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Fatigue Crack Initiation and Propagation Dominated by Crystallographic Factors in TiB/near a-Ti

Acta Metallurgica Sinica(English Letters) 2024年第5期37卷 763-776页

作者： fanchao meng Rui Zhang Shuai Wang Fengbo Sun Run Chen Lujun Huang Lin Geng School of Materials Science and Engineering Harbin Institute of TechnologyHarbin 150001China Waikato Centre for Advanced Materials and Manufacturing School of EngineeringUniversity of WaikatoHamilton 3240New Zealand State Key Laboratory of Advanced Welding and Joining Harbin Institute of TechnologyHarbin 150001China

Discontinuously reinforced titanium matrix composites(DRTMCs)with a network structure have been extensively researched due to their superior combination of strength and ductility.However,their fatigue performance has remained unknown.In order to elucidate the fatigue behavior of DRTMCs,a tension-tension fatigue test was performed on a TiB/nearα-Ti composite with network structure.The results showed that the variability of fatigue lifetime increased as the stress level decreased.Fractography analysis indicated that fatigue crack initiation was associated with facet formation,while the subsequent propagation was hindered by the network structure comprising TiB whiskers and silicides.Crystallographic characterization further revealed that facets formed due to a combination of shear and normal stress.The reduction in fatigue lifetime was attributed to an increase in the effective slip length,which was influenced by the orientation of grains near the crack-initiation sites toward basal slip in the life-limiting specimen.Quasi in situ observation suggested that the crack initiation was facilitated by both basal and prismatic slip ofα-Ti as well as fracture of TiBw.Crack propagation was found to be associated with basal and prismatic slip systems with high Schmid factors,regardless of whether the crack was intergranular or intragranular.

关键词： Titanium matrix composite TiBw Fatigue lifetime variability Crack initiation Crack propagation

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Hot deformation behavior and microstructure evolution of GH3536-TiB2 composites fabricated by powder metallurgy

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Science China Technological Sciences 2024年第7期67卷 2107-2124页

作者： ZHOU ShiPeng WANG Shuai HUANG LuJun ZHANG Rui CHEN Xin meng fanchao CHEN Run SUN FengBo WANG CunYu GENG Lin School of Materials Science and Engineering Harbin Institute of Technology State Key Laboratory of Advanced Welding and Joining Harbin Institute of Technology Waikato Centre for Advanced Materials and Manufacturing School of Engineering University of Waikato

The hot deformation behavior and microstructure evolution of GH3536-TiB2composites fabricated by powder metallurgy（PM）were examined in the temperature range of 950–1150°C and strain rate range of 0.001–1 s-1. The hot compression stress-strain curves and the constitutive equation were obtained. In addition, the hot processing map was drawn, which indicated that the appropriate hot working window was 950–1050°C/0.001–0.1 s-1and 1050–1100°C/0.001–0.01 s-1. The microstructure analysis showed that the splitting and spheroidization of M3B2led to a decrease in size and volume fraction at 950–1100°C. At 1150°C,the eutectic microstructure of M3B2+ γ was formed due to the dissolution of M3B2, which caused macroscopic cracking of the deformed sample. Additionally, the deformation temperature and the strain rate had little effect on the size and volume fraction of M3B2. Besides, discontinuous dynamic recrystallization（DDRX） and continuous dynamic recrystallization（CDRX） were found in the deformed microstructure, while the former was dominant. Within the test range of this work, the dynamic recrystallization（DRX） fraction of the deformed composites was high due to the bulging nucleation of numerous interfaces. The DRX grain size increased with increasing deformation temperature or decreasing strain rate. Texture analysis showed that the deformation texture of //compression direction RD existed in the matrix when the deformation temperature was below 1100°C, and the texture type became //RD at 1100°C. Additionally, it was also found that the //RD texture was formed in M3B2under the strain rates of 0.1 and 0.01 s-1.

