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Journal of Wuhan University of Technology(Materials Science) 2013年第6期28卷 1096-1100页

作者： SHEN Junjie Ikeda Kenichi hata satoshi Nakashima Hideharu School of Mechanical Engineering Tianjin University of Technology Department of Electrical and Materials Science Faculty of Engineering SciencesKyushu University

Instantaneous creep in face-centered cubic metals, 5N Al（99.999%）, 2N Al （99%） and 4N Cu （99.99%） with different grain sizes, was firstly investigated by sudden stress-change experiments at ultra- low strain rates ε ≤10-10 s-1 and temperature T 〈 0.32 Tn. The experimental results indicate that the observed instantaneous creep is strongly dependent on grain size, the concentration of impurity, and stacking fault energy. Creep in high-purity aluminum, 5N Al, with a very large grain size, d 〉 1600μm, shows non-viscous behavior, and is controlled by the recovery of dislocations in the boundary of dislocation cells. On the other hand, for 5N A1 with a small grain size, d=30μm, and low-purity aluminum, 2N A1, with d8= 25μm, creep shows viscous behavior and may be related to ＇low temperature grain boundary sliding＇. For high-purity copper, 4N Cu, with d= 40 grn and lower stacking fault energy, creep shows a non-viscous behavior, and is controlled by the recovery process of dislocations. For all of the samples, creep shows anelastic behavior.

关键词： face-centered cubic metals instantaneous creep ultra-low strain rate high strain resolution measurement

Microstructural evolution and mechanical properties of a low-carbon quenching and partitioning steel after partial and full austenitization

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International Journal of Minerals,Metallurgy and Materials 2016年第8期23卷 906-919页

作者： Wan-song Li Hong-ye Gao Hideharu Nakashima satoshi hata Wen-huai Tian School of Materials Science and Engineering University of Science and Technology Beijing Interdisciplinary Graduate School of Engineering Sciences Kyushu University

In this work, low-carbon steel specimens were subjected to the quenching and partitioning process after being partially or fully austenitized to investigate their microstructural evolution and mechanical properties. According to the results of scanning electron microscopy and transmission electron microscopy observations, X-ray diffraction analysis, and tensile tests, upper bainite or tempered martensite appears successively in the microstructure with increasing austenitization temperature or increasing partitioning time. In the partially austenitized specimens, the retained austenite grains are carbon-enriched twice during the heat treatment, which can significantly stabilize the phases at room temperature. Furthermore, after partial austenitization, the specimen exhibits excellent elongation, with a maximum elongation of 37.1%. By contrast, after full austenitization, the specimens exhibit good ultimate tensile strength and high yield strength. In the case of a specimen with a yield strength of 969 MPa, the maximum value of the ultimate tensile strength reaches 1222 MPa. During the partitioning process, carbon partitioning and carbon homogenization within austenite affect interface migration. In addition, the volume fraction and grain size of retained austenite observed in the final microstructure will also be affected.

关键词： low-carbon steel quenching partitioning microstructure mechanical properties interfaces

Effect of lower bainite/martensite/retained austenite triplex microstructure on the mechanical properties of a low-carbon steel with quenching and partitioning process

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International Journal of Minerals,Metallurgy and Materials 2016年第3期23卷 303-313页

作者： Wan-song Li Hong-ye Gao Zhong-yi Li Hideharu Nakashima satoshi hata Wen-huai Tian School of Materials Science and Engineering University of Science and Technology Beijing Interdisciplinary Graduate School of Engineering Sciences Kyushu University

We present a study concerning Fe-0. 176C-1.31Si-1.58Mn-0.26Al-0.3Cr （wt%） steel subjected to a quenching and partitioning （Q＆P） process. The results of scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and tensile tests demon- strate that the microstructures primarily consist of lath martensite, retained austenite, lower bainite （LB）, and a small amount of tempered martensite; moreover, few twin austenite grains were observed. In the microstrucmre, three types of retained austenite with different sizes and morphologies were observed： blocky retained austenite （-300 nm in width）, film-like retained austenite （80-120 nm in width）, and ul- tra-fine film-like retained austenite （30-40 nm in width）. Because of the effect of the retained austenite/martensite/LB triplex microstructure, the specimens prepared using different quenching temperatures exhibit high ultimate tensile strength and yield strength. Furthermore, the strength effect of LB can partially counteract the decreasing strength effect of martensite. The formation of LB substantially reduces the amount of retained austenite. Analyses of the retained austenite and the amount of blocky retained austenite indicated that the carbon content is critical to the total elongation of Q＆P steel.

