MATERIALS TRANSACTIONS
Online ISSN : 1347-5320
Print ISSN : 1345-9678
ISSN-L : 1345-9678
最新号
選択された号の論文の13件中1~13を表示しています
Regular Article
Materials Physics
  • Tomoshi Takahashi, Yoritoshi Minamino, Toshiaki Manaka, Mitsuharu Toda ...
    原稿種別: Regular Article
    2022 年 63 巻 12 号 p. 1597-1606
    発行日: 2022/12/01
    公開日: 2022/11/25
    ジャーナル フリー HTML

    Interdiffusion in Ti-rich β solid solutions in Ti–Al–Zr alloys was investigated at 1473 K. In the β Ti–Al–Zr alloys, the main interdiffusion coefficients (i.e., and , respectively) and the cross interdiffusion coefficients, (i.e., and , respectively) have positive values, as well as a slight concentration dependence. The values of are larger than those of . In Ti–Al–X (= V, Cr, Fe, Co, Zr) alloys, the values of the main coefficients are at 1473 K. Repulsive interactions occur between Al and X (= V, Cr, Fe, Co, Zr) atoms in the Ti–Al–X alloys, because the ratio values of the cross coefficients to the main ones are positive in sign. On the other hand, the interactions between Ti (solvent) and X (= V, Cr, Fe, Co, Zr) (or Al) atoms are attractive in the present alloys because the ratio of the converted interdiffusion coefficients is negative values.

     

    This Paper was Originally Published in Japanese in J. JILM 71 (2021) 539–548.

Mechanics of Materials
  • Ryoichi Oikawa, Kazuyuki Shimizu, Yasuhiro Kamada, Hiroyuki Toda, Hiro ...
    原稿種別: Regular Article
    2022 年 63 巻 12 号 p. 1607-1616
    発行日: 2022/12/01
    公開日: 2022/11/25
    [早期公開] 公開日: 2022/10/17
    ジャーナル フリー HTML

    In recent years, it has been reported that intermetallic compound particles can suppress hydrogen embrittlement by hydrogen trapping. Some intermetallic particles in aluminum alloys, such as Al7Cu2Fe, have internal hydrogen trap sites; it is proposed that hydrogen embrittlement can be suppressed by preferential hydrogen partitioning in these sites. However, intermetallic compound particles act as fracture origin sites, and excessive addition degrades the mechanical properties of the material. In this study, we quantitatively evaluated the damage and decohesion behavior of intermetallic compound particles in high-hydrogen content 7XXX aluminum alloys by using in situ synchrotron radiation X-ray tomography. The results revealed that the hydrogen particles induced early high-strain localization, and the Al7Cu2Fe particles were damaged in that region due to its brittleness, resulting in early fracture. Hydrogen had no effects on the fracture and debonding behaviors of intermetallic compound particles, suggesting that the observed particle brittle fracture is dependent on their mechanical properties.

     

    This Paper was Originally Published in Japanese in J. JILM 72 (2022) 411–419. Abstract and the captions of Figs. 1, 2, 4, 5, 6, 7, 9 and 10 are slightly modified.

  • Ryohei Shinno, Makoto Hino, Ryoichi Kuwano, Koji Monden, Masaaki Sato, ...
    原稿種別: Regular Article
    2022 年 63 巻 12 号 p. 1617-1621
    発行日: 2022/12/01
    公開日: 2022/11/25
    [早期公開] 公開日: 2022/10/28
    ジャーナル フリー HTML

    In this study, with the aim of improving the fatigue characteristics of the A7075 aluminum alloy, A7075-T6511 alloy rod specimens were plated with electroless Ni–P with different compositions, and the fatigue characteristics were evaluated by a rotary bending fatigue test. The fatigue strength of the specimen plated with low-P type was higher than that of the un-plated specimen. However, the fatigue strength of the specimen plated with high-P type was significantly lower than that of the un-plated specimen, and the fatigue strength of the specimen plated with medium-P type was also lower though the extent was not so significant. It was speculated that these reductions in fatigue strength were due to hydrogen embrittlement by the hydrogen introduced into the specimen during the plating.

     

    This Paper was Originally Published in Japanese in J. JILM 71 (2021) 534–538.

