著者

Toshihiro Tsuchiyama Yoshikazu Nakamura Hideyuki Hidaka Setsuo Takaki

出版者

The Japan Institute of Metals and Materials

雑誌

MATERIALS TRANSACTIONS (ISSN:13459678)

巻号頁・発行日

vol.45, no.7, pp.2259-2263, 2004 (Released:2005-06-24)

参考文献数

12

被引用文献数

7 10

---

Ultrafine grained austenitic structure was obtained in 18Cr-9Ni stainless steel by thermomechanical treatment using reversion from deformation-induced martensite. The superplastic deformation behavior was investigated at 923 K for the steels containing various amounts of retained martensite particles in the initial structure before tensile testing. The retained martensite was effective for suppressing grain growth of austenite and necessary for the superplasticity although it was thermodinamically unstable phase and gradually decreased its volume fraction with superplastic deformation. Therefore, the superplastic elongation was strongly dependent on the initial volume fraction of the retained martensite. The total superplastic elongation was enlarged with increasing the initial amount of martensite, and the maximum elongation of about 270% was obtained when the volume fraction was controlled to be around 10 vol%. However, the increase in elongation was leveled off in the range above 15 vol% martensite. The effect of the retained martensite on the superplasticiy was discussed in connection with the changes in volume fraction of the martensite, austenite grain size and deformation mechanism.

著者

Hao Yu Shigeharu Ukai Shigenari Hayashi Naoko Oono

出版者

The Japan Institute of Metals and Materials

雑誌

MATERIALS TRANSACTIONS (ISSN:13459678)

巻号頁・発行日

vol.59, no.4, pp.563-567, 2018-03-25 (Released:2018-03-25)

参考文献数

23

被引用文献数

4 6

---

Alumina-forming oxide dispersion strengthened (ODS) superalloys are favorable oxidation-resistant materials for extremely high temperature applications. In order to develop the advanced Co-based superalloys with high strength and superior oxidation resistance at elevated temperature of 1000℃, a new series of Co-Cr-Al ODS superalloys were designed and fabricated by mechanical alloying (MA) and spark plasma sintering (SPS), and then followed by hot rolling and annealing at 1200℃. In this work, the oxidation behavior of Co-10Al (mass%) ODS superalloys with/without 20Cr was investigated at 1000℃ in air to understand the effect of Cr on oxidation resistance. The results indicate that the addition of Cr improves the oxidation resistance significantly through optimizing the oxide scales from the multilevel scales with an external CoO/CoAl2O4 and an internal Al2O3 to a single layer of Al2O3. The alumina-forming Co-20Cr-10Al (mass%) ODS superalloys are expected to be applicable at 1000℃.

著者

Takeshi Waki Kento Hani Yoshikazu Tabata Hiroyuki Nakamura

出版者

The Japan Institute of Metals and Materials

雑誌

MATERIALS TRANSACTIONS (ISSN:13459678)

巻号頁・発行日

vol.64, no.2, pp.564-567, 2023-02-01 (Released:2023-01-25)

参考文献数

12

被引用文献数

3

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The La–Co cosubstituted M-type strontium ferrite attracts attention as a base material for high-performance ferrite magnets. It is known that the uniaxial magnetic anisotropy of the material is enhanced by increasing the amount of Co by heat treatment under high oxygen pressure, but there is a problem in obtaining a pure sample. The present study investigated the conditions to obtain a single phase with increased La–Co substitution by heat treatments under several oxygen pressures. A single phase of M-type ferrite was obtained up to x = 0.35 at pO2 = 1 atm, and up to x = 0.65 at pO2 = 10 atm with the composition formula of Sr1−xLaxFe12−xCoxO19. The magnetic anisotropy is enhanced according to the Co concentration in these samples. This Paper was Originally Published in Japanese in J. Jpn. Soc. Powder Powder Metallurgy 69 (2022) 288–292.

