MATERIALS TRANSACTIONS
Online ISSN : 1347-5320
Print ISSN : 1345-9678
ISSN-L : 1345-9678
早期公開論文
早期公開論文の23件中1~23を表示しています
  • Takumi Kosaba, Izumi Muto, Masashi Nishimoto, Yu Sugawara
    論文ID: MT-L2022021
    発行日: 2023年
    [早期公開] 公開日: 2023/01/27
    ジャーナル フリー 早期公開

    The role of KMnO4-NaF conversion treatment in the galvanic corrosion resistance of AA5083 aluminum alloy coupled to AISI 1045 carbon steel in synthetic seawater (diluted 100 times) was investigated. The 10 min-treated AA5083 was observed to reduce the period of high current density during the early stage of coupling and decrease the number of localized corrosion damages on the AA5083. The 10 min conversion treatment significantly reduced the electrode potential of bulk Al6(Fe, Mn), and it was concluded that the Al6(Fe, Mn) particles on the conversion-treated AA5083 no longer acted as a local cathode at the electrode potential when the AA5083 was in contact with AISI 1045 carbon steel. The decrease in cathodic activity of Al6(Fe, Mn) was attributed to the removal of Fe from the surface film of Al6(Fe, Mn), addition of Mn by the conversion treatment, and thickening of the film.

  • Kong Xiang-nan, Liu Bin, Li Zhong-Hua, Zhang Peng-Fei, Shi Chao
    論文ID: MT-M2022164
    発行日: 2023年
    [早期公開] 公開日: 2023/01/27
    ジャーナル 認証あり 早期公開

    Triply Periodic Minimal Surface (TPMS) sandwich structure has the characteristics of lightweight, high specific strength, specific stiffness, vibration, and noise reduction. There is relatively little research on its sound absorption performance. TPMS sandwich structure based on selective laser melting (SLM) technology can achieve precise control of structure type, porosity, and so on, and has broad prospects in noise control applications. In this paper, the sandwich structure is designed based on tri-periodic minimal surface implicit function, and the titanium alloy sandwich structure is formed by SLM technology, and the sound absorption performance of titanium alloy TPMS sandwich structure is studied. The effects of volume fraction, panel thickness, and cell layer number on the sound absorption performance of the two TPMS structures were systematically analyzed using the transfer function method. The results show that: The GP10 sandwich structure with the volume fraction of 20%, the thickness of the panel is 1.0mm, and the number of cell layers is 3C parameter combination has better sound absorption performance and higher sound absorption bandwidth, and the sound absorption coefficient is 0.36. For Ti6Al4V sandwich sound absorption structure, it is not suitable to design too thick panels. When the volume fraction is lesser, the increase of the tortuosity factor τ improves the sound absorption performance of the two structures, and excessive volume fraction leads to a decrease of sound absorption performance. The increase of cell layers can broaden the sound absorption bandwidth of the two structures, and the sound absorption capacity increases and then decreases in the range of 150-6400Hz. The Gyroid structure mostly exhibits resonance sound absorption mechanism, while the Diamond structure exhibits resonance sound absorption mechanism combined with the viscous loss of sound wave. The work done in this paper can provide a theoretical basis for the study of the sound absorption characteristics of TPMS sandwich structure.

  • Ali Haider, Syed Husain Imran Jaffery, Aamir Nusair Khan, Najam Ulqadi ...
    論文ID: MT-M2022170
    発行日: 2023年
    [早期公開] 公開日: 2023/01/27
    ジャーナル 認証あり 早期公開

    Nickel-Chromium-Molybdenum (Ni-Cr-Mo) alloys are widely used for dental applications. This research was aimed to investigate improvement in the mechanical properties of Ni-Cr-Mo alloy through Boron and Cerium doping. These alloys were doped with boron and boron+cerium alloying elements. The mechanical testing of the samples revealed that minor addition of these alloying elements significantly improved the ultimate tensile strength and yield strength. Moreover, the melting points of the doped samples, determined by differential thermal analysis, decreased appreciably with doping elements. Furthermore, detailed wear testing was carried out to analyze the in-situ behavior of the alloys. Significant improvement in wear rate was noted for the boron and boron+cerium added alloy samples. Also biocompatibility for the three alloys in cytotoxicity test proved the suitability for the use of these alloys in dental prostheses.

