MATERIALS TRANSACTIONS
Online ISSN : 1347-5320
Print ISSN : 1345-9678
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Volume 59 , Issue 1
Showing 1-22 articles out of 22 articles from the selected issue
  • Mitsuo Niinomi
    Type: Overview
    2018 Volume 59 Issue 1 Pages 1-13
    Published: January 01, 2018
    Released: December 25, 2017
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    The progress of metallic structural biomaterials, mainly titanium alloys, for implants with mainly focusing on mechanical biocompatibility is described. Mechanical biocompatibility includes not only Young's modulus but also broad sense of mechanical biocompatibilities such as balance of strength and elongation, fatigue endurance (fatigue strength) and fracture toughness. Specially, the present paper focuses on developments of high fatigue strength of (α + β)-type titanium alloys composed of non-toxic elements, low Young's modulus β-type titanium alloys composed of non-toxic and allergy-free elements, Young's modulus self-adjustable β-type titanium alloys composed of non-toxic elements, Ni-free β-type titanium alloys for biomedical applications. Ni-free stainless steels and Co-Cr-Mo alloys, cell viability of pure metals, and some very recent research and development topics are also briefly introduced in the present paper.

     

    This Paper was Originally Published in Japanese in Materia Japan 56 (2017) 205–210. In order to introduce more recent topics on metallic biomaterials, sections 4, 5, 9, and 10 were newly added. According to adding new sections, Tables 2 and 3, and Figs. 1–6, 8, 9, 13, and 19–25 were newly added. The Refs. 1), 4–12), 14), 28–39), 51), and 57–72) were also newly added. Following these changing, the numbers of tables, figures, and references were newly changed.

  • Yuji Okuyama, Takuya Ymaguchi, Naoki Matsunaga, Go Sakai
    Subject area: Special Issue on Recent Advances in Solid State Ionics and Its Applications
    2018 Volume 59 Issue 1 Pages 14-18
    Published: January 01, 2018
    Released: December 25, 2017
    [Advance publication] Released: July 07, 2017
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    In order to clarify the effect of the dopant concentration and phase transition on the proton conduction and proton concentration, the electrical conductivity and proton concentration were determined for La1−xBaxYb0.5In0.5O3−δ (x = 0.1. 0.3. 0.5, 0.7). The phase transition from the orthorhombic system to the cubic system was over x = 0.3. The proton/deuteron isotope effect on the conductivity was observed for all samples at 673 K. The proton concentration was independent of the barium content above 673 K. The proton concentration increased with the barium content below 673 K, but the concentration ratio of the proton to dopant decreased following an increase in the barium concentration. It was determined that the dopant concentration and phase transition do not have an influence on the conduction and incorporation of protons into the La1−xBaxYb0.5In0.5O3−δ.

  • Young-Sung Lee, Yasuhiro Takamura, Yi-Hsuan Lee, Kwati Leonard, Hirosh ...
    Subject area: Special Issue on Recent Advances in Solid State Ionics and Its Applications
    2018 Volume 59 Issue 1 Pages 19-22
    Published: January 01, 2018
    Released: December 25, 2017
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    The influences of In- and Y-doping on the electrical conduction properties of barium zirconate were investigated. The electrical conductivity measured on of BaZr1−xyInxYyO3−δ (x = 0, 0.1, 0.2 and y = 0, 0.1, 0.2) could be understood that yttrium doping causes high bulk conductivity and indium doping leads to lowering activation energy of the grain boundary. Co-doping of yttrium and indium promotes the enhancement effect of improving the bulk conductivity and lowering of activation energy, and it is thus expected that the co-doping with yttrium and indium can work for controlling the bulk and grain boundary conduction specifically in the materials.