    Fig. 4 Relation between stress amplitude (σa) and number of cycles to failure (N) for the four types of specimens. Fullsize Image
  • Kota Notani, Takahiro Hayashi, Naoki Mori
    原稿種別: Regular Article
    2022 年 63 巻 12 号 p. 1622-1630
    発行日: 2022/12/01
    公開日: 2022/11/25
    [早期公開] 公開日: 2022/10/28
    ジャーナル 認証あり HTML

    Abnormal sound detection using a one-class support vector machine (OCSVM) and a principal component analysis (PCA) is proposed aiming to stable and objective inspection without skilled plant inspectors. For measurement of acoustic signals, we developed a compact microphone unit that can work in sound detection, signal transmission, and power supply, wirelessly. Six signal parameters were extracted as features from filtered and segmented acoustic signals. Using the features standardized and reduced in dimensionality by PCA, an anomaly detection model using OCSVM is built to detect abnormal sounds. The proposed method is verified by acoustic diagnosis of sound waves leaking from pipeworks with running water. Diagnostic accuracies were evaluated for artificial abnormal sounds with different types of burst waves output from a piezoelectric element attached to the pipe and Pencil Lead Break sound in water flowing background noise. Burst wave changes could be detected in almost all patterns, and the diagnostic accuracy was 100% for the Pencil Lead Break sound.

  • Nasa Kawagoshi, Shohei Tamura, Takeshi Kawachi
    原稿種別: Regular Article
    2022 年 63 巻 12 号 p. 1631-1638
    発行日: 2022/12/01
    公開日: 2022/11/25
    [早期公開] 公開日: 2022/10/28
    ジャーナル フリー HTML

    With the focus on the forming of a tube with differential wall thickness by the ironing of the inner surface, the interaction of the effects of punch geometry (length of parallel part LP, semiangle αP and clearance CP) on the formability and forming load is investigated by experimentally consistent finite element analysis. Results of the analysis show that LP and αP significantly affect the forming load, while CP has little effect on the load. The punch with larger LP, or the punch with smaller αP or smaller CP, realizes a higher formability because the slipping of steel tube, which is a result of shape defects, does not occur even if Δμ is small. Furthermore, it is theoretically clarified, through discussions on the forces that suppress/induce the slipping of the tube, that slipping does not occur if a large surface pressure is generated on the parallel part of the punch. Since the surface pressure generated on the parallel part of the punch during tube forming varies depending on αP and the area of the parallel part of the punch varies depending on LP, LP and αP should both be taken into account in designing the punch. On the other hand, CP does not affect the other design factors and can be designed independently.

     

    This Paper was Originally Published in Japanese in J. Japan Soc. Technol. Plasticity 62 (2021) 87–94.

    Fig. 19 Relationship between punch shape and formability (Δμ = 0.10). Lines showing the forming limit for each αP. Fullsize Image
  • Kotone Sakemoto, Masaji Kato, Yusuke Ishii, Kiyofumi Kurumisawa, Yoshi ...
    原稿種別: Regular Article
    2022 年 63 巻 12 号 p. 1639-1644
    発行日: 2022/12/01
    公開日: 2022/11/25
    ジャーナル フリー HTML

    Information on the water permeability of materials for radioactive waste disposal in geological repositories is essential. High strength and ultra-low permeability concrete (HSULPC) is being considered as a material used to package transuranic (TRU) waste. HSULPC would be reinforced by steel fiber to increase its tensile strength and toughness, but the effect of reinforcing steel fiber on permeability is unclear. Permeability tests need to be highly accurate to determine the hydraulic properties of low permeability materials. In this study, the hydraulic conductivity of HSULPC with steel fiber using the transient pulse method. The hydraulic conductivities of HSULPC with/without steel fiber were determined to be around 10−13 to 10−11 m/s under the confining pressures between 2 and 10 MPa and pore pressure of 1 MPa constant. The results further showed that the permeability of these materials had a hysteretic dependence on the effective confining pressure. There was no remarkable difference of hydraulic conductivity between HSULPC with and without steel fiber. SEM observation revealed that HSULPC with steel fiber has isolated voids to some extent included during mixing of concrete but there are few voids on the interface of steel fiber for water channel. However, due to the higher porosity, the hydraulic conductivity of HSULPC with steel fiber is relatively higher than that without fiber. Still, the permeability of fiber reinforced HSULPC is low enough compared with Horonobe mudstone and Toki granite and would enable it to effectively confine 14C radionuclides in TRU waste.

     

    This Paper was Originally Published in Japanese in J. Soc. Mater. Sci., Japan 71 (2022) 228–234.

