Search Sites

MATERIALS TRANSACTIONS Vol. 45 (2004), No. 2

ISIJ International
belloff
ONLINE ISSN: 1347-5320
PRINT ISSN: 1345-9678
Publisher: The Japan Institute of Metals and Materials

Backnumber

  1. Vol. 65 (2024)

  2. Vol. 64 (2023)

  3. Vol. 63 (2022)

  4. Vol. 62 (2021)

  5. Vol. 61 (2020)

  6. Vol. 60 (2019)

  7. Vol. 59 (2018)

  8. Vol. 58 (2017)

  9. Vol. 57 (2016)

  10. Vol. 56 (2015)

  11. Vol. 55 (2014)

  12. Vol. 54 (2013)

  13. Vol. 53 (2012)

  14. Vol. 52 (2011)

  15. Vol. 51 (2010)

  16. Vol. 50 (2009)

  17. Vol. 49 (2008)

  18. Vol. 48 (2007)

  19. Vol. 47 (2006)

  20. Vol. 46 (2005)

  21. Vol. 45 (2004)

  22. Vol. 44 (2003)

  23. Vol. 43 (2002)

  24. Vol. 42 (2001)

MATERIALS TRANSACTIONS Vol. 45 (2004), No. 2

Smart Materials Group at the National Institute of Applied Science Recent Data and Trends

Pierre. F. Gobin, Yves Jayet, Phillipe Guy, Nathalie Godin, Michel Morin, Catherine Gauthier, Xavier Kléber, Pascal Reynaud, Joel Courbon, Jean Y. Cavaillé

pp. 166-172

Abstract

During the last decade constant improvements have been made in materials and structures design and control. But now some performance objectives in particular in the field of the reliability cannot be achieved using classical technologies and require the use of the ‘smart materials concept’. Periodical maintenance NDT based inspections are today of a general acceptance for almost all complex technological structures. Nevertheless the idea that the integrated and continuous sensing techniques can optimize the operating conditions is now in progress. Different aspects of this evolution towards the desirable continuous health monitoring are discussed in relation with the smart materials concept through this non exhaustive review of some realisations or experiences. In the domain of sensitive materials, passive techniques such as Barkhausen effect, thermoelectric power, electrical impedance monitoring, acoustic emission, and active piezoelectric implant based methods, are briefly presented. Moreover, taking into account the growing demand in the field of actuators and artificial muscles for robotic and biomimetic devices, shape memory alloys and electroactive polymers are in progress. Finally the ‘self healing’ concept will be presented in the case of one ceramic-ceramic composite.

Bookmark

Share it with SNS

Article Title

Smart Materials Group at the National Institute of Applied Science Recent Data and Trends

Combinatorial Investigation of Ferromagnetic Shape-Memory Alloys in the Ni-Mn-Al Ternary System Using a Composition Spread Technique

Olugbenga O. Famodu, Jason Hattrick-Simpers, Maria Aronova, Kao-Shuo Chang, Makoto Murakami, Manfred Wuttig, Teiko Okazaki, Yasubumi Furuya, Lee A. Knauss, Leonid A. Bendersky, Frank. S. Biancaniello, Ichiro Takeuchi

pp. 173-177

Abstract

Using a thin-film composition spread technique, we have mapped the phase diagram of the Ni-Mn-Al ternary system in search of ferromagnetic shape-memory alloys (FMSA). A characterization technique that allows detection of martensitic transitions by visual inspection using micromachined cantilever arrays was combined with quantitative magnetization mapping using scanning superconducting quantum interference device (SQUID) microscopy. A large compositional region in the Al deficient part of the phase diagram was found to be ferromagnetic and reversibly martensitic at room temperature. In addition, in the Al rich region, a new compositional range that displays marked ferromagnetism was found.

Bookmark

Share it with SNS

Article Title

Combinatorial Investigation of Ferromagnetic Shape-Memory Alloys in the Ni-Mn-Al Ternary System Using a Composition Spread Technique

Enhanced Piezoelectric Properties of Piezoelectric Single Crystals by Domain Engineering

Satoshi Wada, Hirofumi Kakemoto, Takaaki Tsurumi

pp. 178-187

Abstract

Various engineered domain configurations were induced into barium titanate (BaTiO3) single crystals, and their piezoelectric properties were investigated as a function of (1) the crystal structure, (2) the crystallographic orientation and (3) the domain size. As a result, the orthorhombic mm2 BaTiO3 crystals showed the highest piezoelectric properties among three kinds of BaTiO3 crystals such as tetragonal 4mm, orthorhombic mm2 and rhombohedral 3m phases. On the other hand, the [001]c oriented BaTiO3 crystals always exhibited the larger piezoelectric properties than the [111]c oriented BaTiO3 crystals. Moreover, the domain size dependence on the piezoelectric properties was discussed, and this result revealed that the piezoelectric property was strongly dependent on the domain size, i.e., the piezoelectric properties significantly increased with decreasing domain size. On the basis of the above results, the most suitable engineered domain configuration was proposed for the high-strain high-coupling piezoelectric application.

Bookmark

Share it with SNS

Article Title

Enhanced Piezoelectric Properties of Piezoelectric Single Crystals by Domain Engineering

Rearrangement of Martensite Variants in Iron-Based Ferromagnetic Shape Memory Alloys under Magnetic Field

Takashi Fukuda, Tatsuaki Sakamoto, Tomoyuki Kakeshita, Tetsuya Takeuchi, Kohji Kishio

pp. 188-192

Abstract

We have investigated magnetic field-induced strain (MFIS) associated with rearrangement of martensite variants and its corresponding magnetization process in a disordered Fe-31.2Pd(at%) single crystal and an ordered Fe3Pt single crystal, exhibiting a cubic to tetragonal martensitic transformation at 230 K and 85 K, respectively. When magnetic field is applied along [001] direction to a specimen with a multivariant state, it expands along the field direction for Fe-31.2Pd and contracts for Fe3Pt, because the variants whose easy axis of magnetization (a axis for Fe-31.2Pd and c axis for Fe3Pt) lies along the field direction is selected to grow. The fraction of such variants reaches 100% for Fe-31.2Pd but does not for Fe3Pt. In the field removing process, a part of the MFIS recovers for Fe3Pt but does not for Fe-31.2Pd. From the magnetization curve, the energy dissipated due to the rearrangement of variants by magnetic field is obtained to be about 260 kJ/m3 for Fe-31.2Pd and about 180 kJ/m3 for Fe3Pt. Concerning Fe-31.2Pd, this value is roughly the same as that evaluated by stress-strain curves, suggesting that the rearrangement of variants by magnetic field takes essentially the same path as that by external stress. Based on these results and magnetocrystalline anisotropy constants of martensite phases, the mechanism of rearrangement of variants under magnetic field is discussed from a macroscopic point of view.

Bookmark

Share it with SNS

Article Title

Rearrangement of Martensite Variants in Iron-Based Ferromagnetic Shape Memory Alloys under Magnetic Field

Microstructure and Magnetostriction of Rapid-Solidified Fe-15 at%Ga Alloy

Chihiro Saito, Yasubumi Furuya, Teiko Okazaki, Takashi Matsuzaki, Tadao Watanabe

pp. 193-198

Abstract

Melt-spun, rapid solidified Fe-Ga ribbon sample exhibited large magnetostriction and good ductility as compared with conventional bulk sample. But the origin was not clear yet. In order to investigate the occurrence of large magnetostriction in Fe-Ga ribbon sample, the correlation between magnetostriction and the crystal grain morphology was inspected in detail by SEM/EBSP method for Fe-15 at%Ga alloy. In comparison with as-spun ribbon sample, short-time (0.5 h) heat treated ribbon had stronger [100] oriented texture and exhibited larger magnetostriction of 140 ppm (×10−6) at 800 kA/m. These phenomena suggest that such a large magnetostriction is caused by the release of considerable large internal stresses in as-spun ribbon as well as the remained strong textures after annealing.

Bookmark

Share it with SNS

Article Title

Microstructure and Magnetostriction of Rapid-Solidified Fe-15 at%Ga Alloy

Magnetostriction of Fe-Ga-B Alloys in Amorphous and Crystallized States

Takeshi Kubota, Akihisa Inoue

pp. 199-203

Abstract

A ternary (Fe0.82Ga0.18)85B15 alloy was vitrified by melt spinning at wheel velocities of over 28.5 m/s. Two exothermic peaks were observed at onset temperatures of 692 K and 787 K. The melt-spun amorphous alloy ribbon exhibits saturation magnetostriction of +30 × 10−6 at the field of 80 kA/m. The magnetostriction increased by crystallization, i.e. precipitation of the bcc-Fe(Ga) phase, and reached a maximum value of +62 × 10−6 in conjunction with good response which is same as that for the as-spun amorphous sample. The maximum value is equivalent to that of the random orientated polycrystalline Fe82Ga18 alloy. In addition, the crystallized Fe-Ga-B alloy had better response as compared with the polycrystalline Fe82Ga18 alloy. The reason why the Fe-Ga-B alloy exhibits the high magnetostriction even in the coexistent state with C16-Fe2B and L12-Fe3Ga phases, seems to result from the precipitation of the supersaturated bcc-Fe(Ga) solid solution with high Ga concentrations as the crystallization -included phase.