  • Hideaki Ito, Kazuhisa Sato, Atsushi Unemoto, Shin-ichi Hashimoto, Koji ...
    Subject area: Special Issue on Recent Advances in Solid State Ionics and Its Applications
    2018 Volume 59 Issue 1 Pages 23-26
    Published: January 01, 2018
    Released: December 25, 2017
    [Advance publication] Released: November 06, 2017
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    Nano-indentation tests with a Vickers-type diamond tip were carried out on the {100} surface of a single crystal of 10 mol% yttria-stabilized zirconia (10YSZ), (Y2O3)0.1(ZrO2)0.9. By changing the contact angle of the indentation tip against the single crystal sample, the fracture toughness of 10YSZ was investigated as a function of the crystal orientation from <100> to <110> on the {100} surface. It was empirically shown that the fracture toughness of 10YSZ is anisotropic. The fracture toughness of 10YSZ was lowest in the direction of <100> among investigated orientations. This result suggests that mechanical failures in 10YSZ may occur preferentially along the direction of <100>.

  • Fumitada Iguchi, Sarana Akrasevee, Yutaro Miyoshi
    Subject area: Special Issue on Recent Advances in Solid State Ionics and Its Applications
    2018 Volume 59 Issue 1 Pages 27-32
    Published: January 01, 2018
    Released: December 25, 2017
    [Advance publication] Released: October 27, 2017
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    The residual strains in the composites of nickel oxide (NiO) and yttria-stabilized zirconia (YSZ) and in the cermets of reduced nickel (Ni) and YSZ, which were used as anodes for solid oxide fuel cells (SOFCs), were measured using X-ray diffraction. The influence of Ni reduction on the residual strain was evaluated. Tensile and compressive residual strains caused by thermal strain were observed in NiO and YSZ phases, respectively. They clearly depended on the volume fraction of NiO and YSZ, and changed proportionally. The YSZ phase in the Ni-YSZ cermets also showed a similar dependence on the volume fraction of NiO. The compressive strain increased as the NiO increased; however, a local maximum was observed for NiO 50 vol%, beyond which it decreased with increasing amount of NiO. Compressive strain in the YSZ phase in the Ni-YSZ with NiO of 60 vol%, which is a common volume fraction of SOFC anodes, was only 30% of that in the NiO-YSZ. Plastic deformation of the Ni phase near the interfaces, and relaxation of the compressive strain in the YSZ phase were responsible for this phenomenon. This revealed the difference in the residual strain in the YSZ phase after reduction.

    Fig. 8 Schematic illustration of Ni plastic deformation near the interfaces between Ni and YSZ phases. Fullsize Image
  • Akihiro Ishii, Itaru Oikawa, Masaaki Imura, Toshimasa Kanai, Hitoshi T ...
    Subject area: Special Issue on Recent Advances in Solid State Ionics and Its Applications
    2018 Volume 59 Issue 1 Pages 33-38
    Published: January 01, 2018
    Released: December 25, 2017
    [Advance publication] Released: December 08, 2017
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    The preparation of a transparent and smooth rutile-type TiO2 thin film without the use of the crystallographical effect of the substrate is a challenge for the advanced utilization of TiO2 in the fields of optics and solid state ionics. Because acceptor doping leads to the formation of oxygen vacancies, this method has promise as a new approach to promote the formation of rutile-type TiO2. Mg2+-doped TiO2 thin films were prepared by pulsed laser deposition, and the effects of Mg2+ doping on the phases present, the microstructure, the optical properties, and the surface roughness of the films were investigated. Particular attention was paid to the Mg2+ distribution in the prepared films. The formation of the rutile phase was promoted by 2.7 mol% and 5.5 mol%Mg2+ doping. The negligible segregation of Mg2+ and absence of change in the extinction coefficient by Mg2+ doping indicate that Mg2+ worked as the acceptor and induced oxygen vacancies for charge compensation, which promoted the formation of the rutile phase. Given that Mg2+ is a doubly charged acceptor, Mg2+ doping is a more effective method for promoting the formation of the rutile phase than trivalence doping. Besides the excellent optical properties (n ≈ 3.03 and k < 0.02 at λ = 400 nm) of the 2.7%Mg2+-doped rutile-type TiO2 thin film deposited at 350℃, the films were smooth, with a roughness index of only approximately 0.8 nm. This method of preparing smooth rutile-type TiO2 thin films has potential for the further development of TiO2-based resistive memory devices.