关键词： low-carbon steel quenching partitioning retained austenite rnicrostructure mechanical properties

“Abnormal transient creep” in fine-grained Al-5356 alloy observed at low strain rates by high-resolution strain measurement

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Transactions of Nonferrous Metals Society of China 2013年第5期23卷 1209-1214页

作者：申俊杰 Kenichi IKEDA satoshi hata Hideharu NAKASHIMA 天津理工大学机械工程学院天津300191 Department of Electrical and Materials Science Faculty of Engineering SciencesKyushu University

Transient creep at very low strain rates （less than 10-10 s-1） is still unclear. The traditional uniaxial creep testing is less useful due to unsatisfied resolution strain （~10-6）. To study transient creep behavior at such low strain rates, a high-resolution strain measurement using the helicoid spring specimen technique was employed in a fine-grained Al-5356 alloy at temperatures ranging from 0.47Tm to 0.74Tm （Tm： melting point）. To clarify transient creep mechanism at such low strain rates, transmission electron microscopy （TEM） was used in microstructure observation of crept specimens. The abnormal transient creep, high temperature strengthening at T〉Tp （Tp： the phase transformation temperature, 0.58Tm） or intermediate temperature softening at 0.4Tm〈T￡Tp and double-normal type （creep curves including double work-hardening stages） at T=Tp, were firstly observed. The substructure observation in a crept specimen at T=0.58Tm and e=1×10-4 shows pile-up dislocations including many small jogs with equal interval, and dislocations emitted from grain boundaries. The b-Al3Mg2 phase dissolves under the condition of testing temperatures higher than 523 K, which causes solid-solution quantity of Mg atoms to increase. Therefore, the “abnormal transient creep” may be related to the difference of solid solution strengthening caused by phase change during the creep tests.

关键词： Al-5356 alloy transient creep phase change low strain rate

Primary-transient creep and anelastic backflow of pure copper deformed at low temperatures and ultra-low strain rates

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Transactions of Nonferrous Metals Society of China 2016年第7期26卷 1729-1735页

作者：申俊杰 Ken-ichi IKEDA satoshi hata Hideharu NAKASHIMA 天津理工大学机械工程学院天津300191 Department of Electrical and Materials Science Faculty of Engineering SciencesKyushu University

Creep and anelastic backflow behaviors of pure copper （4N Cu） with grain size dg=40 μm were investigated at low temperatures of T〈0.3Tm （Tm is melting point） and ultra-low creep rates of ε≤1×10^-10 s^-1 by a high strain-resolution measurement （the helicoid spring specimen technique）. Analysis of creep data was based on the scaling factors of creep curves instead of the conventional extrapolated steady-state creep rate. Power-law creep equation is suggested to be the best for describing the primary transient creep behavior, because the pre-parameter does not apparently change with elapsed time. The observed anelastic strains are 1/6 of the calculated elastic strains, and linear viscous behavior was identified from the logarithm plot of the anelastic strain rate versus anelastic strain （slope equals 1）. Therefore, the creep anelasticity is suggested to be due to the unbowing of there-dimensional network of dislocations.

关键词： pure copper creep dislocation anelasticity constitutive creep equation

A New Deformation Region and How Low Do You Go? - "Intrinsic Deformation Limit"

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A New Deformation Region and How Low Do You Go? - "Intrinsic...

TEM TOMOGRAPHIC OBSERVATION OF ORDERED PARTICLES IN Ni-BASED ORDERING ALLOYS

中国材料大会2012

作者： Junjie Shen Kenichi Ikeda satoshi hata Hideharu Nakashima School of Mechanical Engineering Tianjin University of Technology Department of Electrical and Materials Science Faculty of Engineering Sciences Kyushu University

ISBN: (纸本)9783037856086

The creep deformation in pure aluminum was investigated using helicoid spring samples at room temperature, 298 K, and δ ＜ 1.19 MPa. It was found that the stress exponent is n = 0, which means the creep behavior in this region is independent on applied stress but some physical properties of materials. The creep behavior was suggested to be controlled by surface diffusion based on the strongly effect of surface area on creep behavior only in this creep region （n = 0）. The threshold creep rate, εth , called "intrinsic deformation limit", decided by surface diffusion was suggested. This discovery provided a new perspective to understand the extremely slow deformation in the nature.