Bookmark

Share it with SNS

Article Title

Magnetostriction of Fe-Ga-B Alloys in Amorphous and Crystallized States

Phase Transformation and Magnetic Property of Heusler Type Co2NiGa Alloys

Mitsutaka Sato, Teiko Okazaki, Yasubumi Furuya, Yoichi Kishi, Manfred Wuttig

pp. 204-207

Abstract

We studied the phase transformation of a new Heusler type ferromagnetic shape memory alloy, Co2NiGa, by using an Acoustic Elastometer method. The alloy displays large magnetostriction, caused by the magnetic-field-induced rearrangement of martensite twin boundary. The ribbon samples produced by rapidly solidified melt-spinning method show large magnetostriction of about 100 × 10−6 at room temperature. While heating and cooling, the modulus defect, ΔM/M, and damping, Q−1, of the ribbon sample exhibits drastic changes at As and Mf, which differ slightly from the magnetic results.

Bookmark

Share it with SNS

Article Title

Phase Transformation and Magnetic Property of Heusler Type Co2NiGa Alloys

Texture Analysis and Properties of Rapidly Solidified Ti52Ni38Cu10 Shape Memory Alloy

Venky Saravanan, Anak Khantachawana, Shuichi Miyazaki

pp. 208-213

Abstract

Texture of Ti52Ni38Cu10 rapidly solidified ribbons was investigated. Characterization of some of the properties such as transformation temperatures, deformation behavior, transformation strain, microstructure etc. was also carried out for the rapidly solidified ribbons in as-spun condition and after heat-treatment at 1073 K. The transformation temperatures of the ribbon specimens are found to be less than those of ingot specimens. As-spun ribbons were found to be slightly amorphous in nature, while after heat-treatment they became completely crystalline. Asspun and heat-treated ribbons show strong ‹200› fiber texture. From the thermomechanical studies it was observed that the hysteresis of the heat-treated ribbon specimen decreased whereas the transformation strain and the transformation temperatures showed an increase with increase in stress.

Bookmark

Share it with SNS

Article Title

Texture Analysis and Properties of Rapidly Solidified Ti52Ni38Cu10 Shape Memory Alloy

Texture and Microstructure of Ti-Ni Melt-Spun Shape Memory Alloy Ribbons

Anak Khantachawana, Hiroshi Mizubayashi, Shuichi Miyazaki

pp. 214-218

Abstract

The shape memory behavior, texture and microstructure were studied for Ti-Ni ribbons fabricated by a melt-spinning method where the Ni contents were designed to be 49.0 at%, 50.0 at% and 51.0 at%. The texture of the parent B2 phase was determined by X-ray diffraction pole figures. A strong ‹100› fiber texture was found in both pole figures and orientation distribution functions (ODF). TEM observation revealed that all the ribbons are fully crystallized and that disk-type precipitates of about 10 nm in length locate on {100} of B2 phase uniformly. The thermal cyclic tests under various constant stresses showed shape recoverable strains exceeding 5% and critical stresses for plastic deformation being higher than 400 MPa for Ti-49.0 at%Ni and Ti-50.0 at%Ni as-spun ribbons. These excellent shape memory characteristics of the melt-spun ribbons are due to the formation of these disk-type precipitates. In addition, Ti2Ni precipitates of 25 nm in diameter appeared along grain boundaries of Ti-51.0 at%Ni as-spun ribbon. Since the Ni content of the matrix is condensed due to the formation of Ti2Ni precipitates, no shape memory effect was observed in Ti-51.0 at%Ni as-spun ribbon under the experimental conditions.

Bookmark

Share it with SNS

Article Title

Texture and Microstructure of Ti-Ni Melt-Spun Shape Memory Alloy Ribbons

Influence of Heat Treatment on Phase Transformation of Ni-rich TiNi Foils Produced via Ultrafine Laminates

Dacian Tomus, Koichi Tsuchiya, Takeshi Nagano, Akihide Hosokawa, Toshiki Ohmori, Masahiro Sasaki, Yoshikazu Todaka, Minoru Umemoto

pp. 219-224

Abstract

Using the ultrafine laminate method, thin foils (50 μm) of Ni-rich TiNi shape memory alloys were produced. Overall composition of the Ti/Ni laminate is Ti-50.7%Ni. TiNi (B2) phase was obtained after different diffusion treatments at 1073 K for 259.2 ks and 1173 K for 36 ks and 259.2 ks. Aging treatments at 773 K for 3.6, 18, 36, 72 and 144 ks were also performed. Multiple step martensitic transformation was observed for aged samples. The shape memory strain was 3.69 × 10−2 in the sample aged at 773 K for 18 ks.

Bookmark

Share it with SNS

Article Title

Influence of Heat Treatment on Phase Transformation of Ni-rich TiNi Foils Produced via Ultrafine Laminates

Ar Ion Beam Irradiation Effects on Magnetostrictive Characteristics of Tb-Fe Thin Film

Mitsuaki Takeuchi, Yoshihito Matsumura, Hirohisa Uchida, Toshiro Kuji

pp. 225-228

Abstract

TbFe2 films prepared by a flash evaporation system onto Si(100) or polyimide substrate have been irradiated with different Ar ion doses at zero, 1.3 × 1017 and 2.7 × 1017 cm−2 and at 10 kV. Magnetostrictive properties, i.e., saturated magnetostriction and magnetostrictive susceptibility, of TbFe2 film with disordered structure were improved by Ar ion beam irradiation. This result was probably caused increasing of in-plane compressive stress corresponding to change of volume magnetostriction.

Bookmark

Share it with SNS

Article Title

Ar Ion Beam Irradiation Effects on Magnetostrictive Characteristics of Tb-Fe Thin Film

Electrical Nondestructive Determination of Collision Fatigue Limit for PZT

Yoshitake Nishi, Ryosuke Kondoh, Kunio Yamada, Hayato Irisawa

pp. 229-232

Abstract

To determine the collision fatigue limit for piezoelectric ceramics, an electrical nondestructive method was suggested. The materials show large changes in electrical potential induced by pressure on the collision. Measurements on this type of material found a relationship between the maximum value of electrical potential (Vm) and supplied collision energy (Ecs) below the collision fatigue limit. It was expressed by the following simple equation.
Vm = 9.5(Ecs)0.5
Applying the critical differential electrical potential (Vc = 4 V), we confirmed that the collision fatigue limit was nondestructively determined for PZT materials.

Bookmark

Share it with SNS

Article Title

Electrical Nondestructive Determination of Collision Fatigue Limit for PZT

Ferroelectric and Piezoelectric Properties of Disk Shape Lead Zirconate Titanate Thick Films

Takashi Iijima, Sachiko Ito, Hirofumi Matsuda, Robert Dugnani, Fu-Kuo Chang

pp. 233-235

Abstract

A combination of the preparation techniques for the ferroelectric films and the micro machining of Si is considered to be an effective way to fabricate microelectromechanical systems (MEMS), such as piezoelectric micro-transducer devices for the electrical and medical fields. In this study, disk shape lead zirconate titanate (PZT) thick films were successfully fabricated. 10-μm-thick PZT films were deposited onto Pt/Ti/SiO2/Si substrate using a chemical solution deposition (CSD) process. Pt top electrode and PZT layer were etched by reactive ion etching (RIE) process, and 100 to 500-μm-diameter PZT thick film disks were fabricated. The relative dielectric constant, dissipation factor, remnant polarization and coercive field were εr = 1130, tanδ = 0.02, Pr = 0.14 C/m2 and Ec = 2.5 MV/m, respectively. This means that the ferroelectric and dielectric properties of the PZT thick film disks were comparable with that of the bulk PZT ceramics. Moreover, the prepared PZT thick film disks showed the butterfly-shaped displacement curve, related with piezoelectric response, in the case of bipolar measurement. The PZT thick film disks could be poled with 80 V at room temperature, which is easier than the poling condition of bulk PZT. The piezoelectric constant of the poled PZT thick film disks was estimated to be AFM d33 = 221 pm/V. Therefore, the micro fabricated 10-μm-thick PZT disks is considered to be applicable for piezoelectric micro devices.

Bookmark

Share it with SNS

Article Title

Ferroelectric and Piezoelectric Properties of Disk Shape Lead Zirconate Titanate Thick Films

Estimating Noise Level in Dynamical Behavior for Detecting Mechanical Damage

Takaya Miyano

pp. 236-239

Abstract

The diagnostic algorithm introduced by Wayland et al. to test for degrees of visible determinism in complex dynamical behavior is applied to precise estimation of noise level for the gear-noise sound emanated from automobile automatic transmissions. It is shown that the method successfully captures such a small difference in acoustical characteristics indicating micro mechanical flaws on the gear surface that power spectral analysis fails to detect.