著者

Yudai Iwamizu Kota Suzuki Naoki Matsui Masaaki Hirayama Ryoji Kanno

出版者

The Japan Institute of Metals and Materials

雑誌

MATERIALS TRANSACTIONS (ISSN:13459678)

巻号頁・発行日

vol.64, no.1, pp.287-295, 2023-01-01 (Released:2022-12-25)

参考文献数

42

被引用文献数

1

---

A machine learning method was developed, which predicts ionic conductivity based on chemical composition alone, aiming to develop an efficient method to search for lithium conductive oxides. Under the obtained guideline, the material search was focused on the Li2O–SiO2–MoO3 pseudo-ternary phase diagram, which is predicted to have high ionic conductivity (>10−4 S·cm−1). We investigated the formation range, ionic conductivity, and crystal structure of the lithium superionic conductor (LISICON) solid solution on the Li4SiO4–Li2MoO4 tie line. The ionic conductivity of the LISICON phases is about 10−7 S·cm−1, which is higher than that of the end members; however, two orders of magnitude lower than that of the analogous LISICON materials. In addition, the experimental values were two or three orders of magnitude lower than the predicted conductivity values by machine learning. However, the developed prediction model can be used as an initial guideline for material exploration since the predicted values follow the trend of practical conductivity in the phase diagram. The crystal structure analysis indicated that the distance between the lithium sites and the occupancy of each lithium site in the crystal structure contributed to the decrease in ionic conductivity. This strong correlation between crystal structure and ionic conductivity was one of the reasons for the discrepancy between the predicted ionic conductivity based on chemical composition alone and the experimental value. This Paper was Originally Published in Japanese in Japan Soc. Powder Powder Metallurgy 69 (2022) 108–116.

著者

Kyosuke Hirayama Hiroyuki Toda Takafumi Suzuki Masayuki Uesugi Akihisa Takeuchi Wolfgang Ludwig

出版者

The Japan Institute of Metals and Materials

雑誌

MATERIALS TRANSACTIONS (ISSN:13459678)

巻号頁・発行日

vol.63, no.4, pp.586-591, 2022-04-01 (Released:2022-03-25)

参考文献数

26

被引用文献数

1

---

Crystallographic assessment of the hydrogen embrittlement behavior of Al–Zn–Mg alloy was performed by means of a technique combining fracture trajectory analysis and synchrotron X-ray diffraction contrast tomography. The 3D microstructure reconstructed using diffraction contrast tomography contained 119 grains. Fracture surfaces revealing intergranular fracture, ductile fracture, and quasi-cleavage fracture were observed in the alloy. While the intergranular crack initiated at a grain boundary with high grain boundary energy and a high angle between the grain boundary plane and loading direction, the crack propagation itself was not observed to be sensitive to these two parameters. The quasi-cleavage fracture surfaces were not characterized by any specific crystal orientation because of variation in the free surface segregation energy of hydrogen uniforms without depending on surface orientation.

著者

Satoru Nishida Souichiro Nishino Masahiko Sekine Yuuki Oka Stefanus Harjo Takuro Kawasaki Hiroshi Suzuki Yukio Morii Yoshinobu Ishii

出版者

The Japan Institute of Metals and Materials

雑誌

MATERIALS TRANSACTIONS (ISSN:13459678)

巻号頁・発行日

vol.62, no.5, pp.667-674, 2021-05-01 (Released:2021-04-25)

参考文献数

19

被引用文献数

5

---

In this study, we used neutron diffraction to analyze in a non-destructive method the distribution of internal residual stress in a free-cutting steel bar processed by cold drawing and straightening. Since a change in lattice-plane spacing occurs in a strain-free standard sample used as a reference due to the cold-drawing and straightening processes, it was necessary for the sake of improving measurement accuracy to prepare strain-free standard samples for each individual process. As a result, the residual stresses were successfully measured with excellent stress balance. The residual stresses generated by the cold-drawing process were reduced by subsequent straightening, and the distribution of residual stresses by finite element method (FEM) simulation was consistent with the measured values by neutron diffraction. As a result of the FEM analysis, it is assumed that the rod was subjected to strong tensile strains in the axial direction during the drawing process, and the residual stresses were generated when the rod was unloaded. Those residual stresses were presumably reduced by the redistribution of residual stresses in the subsequent straightening process.

著者

Kazuhiro Nogita Stuart D. McDonald Arne K. Dahle

出版者

The Japan Institute of Metals and Materials

雑誌

MATERIALS TRANSACTIONS (ISSN:13459678)

巻号頁・発行日

vol.45, no.2, pp.323-326, 2004 (Released:2005-06-24)

参考文献数

13

被引用文献数

115 177

---

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.