  • Chunyang Shi, Jicheng He
    2018 Volume 59 Issue 1 Pages 39-46
    Published: January 01, 2018
    Released: December 25, 2017
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    Improving the efficiency of electromagnetic steel teeming systems have included methods to accelerate the heating process, wherein the most convenient and effective is to adjust the position of the blocking layer. Herein, numerical simulation is used to initially optimize the physical parameters (material type, shape and particle size) of the Fe-C alloy to identify the most effective induction heating area for the blocking layer. Next, 110 Mg of steel ladle from a steel mill is used as the experiment carrier to verify the numerical simulation results and the following conclusions are made: the position of the blocking layer is related to all Fe-C alloy parameters of material type, shape and particle size, whose respective optimal values are 10# steel material, cylindrical shape, and 2.0 mm particle size for 110 Mg steel ladle electromagnetic steel teeming system; and 10# steel material, cylindrical shape, and 2.5 mm particle size for a 260 Mg ladle. Furthermore, through comparative analysis of the numerical simulation models of the 110 and 260 Mg steel ladles it is found that long molten steel channels require a large amount of Fe-C alloy filling, and that the blocking layer tends to move upward and become thinner. Additionally, it is verified using a self-designed experimental device that the thickness of the blocking layer increases with higher temperatures and longer standing times of the molten steel. This work provides reference for the improvement of the efficiency of electromagnetic steel teeming systems.

    Fig. 1 Schematic illustration of the blocking layer experiment. Fullsize Image
  • Terigele Xi, Takahiro Sato, Ryoma Suzuki, Hisanori Tanimoto
    2018 Volume 59 Issue 1 Pages 47-52
    Published: January 01, 2018
    Released: December 25, 2017
    [Advance publication] Released: November 27, 2017
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    Characteristic property changes were observed for high density and high purity nanocrystalline (n-) Au prepared by the gas deposition method. The increase in internal friction with a modulus defect started at ~180 K and became steep above 200 K. An increase in endothermic heat flow began at ~170 K. The electrical resistivity showed a deviation from a linear increase with the temperature at ~130 K. All the characteristic changes were reproduced by the repetition of the thermal cycle below 300 K, but the amounts diminished after the grain growth. These characteristic temperature changes indicate a glass-transition-like behavior of the grain boundaries in n-Au.

  • Peng Luo
    2018 Volume 59 Issue 1 Pages 53-60
    Published: January 01, 2018
    Released: December 25, 2017
    [Advance publication] Released: November 17, 2017
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    Pure titanium chips were consolidated by a solid-state recycling process in the form of multi-pass equal channel angular pressing (ECAP) with the number of passes up to 16 passes. Electron backscatter diffraction reveals that low angle grain boundaries (with misorientation <15°) were substantially presented within coarse grains which were enclosed by high angle grain boundaries (≥15°). Adequate yield strength (above 300 MPa) was achieved. It was contributed not only by high angle grain boundary, but also low angle grain boundary. At the same time, high ductility (with a uniform elongation up to 27%) is derived from the strain hardening owing to the existence of low angle grain boundaries and coarse grains. The mechanical properties of the recycled titanium are good enough to compare with those of the reference ingot subjected to the multi-pass ECAP.

  • Yasuhiro Yamabe, Junko Umeda, Hisashi Imai, Katsuyoshi Kondoh
    2018 Volume 59 Issue 1 Pages 61-65
    Published: January 01, 2018
    Released: December 25, 2017
    [Advance publication] Released: November 10, 2017
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    Mechanical and tribological properties of powder metallurgy (PM) α-titanium (Ti) materials with dissolved nitrogen atoms were evaluated in this study. Pin-on-disk wear test was carried out under dry condition, where a SKD61 disk specimen was used as a counter material. The elemental mixture of Ti and TiN powders was compacted and sintered in vacuum, and then extruded to the full-dense PM Ti rods. During sintering in vacuum, TiN particles were completely decomposed via reaction with Ti powder. Nitrogen atoms originated from TiN were dissolved into α-Ti matrix, and resulted in the remarkable improvement of micro-hardness and tensile strength. The additional heat treatment on the sintered Ti materials was effective to improve further elongation in tensile test because the localization of dissolved nitrogen atoms was decreased. The friction coefficient of nitrogen dissolved Ti material was extremely lower and more stable compared to pure Ti specimen employed as a reference material. The wear loss of the former was significantly smaller than that of the latter specimen. This is because of superior wear resistance of α-Ti material with nitrogen solid-solution due to a large increment of micro-hardness of Ti matrix.