Bookmark

Share it with SNS

Article Title

Estimating Noise Level in Dynamical Behavior for Detecting Mechanical Damage

Ionic Conductivity Enhancement of YSZ Film Induced by Piezoelectric Vibration

Hiroshi Masumoto, Takashi Goto

pp. 240-243

Abstract

To improve electric properties of oxide ion conducting yttria-stabilized zirconia (YSZ) films at low temperatures, a mechanical distortion was induced by a piezoelectric actuator. YSZ films containing 8 mol%Y2O3 were prepared by metalorganic chemical vapor deposition. The YSZ film was placed on a PZT (lead zirconate titanate) multilayer piezoelectric actuator. The effect of piezoelectric vibration on electric properties of the YSZ film was investigated. The resistivity of the YSZ film decreased with increasing amplitude of the piezoelectric vibration. Electrical conductivity of the YSZ film at 353 K vibrated by the actuator was 2 × 10−6 Sm−1, 103 times greater than that without vibration.

Bookmark

Share it with SNS

Article Title

Ionic Conductivity Enhancement of YSZ Film Induced by Piezoelectric Vibration

Magnetostrictive LC Circuit Sensors

Eckhard Quandt, Michael Frommberger

pp. 244-248

Abstract

Magnetostrictive thin films in electric resonant LC circuits are attractive as novel strain sensors. In order to achieve high resonance frequencies exchange coupled nanometer multilayers were used. LC circuits incorporating Fe50Co50/Co80B20 multilayers exhibited a gauge factor ((Δf/f)/Δε) of the order of 1000. This LC circuit sensor enables wireless interrogation, which is demonstrated in a torque measurement.

Bookmark

Share it with SNS

Article Title

Magnetostrictive LC Circuit Sensors

Properties of Ti-Aluminides-Reinforced Ti-Matrix Laminate Fabricated by Pulsed-Current Hot Pressing (PCHP)

Kiyoshi Mizuuchi, Kanryu Inoue, Masami Sugioka, Masao Itami, Masakazu Kawahara

pp. 249-256

Abstract

Ti-aluminides-reinforced Ti-matrix composites were fabricated from 0.04 mm-thick Ti foils and 0.012 mm- and 0.024 mm-thick aluminum foils, in a process using a pulsed-current hot pressing (PCHP) equipment, and the effect of reaction temperature on properties of the composites was investigated. The composites were of laminated structure and composed of Ti and reacted layers containing Ti-aluminides. The composition of the reacted layers was dependent on the reaction temperature employed. Tensile testing at room temperature revealed that the reaction temperature was effective for the mechanical properties, including tensile strength, elongation and fracture mode, of the composites. The tensile strength and the elongation of composites fabricated at 1273 K from 0.04-mm-thick Ti and 0.012-mm-thick Al foils were 810 MPa and 3.64%, respectively, while they were 677 MPa and 3.44% for composites fabricated at 1173 K. Microstructure observations of fractured specimens showed that Ti layers of the composites fabricated at 1173 and 1273 K played a significant role in improving ductility by prohibiting the growth of numerous cracks emanating from Ti-aluminides.

Bookmark

Share it with SNS

Article Title

Properties of Ti-Aluminides-Reinforced Ti-Matrix Laminate Fabricated by Pulsed-Current Hot Pressing (PCHP)

Evaluation of Thermal Deformation Process of Nickel Based Active Composites by Laser AE Technique

Satoshi Nishinoiri, Manabu Enoki, Takeshi Mochizuki, Hiroshi Asanuma

pp. 257-263

Abstract

A fiber reinforced nickel was developed base on the concept of active composites due to the thermal deformation, and its reproducibility at elevated temperature has been investigated. It was reported that curvature of the composite changed non-linearly during heating/cooling cycle. This hysterisis behavior may be involved with microfracture in the composites. Acoustic emission (AE) technique is very useful to monitor a dynamic microfracture. However, conventional AE technique has a limit in application at elevated temperature. We have investigated the non-contact laser AE technique using laser interferometer as a sensor. In this study, we tried to evaluate thermal deformation process of the active composite by this method. Specimens of pure nickel plate as matrix, SiC continuous fiber as reinforcement fiber and pure aluminum plate as insert layer were prepared by hot pressing. AE signals during heating and cooling processes were detected at the reverse of the specimen using a heterodyne type laser interferometer. Observation results showed that three failure modes such as cracking in matrix layer, debonding of matrix/fiber interface, and breakage of SiC fiber occurred during thermal deformation process. These failure modes were discussed based on AE source models. AE behavior of the composite showed thermal Keiser effect. This indicates thermal stresses in the composite cause microfracture during thermal deformation process. As a result of the test with the maximum temperature of 1073 K, AE event rate increased rapidly at 960 K and AE signals were detected even in cooling process. This temperature was identified to be the transition temperature of microfracture process in this composite. AE generation temperature was also in good agreement with the critical temperature of hysterisis of curvature.

Bookmark

Share it with SNS

Article Title

Evaluation of Thermal Deformation Process of Nickel Based Active Composites by Laser AE Technique

A Study on the Fabrication of TiNi/Al6061 Shape Memory Composite Material by Hot-Press Method and its Mechanical Property

Young Chul Park, Gyu Chang Lee, Yasubumi Furuya

pp. 264-271

Abstract

An attempt was made to fabricate composite material of an Al alloy matrix reinforced by TiNi shape memory fiber using a hot-press method and to investigate its microstructures and mechanical properties. The analysis of SEM and EDS showed that the composite material had good interface bonding. The stress-strain behavior of the composite material was evaluated at room temperature and 363 K as a function of pre-strain, and it showed that the yield stress at 363 K is higher than that at room temperature. It is also found that the yield stress of the composite material increased with increasing the amount of pre-strain and depended on the volume fraction of the fiber and heat treatment. The smartness of the composite could be given due to the shape memory effect of the TiNi fiber, which generated compressive residual stress in the matrix material when heated after being pre-strained. Microstructural observation revealed that interfacial reactions occurred between the matrix and fiber, creating two intermetallic layers.

Bookmark

Share it with SNS

Article Title

A Study on the Fabrication of TiNi/Al6061 Shape Memory Composite Material by Hot-Press Method and its Mechanical Property

Shape Memory Alloy Artificial Muscles for Treatments of Fecal Incontinence

Yun Luo, Toshiyuki Takagi, Shintaro Amae, Motoshi Wada, Tomoyuki Yambe, Takamichi Kamiyama, Kotaro Nishi, Takeshi Okuyama, Toshihiko Komoriya, Hidetoshi Matsuki

pp. 272-276

Abstract

Shape memory alloys (SMAs) have the features of large force-to-weight ratio and large deformation, are considered suitable for actuator uses. This paper describes the applications of an SMA material with two-way shape memory as artificial muscles for the treatment of fecal incontinences. Two designs of the proposed artificial sphincters are presented; one for a complete replacement of the anal sphincter and the other as an auxiliary sphincter to assist the puborectal muscles for maintaining fecal continence. Their functional evaluations have been conducted through fundamental experiments on the thermal responses and the mechanical deformation. The functionality of both was confirmed by in vitro experiments. The first design, the artificial anal sphincter was subjected to animal experiments for up to 4 weeks. Satisfactory results in respects of the biofunctionality of the SMA artificial sphincter imply its potential for practical uses.

Bookmark

Share it with SNS

Article Title

Shape Memory Alloy Artificial Muscles for Treatments of Fecal Incontinence

Effect of pH on the Electrodeposition of ZnTe Film from a Citric Acid Solution

Takahiro Ishizaki, Takeshi Ohtomo, Yusuke Sakamoto, Akio Fuwa

pp. 277-280

Abstract

Potentiostatic cathodic electrodeposition of ZnTe was investigated from the viewpoint of the effect of pH on the deposits' composition and crystallinity using citric acidic electrolytic baths, in which Zn(II) and Te(IV) species were dissolved to form ZnH2Cit+, ZnHCit, ZnCit, Zn(Cit)24− and HTeO2+, HTeO3, respectively (Cit: citrate) at various pH. The complex equilibrium calculation was carried out to examine the most predominant complex ion for Zn-Cit system at different pH. Deposition of three kinds of deposits, i.e., polycrystalline ZnTe with closely stoichiometric composition, crystalline Te, and the mixed crystal due to Te and ZnTe, can be controlled by changing the pH and [Zn(II)]/[Te(IV)] concentration ratio of the baths. All the deposits obtained at pH 4.0 were well crystallized with a ZnTe cubic preferential orientation along the (111) plane without any post-treatment. The difference of the electrodeposition behavior at various pH was also discussed.