著者

Satoshi Minamoto Takuya Kadohira Kaita Ito Makoto Watanabe

出版者

The Japan Institute of Metals and Materials

雑誌

MATERIALS TRANSACTIONS (ISSN:13459678)

巻号頁・発行日

vol.61, no.11, pp.2067-2071, 2020-11-01 (Released:2020-10-25)

参考文献数

14

被引用文献数

17

---

The concept of the Materials Integration (MI) has been proposed as a framework to evaluate the performance of structural materials based on the PSPP (Process, Structure, Property, Performance) linkage. In order to solve direct problems for structural materials with complex input and output, this system designs and executes a workflow that enables continuous computation while focusing on data coordination and aggregation, and aggregates data.In the second phase of our project, we will develop an Application Programming Interface (API) to drive the MI-System from external programs so that the MI-System can be used in combination with various algorithms used to solve inverse problems, such as optimization and Bayesian statistical algorithms. In addition, we aim to solve the inverse problem systematically and efficiently by developing a mechanism to effectively utilize the computational resources distributed in various places and to handle large scale computations. This Paper was Originally Published in Japanese in Materia Japan 58 (2019) 511–514.

著者

Osamu Otsuka Yutaka Yanaba Takeshi Yoshikawa Mitsuo Yamashita

出版者

(公社)日本金属学会/(一社)軽金属学会,(一社)資源・素材学会,ナノ学会,(公社)日本金属学会,(一社)日本塑性加工学会,(公社)日本鋳造工学会,日本銅学会,(一社)日本熱処理技術協会,(一社)日本熱電学会,(一社)日本非破壊検査協会,(一社)日本溶射学会,(一社)粉体粉末冶金協会,(公社)腐食防食学会

雑誌

MATERIALS TRANSACTIONS (ISSN:13459678)

巻号頁・発行日

vol.57, no.7, pp.1183-1191, 2016-07-01 (Released:2016-06-25)

参考文献数

20

被引用文献数

1

---

A method has been developed for the recovery and recycling of selenium (Se) from Se-containing wastewater using the Se reducing bacterium, Pseudomonas stutzeri NT-I. The treatment of Se-containing wastewater with strain NT-I produced the bioselenium, which was composed mainly of organic matter and 11–14 mass% of Se. Specifically, the recovery of Se from the bioselenium by oxidizing roasting followed by wet reduction was studied. After thermodynamic calculations were performed to estimate the oxidizing behavior during roasting, experiments were conducted on the bioselenium for various roasting conditions. Selenium in the bioselenium was recovered in the form of solid SeO2 with a purity of 99% (metal basis) and a maximum yield of 97 mass% after roasting at 700℃. Wet reduction of SeO2 to metallic Se was achieved with a purity of 99% (metal basis).

著者

Ikuya Yamada Atsushi Tanaka Seiji Oda Yuichi Okazaki Fumito Toda Yuta Kato Yuta Kizawa Masaya Oshita Manami Goto Amane Morimura Asuka Ochi Kaoru Toda Wencong Wang Hajime Yamamoto Hidekazu Ikeno Shunsuke Yagi

出版者

The Japan Institute of Metals and Materials

雑誌

MATERIALS TRANSACTIONS (ISSN:13459678)

巻号頁・発行日

vol.64, no.9, pp.2097-2104, 2023-09-01 (Released:2023-08-25)

参考文献数

37

---

Chemical substitution is an effective way to improve electrocatalytic properties in transition metal oxides. We investigate the synergistic effect between Fe4+ and Co4+ ions on the catalytic activity for oxygen evolution reaction (OER) in the Fe–Co-mixed perovskite oxide CaFe1−xCoxO3. The OER activity of CaFe1−xCoxO3 is substantially increased by small amounts of Co (Fe) doping into CaFeO3 (CaCoO3), leading to the superiority compared to the pure Fe and Co perovskite oxides. The x dependences of the OER overpotential and specific activity for CaFe1−xCoxO3 (0.05 ≦ x ≦ 0.95) are expressed by constant offset from the weighted average between CaFeO3 and CaCoO3, which can be interpreted to be the synergistic effect between Fe4+ and Co4+ ions on OER activity. The absence of the optimum x for the highest activity for CaFe1−xCoxO3 contrasts with the volcano-like plots reported in various mixed-metal oxides. First-principle calculations using the special quasirandom structure models on CaFe1−xCoxO3 (x = 0.03–0.5) demonstrate that about half the amount of Fe4+ is electronically activated to possess smaller charge-transfer energies, corroborating the enhancement of catalytic activity in CaFe1−xCoxO3. These findings provide new insight into the synergistic effects in complex transition metal oxide catalysts.