     

    This Paper was Originally Published in Japanese in J. Jpn. Soc. Powder Powder Metallurgy 64 (2017) 275–280.

  • Yosuke Tamura, Hiroshi Soda, Alexander McLean
    2018 Volume 59 Issue 1 Pages 66-71
    Published: January 01, 2018
    Released: December 25, 2017
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    The hardness and tensile properties of Mg-La-Zr alloys with various lanthanum contents were investigated, and the microstructures of the alloys were examined. The microstructure was composed of fine globular primary α-Mg grains and eutectic areas. The values of yield stress and modulus of the eutectic were, respectively, about 3 times and 1.7 times higher than those of the primary α-Mg. The increase in the yield stress of the alloys with less than 1.2%La is due to a rapid increase in coverage of the α-Mg grain boundary by the eutectic. As the increment in the grain boundary coverage decreases with lanthanum content, the composite strengthening (composite materials effect) starts to play a more significant role in increasing yield stress. As the grain boundary coverage reaches a plateau at about 2%La, further increase in the yield stress is mainly due to the composite strengthening, the effect of which is dependent on the volume fraction of eutectic. During tensile-testing at 150℃, the alloys with higher lanthanum content exhibited dual yield points, the first from yielding of the primary α-Mg, followed by the higher-yield point associated with the eutectic. This suggests that composite strengthening is in effect.

     

    This Paper was Originally Published in Japanese in J. JILM 66 (2016) 647–651.

  • G.G.N.N. Amarakoon, Satoru Kawasaki
    2018 Volume 59 Issue 1 Pages 72-81
    Published: January 01, 2018
    Released: December 25, 2017
    [Advance publication] Released: December 01, 2017
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    Biomineralization is an environmentally friendly technology for improving soil-engineering properties. One of the most common biomineralization processes is microbially induced calcite precipitation (MICP). In this study, sand solidification tests were conducted using Pararhodobacter sp., which is a local ureolytic bacteria obtained from the sand near beach rock in Okinawa, Japan. The goal of this study was to solidify a specimen having an estimated unconfined compressive strength (UCS) of more than several MPa to improve soil properties and investigate the influence of various factors on the engineering properties of treated soil catalyzed by ureolytic bacteria (curing temperature, injection interval of cementation solution, Ca2+ concentration, curing time, bacterial population, re-injection of bacteria and particle size of sand). Model test specimens were cemented up to an estimated UCS of 10 MPa after 14 days under the following conditions: a curing temperature of 30℃, an injection interval of 1 day, and a Ca2+ concentrations in cementation solution of 0.5 M. Multiple regression analysis showed that the relevant conditions for estimating UCS were test period, D (days), and Ca2+ concentration of the cementation solution, Cca (M). The formula for predicting the estimated UCS (qeu (MPa)) was qeu = 13.99 Cca + 0.37 D − 0.09. Overall, the results of this study will contribute to the application of a new technique to sand improvement and bio-stimulation.

  • Shigehiro Kawamori, Yoshihumi Kawashima, Hiroshi Fujiwara, Kiyoshi Kur ...
    2018 Volume 59 Issue 1 Pages 82-87
    Published: January 01, 2018
    Released: December 25, 2017
    [Advance publication] Released: November 27, 2017
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    To enhance the mechanical properties of Mg alloys, we have fabricated Mg/TiC composites by reinforcing the Mg matrix composed of nanosize crystal grains with 20 vol% TiC nanoparticles. The Mg/TiC nanocomposites were fabricated by mechanical milling (MM) and spark plasma sintering (SPS). The TiC nanoparticles were produced by mechanical alloying (MA). The effects of the applied pressure and holding time during SPS on the mechanical properties of this nanocomposite were investigated. Microstructure observations and elemental analysis show that the TiC particles (TiCp) in the nanocomposites have an ultrafine microstructure with an average particle size of approximately 9 nm and they aggregate within the Mg matrix. The Vickers hardness of the nanocomposites increases to 150 HV when the SPS applied pressure and holding time are increased. However, the increase in the hardness is accompanied by a decrease in the bending strength. The main factors for the improvement of the mechanical properties of the 20 vol% TiCp/Mg nanocomposite are considered to be the density and compressive residual stress.

