior of the rust was investigated by the electrochemical impedance spectroscopy (EIS) method after the exposure test. The Si bearing steel showed high corrosion resistance compared to carbon steel (SM) and conventional weathering steel (SMA) in the exposure test. EIS measurement was taken to estimate the rust resistance (Rrust) and corrosion resistance (Rt) of the rusted steel. It was found that Rrust and Rt of Si bearing steel were much larger than those of SMA or SM. EXEFS (Extended X-ray Emission Fine Structure) and the Characteristic X-rays analysis by EPMA and TEM-EELS showed that Si existed as oxidized-state in the inner iron rust layer for Si bearing steel. FIB-TEM showed that nano-scale complex iron oxides containing Si were formed in the inner rust of the Si bearing steel. Finally, it was found that the corrosion resistance of Si bearing steel could be increased by the formation of the nano-scale complex oxides containing Si in inner rust to prevent the penetration of Cl ions.
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Takeshi Hamada, Seiji Nishi, Toshiaki Takagi, Tetsuji Miyoshi, Naoyuki ...2009 Volume 73 Issue 2 Pages 88-94
Published: 2009
Released on J-STAGE: February 01, 2009
JOURNAL FREE ACCESSIn this research, for the closed cell Al-Zn-Mg alloy foams which are fabricated by adding foaming agent to molten aluminum (direct aluminum foaming in melt), the effect of alloy contents and heat-treatment on the uniaxial static compression strength was examined.
As a result, it was possible to achieve high compression strength by an increase in hardness and using appropriate alloy contents. The plateau region becomes longer, because the cell wall of Al-Zn-Mg alloy foams tends to incur brittle fracture by alloying. However, Al-Zn-Mg alloy foam with excessive alloy contents exhibits lower compression strength.
There were few hardness improvements caused by heat treatment. Heat treatment did not cause improvement of compression strength. When the compression strength of Al foams is shown in relation to density and plateau stress, plateau stress of Al-10.0%Zn-0.3%Mg (mass%) alloy foam was about 1.7 times, and Al-10.0%Zn-1.0%Mg alloy foam was about 2 times higher than Al foam in density.
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Masashi Yoshida, Tsunetaka Sumomogi, Takao Kino, Masahiro Okumiya, Yos ...2009 Volume 73 Issue 2 Pages 95-102
Published: 2009
Released on J-STAGE: February 01, 2009
JOURNAL FREE ACCESSYield load and hardness on nanoscale have been reported using nanoindentation. However, the effect of crystallographic planes on the yield load and the hardness is not well understood. In order to investigate the effect of the crystallographic planes on the yield load and the hardness of the metals in nearly perfect crystal, nanoindentation test is performed on (111), (110) and (100) planes of aluminum single crystal with 99.9999% ultra-high purity. The yield load at a loading stage is found to be closely related to the crystallographic plane. The yielding behavior is also observed at an unloading stage under some conditions. In the loading stage, two kinds of yield processes, minor and major burst, are observed on (100) plane. The critical shear stress is estimated from the yield load in the loading curve. The estimated stress shows close agreement with the ideal strength of aluminum. The relationship between the hardness and the crystallographic plane is investigated by means of nanoindentation and micro-indentation. The hardness is strongly affected by crystallographic planes on the nano-scale, and the result is discussed from a viewpoint of the appearance of the slip line and the pile up around the indent.
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Naotsugu Yamamoto, Jinsun Liao, Shuhei Watanabe, Kazuhiro Nakata2009 Volume 73 Issue 2 Pages 103-109
Published: 2009
Released on J-STAGE: February 01, 2009
JOURNAL FREE ACCESSFriction stir weldability of a fine-grained high tensile strength AZ31 magnesium alloy to an Al-Mg alloy A5083 was evaluated by changing joining parameters, such as tool rotating speed, welding speed and insertion position of probe. A square butt dissimilar joint without any defect was obtained at the condition of welding speed 100 mm/min, tool rotating speed 500 rpm and offset 0 mm, by using a tool with shoulder diameter of 15 mm, pin diameter of 5 mm and pin length of 3.9 mm. Higher or lower welding speeds or rotating speeds led to the lack of bonding in the joint. Defects also occurred in the case that the offset was not 0 mm, i.e. the insertion position of the probe was shifted to either Mg side or Al side, even though the tool rotating speed was about 500 rpm and welding speed 100 mm/min. The maximum tensile strength of the dissimilar joints was about 115 MPa, lower than that of Al alloy base metal (about 308 MPa). Based on transmission electron microscopy, it can be suggested that the tensile strength of the dissimilar joint is mainly controlled by the thickness of IMC layer, which consists of Al12Mg17 and Al3Mg2, and mechanical interlock between magnesium and aluminum alloys. Bond strength decreases remarkably when the mechanical interlock becomes weak due to the increase of the thickness of IMC layer.