Bookmark

Share it with SNS

Article Title

Effect of pH on the Electrodeposition of ZnTe Film from a Citric Acid Solution

Anisotropic Behavior of Water Vapor Corrosion of Rutile TiO2 at High Temperature

Shunkichi Ueno, D. Doni Jayaseelan, Naoki Kondo, Tatsuki Ohji, Shuzo Kanzaki

pp. 281-283

Abstract

Water vapor corrosion behavior of rutile TiO2 was examined at 1773 K in 30 mass% H2O environment. The corrosion rate for this sample was 2.2 × 10−4 kg·m−2·h under this experimental conditions. Anisotropic corrosion behavior was recognized in the planes that are parallel to c-axis. Many rectangular shaped etch-pits were generated at the grain surfaces. The corrosion proceeded from the side wall of the etch-pits and then, terrace fields were grown on the grain surface. Ridge-shaped microstructure was observed on the side wall of the terrace owing to the anisotropic corrosion.

Bookmark

Share it with SNS

Article Title

Anisotropic Behavior of Water Vapor Corrosion of Rutile TiO2 at High Temperature

Retraction:Effect of Carbon Nanotube Addition on the Compressive Fracture Characteristics of Zr-based Bulk Metallic Glass Composites

Zan Bian, Tao Zhang, Akihisa Inoue

pp. 284-287

Abstract

This article was retracted. See the Notification.

Bookmark

Share it with SNS

Article Title

Retraction:Effect of Carbon Nanotube Addition on the Compressive Fracture Characteristics of Zr-based Bulk Metallic Glass Composites

Microscopic Observations of Friction Stir Welded 6061 Aluminum Alloy

Li Liu, Hideyuki Nakayama, Shiji Fukumoto, Atushi Yamamoto, Harushige Tsubakino

pp. 288-291

Abstract

As the automotive industry trends towards increased use of aluminum, the friction stir welding process offers many potential benefits for joining of aluminum. In this study, the microstructure in friction stir welded 6061 aluminum alloy was observed by metallographic technique, electron backscatter diffraction pattern (EBSD) and optical microscopy. The microstructure in the heat affected zone (HAZ) was significantly different from that in a thermo-mechanically affected zone (TMAZ). EBSD indicated that many more low-angle grain boundaries in TMAZ, i.e., subgrains with a recovered granular structure, were observed than in HAZ. Friction heating and plastic flow during friction stir welding created fine recrystallized grains and recovered grains in the TMAZ. The friction stir welding process produced a softened region in the 6061 Al welded alloy. In the stir zone, equiaxed grains were created and the grain size was smallest in the bottom area.

Bookmark

Share it with SNS

Article Title

Microscopic Observations of Friction Stir Welded 6061 Aluminum Alloy

Hydrogenation and Dehydrogenation Properties of RHNi5 (RH = Heavy Rare Earth) Binary Intermetallic Compounds

Hiroshi Senoh, Tetsu Kiyobayashi, Nobuhiko Takeichi, Hideaki Tanaka, Qiang Xu, Hiroyuki T. Takeshita, Masaru Toyouchi, Toshio Oishi, Nobuhiro Kuriyama

pp. 292-295

Abstract

We systematically investigated the hydrogenation and dehydrogenation properties for heavy rare earth-based binary RHNi5 (RH = Gd, Tb and Dy) intermetallic compounds and evaluated the correlations between crystallographic and thermodynamic properties. XRD analysis shows that all RHNi5 compounds crystallize in the hexagonal CaCu5-type crystal structure. In analogy to the light rare earth-based RLNi5 (RL = La, Pr, Nd and Sm) compounds both lattice constants of RHNi5 compounds decrease with increasing the atomic number of RH element due to the lanthanide contraction. On the pressure-composition (P-C) isotherms, GdNi5-H2 system shows two well-separated pressure plateaux qualitatively similar to RLNi5-H2 systems. Looking over from Gd to Dy in the RHNi5 compounds, we find three specific dehydrogenation properties on the P-C isotherms: 1. The first plateau pressure (pP1) increases in this order (at around H/RHNi5 = 2.5) due to less stability of hydrogen in the unit cell by the lanthanide contraction. Linear correlations are also observed between log pP1 and the unit cell volume (V) which fall onto the same lines extrapolated from those observed in case of the RLNi5 compounds. 2. The second plateau (P2) tends to disappear because the P-C isotherm goes beyond the critical point of the phase transition. 3. Fairly flat first plateau separates into two parts in which a new plateau (PN) appears at low hydrogen content (H/RHNi5 ≤ 2) with hysteretic phase transition. So long as the first plateau of dehydrogenation is concerned, from LaNi5 to DyNi5 we can predict the first plateau pressure from the unit cell volume of compounds and temperature.

Bookmark

Share it with SNS

Article Title

Hydrogenation and Dehydrogenation Properties of RHNi5 (RH = Heavy Rare Earth) Binary Intermetallic Compounds

Interfacial Layer in Friction-Bonded Joint of Low Carbon Steel to Al-Mg Alloy (AA5083) and its Influence on Bond Strength

Naotsugu Yamamoto, Makoto Takahashi, Kenji Ikeuchi, Masatoshi Aritoshi

pp. 296-299

Abstract

The metallographic factor controlling the strength of friction-bonded interface of low carbon steel (approximately 0.10 mass%C) to aluminum-magnesium (Al-Mg) alloy (equivalent to AA5083) has been investigated by TEM observations. The bond strength, estimated from the tensile strength of a specimen with a circumferential notch at the interface, rose rapidly with an increase in friction time, and then reduced. A maximum strength of 306 MPa was obtained at a friction time of 2 s (rotation speed = 20 s−1, friction pressure = 40 MPa, and forge pressure = 230 MPa). At a friction time of 1 s, an IMC layer about 100 nm wide that consisted of (Fe,Mn)Al6 and Mg2Si was formed at the interface, and an Al-oxide layer of a width less than 10 nm was observed between this IMC layer and low carbon steel substrate. In a joint showing the highest bond strength (friction time = 2 s), no Al-oxide layer could be detected between the low carbon steel substrate and IMC layer which consisted of (Fe,Mn)Al6, Fe4Al13, Fe2Al5, and Mg2Si. The width of the interfacial layer was increased to about 300 nm. At a friction time of 4 s, a layer of MgAl2O4 was observed in addition to intermetallic compounds of (Fe,Mn)Al6, Fe4Al13, Fe2Al5 and Mg2Si. The width of this layer was about 700 nm. Thus the phases formed in the interfacial layer as well as its width were altered depending on the friction time. The change in the bond strength with friction time was discussed in view of these differences in the interfacial microstructure.

Bookmark

Share it with SNS

Article Title

Interfacial Layer in Friction-Bonded Joint of Low Carbon Steel to Al-Mg Alloy (AA5083) and its Influence on Bond Strength

Behavior of Superficial Oxide Film at Solid-State Diffusion-Bonded Interface of Tin

Shinji Koyama, Makoto Takahashi, Kenji Ikeuchi

pp. 300-302

Abstract

The microstructure of the solid-state diffusion-bonded interface of tin has been investigated by TEM observations in order to reveal the evolution of the superficial oxide film of tin with the progress in bonding. The diffusion bonding was carried out in a vacuum chamber at bonding temperatures Tj of 373—493 K and at bonding pressures Pj of 90—170 MPa (bonding time = 1.8 ks). The tensile strength of the joint was increased with bonding temperature and pressure; joints having tensile strength comparable with the base metal were obtained at Tj = 493 K at Pj = 130 MPa and at Tj = 443 K at Pj = 130 MPa. When the joint strength was much lower than the base-metal strength, an interfacial region ∼500 nm in width was observed where a number of very fine inclusions that could be regarded as tin oxide were distributed. As the joint strength increased with bonding temperature, these inclusions were coarsened, and their number density was decreased. The increase in the bonding pressure enhanced these changes in the inclusion. The rise in the joint strength with bonding temperature corresponded well with the observed change in the size and density of the inclusion.

Bookmark

Share it with SNS

Article Title

Behavior of Superficial Oxide Film at Solid-State Diffusion-Bonded Interface of Tin

Microstructure and High-Temperature Strength of Directionally Solidified Al2O3/YAG/ZrO2 Eutectic Composite

Yonosuke Murayama, Shuji Hanada, Jong Ho Lee, Akira Yoshikawa, Tsuguo Fukuda

pp. 303-306

Abstract

The microstructures of an A2O3/YAG/ZrO2 eutectic Melt-Growth-Composite (MGC) solidified unidirectionally by the modified-pulling-down method were studied by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM) and electron backscattered pattern (EBSP) method. The anisotropy of strength was investigated by hardness tests and compression tests at various directions of the composite at elevated temperatures. The eutectic MGC has strong preferred growing orientation and the constituent phases hold the orientation relationship. The eutectic MGC shows excellent high-temperature strength and can deform plastically above about 1500 K. High-temperature strength above 1500 K depends on strain rate, temperature and orientation.