  • Yu-ki Taninouchi, Toru H. Okabe
    2018 Volume 59 Issue 1 Pages 88-97
    Published: January 01, 2018
    Released: December 25, 2017
    [Advance publication] Released: November 17, 2017
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    An effective alloying treatment for Pt using FeClx (x = 2, 3) vapor was demonstrated towards developing a novel recovery process for platinum group metals (PGMs) in catalyst scrap. Suitable reaction conditions were discussed from the perspective of thermodynamics, and its validity was confirmed experimentally. When pure Pt samples were reacted with FeCl2 vapor at 1200 K under the coexistence of metallic Fe, an Fe-Pt alloy showing ferromagnetism was easily formed, even though the samples were not in physical contact with the metallic Fe. On the basis of thermodynamic considerations, alloying of Pt mainly proceeds via the disproportionation of FeCl2 vapor, with the gaseous phase containing FeClx acting as the medium to transport Fe from the metallic Fe to the Pt samples. When the alloyed sample was kept under FeCl3 vapor at 1200 K, Fe was removed and ferromagnetism was lost. Therefore, it is concluded that FeCl2 vapor treatment under the coexistence of Fe is a feasible and useful technique for alloying Pt and forming a ferromagnetic Fe-Pt alloy. The results obtained in this study indicate that treatment with FeCl2 vapor followed by magnetic separation has potential as an effective technique for concentrating PGMs directly from catalyst scrap.

    Fig. 1 Schematic illustration of alloying treatment using FeClx (x = 2, 3) vapor. After the alloying treatment, PGMs can be effectively concentrated by magnetic separation. Fullsize Image
  • Yong Hou, Guo-Hua Zhang, Kuo-Chih Chou
    2018 Volume 59 Issue 1 Pages 98-103
    Published: January 01, 2018
    Released: December 25, 2017
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    In the present study, the solid state reaction between silicon carbide (SiC) and ferric oxide (Fe2O3) under different molar ratios and different reaction temperatures have been investigated. It was found that Fe and SiO2 were generated by the reaction between SiC and Fe2O3 with molar ratio of 1.2:1 at 1473 K (1200℃) for 30 minutes. The results of this study may provide a basis for the better use of SiC containing wastes.

  • Yosuke Tamura, Soichiro Suematu
    2018 Volume 59 Issue 1 Pages 104-109
    Published: January 01, 2018
    Released: December 25, 2017
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    In this study, a simple boron addition process for producing 6063 aluminum alloy containing 0.03% B was investigated. KBF4 (98.0 mass%) and commercial-purity aluminum powder (>99.7 mass%, particle size: 30 μm) were weighed, mixed, wrapped in aluminum foil, and placed in a phosphorizer. The phosphorizer was then immersed in a molten 6063 aluminum alloy at a temperature of 720, 760, 810, or 860℃. The boron recovery rate depends on the amount of aluminum powder in the mixture and the melt temperature. Optimizing these factors gives a 90% boron recovery rate. Excess aluminum powder in the mixture leads to an increase in the specific surface area of the KBF4 particles and promotes the reaction, 2KBF4 + 3Al → AlB2 + 2KAlF4. The AlB2 contained within the KAlF4 migrates into the melt as the KAlF4 evaporates. Therefore, a mixed powder of KBF4 and aluminum can be an effective means of adding boron to 6063 aluminum alloy if the amount of aluminum and the temperature are carefully controlled. For the present experimental conditions, it was difficult to find AlB2 in the alloy by EPMA, because only a small amount of boron was added. Boron seems to form a solid solution with aluminum without forming coarse intermetallic compounds.

     

    This Paper was Originally Published in Japanese in J. JILM 67 (2017) 222–227.

