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The thermal instability mechanism and annealed deformation behavior of Cu/Nb nanolaminate composites

Journal of Materials Science & Technology 2023年第26期157卷 163-173页

作者： chaogang ding Jie Xu Debin Shan Bin Guo Terence G.Langdon Key Laboratory of Micro-systems and Micro-structures Manufacturing of Ministry of Education Harbin Institute of TechnologyHarbin 150080China National Key Laboratory for Precision Hot Processing of Metals Harbin Institute of TechnologyHarbin 150001China Materials Research Group Department of Mechanical EngineeringUniversity of SouthamptonSouthampton SO171BJUK

Nanoscale metallic multilayers(NMMs)have attracted significant attention owing to their enhanced me-chanical properties and excellent thermal ***,the underlying deformation mechanisms of the high-temperature annealed microstructures have not been well *** this study,the effect of annealing temperatures(500,600,700,800,and 1000℃)on the microstructural evolution and mechan-ical properties of Cu/Nb NMMs was investigated *** results show that when the anneal-ing temperature is lower than 800℃the Cu/Nb NMMs maintain their initial continuous nanolayered *** the annealing temperature reaches 1000℃,a thermal instability,driven by thermal grain boundary grooving and a Rayleigh instability,leads to the pinching offof the nanolayered structure and even a complete disintegration into an equiaxed grain *** tensile tests show that 1000℃annealed samples exhibit an enhanced strain hardening capability compared to as-rolled NMMs and this imparts superior ultimate tensile strength(∼492 MPa)and a high elongation(∼20%).TEM observations demonstrate that high-density entangled dislocations exist in the Cu-Nb interface and layers after tensile testing of the high-temperature annealed *** dislocation tangles lead to stable and progres-sive strain hardening which is the dominant factor in determining the superior combination of strength and ductility of the high-temperature annealed ***,this study offers a promising strategy for evading the strength-ductility dilemma and instead promotes a more in-depth understanding of the de-formation mechanisms of heterostructured materials.

关键词： Annealing Interfaces Mechanical properties Nanoscale metallic multilayers Thermal stability

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复杂微型构件特种能场辅助微成形研究进展

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精密成形工程 2024年第7期16卷 23-47页

作者：单德彬李虎山陈俞希丁朝刚徐振海徐杰郭斌哈尔滨工业大学微系统与微结构制造教育部重点实验室哈尔滨150001 哈尔滨工业大学金属精密热加工国家级重点实验室哈尔滨150001 哈尔滨工业大学材料科学与工程学院哈尔滨150001

随着复杂微型构件特征尺寸的不断减小,尺度范围不断扩大,材料种类日益增多,单纯依靠模具施加载荷的塑性微成形技术受到越来越多的挑战,成为制约微型构件实际应用的关键技术瓶颈。特种能场微成形技术利用超声场、电场和电磁场等能场与材... 详细信息

随着复杂微型构件特征尺寸的不断减小,尺度范围不断扩大,材料种类日益增多,单纯依靠模具施加载荷的塑性微成形技术受到越来越多的挑战,成为制约微型构件实际应用的关键技术瓶颈。特种能场微成形技术利用超声场、电场和电磁场等能场与材料相互作用产生的特殊物理效应进行微加工,可以明显改善材料的塑性流动,降低微成形载荷,从而显著提高微型构件成形质量。本文综述了超声场、电场和电磁场等特种能场作用下塑性微成形的研究进展。首先探讨了特种能场作用下材料力学性能响应机制及微成形尺度极限,其次介绍了特种能场作用下微成形过程中材料微观组织结构演化与缺陷形成机理,最后总结了特种能场辅助微成形的关键工艺参数及其对成形质量的影响规律,强调了通过优化工艺参数实现高精度成形的重要性,为复杂微型构件的低成本、高效制造提供了新的技术路径。

关键词：微成形尺度效应微观组织特种能场微型构件

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Electroplasticity in the Al_(0.6) CoCrFeNiMn high entropy alloy subjected to electrically-assisted uniaxial tension

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Journal of Materials Science & Technology 2023年第17期148卷 209-221页