Bookmark

Share it with SNS

Article Title

Microstructure and High-Temperature Strength of Directionally Solidified Al2O3/YAG/ZrO2 Eutectic Composite

Effect of Heat Treatment on Microstructure and Mechanical Properties of Stoichiometric SiC/SiC Composites

Takashi Nozawa, Kazumi Ozawa, Yutai Katoh, Akira Kohyama

pp. 307-310

Abstract

Polymer impregnation and pyrolysis (PIP) is one of the most attractive fabrication processes for silicon carbide (SiC) composites due to the shape flexibility, mass production and relatively low cost. In particular, advanced PIP SiC/SiC composite with high-crystallinity and near-stoichiometric composition is expected to have superior thermo-mechanical properties including good oxidation resistance, due to the reduction of impurities and well-organized crystal structure. Additionally, by applying a thin carbon interphase by chemical vapor infiltration (CVI), control of the crack propagation and oxidation resistance are also achieved. In this study, a CVI + PIP hybrid process based on the recently developed stoichiometric PIP process was performed. Specifically, matrix crystallization was enhanced by heat treatment in Ar, and its effect on microstructures and mechanical properties were evaluated. Stoichiometric SiC/SiC composites exhibit superior flexural strength up to 1573 K in Ar and 1273 K in air. This is because the stoichiometric composition in PIP-SiC matrix reduces inner oxidation by impurities. Also, the thin pyrolytic carbon interphase tailored by CVI process effectively controls crack propagation at fiber and matrix interphase. In a similar manner, the microstructure of the stoichiometric PIP-SiC matrix, constructed by the mixture of amorphous SiC and highly crystalline SiC, was stable against the high-temperature heat exposure up to 1773 K in Ar. In particular, stoichiometric SiC/SiC composites heated at 1773 K in Ar provides superior stability of mechanical properties up to 1573 K even in air atmosphere, although extensive crystallization, in the case of heat treatment at 1973 K in Ar, caused brittle composite fracture.

Bookmark

Share it with SNS

Article Title

Effect of Heat Treatment on Microstructure and Mechanical Properties of Stoichiometric SiC/SiC Composites

Structural Transformation of MnAs1-xSbx under High Magnetic Fields

Fumihiro Ishikawa, Keiichi Koyama, Kazuo Watanabe, Tetsuya Asano, Hirofumi Wada

pp. 311-314

Abstract

Structural transformation induced by magnetic fields on MnAs and MnAs0.9Sb0.1 was investigated by the X-ray diffraction measurements in high magnetic fields up to 5 T. The X-ray diffraction profiles at 319 K for MnAs showed a single phase of the orthorhombic MnP-type structure in zero field, and applying a magnetic field of 3 T caused an appearance of the hexagonal NiAs-type structure. On further increase of magnetic fields, the single phase with the hexagonal structure was confirmed above 3.5 T in a forced ferromagnetic state. The X-ray diffraction profiles at 295 K for MnAs0.9Sb0.1 showed the hexagonal NiAs-type structure. However, the coexistence of two kinds of the NiAs-type structure with different lattice parameters was confirmed in the magnetic field of 2.5 T. The two phase coexistence was also confirmed in the temperature variation measurements in zero magnetic field. The lattice volume of the ferromagnetic phase was 1.1% larger than that of the paramagnetic phase. These results imply that the transition at TC for MnAs0.9Sb0.1 is of the first-order.

Bookmark

Share it with SNS

Article Title

Structural Transformation of MnAs1-xSbx under High Magnetic Fields

Visualization of Hydrogen Distribution in Tensile-Deformed Al-5%Mg Alloy Investigated by means of Hydrogen Microprint Technique with EBSP Analysis

Keitaro Horikawa, Kenichi Yoshida

pp. 315-318

Abstract

Hydrogen distribution in high-purity-based polycrystalline Al-5%Mg alloys prepared by changing the melting atmosphere was visualized by means of hydrogen microprint technique with electron backscattering pattern analysis after a tensile deformation at room temperature. The number of hydrogen atoms observed as silver particles on the slip lines was increased when the applied strain was increased. Hydrogen atom observed on the slip lines was totally increased when the melting atmosphere of the alloys was changed from argon to air. Hydrogen atom was observed at both slip lines and special grain boundaries when an air-melted specimen was deformed. It was shown that hydrogen atom accumulation at grain boundaries varied with the misorientation of grains and the angle to the tensile direction.

Bookmark

Share it with SNS

Article Title

Visualization of Hydrogen Distribution in Tensile-Deformed Al-5%Mg Alloy Investigated by means of Hydrogen Microprint Technique with EBSP Analysis

Fabrication of Dense Shoulder Components through Traveling Zone Sintering Assisted by a Multi-Way Loading System

Shuji Tada, Zheng Ming Sun, Hitoshi Hashimoto, Toshihiko Abe

pp. 319-322

Abstract

Dense forming of shoulder components through the pulse discharge sintering process was examined. A new technique of multi-way loading system is proposed. This loading system is able to control the pressure in a powder compact body equally even if it has an irregular sectional profile. The traveling zone heating method combined with this loading system will allow the successful sintering of shoulder components through the PDS process, since no sinking due to pressure difference occurs in a powder compact. Based on this idea, the conventional sintering procedure with a perforated spacer was applied to production of a shoulder component. The spacer dictated the loading stroke on the thin side. The result was that an aluminum shoulder component with diameters of φ15 mm at the thin side and φ25 mm at the thick side was satisfactorily produced. The relative density of the component exceeded 99%. Some problems remain to be solved, but this procedure has potential for achieving high reproducibility by developing a precise load control system and stable contact between the electrode and the cylinder.

Bookmark

Share it with SNS

Article Title

Fabrication of Dense Shoulder Components through Traveling Zone Sintering Assisted by a Multi-Way Loading System

Eutectic Modification of Al-Si Alloys with Rare Earth Metals

Kazuhiro Nogita, Stuart D. McDonald, Arne K. Dahle

pp. 323-326

Abstract

The effects of different concentrations of individual additions of rare earth metals (La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb and Lu) on eutectic modification in Al-10 mass%Si has been studied by thermal analysis and optical microscopy. According to the twin-plane reentrant edge (TPRE) and impurity induced twinning mechanism, rare earth metals with atomic radii of about 1.65 times larger than that of silicon, are possible candidates for eutectic modification. All of the rare earth elements caused a depression of the eutectic growth temperature, but only Eu modified the eutectic silicon to a fibrous morphology. At best, the remaining elements resulted in only a small degree of refinement of the plate-like silicon. The samples were also quenched during the eutectic arrest to examine the eutectic solidification modes. Many of the rare-earth additions significantly altered the eutectic solidification mode from that of the unmodified alloy. It is concluded that the impurity induced twinning model of modification, based on atomic radius alone, is inadequate and other mechanisms are essential for the modification process. Furthermore, modification and the eutectic nucleation and growth modes are controlled independently of each other.

Bookmark

Share it with SNS

Article Title

Eutectic Modification of Al-Si Alloys with Rare Earth Metals

Effects of the Density on Compressive Properties in Cellular Aluminum Produced by the Sintering Method

Cui'e Wen, Yasuo Yamada, Tadashi Asahina, Kiyotaka Kato, Tutomu Sonoda, Akira Watazu, Mamoru Mabuchi

pp. 327-329

Abstract

The cellular aluminum materials with relative densities of 0.1∼0.25 were fabricated by the sintering method and effects of the density on mechanical properties of the cellular aluminum were investigated by compressive tests. The cellular aluminum exhibited a plateau region with a nearly constant flow stress. The stress in the plateau region increased with increasing relative density, on the other hand, the densification strain decreased with increasing relative density. Observation of the deformed cells revealed that the cell walls were bent. Besides, the stress in the plateau region was proportional to 1.9 power of the density. These suggest that plastic collapse is dominated by bending of the cell walls for the cellular aluminum produced by the sintering method.

Bookmark

Share it with SNS

Article Title

Effects of the Density on Compressive Properties in Cellular Aluminum Produced by the Sintering Method

The Effect of Additional Elements on Hydrogen Permeation Properties of Melt-Spun Ni-Nb-Zr Amorphous Alloys

Shin-ichi Yamaura, Yoichiro Shimpo, Hitoshi Okouchi, Motonori Nishida, Osamu Kajita, Akihisa Inoue

pp. 330-333

Abstract

The (Ni0.6Nb0.4)45Zr50X5 (X = Al, Co, Cu, P, Pd, Si, Sn, Ta or Ti) alloy ribbons were produced by the melt-spinning technique. All ribbon specimens were confirmed to have a single amorphous phase by XRD analysis. The crystallization temperatures of the melt-spun (Ni0.6Nb0.4)45Zr50X5 (X = Al, P, Pd, Si or Sn) amorphous alloys are higher than that of the (Ni0.6Nb0.4)50Zr50 amorphous alloy (727 K). Although the hydrogen permeability of the (Ni0.6Nb0.4)45Zr50X5 (X = Si, Sn, Ta or Ti) amorphous alloys could not be measured due to severe embrittlement during the permeation test, the (Ni0.6Nb0.4)45Zr50X5 (X = Al, Co, Cu, P or Pd) amorphous alloys had high ductility which was enough to measure the permeability. The hydrogen permeabilities of the (Ni0.6Nb0.4)45Zr50Co5 and the (Ni0.6Nb0.4)45Zr50Cu5 amorphous alloys were 2.46 × 10−8 and 2.34 × 10−8 [mol·m−1·s−1·Pa−1/2] at 673 K, respectively. The (Ni0.6Nb0.4)45Zr50P5 amorphous alloy possesses the lowest permeability of 1.36 × 10−8 [mol·m−1·s−1·Pa−1/2] at 673 K among the alloys where the permeability was measured. The reduction of the permeability in the (Ni0.6Nb0.4)45Zr50P5 amorphous alloy is thought to be due to a preferential development of Zr-P atomic pairs which may suppress hydrogen solubility and hydrogen diffusivity in the alloy, because the heat of mixing for Zr-P atomic paris is negatively larger than those of other pairs such as Ni-P and Nb-P. It is concluded that the Ni-Nb-Zr-X (X=Co or Cu) amorphous alloys have high potential to hydrogen permeable membranes.