关键词： GH3536 alloy matrix composites powder metallurgy hot deformation behavior microstructure evolution

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All-solid anti-resonant single crystal fibers

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Frontiers of Optoelectronics 2022年第1期15卷 34-42页

作者： Jinmin Ding fanchao meng Xiaoting Zhao Xin Wang Shuqin Lou Xinzhi Sheng Luyun Yang Guangming Tao Sheng Liang Key Laboratory of Education Ministry on Luminescence and Optical Information Technology National Physical Experiment Teaching Demonstration CenterDepartment of PhysicsSchool of ScienceBeijing Jiaotong UniversityBeijing 100044China School of Electronic and Information Engineering Beijing Jiaotong UniversityBeijing 100044China Wuhan National Laboratory for Optoelectronics Huazhong University of Science and TechnologyWuhan 430074China State Key Laboratory of Crystal Materials Shandong UniversityJinan 250100China

In this paper,a novel all-solid anti-resonant single crystal fiber(AR-SCF)with high refractive index tubes cladding is proposed.By producing the cladding tubes with high refractive index material,the AR guiding mechanism can be realized for the SCF,which can reduce the mode number to achieve single-mode or few-mode transmission.The influences of dif-ferent materials and structures on the confinement loss and effective guided mode number for wavelengths of 2-3μm are investigated.Then,the optimal AR-SCF structures for different wavelengths are determined.Furthermore,the influences of different fabrication errors are analyzed.This work would provide insight to new opportunities in the novel design of SCFs by AR,which would greatly impact the fields of laser application,supercontinum generation,and SCF sensors.

关键词： Single crystal fiber(SCF) Anti-resonant(AR)optical fiber Few-mode fiber Modal reduction Confinement loss Finite element method

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Cenozoic potassic volcanic rocks from the Keluo and Wudalianchi volcanic districts,northeast China:origin from the new sub-continental lithospheric mantle(SCLM)metasomatized by potassium-rich fluids from delaminated lower crust

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Frontiers of Earth Science 2022年第4期16卷 989-1004页

作者： fanchao meng Yulu TIAN Yaoqi ZHOU Jiaqi LIU Gengchao ZUO Qing DU School of Geosciences China University of Petroleum(East China)Qingdao 266580China Pilot National Laboratory for Marine Science and Technology(Qingdao) Qingdao 266061China Shandong Provincial Key Laboratory of Deep Oil and Gas China University of Petroleum(East China)Qingdao 266580China Institute of Geology Chinese Academy of Geological SciencesBeijing 100037China

A series of Cenozoic potassium-rich volcanic rocks developed in the Xiaoguli-Keluo-Wudalianchi-Erkeshan districts,northeast China.The source region and potassium-rich mechanism of the potassic rocks remain highly disputed.In this paper,the major elements,trace elements,and Sr-Nd-Pb isotopes of the volcanic rocks in Keluo(KL)and Wudalianchi(WDLC)volcanic districts were analyzed systematically.The results show that the volcanic rocks are characterized by high K2O(4.36wt.%-6.13wt.%),remarkable enrichment in LREEs and LILEs,as well as the strong fractionation of HREEs.The isotopic characteristics with high 87Sr/86Sr(0.704990-0.705272),low 143Nd/144Nd(0.512306-0.512417),low 206Pb/204Pb(16.546-17.135)and 207Pb/204Pb(15.002-15.783)of the volcanic rocks suggest the involvement of EM-I-type mantle.On the basis of the geochemical characteristics,the potassium-rich volcanic magma originated from the new SCLM forming after delamination of the ancient SCLM,with metasomatism of the potassium-rich fluids released from the ancient lower crust during the Late Mesozoic.The proposed genetic model assumes the source which represented by a phlogopite-bearing garnet peridotite(with modal garnet in the range of 2%-10%)experienced very low degrees(i.e.,~0.5)of partial melting.During Cenozoic,the lithosphere in northeast China was affected by the extension and decompression of continental rift,and the metasomatized SCLM underwent low degree partial melting,resulting in the formation of potassium-rich primitive basaltic magma.

关键词： northeast China Keluo-Wudalianchi volcanic districts Cenozoic potassic volcanic rocks petrogenesis sub-continental lithospheric mantle

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Finite Element Prediction of Residual Stress in Rhombic Dodecahedron Ti‑6Al‑4V Titanium Alloy Additively Manufactured by Electron Beam Melting

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Acta Metallurgica Sinica(English Letters) 2023年第1期36卷 35-47页

作者： Shangzhou Zhang Yuankang Wang Bing Zhou fanchao meng Hua Zhang Shujun Li Qingmiao Hu Li Zhou Institute for Advanced Studies in Precision Materials Yantai UniversityYantai 264005China School of Electromechanical and Automotive Engineering Yantai UniversityYantai 264005China Institute of Metal Research Chinese Academy of SciencesShenyang 110016China