作者： Zhiqin Yang Jianxing Bao chaogang ding Sujung Son Zhiliang Ning Jie Xu Debin Shan Bin Guo Hyoung Seop Kim State Key Laboratory of Precision Hot Processing Harbin Institute of TechnologyHarbin 150001China School of Materials Science and Engineering Harbin Institute of TechnologyHarbin 150001China Department of Materials Science and Engineering Pohang University of Science and TechnologyPohang 37673Republic of Korea Graduate Institute of Ferrous Technology Pohang University of Science and TechnologyPohang 37673Republic of Korea

Electrically assisted deformation(EAD)was adopted in this work to overcome the shortcomings such as poor formability and easy cracking in the processing of dual-phase the Al_(0.6) CoCrFeNiMn high entropy al-loy(HEA)at room *** of the Al_(0.6) CoCrFeNiMn HEA was studied systematically using electrically assisted uniaxial *** results showed that pulse current caused the temperature gradient along the tensile direction and the temperatures of the samples increased with the current *** flow stress decreased,and the elongation increased with increasing current density during the *** the current density was 30 A mm-2,the total elongation of the samples could be increased by 50%compared to that with no *** current can reduce local stress concentration and post-pone microcracks initiation in the body-centered cubic(BCC)phases,and hence can effectively inhibit cracks and *** dislocation tangles were opened by pulse current,and the dislocation recovery was enhanced at a high current *** with dilute solid solution alloys,the lattice distortion effect,the high fraction of the BCC phases,and the dislocations in HEAs can lead to the enhancement of the local Joule heating,which accelerated dislocation slip and dislocation *** study con-firms that EAD can effectively im prove the formability of HEAs and provides theoretical guidance and an experimental basis for forming HEAs components.

关键词： Electrically-assisted deformation Electroplasticity Microstructural evolution Tensile behavior High entropy alloys

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Strongly Coupled Ag/Sn-SnO_(2)Nanosheets Toward CO_(2)Electroreduction to Pure HCOOH Solutions at Ampere‑Level Current

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Nano-Micro Letters 2024年第3期16卷 212-226页

作者： Min Zhang Aihui Cao Yucui Xiang chaogang Ban Guang Han Junjie ding Li‑Yong Gan Xiaoyuan Zhou College of Physics and Center of Quantum Materials and Devices Chongqing UniversityChongqing 401331People’s Republic of China State Key Laboratory of Structural Chemistry Fujian Institute of Research on the Structure of MatterChinese Academy of Sciences(CAS)Fuzhou 350002People’s Republic of China College of Materials Science and Engineering Chongqing UniversityChongqing 400044People’s Republic of China Institute of New Energy Storage Materials and Equipment Chongqing 401135People’s Republic of China State Key Laboratory of Coal Mine Disaster Dynamics and Control Chongqing UniversityChongqing 400044People’s Republic of China

Electrocatalytic reduction of CO_(2) converts intermittent renewable electricity into value-added liquid products with an enticing prospect,but its practical application is hampered due to the lack of high-performance ***,we elaborately design and develop strongly coupled nanosheets composed of Ag nanoparticles and Sn-SnO_(2) grains,designated as Ag/Sn-SnO_(2) nanosheets(NSs),which possess optimized electronic structure,high electrical conductivity,and more accessible *** a result,such a catalyst exhibits unprecedented catalytic performance toward CO_(2)-to-formate conversion with near-unity faradaic efficiency(≥90%),ultrahigh partial current density(2,000 mA cm^(−2)),and superior long-term stability(200 mA cm^(−2),200 h),surpassing the reported catalysts of CO_(2) electroreduction to ***,in situ attenuated total reflection-infrared spectra combined with theoretical calculations revealed that electron-enriched Sn sites on Ag/Sn-SnO_(2)NSs not only promote the formation of*OCHO and alleviate the energy barriers of*OCHO to*HCOOH,but also impede the desorption of H*.Notably,the Ag/Sn-SnO_(2)NSs as the cathode in a membrane electrode assembly with porous solid electrolyte layer reactor can continuously produce~0.12 M pure HCOOH solution at 100 mA cm^(−2)over 200 *** work may inspire further development of advanced electrocatalysts and innovative device systems for promoting practical application of producing liquid fuels from CO_(2).