Bookmark

Share it with SNS

Article Title

The Effect of Additional Elements on Hydrogen Permeation Properties of Melt-Spun Ni-Nb-Zr Amorphous Alloys

Evaporation Behavior of SiO2 in N2-O2-H2O Atmospheres

Takao Nakagiri, Kazuya Kurokawa

pp. 334-337

Abstract

In order to clarify the influence of water vapor on evaporation and crystallization of an amorphous SiO2 scale formed on SiO2-formers, fused silica was exposed for up to 49 h at 1373—1673 K in N2-O2-H2O atmospheres. The water vapor concentration was regulated to 19.6 and 46.7% (vol%). Under conditions of low water vapor concentration, the mass change in the fused silica was negligible. On the other hand, the mass linearly decreased with the duration of exposure under high water vapor concentration. From the temperature dependence of the evaporation rate, it was speculated that the main volatile species were Si(OH)4 and SiO(OH)2 in N2-H2O and N2-O2-H2O, respectively. Moreover, although crystallization of fused silica was observed in both atmospheres, air and N2-O2-H2O, the rate of crystallization in the N2-O2-H2O atmosphere was much higher than that in air. These results indicate that crystallization is accelerated by the presence of water vapor.

Bookmark

Share it with SNS

Article Title

Evaporation Behavior of SiO2 in N2-O2-H2O Atmospheres

Factors Controlling Irradiation Hardening of Iron-Copper Model Alloy

Takeshi Kudo, Ryuta Kasada, Akihiko Kimura, Kazuhiro Hono, Kouji Fukuya, Hideki Matsui

pp. 338-341

Abstract

The factors controlling irradiation hardening and their contributions to the hardening in electron irradiated pure-iron and Fe-0.15 mass%Cu alloy were determined by means of post-irradiation annealing experiments, such as hardness measurements, positron annihilation spectroscopy (PAS) measurements, transmission electron microscope (TEM) observations and three dimensional atom probe (3DAP) analyses. In pure-iron, almost complete recovering of the hardness was observed after the annealing to 773 K, which was accompanied by disappearing of the interstitial type dislocation loops (I-loops) that were observed in as-irradiated specimen. In contrast, the hardening of Fe-0.15 mass%Cu alloy recovered in a two-step mode; about a half of the hardening recovered by the 773 K annealing, and a complete recovery was observed after annealing to 973 K. Most of the I-loops observed in as-irradiated specimen again disappeared after the annealing to 773 K. These clearly show that the I-loops are one of the main factors controlling irradiation hardening in iron-copper alloy. The residual hardening in the Fe-0.15 mass%Cu alloy after the annealing to 773 K, which is about a half of the irradiation hardening, was attributed to the copper-rich precipitates (CRP) through the direct observation by 3DAP analysis. PAS measurements revealed the disagreement between the recovery behaviors of the hardness and lifetime parameters. Based on the quantitative data analysis, it was concluded that the factor controlling the irradiation hardening of pure-iron is the I-loops, and those in Fe-0.15 mass%Cu alloy are both the I-loops and CRP of which the contributions to the hardening are almost same.

Bookmark

Share it with SNS

Article Title

Factors Controlling Irradiation Hardening of Iron-Copper Model Alloy

High-Cycle Fatigue Properties at Cryogenic Temperatures in INCONEL 718 Nickel-based Superalloy

Yoshinori Ono, Tetsumi Yuri, Hideshi Sumiyoshi, Etsuo Takeuchi, Saburo Matsuoka, Toshio Ogata

pp. 342-345

Abstract

High-cycle fatigue properties at 4 K, 77 K and 293 K were investigated in forged-INCONEL 718 nickel-based superalloy with a mean gamma (γ) grain size of 25 μm. In the present material, plate-like delta phase precipitated at γ grain boundaries and niobium (Nb)-enriched MC type carbides precipitated coarsely throughout the specimens. The 0.2% proof stress and the ultimate tensile strength of this alloy increased with decreasing temperature, without decreasing elongation or reduction of area. High-cycle fatigue strengths also increased with decreasing temperature although the fatigue limit at each temperature didn't appear even around 107 cycles. Fatigue cracks initiated near the specimen surface and formed faceted structures around crack initiation sites. Fatigue cracks predominantly initiated from coarse Nb-enriched carbides and faceted structures mainly corresponded to these carbides. In lower stress amplitude tests, however, facets were formed through transgranular crack initiation and growth. These kinds of distinctive crack initiation behavior seem to lower the high-cycle fatigue strength below room temperature in the present material.

Bookmark

Share it with SNS

Article Title

High-Cycle Fatigue Properties at Cryogenic Temperatures in INCONEL 718 Nickel-based Superalloy

Oxidation Restriction of In-flight Particles upon GS-HVOF Spraying by Nitrogen Addition to Combustion Gas

Jin Kawakita, Seiji Kuroda

pp. 346-349

Abstract

In order to improve the environmental barrier property of coatings fabricated by the HVOF spray process with a gas shroud, their oxygen content of 0.19 mass% as the lowest conventional figure was still more reduced by changing the composition of combustion gas. Introduction of nitrogen gas to the combustion chamber lowered the temperature of the in-flight spray particles while maintaining their high velocity. This method could reduce the oxygen level of a HastelloyC coating to 0.063 mass% at the lowest present value, which is comparable to that of the feedstock with 0.042 mass%. Other coating with 0.14 mass% could be obtained along with the open porosity below 0.1 vol%. The latter coating exhibited the improved environmental barrier property in artificial seawater.

Bookmark

Share it with SNS

Article Title

Oxidation Restriction of In-flight Particles upon GS-HVOF Spraying by Nitrogen Addition to Combustion Gas

Effect of Cobalt Addition on Shape Memory Properties of Ferromagnetic Ni-Mn-Ga Sputtered Films

Yoshiharu Katano, Makoto Ohtsuka, Minoru Matsumoto, Kunihiro Koike, Kimio Itagaki

pp. 350-352

Abstract

Effect of adding cobalt on the shape memory properties of Ni-Mn-Ga sputtered films was investigated. It was found that the films containing cobalt less than 5.1 mol% has a single phase and those with more than 6.8 mol%Co has two phases. The Curie temperature increased and the saturation magnetization decreased with increasing cobalt content. These films exhibited one way shape memory effect. The shape recovery start temperature increased and the temperature range of shape change broadened with increasing cobalt content.

Bookmark

Share it with SNS

Article Title

Effect of Cobalt Addition on Shape Memory Properties of Ferromagnetic Ni-Mn-Ga Sputtered Films

Unidirectional Solidification of Aluminum-Indium Monotectic Alloys by Ohno Continuous Casting

Shumpei Ozawa, Tetsuichi Motegi, K. Kuribayashi

pp. 353-356

Abstract

The vertical Ohno Continuous Casting (OCC) process was used to examine the possibility of casting Al-In monotectic alloys with a homogeneous microstructure. Three compositions, Al-17.3 mass%In, Al-20 mass%In, and Al-25 mass%In were used in this study. Al-In alloy ingots with a diameter of 8 mm and a length of 400 mm could be continuously cast by controlling the temperature and solidification velocity of the melt regardless of the alloy compositions. The Al-In alloy ingots had a very beautiful surface and a unidirectional macrostructure. Furthermore, the Al-In alloys exhibited a good distribution of β-In particles throughout all sections without any segregation of β-In phase.