著者

Hiroki Kanai Yoshiharu Kariya Hiroshige Sugimoto Yoshiki Abe Yoshinori Yokoyama Koki Ochi Ryuichiro Hanada Shinnosuke Soda

出版者

The Japan Institute of Metals and Materials

雑誌

MATERIALS TRANSACTIONS (ISSN:13459678)

巻号頁・発行日

vol.63, no.6, pp.759-765, 2022-06-01 (Released:2022-05-25)

参考文献数

12

被引用文献数

2

---

A method for predicting the lifetime of fatigue crack network formation in die-attach joints is considered through experiments on high-speed thermal cycling using a Si/solder/Si joint specimen and the mechanism is identified. Equibiaxial stresses are generated in the solder layer because thermal deformation of the solder is constrained by the Si, which causes continuous initiation and propagation of crisscross-shaped cracks. When the crack density is sufficiently high, crack growth is arrested by collisions between cracks, and the formation of the fatigue crack network is completed. Based on these results, development of the damaged area and arrest of the development by collisions between the cracks is expressed in terms of extended volume theory incorporating crack initiation and propagation functions for solder as well as considering the damage rate equation. The experimental result for the relationship between the damage ratio in the die-attach joint and the number of cycles under each thermal condition are reproduced by the damage rate equation.

著者

Yoshitaro Nosé Ayako Kushida Teruyuki Ikeda Hideo Nakajima Katsushi Tanaka Hiroshi Numakura

出版者

The Japan Institute of Metals and Materials

雑誌

MATERIALS TRANSACTIONS (ISSN:13459678)

巻号頁・発行日

vol.44, no.12, pp.2723-2731, 2003 (Released:2005-09-06)

参考文献数

19

被引用文献数

33 39

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The phase boundaries pertaining to γ2 (FePt) and γ3 (FePt3) phases in the Fe-Pt system have been re-examined by measuring (1) the compositions of interphase boundaries in diffusion couples, (2) the equilibrium compositions in two-phase alloys and (3) the electrical resistivity as a function of temperature. The results obtained by the three methods are consistent with each other. The γ (fcc solid solution) ↔ γ2+γ3 eutectoid has been found to be located at a point higher in Pt concentration and lower in temperature than in the currently adopted phase diagram, the stability range of the γ2 phase exhibits considerable asymmetry. Other phase boundaries, as well as the ferromagnetic ↔ paramagnetic transition in the γ2 phase detected by the resistivity measurements, are in fair agreement with the data in the literature.

著者

Junyuan Zhong Fan Zhang Xiangling Tong Xinxin Hu Bo Wang

出版者

The Japan Institute of Metals and Materials

雑誌

MATERIALS TRANSACTIONS (ISSN:13459678)

巻号頁・発行日

vol.64, no.7, pp.1376-1386, 2023-07-01 (Released:2023-06-25)

参考文献数

99

被引用文献数

2

---

The development of hydrogen energy will help to reduce the use of nonrenewable energy sources and achieve global carbon neutrality. The aluminum-water reaction is an important method of producing hydrogen because aluminum has abundant reserves, a high yield, and no pollution. However, the dense passive oxide film on the surface of aluminum, on the other hand, often obstructs this reaction, which is the primary issue limiting the development of aluminum-based hydrolytic materials. Mechanochemical activation by processing severely plastic deformed aluminum-based materials is one effective approach and has been developed in recent years. This article reviews recent progress of hydrogen production from hydrolysis of severely plastic deformed aluminum-based materials. The kinetic model of aluminum-water reaction, aging protection of the materials, catalytic mechanism and stable rate control for the hydrolysis of aluminum-based materials are reviewed. Furthermore, some existing problems as well as some suggestions for future research on hydrogen production from aluminum-based materials are also discussed.