关键词： Electrochemical CO_(2)reduction Coupled Ag/Sn-SnO_(2)nanosheets Electronic structure Porous solid electrolyte Pure

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纳米多层金属复合材料研究进展

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中国材料进展 2022年第10期41卷 808-818页

作者：丁朝刚徐杰单德彬郭斌哈尔滨工业大学微系统与微结构制造教育部重点实验室黑龙江哈尔滨150080 哈尔滨工业大学材料科学与工程学院黑龙江哈尔滨150001

向金属中加入纤维、颗粒、晶须等增强体是提高金属复合材料力学性能的重要途径。而现代工业的不断发展对材料的多功能性提出了更高的要求。为改善材料的综合性能,保证其在高温、辐照等极端条件下的使用,研究人员设计了由纳米级交替层组... 详细信息

向金属中加入纤维、颗粒、晶须等增强体是提高金属复合材料力学性能的重要途径。而现代工业的不断发展对材料的多功能性提出了更高的要求。为改善材料的综合性能,保证其在高温、辐照等极端条件下的使用,研究人员设计了由纳米级交替层组成的材料体系——纳米多层金属复合材料。由于其具有极高的界面密度,可以有效地阻碍位错移动从而强化材料,同时促进了辐照缺陷的吸收,有效减轻金属的辐照损伤,在快堆、聚变堆等先进核反应堆中具有重要的应用前景。近年来,纳米多层金属复合材料在国内外得到了广泛而深入的研究,在制备技术、结构表征和综合性能等研究方面取得了长足的进步。以Cu/Nb纳米多层复合材料为例,综述了其制备技术、变形行为及热稳定性、抗辐照性、导电性等综合性能的研究进展,并探讨了纳米多层金属复合材料的发展趋势及应用前景。

关键词：纳米多层金属复合材料沉积复合技术累积叠轧技术 Cu/Nb纳米多层复合材料变形行为抗辐照损伤导电性

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Natural vibration and critical velocity of translating Timoshenko beam with non-homogeneous boundaries

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Applied Mathematics and Mechanics(English Edition) 2024年第9期45卷 1523-1538页

作者： Yanan LI Jieyu ding Hu ding Liqun CHEN Shanghai Institute of Applied Mathematics and Mechanics Shanghai Key Laboratory of Mechanics in Energy EngineeringShanghai Frontier Science Center of MechanoinformaticsSchool of Mechanics and Engineering ScienceShanghai UniversityShanghai 200072China School of Mathematics and Statistics Qingdao UniversityQingdao 266071Shandong ProvinceChina

In most practical engineering applications,the translating belt wraps around two fixed *** boundary conditions of the dynamic model are typically specified as simply supported or fixed *** this paper,non-homogeneous boundaries are introduced by the support *** the translating belt as the mechanical prototype,the vibration characteristics of translating Timoshenko beam models with nonhomogeneous boundaries are investigated for the first *** governing equations of Timoshenko beam are deduced by employing the generalized Hamilton's *** effects of parameters such as the radius of wheel and the length of belt on vibration characteristics including the equilibrium deformations,critical velocities,natural frequencies,and modes,are numerically calculated and *** numerical results indicate that the beam experiences deformation characterized by varying curvatures near the *** radii of the wheels play a pivotal role in determining the change in trend of the relative difference between two beam *** the results unearths that the relative difference in equilibrium deformations between the two beam models is more pronounced with smaller-sized *** the two wheels are of equal size,the critical velocities of both beam models reach their respective *** addition,the relative difference in natural frequencies between the two beam models exhibits nonlinear variation and can easily exceed 50%.Furthermore,as the axial velocities increase,the impact of non-homogeneous boundaries on modal shape of translating beam becomes more *** dealing with non-homogeneous boundaries is challenging,beam models with non-homogeneous boundaries are more sensitive to parameters,and the differences between the two types of beams undergo some interesting variations under the influence of non-homogeneous boundaries.

关键词： translating beam Timoshenko beam non-homogeneous boundary natural frequency critical velocity

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Whittle’s Index Based Sensor Scheduling for Multiprocess Systems Under DoS Attacks

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Journal of Systems Science & Complexity 2024年第1期37卷 329-350页

作者： CAI Zai ding Kemi Shenzhen Key Laboratory of Control Theory and Intelligent Systems Southern University of Science and TechnologyShenzhen 518055China.