Bookmark

Share it with SNS

Article Title

Unidirectional Solidification of Aluminum-Indium Monotectic Alloys by Ohno Continuous Casting

Precipitation of the Icosahedral Quasicrystalline Phase, R-phase and Laves Phase in Ferritic Alloys

Keisuke Yamamoto, Yoshisato Kimura, Yoshinao Mishima

pp. 357-360

Abstract

Precipitation behavior of intermetallic phases in ferrite matrix is investigated by transmission electron microscopy (TEM) in Fe-10Cr-1.4W-4.5Co (at%) alloys with and without 0.3 at%Si. It is intended to provide basic information for the alloy design of ferritic heat resistant alloys strengthened by intermetallic compounds. In the alloy containing Si, icosahedral quasicrytalline phase (I-phase) is found to precipitate during aging at 873 K. It is confirmed that selected area diffraction (SAD) patterns of the precipitates exhibit two-, three- and five-fold symmetry and have diffraction spots in the positions related to the golden section. In the Si-free alloy, the R-phase precipitates instead of I-phase at 873 K, and the Laves phase precipitates in both alloys during aging at higher temperature, 973 K. The Laves phase formed at 973 K transforms to the I-phase in the alloy containing Si but to the R-phase in the Si-free alloy during subsequent aging at 873 K. It is found that the structures among icosahedral quasicrystalline and crystalline R- and Laves phases are closely similar by comparing the orientation relationship, precipitate morphology and stability of I-phase with those of R- and Laves phases.

Bookmark

Share it with SNS

Article Title

Precipitation of the Icosahedral Quasicrystalline Phase, R-phase and Laves Phase in Ferritic Alloys

Blow Forming of Mg Alloy Recycled by Solid-State Recycling

Yasumasa Chino, Masaaki Kobata, Koji Shimojima, Hiroyuki Hosokawa, Yasuo Yamada, Hajime Iwasaki, Mamoru Mabuchi

pp. 361-364

Abstract

Blow forming characteristics of AZ31 Mg alloy recycled by solid-state recycling were investigated. Cylindrical scraps and machined chips were recycled by hot extrusion and hot rolling in air. Oxide layers were observed in the recycled specimens by oxygen mapping with EPMA (Electron Probe Micro Analyser). The interval of the oxygen layers for the specimen from machined chips was much shorter than that for the specimen from cylindrical scraps. As a result of tensile tests, the mechanical properties of the specimen from cylindrical scraps were found to be almost the same as those of a rolled specimen from a virgin ingot. On the other hand, at elevated temperatures, the elongation of the specimens from machined chips was low, compared with those of the rolled specimens from a virgin ingot. The large amount of oxide contamination is likely to be responsible for the lower elongation of the specimens from machined chips. In blow-forming tests, the specimen from cylindrical scraps exhibited excellent formability similar to the rolled specimen from a virgin ingot. However, the specimen from machined chips showed poor formability. Thus, oxide contamination adversely affected the formability of recycled Mg alloy.

Bookmark

Share it with SNS

Article Title

Blow Forming of Mg Alloy Recycled by Solid-State Recycling

Surface Oxidation of Fe-48 mol%Al Single Crystal under a High Vacuum

Akira Yamauchi, Kyousuke Yoshimi, Tomohide Haraguchi, Shuji Hanada

pp. 365-368

Abstract

In order to investigate the effect of aging heat treatment and surface orientation on oxidation during the nanopore formation of B2-type FeAl, the surface of Fe-48 mol%Al single crystal was analyzed by Auger Electron Spectroscopy (AES). Electropolished and plasma-cleaned surfaces were aged for 18 ks at 723 K, in vacuum (about 5 × 10−4 Pa). A thin oxide layer was already formed on the non-aged surface. A thicker oxide layer was grown on the aged surface, but the difference in thickness of the oxide layers was slight. Further, the orientation dependence of the thickness of the oxide layers was even smaller. The thickness of the oxide layer on the FeAl single crystal is comparable to that of the passive film on the aluminum foil. Therefore, it is concluded that the influence of the aging heat treatment on oxidation during the nanopore formation of B2-type FeAl is negligible.

Bookmark

Share it with SNS

Article Title

Surface Oxidation of Fe-48 mol%Al Single Crystal under a High Vacuum

Microstructures and Magnetic Properties of Sm-Fe-N Thick Films Produced by the Aerosol Deposition Method

Tomohito Maki, Satoshi Sugimoto, Toshio Kagotani, Koichiro Inomata, Jun Akedo

pp. 369-372

Abstract

This paper describes magnetic properties and microstructures of Sm-Fe-N thick films prepared by the aerosol deposition (AD) method. The maximum thickness (d) of 77 μm was obtained in the AD conditions of gas flow rate (gfr) = 6 × 10−3 m3/min for 4 min. From this result, the deposition rate was estimated as 19 μm/min. The density (ρ) of Sm-Fe-N films were in the range of 4.9 × 103−5.9 × 103 kg/m3, which were 64—77% of the X-ray density of the Sm2Fe17N3 compound reported (7.67 × 103 kg/m3). However, they were higher than the density of the green compact of Sm-Fe-N host powders (3.86 × 103 kg/m3). The Sm-Fe-N AD films showed the remanences (Br) of 0.36—0.42 T, which were 58—68% of that of host powder (0.62 T). The coercivities (μ0HcJ) increased from 1.16 T to 1.69—1.86 T after the deposition because the average grain size decreased from 1.94 to 0.32 μm. XRD analysis revealed that the ratio of peak intensity of (006) to (033) in the Sm-Fe-N AD films was higher than that in the host powder. In addition, the remanence measured in perpendicular to the film plane was higher than that in parallel after the compensation of demagnetizing field. Therefore, it is considered that the c-axis in Sm-Fe-N AD films has a tendency to align in perpendicular to the film plane.

Bookmark

Share it with SNS

Article Title

Microstructures and Magnetic Properties of Sm-Fe-N Thick Films Produced by the Aerosol Deposition Method

Synthesis and Consolidation of Ternary Compound Ti3SiC2 from Green Compact of Mixed Powders

Zheng Ming Sun, Songlan Yang, Hitoshi Hashimoto, Shuji Tada, Toshihiko Abe

pp. 373-375

Abstract

Ternary compound Ti3SiC2 has been successfully synthesized and concurrently consolidated by sintering green compact of starting powder mixture. 3Ti/SiC/C powder mixture was compacted and heated in vacuum or in Ar atmosphere at temperatures from 1573 to 1773 K for a time period ranged from 2 to 6 hours. It has been found that either in vacuum or in Ar atmosphere the Ti3SiC2 content reached 100% in the surface layer. The growth of Ti3SiC2 in a layered manner on the surface of the sample was observed. It was also found that the sample sintered in Ar atmosphere is denser than those sintered in vacuum. After sintered in Ar atmosphere at 1773 K for 2 hours, the relative density of the compound reached 97%. Occurrence of liquid phase during sintering contributed to the densification of the compound.

Bookmark

Share it with SNS

Article Title

Synthesis and Consolidation of Ternary Compound Ti3SiC2 from Green Compact of Mixed Powders

Comparison of Nanocrystalline Surface Layer in Steels Formed by Air Blast and Ultrasonic Shot Peening

Yoshikazu Todaka, Minoru Umemoto, Koichi Tsuchiya

pp. 376-379

Abstract

Surface nanocrystallization in various steels by shot peening (both air blast (ABSP) and ultrasonic (USSP)) was investigated. In all the shot-peened specimens, the equiaxed nanocrystals with grain size of several 10 nm were observed at the surface regions. The depth of nanocrystalline (NC) layers was several μm. The NC layers have extremely high hardness and were separated from the deformed structure regions just under the NC layers with sharp boundaries. By annealing, the NC layers show the substantially slow grain growth without recrystallization. These characteristics are similar to those observed in the specimens treated by ball milling, ball drop and particle impact deformation. Comparing ABSP and USSP at the similar peening condition, the produced volume of NC region in ABSP is larger than that in USSP.

Readers Who Read This Article Also Read

Bookmark

Share it with SNS

Article Title

Comparison of Nanocrystalline Surface Layer in Steels Formed by Air Blast and Ultrasonic Shot Peening

Thermodynamic Study of the Phase Equilibria in the Sn-Ag-Bi-Cu Quaternary System

Kodai Doi, Hiroshi Ohtani, Mitsuhiro Hasebe

pp. 380-383

Abstract

The phase equilibria in the Sn-Ag-Bi-Cu quaternary system have been studied experimentally and using thermodynamic calculations. The phase boundaries in some vertical sections of the Sn-Bi-Cu and Sn-Ag-Bi-Cu systems were determined using differential scanning calorimetry. The experimental values of the thermodynamic parameters were used in the calculations of the phase diagrams for the quaternary system. Thermodynamic evaluation of the Sn-Bi-Cu system was performed by considering a two-phase separation of the liquid phase. The phase diagram calculations showed that the Cu-Sn-based compounds form as the primary crystals, even for low Cu concentrations, and accordingly, the melting point of the alloys rises markedly. The microstructure of the solidified alloys was observed using a scanning electron microscope. We observed that coarsened Bi particles existed alongside the Cu-Sn-based primary crystals. Based on these results, a non-equilibrium solidification process using the Scheil model was simulated and compared with the observed structures. Our calculations reasonably explain the Bi-enrichment in the final solidification zone.