  • Ram Song, Yohei Harada, Shinji Kumai
    2018 Volume 59 Issue 1 Pages 110-116
    Published: January 01, 2018
    Released: December 25, 2017
    [Advance publication] Released: November 17, 2017
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    Binary Al-Mn, ternary Al-Mn-Fe and Al-Mn-Si alloys were prepared by different cooling rates during solidification using direct chill-casting and high-speed twin-roll casting. Mn concentration and solute distribution in Al matrix were examined. The Mn concentration in solid solution was considered almost equivalent in as-cast condition. In contrast, much amount of decomposition of supersaturated Mn in solid solution occurred in high-speed twin-roll cast alloys after homogenization. In high-speed twin-roll cast strips, fine distribution of constituent particles in Al-Mn-Fe alloy and homogeneous solute distribution in Al matrix in Al-Mn-Si alloy were obtained due to the high cooling rate of the high-speed twin-roll casting. After homogenization treatment, coarsening and spheroidization of the constituent particles were mainly observed in Al-Mn-Fe alloy, while formation of fine dispersoids was predominantly observed in Al-Mn-Si alloy. Such differences in microstructure resulted from the decomposition behavior of supersaturated Mn in solid solution.

  • Ryoichi Soba, Yukiko Tanabe, Takayuki Yonezawa, Junko Umeda, Katsuyosh ...
    2018 Volume 59 Issue 1 Pages 117-122
    Published: January 01, 2018
    Released: December 25, 2017
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    In this study, microstructural and mechanical properties of the extruded and heat-treated TiNi alloys by sintering the mixture of TiNi pre-mixed powder with titanium dioxide (TiO2) particles were investigated. Pure Ti and pure Ni powder with TiO2 particles were mixed and consolidated by spark plasma sintering (SPS). SPSed TiNi alloy compacts were extruded and heat-treated subsequently. SPSed TiNi alloy compacts had TiNi matrix and Ti4Ni2O phase. Ti4Ni2O phase was formed during SPS by reaction between TiNi matrix and oxygen atoms originated from additive TiO2 particles. Consequently, the heat-treated Ti-50.5 at%Ni alloy using pre-mixed powder with 1.0 vol% TiO2 particles showed a high plateau stress of 630 MPa and a good shape recovery of 79.7% in 8% strain applied. The heat-treated TiNi alloy with 1.0 vol% TiO2 particles revealed the high strength and good shape memory properties. The high strengthening mechanism of the TiNi alloy using pre-mixed powder with TiO2 particles was mainly due to a decrease martensitic transformation temperature by an increase solute Ni content in TiNi matrix after reaction between TiNi and TiO2.

     

    This Paper was Originally Published in Japanese in J. Jpn. Soc. Powder Powder Metallurgy 64 (2017) 589–594.

  • Isao Matsui, Naoki Omura
    2018 Volume 59 Issue 1 Pages 123-128
    Published: January 01, 2018
    Released: December 25, 2017
    [Advance publication] Released: November 27, 2017
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    The effects of current types on the microstructure and tensile properties of electrodeposited bulk nanocrystalline Ni–W alloys were studied. We electrodeposited bulk Ni–W alloys using direct current, pulsed current, and pulsed-reverse current. We measured the W content of the resulting samples to be in the range of 0.8–2.2 at%. An increase in the peak current density or the use of a reverse current reduced the W content. The reduction of W content increased the grain size from 26 to 40 nm. The hardness and yield strength increased as the grain size decreased. However, tensile elongation showed no dependence on grain size or W content. Most alloys exhibited a similar uniform elongation of approximately 5%, while the local elongation varied from 0.1% to 6.9%. The application of a pulsed current increased the peak current density and reduced the tensile elongation. The use of a reverse current stripped the surface of deposits formed during electrodeposition, resulting in higher tensile elongation at the same peak current densities. The results of this study indicate the effectiveness of a reverse current in electrodeposition for adjusting solute content and reducing processing defects.