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Hideki Okada, Takayoshi Kaneuchi, Hideki Takagi, Osamu Ohashi2009 Volume 73 Issue 2 Pages 110-115
Published: 2009
Released on J-STAGE: February 01, 2009
JOURNAL FREE ACCESSBorosilicate glass is often used as a material during the anodic bonding process because the thermal expansion coefficient of glass is very close to that of silicon. However, in recent years, a new chemical composition of glass was developed as a joinable glass at a lower bonding temperature. To ensure the reliability of anodic bonding joints of the new glass to silicon, it is necessary to clarify the influence of bonding conditions and the comparison of performance of anodic bonding joints of new glass and borosilicate glasses. In this study, the effect of the bonding conditions on the tensile strength and thickness of the reaction layer and bonding charge density of anodic bonding joint of three glasses (TEMPAX, PYREX, SW-YY) to silicon was comparatively investigated. The main results obtained are as follows.
The anodic bonding joints using SW-YY was bonded at a lower bonding temperature than TEMPAX and PYREX. Under the same bonding conditions, thickness of the reaction layer on joints of SW-YY to silicon was the thickest of all. Independent of glasses, the increase in the bonding charge density resulted in stabilized tensile strength and the fracture modes changed to glass fractures. Thus, measuring the bonding charge density during the anodic bonding process helped to clarify the effects of the bonding conditions on the anodic bonding joints of glass to silicon.
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Naoki Okamoto, Yuko Fujii, Hiroaki Kurihara, Kazuo Kondo2009 Volume 73 Issue 2 Pages 116-123
Published: 2009
Released on J-STAGE: February 01, 2009
JOURNAL FREE ACCESSIn this study, we studied how the orientation indexes of the Cu foil, which is used for a substrate, and the crystal grain size of the Sn deposited film affects tin whisker formation and the structure of the intermetallic compound deposits. In particular, we considered the relationship between the crystal grain size of Sn deposited films and the amount of intermetallic compound deposits that is formed at the interface between Sn deposited films with aging and Cu foils. We used two types of Cu foils for a substrate. One is “with gelatin additive” that has granular-shaped grains which are 0.5~1 μm in size and the other is “with Cl- ion additive” that has pillar-shaped grains and their nodules. In addition to this, we used Cu (100), (110), (111) single crystals for a substrate. We used two types of Sn plating bath for plating. One is hydrofluoroboric acid bath and another is organic acid bath. The structure of tin whiskers, tin films and Cu foils were investigated by TEM and SEM. The number of the whiskers that formed on the Sn deposited film increased after aging. And the number of the whiskers that formed on the Sn films, which were made by using hydrofluoroboric acid bath, was larger than that formed on the Sn films, which were made by using organic acid bath. We also investigated the mechanisms of heat treatment for inhibiting whiskers formation. There are no whiskers on the Sn deposited film after an aging with heat treatment. From the analysis of TEM diffraction patterns that were obtained by after-aging with heat treatment sample, there were two kinds of intermetallic compound deposits at the interface between the Sn deposited film and the Cu foils.
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Takaaki Wajima, Yasuyuki Ikegami2009 Volume 73 Issue 2 Pages 124-130
Published: 2009
Released on J-STAGE: February 01, 2009
JOURNAL FREE ACCESSDuring quarrying, waste stone cake is discharged as industrial waste. In this study, we attempted to convert waste sandstone cake to zeolitic materials using alkali fusion method. By varying the experimental conditions different types of the product were obtained, e. g. zeolite-X, zeolite-P, hydroxysodalite, tobermorite, and nepheline. The siliceous minerals in the cake were transformed into soluble phases, while calcite remains in the solid after 24-agitation following alkali fusion. The optimum condition of zeolite-X synthesis in the product is that the mixed ratio of NaOH to the cake is 1.6, fusion temperature is 600°C, and heating time at 80°C is less than 12 h. The results of the sorption experiments suggest that the product can be applied in environmental field such as the removal of pollutant.
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Letters to the Editor
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Yoshihiko Hangai, Takao Utsunomiya2009 Volume 73 Issue 2 Pages 131-133
Published: 2009
Released on J-STAGE: February 01, 2009
JOURNAL FREE ACCESSPorous aluminum is expected to be a multifunctional material of automobile which can realize improvement of both collision safety and fuel efficiency, because of its high energy absorption ability with lightweight property. In this study, closed-cell porous aluminum was fabricated by friction stir processing (FSP) route using inexpensive aluminum plates. This proposed FSP route has great potential to realize high productivity, low energy consumption and low-cost manufacturing. The aim of this study is to investigate the validity of the FSP route for fabricating the closed-cell porous aluminum. Also, the effect of the alumina addition for the purpose of pore stabilization to the morphology of the pores and porosity was investigated. It was shown that porous aluminum with the porosity of 80-90% was realized by adding alumina and optimizing the temperature condition.
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