Readers Who Read This Article Also Read

Bookmark

Share it with SNS

Article Title

Thermodynamic Study of the Phase Equilibria in the Sn-Ag-Bi-Cu Quaternary System

Grain Size Refinements of Mg Alloys (AZ61, AZ91, ZK60) by HDDR Treatment

Takanori Miyazawa, Yuko Kobayashi, Atsunori Kamegawa, Hitoshi Takamura, Masuo Okada

pp. 384-387

Abstract

The present paper describes the grain size refinements of Mg alloys (AZ61, AZ91, ZK60) by HDDR treatment. As a result of the HDDR treatment at 350°C under a hydrogen pressure of 7 MPa for 24 h, following by evacuation at 350°C for 3 h, the grain size of AZ61 alloys was reduced from 10∼20 μm to 100∼200 nm. At the hydrogenation stage for the AZ91 alloys, the disproportionation reaction occurred with forming MgH2, Mg2Al3 and Al phases. At the following desorption stage, the three phases were recombined and the Mg-Al-Zn solid-solution alloy was reformed. After the HDDR treatment, the grain size of AZ91 alloys was reduced to 100∼200 nm. For the ZK60 alloy without Al, the grain size was reduced from 2∼20 μm to about 300 nm by the HDDR treatment.

Readers Who Read This Article Also Read

Bookmark

Share it with SNS

Article Title

Grain Size Refinements of Mg Alloys (AZ61, AZ91, ZK60) by HDDR Treatment

Growth Analysis of Banded Microstructure Formed during Directional Solidification of Peritectic Alloys

Masaki Sumida

pp. 388-391

Abstract

In this work, a growth analysis is made on the banded microstructure formation during directional solidification of peritectic alloys. The convection model, which has been proposed to explain the discrete banded microstructure formation, is extended in the part of the nucleation condition. Applying the nucleation and constitutional undercooling criterion, a new calculation was developed. Concentration profile calculated by the model was compared with experimentally obtained banded microstructure in Fe-Co and also with those of the convection and the diffusion models. Consistent agreement with experiments is shown. In comparison with the other models, interesting difference in predictions of concentration profile is obtained between them.

Readers Who Read This Article Also Read

Bookmark

Share it with SNS

Article Title

Growth Analysis of Banded Microstructure Formed during Directional Solidification of Peritectic Alloys

Effect of Refractory Elements (X: Mo, W, Re) on the Microstructure Evolution of Fe-8Cr-0.1C-X Martensitic Steels during Tempering

Tomonori Kunieda, Yoshinori Murata, Masahiko Morinaga, Toshiyuki Koyama

pp. 392-395

Abstract

It is well known that the refractory elements (Mo, W, Re) play an important role in increasing the creep strength of heat resistant ferritic steels. However, the long-term creep strength of the ferritic steels depends on a number of factors, e.g., phase stability of the martensite, the diffusivity of alloying elements, the coarsening rate of precipitates in the steels, etc. Therefore, it is important for the future alloy design to make it clear the main factor influenced by the refractory elements. The purpose of this study is to examine the effect of the refractory elements only on the phase stability of martensite itself. For this purpose, the microstructure evolution was investigated using quaternary martensitic steels: Fe-Cr-C-X (X: Mo, W, Re). It was found that the microstructure evolution was retarded by the Re addition, since Re worked to increase the phase of the martensite and also to suppress the carbide (M23C6) agglomeration during tempering. On the other hand, it was suggested that W could suppress the recovery of defects such as dislocations in the martensite phase.

Readers Who Read This Article Also Read

Bookmark

Share it with SNS

Article Title

Effect of Refractory Elements (X: Mo, W, Re) on the Microstructure Evolution of Fe-8Cr-0.1C-X Martensitic Steels during Tempering

Thermal-Mechanical Fatigue Property of Ni-Base Single Crystal Superalloys TMS-82+ and TMS-75

Yoshikazu Ro, Hao Zhou, Yutaka Koizumi, Tadaharu Yokokawa, Toshiharu Kobayashi, Hiroshi Harada, Ikuo Okada

pp. 396-398

Abstract

The effect of hold time (th) on the thermal-mechanical fatigue property (TMF) of two nickel-base single crystal superalloys TMS-82+ and TMS-75, which are second- and third-generation single crystals, respectively, was investigated. Cycles to failure for both alloys decreased drastically with the increase in the hold time. The TMS-75 showed a longer life than the TMS-82+ at th=0. The TMS-82+ showed a longer life than the TMS-75 at th≠0, which could be attributed to the higher tensile strength at 400 °C and higher stress relaxation resistance at 900 °C in the TMS-82+. From microstructural studies, a slightly rafted γ/γ′ structure was observed in the TMS-82+ for TMF with a hold time. This work indicates that the TMS-82+ is appropriate to be served in gas turbine engines under specific conditions such as electric power generation.

Readers Who Read This Article Also Read

Bookmark

Share it with SNS

Article Title

Thermal-Mechanical Fatigue Property of Ni-Base Single Crystal Superalloys TMS-82+ and TMS-75

Effect of Heat Treatment on Impact Toughness of Aluminum Silicon Eutectic Alloy Processed by Rotary-Die Equal-Channel Angular Pressing

Aibin Ma, Naobumi Saito, Ichinori Shigematsu, Kazutaka Suzuki, Makoto Takagi, Yoshinori Nishida, Hiroyuki Iwata, Toru Imura

pp. 399-402

Abstract

A Rotary-die equal-channel angular pressing (RD-ECAP) process was applied to improve the impact toughness of Al-11 mass%Si eutectic alloy (AC8A). RD-ECAP was effective at improving impact toughness: the impact toughness increased as the number of pressings increased. In addition, the effects of heat treatments on impact toughness were investigated. When samples were heat-treated under the T6 condition before the RD-ECAP process, they exhibited a higher impact toughness than the samples without T6 treatments. The absorbed energy of the heat-treated samples followed by RD-ECAP 4 times was 4.32 J/cm2, which was much higher than that of the non-heat-treated samples, 2.89 J/cm2, and three times higher than the value of the heat-treated but non-processed samples, 1.08 J/cm2. The results show that the combination of the T6 treatment and the RD-ECAP process is more effective at improving the impact toughness, compared to applying the RD-ECAP process alone.

Readers Who Read This Article Also Read

Bookmark

Share it with SNS

Article Title

Effect of Heat Treatment on Impact Toughness of Aluminum Silicon Eutectic Alloy Processed by Rotary-Die Equal-Channel Angular Pressing

Refined Solidification Structure and Improved Formability of A356 Aluminum Alloy Plate Produced using a High-Speed Twin-Roll Strip Caster

Kenta Suzuki, Shinji Kumai, Yuichi Saito, Akikazu Sato, Toshio Haga

pp. 403-406

Abstract

An A356 aluminum alloy was cast into a 2 mm thick plate by a strip caster equipped with a pair of water-cooled rolls made of pure copper. The twin-roll cast plate exhibited fairly refined primary aluminum dendrite- and eutectic solidified structure. The estimated maximum cooling rate at the near-surface region of the plate is 4000 K/s. These values are significantly higher than the cooling rate for the permanent mold cast (2 K/s). The cast plate was cold-rolled and annealed into a 0.5 mm thick sheet. The resultant sheet was subjected to the 180° bending test. No cracking occurred in the twin-roll cast product. Improved formability is considered to be mainly due to the homogeneous distribution of fine Si particles.

Readers Who Read This Article Also Read

Bookmark

Share it with SNS

Article Title

Refined Solidification Structure and Improved Formability of A356 Aluminum Alloy Plate Produced using a High-Speed Twin-Roll Strip Caster

Mechanical Properties and Microstructure of F82H Steel doped with Boron or Boron and Nitrogen as a Function of Heat Treatment

Eiichi Wakai, Michitaka Sato, Tomotsugu Sawai, Kiyoyuki Shiba, Shiro Jitsukawa

pp. 407-410

Abstract

Effect of heat treatment on mechanical properties and microstructures of Fe-8Cr-2W-0.1C-0.2V-0.04Ta martensitic steel F82H doped with about 60 mass ppm B or both of 60 mass ppm B and 200 mass ppm N has been examined. The normalization was heated at temperatures from 950 to 1250°C for 1.8 ks, followed by air cooling or water quenching. After tempering treatment at 780°C or 750°C, the distributions of boron, boron nitride and oxygen were measured by a secondary ion mass spectrometry (SIMS). Optical microstructural observation and tensile and Charpy impact tests were performed also. In the boron doped F82H the tensile properties were similar to the non-doped F82H, but the ductile-brittle transition temperature (DBTT) shifted from −43°C to 15°C. SIMS images with high intensity of boron were observed in localized regions of the boron doped F82H. Water quenching reduced the DBTT shift, about 30°C, and the localized boron intensity was slightly decreased. In the boron and nitrogen doped tempered-F82H heat-treated by the water quenching from the normalizing temperature, the properties of tensile and Charpy impact were similar to the non doped F82H, and no pronounced localized boron image was observed in the SIMS image and no intensities of oxides and boron nitride were observed either.

Readers Who Read This Article Also Read