  • Min Jeong Ha, Sangil Kim, Won Chul Cho, Jong-Min Kim, Byung-Seung Yim
    論文ID: MT-M2022200
    発行日: 2023年
    [早期公開] 公開日: 2023/01/27
    ジャーナル 認証あり 早期公開

    A solderable polymer composite (SPC) with a low-melting-point solder (LMPS)/high-melting-point solder (HMPS) mixed filler was formulated to solve the bonding property and reliability problems in an SPC system with an LMPS filler. In addition, the possibility of enhancing the mechanical bonding properties of SPC with LMPS/HMPS mixed fillers was investigated. Three types of SPCs (mixing ratios for LMPS and HMPS: 100:0, 50:50, and 0:100) were prepared, and two types of mechanical property investigations (i.e., ball shear and microhardness tests) were performed to measure the mechanical bonding properties of SPCs according to the LMPS/HMPS mixing ratios. The SPC with an LMPS/HMPS mixed filler exhibited enhanced mechanical bonding properties compared with the Sn-58Bi solder paste and SPC with LMPS or HMPS only due to the change in composition and subsequent microstructure transformation of the solder joint after adding HMPS.

  • Yuji Shirakami, Ken-ichi Ikeda, Seiji Miura, Koji Morita, Tohru S. Suz ...
    論文ID: MT-MD2022012
    発行日: 2023年
    [早期公開] 公開日: 2023/01/27
    ジャーナル 認証あり 早期公開

    In order to clarify the orientation dependent deformation behavior of the MAX phase ceramics, compressive deformation behavior was examined in a textured Ti3SiC2 (TSC) at a high temperature of 1200 °C. Depending on the relationship between the texture and loading directions, both the deformation behavior and microstructure were strongly influenced, and the resultant basal slip, kink formation and delamination affected the compression behavior of the textured TSC. When the stress was loaded parallel or perpendicular to the basal plane (0TSC and 90TSC), the stress-strain (S-S) curves showed higher peak stresses followed by the reduction in the flow stress. When the stress was loaded 45° to the basal plane (45TSC), the S-S curve showed strain hardening after yielding, but did not show peak stress. Although the strength was higher both in 0TSC and 90TSC than in 45TSC, both 0TSC and 90TSC showed the formation of cracks and delamination, resulting to the large drop in the flow stress. In contrast to 0TSC and 90TSC, although 45TSC did not exhibit the peak stress, it exhibited work hardening due to the kink boundary formation, irrespective of the formation of delamination. It is reasonable to conclude from the deformation behavior and the deformed microstructures that for the TSC, the kink boundary plays an important role for attaining both deformability and strength.

  • Takashi Koga, Takashi Itoh
    論文ID: MT-Y2022005
    発行日: 2023年
    [早期公開] 公開日: 2023/01/27
    ジャーナル フリー 早期公開

    Magnesium antimonide (Mg3Sb2) is a promising thermoelectric compound utilized for thermoelectric power generation. We have found out that the Mg3Sb2 compound can be made from Mg and Sb powder mixture via the combustion synthesizing reaction. In this study, we manufactured the compounds from the compacted bodies with different Mg fractions between 60.0 and 75.0 at% in an argon gas flow at 650°C for 1 hour via the combustion synthesis process. Morphology, porosity, phases and thermoelectric properties (electrical resistivity and Seebeck coefficient at room temperature to 500°C) were investigated for the manufactured samples. All samples manufactured with different Mg fractions mainly consisted of Mg3Sb2 and became foamed bodies with a porosity between 50 and 70%. The thermoelectric properties changed with the Mg fraction. The maximum power factor of 42.1 μW/mK2 at 488°C was obtained in the foamed body with the Mg fraction of 64 at%. The dimensionless figure of merit (ZT) of the sample was also estimated using the thermal conductivity, which was calculated considering its large porosity. The maximum dimensionless figure of merit (ZTmax) would be 0.13 at 488°C.