著者

Yoichi Ikeda Yoshihiko Umemoto Daiju Matsumura Takuya Tsuji Yuki Hashimoto Takafumi Kitazawa Masaki Fujita

出版者

The Japan Institute of Metals and Materials

雑誌

MATERIALS TRANSACTIONS (ISSN:13459678)

巻号頁・発行日

vol.64, no.9, pp.2254-2260, 2023-09-01 (Released:2023-08-25)

参考文献数

29

被引用文献数

1

---

Extended X-ray absorption fine structure (EXAFS) and neutron diffraction experiments were carried out to clarify the typical features of the local structure of a family of medium-entropy alloys (CrCoNi, MnCoNi, and FeCoNi). A simple random cluster model was constructed for analyzing EXAFS spectra, and static and dynamic components of the mean-square relative displacement (MSRD) were separately extracted. In our analysis, the static MSRD of the MnCoNi sample was slightly larger than those of the CrCoNi and FeCoNi samples, whereas the dynamic MSRDs of these samples were almost identical. Based on the complementary neutron diffraction data, we argued that the origin of the large static displacement in the MnCoNi alloy can be associated with a short-range structural transformation through long-term structural relaxation.

著者

Hiromi Eba Chikako Anzai Satoshi Ootsuka

出版者

The Japan Institute of Metals and Materials

雑誌

MATERIALS TRANSACTIONS (ISSN:13459678)

巻号頁・発行日

vol.59, no.2, pp.244-250, 2018-02-01 (Released:2018-01-25)

参考文献数

21

被引用文献数

8 9

---

The structural irregularities of solid-oxide layers for fuel cells prepared by electrophoretic deposition and co-sintering were examined using electron-probe microanalysis (EPMA) and X-ray analysis. The solid-oxide electrolyte layer with Sr- and Mg-doped lanthanum gallate (LSGM) prepared on a NiO-yttria-stabilized zirconia (YSZ) anode with an inserted Gd-doped ceria (GDC) buffering interlayer was not rigid. EPMA of the cross-section showed diffusion of La and Sr out of LSGM, and Ni, Y, and Zr out of NiO-YSZ. Using synchrotron radiation, X-ray absorption near-edge structures of the layer cross-sections were examined using an X-ray fluorescence yield method. The spectral features supported the formation of SrLaG3O7 and La-doped GDC by a reaction between the layers. The formation of these and other oxides was also confirmed by X-ray powder diffraction patterns. Because the electrophoretic deposition layers were co-sintered, elemental diffusion must have occurred before the synthetic powders were well fused and fixed in each layer. As an alternative to GDC, La-doped ceria (LDC) was synthesized, and La diffusion between LSGM and LDC was examined using X-ray powder diffraction. LDC, which contains 40% La, seems to be the best material to suppress La migration.

著者

Yoshihiko Umemoto Yoichi Ikeda Masaki Fujita

出版者

The Japan Institute of Metals and Materials

雑誌

MATERIALS TRANSACTIONS (ISSN:13459678)

巻号頁・発行日

vol.64, no.8, pp.2018-2021, 2023-08-01 (Released:2023-07-25)

参考文献数

24

被引用文献数

3

---

Neutron scattering experiments were conducted to reveal the origin of diffuse scattering in a medium-entropy alloy (MnCoNi). Results showed that a time-temperature-dependent short- and long-range structural transformation from a face-centered cubic to a primitive tetragonal structure occurs. In the MnCoNi alloy, the long-range ordered phase with a relatively small c/a ratio of 3.7(1)% can only be grown in a limited temperature range, whereas short-range structural transformation with a short correlation length of 1–4 nm can be formed in a wide temperature range. On the contrary, no sign of short-/long-range staggered atomic rearrangement, such as L10 and L12 structures, was observed in the CrCoNi alloy at least at room temperature. The difference in the forming ability of short-/long-range ordering between the MnCoNi and CrCoNi alloys was discussed.