关键词： Pure aluminium Very low stress Creep Stress exponent Surface diffusion

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TEM TOMOGRAPHIC OBSERVATION OF ORDERED PARTICLES IN Ni-BASED...

Advances in quantum dots for classical and non-classical light sources Invited Paper

第十一届北京分析测试学术报告会暨展览会(BCEIA 2005)

作者： Yoshitsugu Tomokiyo Kousuke Kimura Takao Horiuchi satoshi hata Syo Matsumura Department of Applied Science for Electronics and Materials Kyushu University Department of Applied Quantum Physics and Nuclear Engineering Kyushu University

Electron tomography is rapidly absorbing the attention with increase in strong need to examine materials in all three dimensions in the field of *** application of electron tomography in material sciences is,however,limited to images with STEM-HAADF(Z-contrast)and energy-filtered TEM to satisfy the projection requirement that contrast should

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Chinese Optics Letters 2008年第10期6卷 718-723页

作者： Yasuhiko Arakawa satoshi Iwamoto satoshi Kako Masahiro Nomura Denis Guimard Research Center for Advanced Science and Technology Institute for Nano Quantum Information ElectronicsThe University of Tokyo4-6-1 Meguro-ku153-8505 TokyoJapan

Recent advances in quantum dots （QDs） for classical and non-classical light sources are presented. We have established metal organic chemical vapor deposition （MOCVD） technology for InAs-based QD lasers at 1.3 μm and achieved ultralow threshold in QD lasers with photonic crystal （PhC） nanocavity. In addition, single photon emitters at 1.55 μm, GaN-based single photon sources operating at 200 K, and high-Q PhC nanocavity have been demonstrated.

关键词： QDs Advances in quantum dots for classical and non-classical light sources Invited Paper AIN InAs

Application of 3D Scanned Big Data of Large-scale Cultural Heritage Objects Based on Noise-robust Transparent Visualization

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系统仿真学报 2023年第8期35卷 1635-1650页

作者： Tanaka satoshi College of Information Science and Engineering Ritsumeikan UniversityShiga 525-8577Japan

Three-dimensional(3D) scanning technology has undergone remarkable developments in recent *** acquired by 3D scanning have the form of 3D point *** 3D scanned point clouds have data sizes that can be considered big *** also contain measurement noise inherent in measurement *** properties of 3D scanned point clouds make many traditional CG/visualization techniques *** paper reviewed our recent achievements in developing varieties of high-quality visualizations suitable for the visual analysis of 3D scanned point *** demonstrated the effectiveness of the method by applying the visualizations to various cultural heritage *** main visualization targets used in this paper are the floats in the Gion Festival in Kyoto(the float parade is on the UNESCO Intangible Cultural Heritage List) and Borobudur Temple in Indonesia(a UNESCO World Heritage Site).

关键词： 3D scanning point cloud transparent visualization noise transparentization cultural heritage object

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Posture Maintenance Control of 2-Link Object By Nonprehensile Two-Cooperative-Arm Robot Without Compensating Friction

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IEEE/CAA Journal of Automatica Sinica 2019年第6期6卷 1397-1403页

作者： Changan Jiang satoshi Ueno Department of Mechanical Engineering Ritsumeikan University1-1-1 Noji-higashiKusatsuShiga 525-8577Japan

In this paper, a method to posture maintenance control of 2-link object by nonprehensile two-cooperative-arm robot without compensating friction is proposed. In details, a mathematical model of the 2-link object is firstly built. Based on the model, stable regions for holding motion of nonprehensile two-cooperative-arm robot are obtained while the 2-link object is kept stable on the robot arms with static friction. Among the obtained stable regions, the robust pairs of orientation angles of the 2-link object are found. Under the robust orientation angles, a feedback control system is designed to control the arms to maintain the 2-link object's posture while it is being held or lifted up. Finally, experimental results are shown to verify the effectiveness of the proposed method.

关键词： Nursing care nonprehensile robot posture maintenance static friction two-cooperative-arm robot