     

    This Paper was Originally Published in Japanese in J. Jpn. Soc. Powder Powder Metallurgy, 68 (2021) 399-404.

  • Keiji Shiga, Yuichiro Murakami, Naoki Omura
    論文ID: F-M2022815
    発行日: 2023年
    [早期公開] 公開日: 2023/01/20
    ジャーナル 認証あり 早期公開

    A rotating magnetic field was applied during the solidification of Al-Si-Fe alloys (Si = 5mass% or 10mass% and Fe = 0.5mass% or 1mass%) and the effect of electromagnetic stirring on the area and shape of the intermetallic compounds was studied. The phases formed during solidification of the alloys were not influenced by electromagnetic stirring. The alloys consisted of α-Al, Si and intermetallic β-Al9Fe2Si2. At coil current frequencies above 10 Hz, electromagnetic stirring induced fragmentation of dendritic α-Al, giving rise to coarsening of the β-Al9Fe2Si2 present between the fragmented α-Al grains. The application of electromagnetic stirring at coil current frequencies above 80 Hz decreased the aspect ratio of β-Al9Fe2Si2 in Al-10mass%Si-1mass%Fe, while no such decrease was identified in Al-5mass%Si-0.5mass%Fe, Al-5mass%Si-1mass%Fe or Al-10mass%Si-0.5mass%Fe. It was found that the shape of the β-Al9Fe2Si2 phase formed under forced flow of the melt depended significantly on the stirring intensity and the solid fraction of the melt at which intermetallic compounds were formed.

  • Taiki Morishige, Koki Ezumi, Masato Ikoma, Tetsuo Kikuchi, Ryuichi Yos ...
    論文ID: MT-M2022171
    発行日: 2023年
    [早期公開] 公開日: 2023/01/20
    ジャーナル 認証あり 早期公開

    Cu and Ni impurities in Mg alloys are deleterious contaminants that reduce the corrosion resistance of the alloy. Mg2Cu and Mg2Ni precipitates can cause significant anodic dissolution of the Mg matrix, owing to their potential difference. Suppression of these phases can prevent the deterioration of corrosion resistance. The neutralization of these impurities through the formation of Mg-Zn intermetallic phases has been studied, because the atomic radii of Cu and Ni are similar to that of Zn. As a result, the MgZn2 phase may precipitate during the rapid cooling that occurs during the solidification of the Mg-6 mass% Zn alloy, and introduce substitutional impurity atoms in the crystal lattice. Mg(Zn, Cu)2 and Mg(Zn, Ni)2 phases can be formed instead of Mg2Cu and Mg2Ni, in the presence of both of Zn and these impurities. The microstructures and corrosion properties of the Mg-6 mass% Zn alloy with various Cu or Ni concentrations are investigated in this work. The Cu and Ni impurities are concentrated into MgZn2 phase in the Mg-6 mass% Zn alloy without Mg2Cu or Mg2Ni formation when the concentrations of these impurities are within acceptable limits. Consequently, the corrosion rate of the Mg-6 mass% Zn alloy with 1.4 mass% Cu or 0.25 mass% Ni is almost the same as that of the alloy without Cu and/or Ni contaminations.

  • Nobuaki Takeuchi, Daisuke Ando, Junichi Koike, Yuji Sutou
    論文ID: MT-M2022219
    発行日: 2023年
    [早期公開] 公開日: 2023/01/20
    ジャーナル フリー 早期公開

    Cu fine-particle paste is a promising material to form a low-cost interconnect for flexible electronics devices. It has been reported that Cu particles can be sintered at low temperature (well below the half of the melting point) through two-step heat treatment processes of oxidation and reduction. However, the mechanism of the low temperature sintering is not clear yet. In this study, we investigated the oxidation sintering process of Cu fine particles by thermal gravimetric analysis (TGA) in the temperature range of 200°C∼300°C, X-ray diffraction (XRD), and microstructural observation. It was found from TGA that the oxidation process was initially rate-controlled by surface reaction and then by Cu diffusion at grain boundaries of Cu2O. Transmission electron microscopy observation revealed the formation of a core (Cu)-shell (Cu2O) structure during the oxidation process. The adjacent Cu2O shells were bonded to each other resulting in a cross-linked structure. The subsequent reduction process led to the formation of a porous structure by oxygen removal, but the cross-linked structure was maintained, which would make the low-temperature sintered Cu body as robust as solidified solder and sintered Ag paste.