著者

Lukas Weissitsch Franziska Staab Karsten Durst Andrea Bachmaier

出版者

The Japan Institute of Metals and Materials

雑誌

MATERIALS TRANSACTIONS (ISSN:13459678)

巻号頁・発行日

vol.64, no.7, pp.1537-1550, 2023-07-01 (Released:2023-06-25)

参考文献数

137

被引用文献数

5

---

Magnets are key materials for the electrification of mobility and also for the generation and transformation of electric energy. Research and development in recent decades lead to high performance magnets, which require a finely tuned microstructure to serve applications with ever increasing requirements. Besides optimizing already known materials and the search on novel material combinations, an increasing interest in unconventional processing techniques and the utilization of magnetic concepts is apparent. Severe plastic deformation (SPD), in particular by high-pressure torsion (HPT) is a versatile and suitable method to manufacture microstructures not attained so far, but entitling different magnetic coupling mechanisms fostering magnetic properties. In this work, we review recent achievements obtained by HPT on soft and hard magnetic materials, focusing on powder as starting materials. Furthermore, we give specific attention to the formation of magnetic composites and highlight the opportunities of powder starting materials for HPT to exploit magnetic interaction mechanisms.

著者

Daiki Ichikawa Mahiro Sawada Shinsuke Suzuki

出版者

The Japan Institute of Metals and Materials

雑誌

MATERIALS TRANSACTIONS (ISSN:13459678)

巻号頁・発行日

pp.MT-M2023055, (Released:2023-07-21)

被引用文献数

1

---

The validity of the Tsai-Hill criterion for a porous aluminum alloy with regularly aligned unidirectional pores was investigated experimentally and numerically. The Tsai-Hill criterion predicts failure in different directions in anisotropic composite material. Compression tests of porous aluminum alloy were performed with five different compression angles 0, 30, 45, 60, and 90 deg. The compression angle is the angle between the loading direction and the longitudinal direction of the pore. A numerical analysis of a torsion test of the porous aluminum alloy was also performed to obtain shear strength. Compressive yield strength and equivalent shear strength of the specimen with 0 and 90 deg in compression angle were utilized in the Tsai-Hill criterion. As a result, the yield strength of the specimen with 30, 45, and 60 deg in compression angle was successfully predicted with a maximum relative error of 4 pct. The applicable strain range of the Tsai-Hill criterion was also investigated by altering the yield strength to various offset strengths. The resulted prediction showed a maximum relative error of 10 pct when the offset strain was 40 pct or less. Above that offset strain, densification of the porous structure caused a rapid increase in stress, leading to a drastic decrease in prediction accuracy.

著者

Terence G. Langdon

出版者

The Japan Institute of Metals and Materials

雑誌

MATERIALS TRANSACTIONS (ISSN:13459678)

巻号頁・発行日

vol.64, no.7, pp.1299-1305, 2023-07-01 (Released:2023-06-25)

参考文献数

63

被引用文献数

4

---

In tensile testing, polycrystalline materials generally fail at relatively low total elongations but under some limited conditions it is possible to achieve exceptionally high elongations of up to and exceeding 400%. This superplastic condition is important scientifically but also it has important uses through the industrial development of superplastic forming operations. This overview traces the historical development of this superplastic effect and it provides a summary of the main characteristics of the superplastic flow process. Conventional thermomechanical processing is not able to produce exceptionally small grain sizes within the submicrometer or nanometer range but this limitation was effectively overcome through processing using severe plastic deformation (SPD). The advantages of SPD processing are discussed and examples are presented. Finally it is demonstrated that the experimental data may be easily and effectively displayed through the construction of deformation mechanism maps based on combinations of stress, grain size and temperature.

著者

Ichiro Terasaki

出版者

The Japan Institute of Metals and Materials

雑誌

MATERIALS TRANSACTIONS (ISSN:13459678)

巻号頁・発行日

vol.42, no.6, pp.951-955, 2001 (Released:2005-09-06)

参考文献数

27

被引用文献数

38 44

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Layered cobalt oxides and heavy-fermion compounds are quantitatively compared from the viewpoint of thermoelectric materials. These two systems exhibit anomalously large thermopowers with good electric conductivity, which is attributed to a strong electron-electron correlation. In certain materials the pseudogap increases at low temperature, which further enhances the thermopower.