    Fig. 7 Relationships between hydraulic conductivity and effective confining pressure for HSULPC without fiber,15,16) HSULPC with steel fiber, Horonobe mudstone, and Toki granite.17) Fullsize Image
Materials Chemistry
  • Hiroaki Tsuchiya, Satoshi Tokuoka, Shinji Fujimoto
    原稿種別: Regular Article
    2022 年 63 巻 12 号 p. 1645-1650
    発行日: 2022/12/01
    公開日: 2022/11/25
    [早期公開] 公開日: 2022/10/17
    ジャーナル 認証あり HTML

    In this paper, we report that the electrochemical behavior and dissolution of type 304 stainless steel in highly concentrated lithium trifluoromethanesulfonate (LiOTf) solutions depend strongly on the molar fraction of free water molecules in these solutions. Raman spectroscopy of the solutions revealed that the chemical state of the water molecules varied drastically depending on the concentration of the LiOTf solution. More water molecules were found to be coordinated to Li ions in 20 mol% LiOTf solution than that in the 5 mol% solution, resulting in fewer free water molecules in the former. The oxidation of water was suppressed whereas the dissolution of Fe and Cr, which are the main constituents of stainless steel, was enhanced in the 20 mol% LiOTf solution compared to that in 5 mol% solution, except for the dissolution of Fe at higher potentials.

    Fig. 6 Schematic of the state of molecules present in the 5 mol% and 20 mol% LiOTf solutions. Fullsize Image
  • Eiji Fujii, Yoshihiko Kimura, Kazuhiro Takahashi, Mitsuaki Furutani, K ...
    原稿種別: Regular Article
    2022 年 63 巻 12 号 p. 1651-1656
    発行日: 2022/12/01
    公開日: 2022/11/25
    [早期公開] 公開日: 2022/10/28
    ジャーナル フリー HTML

    Silver nanoparticles (NPs)/chitosan nanofibers (ChNF) composite material was fabricated using a high-pressure wet-type jet mill. A mixture comprising an aqueous silver nitrate solution and a ChNF suspension was prepared as a starting material. The mixture was then processed using the high-pressure wet-type jet mill at a discharge pressure of 100 MPa. X-ray diffraction analysis of the obtained samples revealed the presence of not only chitosan crystallites, but also silver metal crystallites. According to field-emission scanning electron microscopy observation, many nano-sized silver particles were immobilized and well-dispersed on the surface of ChNF. The silver NPs had a spherical shape with an average particle size of about 20 nm regardless of the number of jet milling cycles. The silver content in the composite materials increased slightly with the number of jet milling cycles. As a result of investigating the antibacterial properties of the silver NPs/ChNF composite material that is processed five times with the high-pressure wet-type jet mill at a discharge pressure of 100 MPa, it was found that the minimum inhibitory concentration (MIC) of that for E. coli was 4.2 mg/L, although raw ChNF had no antibacterial properties.

     

    This Paper was Originally Published in Japanese in J. Soc. Mater. Sci., Japan 71 (2022) 489–494. The abstract and the caption of Fig. 1, 2 are slightly modified.

    Fig. 4 FE-SEM images of the samples (ChNF-X) prepared using the high-pressure wet-type jet mill at a discharge pressure of 100 MPa. Fullsize Image
Materials Processing
  • Yuichiro Murakami, Kenji Miwa, Junichi Shinoda, Takashi Honda, Naoki O ...
    原稿種別: Regular Article
    2022 年 63 巻 12 号 p. 1657-1661
    発行日: 2022/12/01
    公開日: 2022/11/25
    [早期公開] 公開日: 2022/10/28
    ジャーナル 認証あり HTML

    The amount of the primary phase crystallized in a eutectic alloy at a set cooling rate is determined by the alloy composition. Only a small amount of the primary phase can be crystallized in a near-eutectic composition alloy. Here we show an interesting phenomenon in which the microstructure is changed by the application of mechanical vibration to a near-eutectic Al–Si alloy during cooling from the molten metal to the semi-solid state. The amount of primary α-Al phase can be obtained with the application of mechanical vibration is more than equilibrium solidification. The amount of non-equilibrium α-Al phases, which is more than the amount with equilibrium solidification, increases with the velocity amplitude of the vibration. The non-equilibrium α-Al phases had uniform shape that consisted of fine spherical particles. These non-equilibrium α-Al phase crystals had the same composition as the primary α-Al phase crystals solidified without vibration. Primary Si particles could also be observed by the application of mechanical vibration.

Engineering Materials and Their Applications
  • Arijit Roy, Pil-Ryung Cha
    原稿種別: Regular Article
    2022 年 63 巻 12 号 p. 1662-1669
    発行日: 2022/12/01
    公開日: 2022/11/25
    [早期公開] 公開日: 2022/10/28
    ジャーナル 認証あり HTML

    Formation of oxygen vacancy-rich conducting filament in the metal-oxide insulating layer due to applied electric field is studied using phase field modelling. We consider that the formation of the Frenkel defects plays a dominant role in the process of filament formation. The choice of any other type of defects have been neglected due to the consideration of charge neutrality. We find that during the initial stages of filament formation, intrinsic defect concentration plays a crucial role. However, during the late stages, when the filament formation approaches completion, because of the increased electric field, the generation of new Frenkel defects dominates the growth mechanism. Our observation confirms that the intrinsic defects are not sufficient for the completion of conducting filament in the insulating memresistive layer. Our numerical analysis helps us to better understand the formation mechanism of conducting filament and to determine the key material parameters that influence the operation of oxide based non-volatile random access memory (RAM) i.e. resistive RAM (ReRAM).