     

    This paper was Originally Published in Japanese in J. Japan Inst. Met. Mater. 86(2022)224-231.

  • Hiroshi Okuda, Yoshiaki Maegawa, Kento Shimotsuji, Shin-ichi Inoue, Yo ...
    論文ID: MT-MD2022007
    発行日: 2023年
    [早期公開] 公開日: 2023/01/20
    ジャーナル 認証あり 早期公開

    Synchrotron radiation small-and wide-angle scattering measurements have been performed for Mg98.6-Y1-Zn0.4 alloys. In the early stage of phase transformation from supersaturated solid solutions, isotropic scattering suggesting segregation at grain boundaries was observed. It grew with temperature during heating the sample at a constant rate of 0.133 K/s. Above 600 K where introduction of stacking faults is expected, needle-like scattering became visible, which represents platelet shape segregation of cluster layers called cluster arranged layer (CAL). The layer eventually developed to form multiple layers, cluster arranged nano plates (CANaP) at higher temperatures. Microstructure change by hot rolling after the heat treatments has been examined from a viewpoint of kink-deformed microstructures.

  • Yukino Ito, Shotaro Nishitsuji, Hironari Sano, Masaru Ishikawa, Takash ...
    論文ID: MT-MD2022014
    発行日: 2023年
    [早期公開] 公開日: 2023/01/20
    ジャーナル 認証あり 早期公開

    In the field of metals, especially in magnesium alloys, a new concept has been reported that introducing a kink by applying compression or other deformation to a material with an LPSO structure, in which hard and soft layers are alternately stacked, results in higher strength. Because crystalline polymers are alternately layered with a crystalline phase, the hard layer, and an amorphous phase, the soft layer, it is expected that crystalline polymers can be made stronger if kinks can be introduced by applying compression or other deformation. In this study, the effects of a high-pressure press on the tensile properties and morphology of polypropylene (PP) were investigated. We found that a high-pressure press reduced the strain at break but increased the tensile modulus and the stress at break in the stress–strain curves. Thus, we succeeded in developing high-strength PP using a high-pressure press. In addition, it is found that the tensile properties were isotropic with no directional dependence after press. This implies that the tensile strength can be increased isotropically. Observing the morphology parallel to the press direction by small-angle X-ray scattering (SAXS) and wide-angle X-ray scattering (WAXS), it was found that the crystal lamellae spread isotropically. Conversely, observation of the morphology perpendicular to the press direction by optical microscopy (OM) and transmission electron microscopy (TEM) revealed the formation of a shear band where deformation was concentrated owing to pressure. In the shear band, it was found that lamella fragmentation occurred and a kinked structure was formed. In this region, the molecular chains may be constrained by pressure, and become a tension state, which leads to the improvement of the mechanical properties.

  • Naoto Todoroki, Toshimasa Wadayama
    論文ID: MT-MH2022002
    発行日: 2023年
    [早期公開] 公開日: 2023/01/20
    ジャーナル 認証あり 早期公開

    Alkaline water electrolysis (AWE) is a hydrogen manufacturing process that generates “green hydrogen” using electricity derived from renewable energies. Stainless steel (SS), specifically austenitic SS, has recently attracted attention as an anode material for the oxygen evolution reaction (OER) of the AWE. SS anode surfaces are generally activated by generating surface catalyst layers (SCL) for the OER through specific chemical pre-treatment, although the precise chemical compositions and microstructures of the SCL remain under debate. Furthermore, because fluctuations in the electrode potential derived from renewable energies cause remarkable elution of the constituent elements into the electrolyte, corrosion behaviors of the SS anodes should be clarified. This review introduces the recent progress of the SS anodes, particularly in the context of surface treatments to generate surface catalyst layers with high OER performances under simulated AWE conditions. In general, recent reports have clearly shown that surface-treated SS anodes are superior to the commonly employed Ni-based anodes for AWE applications.