In this work,a three-dimensional nonlinear transient thermo-mechanically coupled finite element model(FEM)is established to investigate the variation in temperature and stress fields during electron beam melting(EBM)of rhombic dodecahedron Ti-6Al-4V alloy.The influence of the processing parameters on the temperature and residual stress evolutions was predicted and verified against existing literature data.The calculated results indicate that the interlayer cooling time has very little effect on both the temperature and stress evolutions,indicating that the interlayer cooling time can be set up as short as possible to reduce manufacturing time.It is presented that the residual stress of the intersection is higher than that of non-intersection.With increasing preheating temperature,the residual stress decreases continuously,which is about 20%–30%for every 50℃rise in temperature.The temperature and stress fields repeated every four layers with the complex periodic scanning strategy.Both x and y-component residual stresses are tensile stresses,while z-component stress is weak compressive or tensile stress in typical paths.It is proposed that the interlayer cooling is necessary to obtain a rhombic dodecahedron with low residual stress.These results can bring insights into the understanding of the residual stress during EBM.

关键词： Electron beam melting Ti-6Al-4V Rhombic dodecahedron Residual stress Finite element analysis Parametric study

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RuO_(2)-PdO nanowire networks with rich interfaces and defects supported on carbon toward the efficient alkaline hydrogen oxidation reaction

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能源化学:英文版 2023年第8期83卷 255-263,I0008页

作者： Yuanyuan Cong fanchao meng Haibin Wang Di Dou Qiuping Zhao Chunlei Li Ningshuang Zhang Junying Tian School of Petrochemical Technology Lanzhou University of TechnologyLanzhou 730050GansuChina Key Laboratory of Low Carbon Energy and Chemical Engineering of Gansu Province Lanzhou University of TechnologyLanzhou 730050GansuChina

Interfacial engineering is a promising approach for enhancing electrochemical performance,but rich and efficient interfacial active sites remain a challenge in fabrication.Herein,RuO_(2)-PdO heterostructure nanowire networks(NWs) with rich interfaces and defects supported on carbon(RuO_(2)-PdO NWs/C) for alkaline hydrogen oxidation reaction(HOR) was formed by a seed induction-oriented attachment-thermal treatment method for the first time.As expected,the RuO_(2)-PdO NWs/C(72.8% Ru atomic content in metal) exhibits an excellent activity in alkaline HOR with a mass specific exchange current density(jo,m) of 1061 A gRuPd-1,which is 3.1 times of commercial Pt/C and better than most of the reported nonPt noble metal HOR electrocatalysts.Even at the high potential(~0.5 V vs.RHE) or the presence of CO(5 vol%),the RuO_(2)-PdO NWs/C still effectively catalyzes the alkaline HOR.Structure/electrochemical analysis and theoretical calculations reveal that the interfaces between RuO_(2) and PdO act as the active sites.The electronic interactions between the two species and the rich defects for the interfacial active sites weaken the adsorption of Had,also strengthen the adsorption of OHad,and accelerate the alkaline HOR process.Moreover,OHadon RuO_(2) can spillover to the interfaces,keeping the RuO_(2)-PdO NWs/C with the stable current density at higher potential and high resistance to CO poisoning.

关键词： Hydrogen oxidation reaction Heterostructure Nanowire networks Defects Interfacial active sites

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Hot deformation behavior and microstructure evolution of GH3536-TiBcomposites fabricated by powder metallurgy

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Science China Technological Sciences 2024年

The hot deformation behavior and microstructure evolution of GH3536-TiB2composites fabricated by powder metallurgy(PM)were examined in the temperature range of 950–1150°C and strain rate range of 0.001–1s-1. The hot compression stress-strain curves and the constitutive equation were obtained. In addition, the hot processing map was drawn, which indicated that the appropriate hot working window was 950–1050°C/0.001–0.1 s-1and 1050–1100°C/0.001–0.01 s-1. The microstructure analysis showed that the splitting and spheroidization of M3B2led to a decrease in size and volume fraction at 950–1100°C. At 1150°C,the eutectic microstructure of M3B2+ γ was formed due to the dissolution of M3B2, which caused macroscopic cracking of the deformed sample. Additionally, the deformation temperature and the strain rate had little effect on the size and volume fraction of M3B2. Besides, discontinuous dynamic recrystallization(DDRX) and continuous dynamic recrystallization(CDRX) were found in the deformed microstructure, while the former was dominant. Within the test range of this work, the dynamic recrystallization(DRX) fraction of the deformed composites was high due to the bulging nucleation of numerous interfaces. The DRX grain size increased with increasing deformation temperature or decreasing strain rate. Texture analysis showed that the deformation texture of //compression direction RD existed in the matrix when the deformation temperature was below 1100°C, and the texture type became //RD at 1100°C. Additionally, it was also found that the //RD texture was formed in M3B2under the strain rates of 0.1 and 0.01 s-1.