  • Kent Mitani, Hiroki Saito, Yuji Ichikawa, Kazuhiro Ogawa, Takaya Masud ...
    原稿種別: Regular Article
    2022 年 63 巻 12 号 p. 1670-1676
    発行日: 2022/12/01
    公開日: 2022/11/25
    [早期公開] 公開日: 2022/10/28
    ジャーナル フリー HTML

    SiC ceramic matrix composites (CMC) are potential materials for hot section gas turbine components due to their high heat resistance and low density. However, SiC CMC degrades over time in steam oxidation environments. Therefore, environmental barrier coatings (EBC) are necessary to protect SiC substrates. Yb2Si2O7 is one of the most potent materials for barrier coatings. In this study, self-healing property is further added to Yb2Si2O7 EBC by incorporating SiC in the form of Yb2Si2O7/SiC granulated powders. We investigated the effect of different SiC contents and particle sizes on the long-term oxidation behavior of Yb2Si2O7/SiC coatings. The self-healing property was observed in the microstructural changes of artificial cracks induced by Vickers indentation. The samples were oxidized at 1300°C, and the structural change before and after the oxidation was evaluated by SEM, XRD, and EDX. The cross-sectional SEM images show that SiC was entirely oxidized in the first 50 h. Meanwhile, the surface SEM results show that small particle size and high SiC content exhibited a significant volume expansion during the oxidation of SiC. In addition, the self-healing property was significantly active in the initial stage of oxidation, but drastically deteriorated as the oxidation progressed.

     

    This Paper was Originally Published in Japanese in J. Japan Thermal Spray Soc. 59 (2022) 27–32.

  • Moe Kimura, Yang Cao, Hanae Kijima-Aoki, Nobukiyo Kobayashi, Shigehiro ...
    原稿種別: Regular Article
    2022 年 63 巻 12 号 p. 1677-1681
    発行日: 2022/12/01
    公開日: 2022/11/25
    [早期公開] 公開日: 2022/10/28
    ジャーナル フリー HTML

    In this study, we investigated the tunneling magnetodielectric (TMD) effect in cobalt–aluminum-oxide (Co–Al2O3) nanogranular films. The films showed a homogeneous granular structure composed of nanometer Co granules dispersed in an Al2O3 matrix and demonstrated a TMD response with a maximum TMD ratio {(ε′H=850kA/m − ε′H=0kA/m)/ε′H=0kA/m} of 1.1% at a frequency of 5.0 MHz at room temperature. These results show the existence of the TMD effect in the magnetic metal–oxide composite, which would promote the wide applications of the magnetic metal–oxide nanogranular materials in magnetoelectric devices.

    Magnetic field vs. tunneling magnetodielectric (TMD) ratio at f = 5.0 MHz and x = 0.23. The solid line presents the normalized magnetization (M/M850k)2, where M850k is the magnetization at H = 850 kA/m. Fullsize Image
  • Noriyuki Tanaka, Toshiki Kitamura, Shigeru Sato, Taro Yamaguchi, Shoic ...
    原稿種別: Regular Article
    2022 年 63 巻 12 号 p. 1682-1685
    発行日: 2022/12/01
    公開日: 2022/11/25
    ジャーナル フリー HTML

    We investigated the occurrence of solvent cracking in unplasticized polyvinyl chloride pipes using test materials prepared by conventional methods. We confirmed that voids were formed on the inner surface of the pipe at a holding time of 2 weeks under conditions of room temperature (298 K), 1.0 g of applied adhesive, and 4 N/m U-band tightening torque. The voids formed linearly in the circumferential direction at regions in contact with the U-band and linearly in the axial direction at regions not in contact. Environmental agents of tetrahydrofuran (THF), 2-butane, and cyclohexanone were detected during analysis of void regions on the inner surface of the pipe and residual gas in the pipe. The results suggest that the stress generated by tightening of the U-band and the environmental agents affected void generation. Furthermore, stress analysis simulation of the U-band contact region show the presence of tensile stress at regions in contact with the U-band and compressive stress at regions not in contact. The difference in these stresses and the regularity of the molecular arrangement during manufacturing of the pipe likely influences the direction of void generation, which can progress into cracks.

     

    This Paper was Originally Published in Japanese in J. Soc. Mater. Sci., Japan 70 (2021) 623–627.

    Fig. 5 Results of GC/MS analysis at normal section, axial void and circumferential. Fullsize Image
feedback
Top