  • Jun-Ru Liu, He Zhang, Yong Zhang, Guo-Hua Zhang, Kuo-Chih Chou
    論文ID: MT-M2022117
    発行日: 2023年
    [早期公開] 公開日: 2023/01/10
    ジャーナル 認証あり 早期公開

    In this paper, the influences of ROH (R=Li, Na, K) additions on the preparations of Tungsten (W)/Molybdenum (Mo) powders by hydrogen reduction of WO3/MoO2 in the temperature range of 800 °C to 1100 °C were studied in detail. In the absence of ROH addition, the prepared W/Mo powders basically maintained the morphology of raw oxide. However, with the assistance of ROH, the morphology and particle size of the products had been greatly changed. The grains of W and Mo were obviously coarsened, and micron-sized Mo powder and W powder with good dispersion can be prepared. In addition, the addition of ROH can promote the reduction rate of WO3 but inhibit the reduction of MoO2. Moreover, the effect of LiOH on grain growth is more significant than that of NaOH and KOH.

  • Motohiro Yuasa, Ryoichi Sato, Takao Hoshino, Daisuke Ando, Yoshikazu T ...
    論文ID: MT-MD2022018
    発行日: 2023年
    [早期公開] 公開日: 2023/01/10
    ジャーナル 認証あり 早期公開

    Mg–9 at%Y–6 at%Zn and Mg–2 at%Y–1 at%Zn alloys were processed by equal-channel-angular extrusion (ECAE) to investigate their microstructure evolution and local hardness. The area fraction of the kink bands in the Mg–9 at%Y–6 at%Zn alloys increased with increasing the number of ECAE passes, resulting in higher hardness. In contrast, the number of kink boundaries in the local region near the indentation was almost constant. The relationship between the microstructure factors of the kink bands and the local hardness is discussed in comparison with the forged alloy. In the Mg–2 at%Y–1 at%Zn alloys, the microstructural evolution of the α-Mg matrix phase and long-period stacking ordered (LPSO) phase by 1-pass ECAE and the increase in local hardness were discussed.

  • D.T. Bui, T.A. Ho, N.N. Hoang, T.L. Phan, B.W. Lee, N.T. Dang, D.T. Kh ...
    論文ID: MT-MG2022003
    発行日: 2023年
    [早期公開] 公開日: 2023/01/10
    ジャーナル 認証あり 早期公開

    We have investigated the hydrogen-annealing influence on the crystalline and electronic structures, and magnetic properties of La2/3Ca1/3MnO3 (LCMO). The results have indicated that the annealing at 700 and 900°C (labeled as LCMO-700 and LCMO-900, respectively) readily reduced single-phase LCMO, resulting in a complex phase composition of several isostructural oxygen-deficient perovskite-type phases coexisting with the Ruddlesden-Popper (La/Ca)2MnO4-type phase. While a Mn3+/Mn4+ mixed valence is present in LCMO, the hydrogen-annealed samples mainly have Mn2+ and Mn3+ ions. Under such circumstance, large changes in magnetic parameters have been recorded, such as remarkable decreases in values of the magnetization, the Curie temperature (from 251 K for the as-prepared LCMO through 240 K for LCMO-700 to ∼221 K for LCMO-900), and the magnetic-entropy change. Particularly, the crystal and electronic-structure changes also enhance the magnetic inhomogeneity, resulting in a strong development of the Griffiths phase, and cause the first-to-second-order phase transformation. These results reflect the instability of the LCMO perovskite-type manganite versus hydrogenation.