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Toward a self-driving ultrafast fiber laser

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Light(Science & Applications) 2020年第1期9卷 1757-1759页

作者： fanchao meng John M.Dudley Universite Bourgogne Franche-Comte Institut FEMTO-ST UMR 6174BesançonFrance

Femtosecond pulses from an ultrafast mode-locked fiber laser can be optimized in real time by combining single-shot spectral measurements with a smart genetic algorithm to actively control and drive the intracavity dy... 详细信息

关键词： fiber laser Femto

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冷战后日本与东南亚地区秩序的构建:观念与政策

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南洋问题研究 2024年第1期 15-26页

作者：张勇孟繁超中国社会科学院大学国际政治经济学院北京102488 中国社会科学院日本研究所北京100007 中国人民大学国际关系学院北京100872

冷战后日本与东南亚地区秩序的构建问题应引起学界足够的重视。地区秩序与国际秩序有相通之处,但也有其独特性。地区范围、地区制度框架及地区统合原则是地区秩序的构成要素。在东南亚秩序构建进程中,日本形成相互并存的、多层次地区概... 详细信息

冷战后日本与东南亚地区秩序的构建问题应引起学界足够的重视。地区秩序与国际秩序有相通之处,但也有其独特性。地区范围、地区制度框架及地区统合原则是地区秩序的构成要素。在东南亚秩序构建进程中,日本形成相互并存的、多层次地区概念。从亚太到扩大的东亚、“自由与繁荣之弧”和“两洋交会”再到“印太构想”,日本的地区秩序观经历经济导向、价值观导向及印太框架3个时期的演变。日本从强调包容性转变为强调同质性,价值观外交愈发突出。日本通过双边与小多边主义强化安全合作,安全议题的分量不断上升。以新版“安保三文件”为指导,日本在2023年推进名为“政府安全保障能力强化支援”(OSA)的安全合作新框架,使援助外交从单一的经济发展援助走向“经济+安全”双轨并行的新态势。日本从均势与陆海对立的思维定势出发,地区概念的适用范围不断扩大,试图借此阻滞与稀释中国的影响力。

关键词：地区秩序日本的东南亚外交印太构想价值观外交小多边主义

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阵列式气囊床垫防压疮辅助翻身建模与舒适性分析

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生物医学工程学杂志 2024年第1期41卷 160-167页

作者：肖云轩刘腾孟垂舟焦子昂孟凡超郭士杰河北工业大学智能康复装置与检测技术教育部工程研究中心天津300401 河北工业大学省部共建电工装备可靠性与智能化国家重点实验室天津300401 河北工业大学机械工程学院天津300401 河北工业大学电气工程学院天津300130

通过辅助长期卧床人员定时翻身,调整压力分布避免单一部位长时间受压是预防压疮的最有效措施。但被动辅助翻身与人体主动翻身相比,身体各部位受力存在明显差异,可能影响翻身舒适性,甚至对外伤及危重患者造成二次伤害。因此,探究被动翻... 详细信息

通过辅助长期卧床人员定时翻身,调整压力分布避免单一部位长时间受压是预防压疮的最有效措施。但被动辅助翻身与人体主动翻身相比,身体各部位受力存在明显差异,可能影响翻身舒适性,甚至对外伤及危重患者造成二次伤害。因此,探究被动翻身舒适性影响因素,确定最优翻身策略具有较大的实用价值。首先,本文研究被动翻身人体各关节承载特征,提出了一种楔形气囊构型,并将床垫楔形气囊对偶布局等效为弹簧-阻尼模型,并基于实验方法进行模型关键参数辨识。然后,通过调整施力位置、顺序,设计了不同辅助翻身策略,建立了基于刚性人体结构与柔性等效弹簧的人-垫力耦合仿真模型,获得了人体主要承压部位受力情况。最后,对15名受试者开展辅助翻身试验,通过分析仿真结果、实验数据及问卷评分,验证了辅助翻身与压力调整效果,阐明了被动翻身过程人体舒适性的力学影响因素,为后续床垫构型设计与辅助翻身策略优化提供了理论基础。

关键词：压疮预防气囊床垫辅助翻身人机耦合建模舒适性评价

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