In this paper,the authors consider how to design defensive countermeasures against DoS attacks for remote state estimation of multiprocess *** each system,a sensor will measure its state and transmits the data packets through an unreliable channel which is vulnerable to be jammed by an *** limited communication bandwidth,only a subset of sensors are allowed for data transmission,and how to select the optimal one to maximize the accuracy of remote state estimation is the focus of the proposed *** authors first formulate this problem as a Markov decision process and investigate the existence of optimal ***,the authors demonstrate the piecewise monotonicity structure of optimal *** the difficulty of obtaining an optimal policy of large-scale problems,the authors develop a suboptimal heuristic policy based on the aforementioned policy structure and Whittle’s ***,a closed form of the indices is derived in order to reduce implementation complexity of proposed scheduling policy and numerical examples are provided to illustrate the proposed developed results.

关键词： DoS attacks Kalman filter remote state estimation Whittle’s index.

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Deep structure of the Southeast Asian curved subduction system and its dynamic process

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Journal of Oceanology and Limnology 2024年第3期42卷 701-704页

作者： Weiwei ding Key Laboratory of Submarine Geoscience&Second Institute of Oceanography Ministry of Natural ResourcesHangzhou 310012China School of Oceanography Shanghai Jiao Tong UniversityShanghai 200030China

The deep structure,material circulation,and dynamic processes in the Southeast Asia have long been an elusive scientific puzzle due to the lack of systematic scientific observations and recognized theoretical *** on the deep seismic tomography using long-period natural earthquake data,in this study,the deep structure and material circulation of the curved subduction system in Southeast Asia was studied,and the dynamic processes since 100 million years ago was *** is pointed out that challenges still exist in the precise reconstruction of deep mantle structures of the study area,the influence of multi-stage subduction on deep material exchange and shallow magma activity,as well as the spatiotemporal evolution and coupling mechanism of multi-plate *** work should focus on high-resolution land-sea joint 3-D seismic tomography imaging of the curved subduction system in the Southeast Asia,combined with geochemical analysis and geodynamic modelling works.

关键词： curved subduction system deep structure material recycling dynamic process Southeast Asia

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A vertical track nonlinear energy sink

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Applied Mathematics and Mechanics(English Edition) 2024年第6期45卷 931-946页

作者： Meng LI Hu ding Shanghai Key Laboratory of Mechanics in Energy Engineering School of Mechanics and Engineering ScienceShanghai Frontier Science Center of MechanoinformaticsShanghai UniversityShanghai 200444China

Eliminating the effects of gravity and designing nonlinear energy sinks(NESs)that suppress vibration in the vertical direction is a challenging task with numerous damping *** this paper,the dynamic design of a vertical track nonlinear energy sink(VTNES)with zero linear stiffness in the vertical direction is proposed and realized for the first *** motion differential equations of the VTNES coupled with a linear oscillator(LO)are *** the strong nonlinearity considered of the VTNES,the steady-state response of the system is analyzed with the harmonic balance method(HBM),and the accuracy of the HBM is verified *** this basis,the VTNES prototype is manufactured,and its nonlinear stiffness is *** damping effect and dynamic characteristics of the VTNES are studied theoretically and *** results show that the VTNES has better damping effects when strong modulation responses(SMRs)***,even for small-amplitude vibration,the VTNES also has a good vibration suppression *** sum up,in order to suppress the vertical vibration,an NES is designed and developed,which can suppress the vertical vibration within certain ranges of the resonance frequency and the vibration intensity.

关键词： track nonlinear energy sink(TNES) vertical direction gravity nonlinear stiffness harmonic balance method(HBM) vibration control

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医事仲裁制度调查分析

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医学与法学 2015年第1期7卷 27-29页

作者：丁朝刚贵阳医学院医学人文学院党委

作为一种处理医疗纠纷的程序制度,医事仲裁在国外被一些国家广泛地使用。一项制度的建立和实施,参与者的态度十分重要;而医事仲裁制度的重要参与者就是医患双方,其态度对医事仲裁制度建立和实施具有举足轻重的作用。本文以问卷调查的方... 详细信息

作为一种处理医疗纠纷的程序制度,医事仲裁在国外被一些国家广泛地使用。一项制度的建立和实施,参与者的态度十分重要;而医事仲裁制度的重要参与者就是医患双方,其态度对医事仲裁制度建立和实施具有举足轻重的作用。本文以问卷调查的方式对医患双方进行调查,并在调查数据的基础上,对医事仲裁制度建立和实施的可行性进行了分析,提出了实行强制医疗纠纷仲裁制度的建议。

关键词：医疗纠纷仲裁医事仲裁

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