    Fig. 3 K-edge XAS spectra of the fabricated samples compared with those of manganese oxides as references. The arrow shows the absorption-edge (Abs. edge) shift of Mn. Fullsize Image
  • Ikuya Yamada, Yuta Kato, Hiroshi Nakajima, Hidekazu Ikeno, Shigeo Mori ...
    論文ID: MT-MG2022005
    発行日: 2023年
    [早期公開] 公開日: 2023/01/10
    ジャーナル 認証あり 早期公開

    A novel oxide YCu3Rh4O12 has been obtained using high-pressure and high-temperature conditions of 12 GPa and 1573 K. Electron diffraction and synchrotron X-ray powder diffraction data demonstrates that YCu3Rh4O12 crystallizes in a cubic AA3B4O12-type quadruple perovskite structure. The valence state is estimated to be Y3+Cu3+3Rh3+4O12 by X-ray absorption spectroscopy. The electric resistivity and magnetization data prove that YCu3Rh4O12 is a diamagnetic insulator, which is expected from the electron configurations of Cu3+ (3d8, low spin, S = 0) and Rh3+ (4d6, low spin, S = 0) ions. The first-principle calculation displays the insulating band structure for YCu3Rh4O12. The valence state transition from Ca2+Cu2.8+3Rh3.4+4O12 to Y3+Cu3+3Rh3+4O12 indicates that the doped electrons by the substitution of Y3+ for Ca2+ are not simply injected to Cu and/or Rh ions, realizing unusual charge redistributions consisting of the simultaneous Cu oxidation (Cu2.8+ → Cu3+) and Rh reduction (Rh3.4+ → Rh3+).

  • Jiangling Xiong, Tomoo Kinoshita, Yongbum Choi, Kazuhiro Matsugi, Yuuj ...
    論文ID: MT-M2022136
    発行日: 2022年
    [早期公開] 公開日: 2022/12/23
    ジャーナル フリー 早期公開

    In this study, polyvinyl alcohol (PVA) - polytetrafluoroethylene (PTFE) - vapor grown carbon fiber (VGCF) sheets are fabricated as a new paper-like thermal interface material (TIM), which is a potential substitute for traditional TIMs. Two types of PVA-PTFE-VGCF sheets were fabricated by using 120nm and 300nm PTFE particles. The microstructure shows that the VGCFs were arranged in random directions inside the sheet and interconnected via the aggregate of PVA. 300nm PTFE particles were well distributed within the sheet, while 120nm PTFE particles aggregated partially and formed pores nearby. The fabricated sheets have a low thickness of 31.2um and 28.2um, and lightweight properties with a density of 0.79 × 106 g·m-3 and 0.91 × 106 g·m-3, respectively. With the addition of 300nm PTFE particles, the fabricated sheet has higher thermal conductivities of 9.81 W·m-1·k-1 in the in-plane direction and 2.11 W·m-1·k-1 in the through-plane direction. In the high temperature and humidity test, the thermal conductivities of the fabricated sheet were increased due to the rearrangement of PVA and PTFE particles.

  • Tomoyuki Yamamoto, Masato Yoshiya, Hoang Nam Nhat
    論文ID: MT-M2022181
    発行日: 2022年
    [早期公開] 公開日: 2022/12/23
    ジャーナル フリー 早期公開

    Microstructure of the materials is essential to design new functional materials, especially from atomic scale to micron order structures. Many attempts have been carried out to give nanostructures and such structures have been analyzed using cutting-edge methods both theoretically and experimentally. In this report, recent trends in research on functional materials related to the micro-structures in nano-meter scale are reviewed by mainly introducing the contents of the special issue published in Materials Transactions, vol. 61, No. 8, in which following 6 categories of the topics are included; computational materials science, magnetic materials, advanced functional oxides, carbon and organic materials, and optical materials.

  • Takayuki Shiraiwa, Naoya Hamada, Fabien Briffod, Manabu Enoki, Koji Ha ...
    論文ID: MT-MD2022005
    発行日: 2022年
    [早期公開] 公開日: 2022/12/23
    ジャーナル 認証あり 早期公開

    In this study, kink band formation behavior of an Al/Al2Cu eutectic alloy with a mille-feuille structure consisting of a hard Al2Cu phase and a soft Al phase was investigated under compression at room temperature. In-situ surface observations during compression tests revealed multiple micro kink-bands occurring simultaneously within a single lamellar colony. To analyze the formation behavior of micro kink-bands, the spatial distribution of the lamellar structure over a wide area of the specimen was quantitatively evaluated by performing image analysis using the Radon transform. The results showed that the micro kink-bands generated synchronously in one direction and rotated at a uniform angle. Such uniform and fine kink-bands are expected to contribute to the improvement of strength. To unravel the linkage between microstructure, kink band formation, and accompanying kink strengthening, an attempt was made to construct a model that predicts the spacing between micro kink-bands and critical stress for kinking from the features of the lamellar structure. The validity of the model to predict the spacing between kink bands was demonstrated by the experimental results.