  • Yoshitake Nishi, Junya Ohkawa, Michael C. Faudree, Masae Kanda, Kaori ...
    2018 Volume 59 Issue 1 Pages 129-135
    Published: January 01, 2018
    Released: December 25, 2017
    [Advance publication] Released: November 27, 2017
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    A unimorph 2-layer (PU:LaNi5/Ti) actuator consisting of a driving composite sheet with large expansion of polyurethane (PU) dispersed with powder mixture of hydrogen storage alloy of 35 vol%-LaNi5 and Pd-Al2O3 catalyst prepared by solution cast method, and a 5 μm thick Ti sheet exhibited reversible and giant rapid bending motion when subjected to hydrogen atmosphere. Reversible motion was achieved below 0.20 MPa-H2 pressure where maximum strain (εmax) values on vertical and horizontal directions were more than 2400 and 1800 ppm, respectively about 1.6 times larger than that reported (1520 and 1120 ppm) for the same actuator PU:LaNi5/Cu with 10 μm thick copper (Cu) sheet. Moreover, the maximum responsiveness (dε/dt)max by hydrogenation of cyclic motion of the PU:LaNi5/Ti was higher than that of the PU:LaNi5/Cu. The increased (dε/dt)max values mostly corresponded to decreasing elastic load resistivity (dF/dε). These were due to Ti having higher stiffness and strength than Cu allowing thinner 5 μm sheet. Caution for safety is advised since values presented herein may be different when applying the actuator to zero gravity environments.

  • Sojiro Uemura, Takateru Yamamuro, Joung Wook Kim, Yasuhiro Morizono, S ...
    2018 Volume 59 Issue 1 Pages 136-145
    Published: January 01, 2018
    Released: December 25, 2017
    [Advance publication] Released: December 01, 2017
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    Mo-Si-B-TiC alloys are expected to be a candidate for an ultrahigh-temperature material beyond Ni-base superalloys. This work quantitatively investigated the microstructure of a Mo-Si-B-TiC alloy with the composition of Mo-5Si-10B-10TiC (65Mo alloy) (at%) produced via arc-melting and tilt-casting techniques. The alloy was composed of four constituent phases: Mo solid solution (Moss), Mo5SiB2(T2), (Ti, Mo)Cx, (Mo, Ti)2C, and their eutectic (or peritecteutectic) phases. The compositions of the constituent phases were determined by electron beam micro analyzer (EPMA). Scanning electron microscopy – backscattered electron diffraction (SEM-EBSD) measurements revealed that T2 and (Ti, Mo)Cx phases have orientation relationships with Mo phase: {110}Mo//(001)T2, <111>Mo//<001>T2 and {110}Mo//{111}(Ti,Mo)Cx, <111>Mo//<001>(Ti,Mo)Cx. Furthermore, the three-dimensional SEM observation with the combination of the focused ion beam (FIB) serial sectioning technique demonstrated that the T2 phase had a thin plate shape with the orientation of (001) as plate surfaces and of {100} as side ones.

    Fig. 10 Three-dimensional phase images reconstructed from serially-sectioned images: (a) (Ti, Mo)Cx and T2 (Mo5SiB2), (b) (Ti, Mo)Cx, (c) T2. Fullsize Image
  • Yasunari Matsuno, Eri Okonogi, Akihiro Yoshimura, Mari Sato, Chikara S ...
    2018 Volume 59 Issue 1 Pages 146-149
    Published: January 01, 2018
    Released: December 25, 2017
    [Advance publication] Released: November 27, 2017
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    In this report, we present a novel method to produce micrometer-sized gold particles by dissolving and recovering gold from a dimethyl sulfoxide/hydrochloric acid (DMSO/HCl) solution containing copper (II) chloride (CuCl2) and sodium chloride (NaCl). It was reported that spherical or confeito-like particles can be formed depending on the concentrations of dissolved gold and Cl ions in the solution. In this paper, in-situ observation of gold particle formation in the solution phase was conducted using atmospheric scanning electron microscopy (ASEM). An electron-permeable window made of a pressure-resistant silicon nitride (Si3N4) film (100 nm-thick), was set at the bottom of the open ASEM sample dish, which facilitated the projection of electron beams from underneath the sample. This structure of ASEM enabled us to observe dynamic phenomena in liquid or gas phase under atmospheric pressure in real time. It was found during the in-situ observation that all of the particles formed were confeito-like in shape, which was different from the expected particle morphology.

     

    This Paper was Originally Published in Japanese in J. Japan Inst. Met. Mater. 81 (2017) 192–195.

    Fig. 7 ASEM images of gold particle formation in the liquid after 46 minutes at a magnification of ×30,000, Experiment 2. Fullsize Image
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