  • Yuji Shirakami, Ken-ichi Ikeda, Seiji Miura, Koji Morita, Tohru S. Suz ...
    論文ID: MT-Y2022006
    発行日: 2022年
    [早期公開] 公開日: 2022/12/23
    ジャーナル フリー 早期公開

    In order to clarify plastic deformation behavior and mechanism of fracture energy absorption of Ti3SiC2, Vickers indentation tests were conducted for Ti3SiC2 sintered bodies with various textured orientations. Textured Ti3SiC2 sintered bodies were fabricated by slip casting in a strong magnetic field and spark plasma sintering (SPS), and their orientation distribution were analyzed by SEM/EBSD. It was found that for the textured Ti3SiC2, the plastic deformation behavior around Vickers indents such as an indent shape and a grain pile-up were strongly affected by basal slip and kink deformation. Furthermore, the fracture energy absorption mechanism around the indents also depended on the texture orientations. From our results, it is concluded that the most effective factor for suppressing the crack propagation was the grain pile-up, and the second one was crack deflections.

     

    This Paper was Originally Published in Japanese in J. Jpn. Soc. Powder Powder Metallurgy 67 (2020) 607-614

  • Yu-ki Taninouchi, Toru H. Okabe
    論文ID: MT-M2022150
    発行日: 2022年
    [早期公開] 公開日: 2022/12/16
    ジャーナル フリー 早期公開

    Spent automobile catalysts are the most important secondary resource for platinum group metals (PGMs), and their recycling is essential not only to ensure a steady supply of PGMs but also to preserve the natural environment. However, several factors limit the efficiency of PGM recovery in current recycling processes. Specifically, PGMs represent a small proportion of the entire catalyst and are difficult to dissolve in aqueous solutions for subsequent separation. In recent decades, multiple technologies have been developed to make the recycling of PGMs more efficient and environmentally-friendly. Herein, we introduce the typical industrial processes for recovering PGMs from spent catalysts, along with established and emerging trends in the technological development of PGM recycling. Furthermore, we review novel recycling techniques for converting PGMs in spent catalysts into more soluble states and/or physically concentrating PGMs from spent catalysts.

     

    This Paper was Originally Published in Japanese in J. Japan Inst. Met. Mater. 85 (2021) 294–304.

  • Shigeru Kimura, Kazushi Sumitani, Kentaro Kajiwara
    論文ID: MT-MD2022001
    発行日: 2022年
    [早期公開] 公開日: 2022/12/16
    ジャーナル 認証あり 早期公開

    We modified a previously developed compact compression-test stage for synchrotron radiation micro-Laue diffraction mapping to investigate the deformation of the long-period stacking-ordered phase of a magnesium polycrystal. This modification made it possible to obtain grain-boundary images from two orthogonal directions, realizing to obtain depth information about the position of kink formation. Also, to compare bulk and surface images, a long-focus optical microscope, which can take photographs of the surface morphology of the sample, was introduced into the apparatus.

  • Masaaki Nakai, Mitsuo Niinomi, Takahiro Oneda
    論文ID: L-M2010824
    発行日: 2011/02/01
    [早期公開] 公開日: 2011/01/13
    ジャーナル フリー 早期公開
    Announcement Concerning Article Retraction
    The following paper has been withdrawn from the database of Mater. Trans., because a description based on a misinterpretation of the experimental results was found by the authors in advance of publication after acceptance.
    Mater.Trans. 52(2011) Advance view.
    Improvement in Fatigue Strength of Biomedical β-Type Ti-Nb-Ta-Zr Alloy while Maintaining Low Young’s Modulus through Optimizing ω-Phase Precipitation
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