检索结果-南通市图书馆

4D imaging of void nucleation,growth,and coalescence from large and small inclusions in steel under tensile deformation

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2022年第28期123卷 168-176页

作者： Yi Guo Timothy L.Burnett Samuel A.McDonald Michael Daly Andrew h.Sherry Philip J.Withers Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China henry Royce Institute Department of MaterialsUniversity of ManchesterM139PLUK European Synchrotron Radiation Facility(ESRF) 6 rue J Horowitz38000 GrenobleFrance National Nuclear Laboratory Chadwick HouseBirchwood ParkWarringtonWA36AEUK

Samples of SA508 grade 3 nuclear pressure vessel ferritic steel were subjected to tensile straining whilst being simultaneously imaged in 3D in real time using high resolution,high frame rate time-lapse synchrotron computed tomography(CT).This enabled direct observation of void development from nucleation,through growth to coalescence and final failure validating many inferences made post-mortem or by theoretical models,as well as raising new *** sparse,large inclusions were found to nucleate voids at essentially zero plastic strain(consistent with zero interfacial strength);these became increasingly elongated with *** contrast,a high density of small spherical voids were found to nucleate from the sub-micron cementite particles at larger strains(>200%)only in the centre of the necked(high triaxiality)*** interfacial strength approaching 2100 MPa was inferred and soon after their nucleation,these small voids coalesce to form internal microcracks that lead to the final failure of the *** surprisingly,under these conditions of generally low triaxial constraint the large voids are simply cut across and appear to play no significant role in determining the final *** implications of these results are discussed in terms of ductile fracture behaviour and the Gurson model for ductile fracture.

关键词： Void growth Ductile fracture Synchrotron X-ray tomography 4D imaging Bainitic steel

Acasta片麻杂岩多期次热事件:来自锆石、榍石和磷灰石的原位微区年代学证据

在线全文

学校读者我要写书评

暂无评论

作者： h. Walter Lack.

学校读者我要写书评

暂无评论

中国科学：地球科学 2024年第3期54卷 693-707页

作者：梅清风杨进辉孙金凤李秋立吴石头凌潇潇彭澎王浩中国科学院地质与地球物理研究所岩石圈演化国家重点实验室北京100029 中国科学院大学地球与行星科学学院北京100049 中国科学院大学计算地球动力学重点实验室北京100049

本文使用激光剥蚀电感耦合等离子体质谱(LA-ICPMS)和二次离子质谱(SIMS)对Acasta片麻杂岩样品碎片(大小约1cm2)中的锆石、磷灰石和榍石进行了原位微区定年,以制约Acasta片麻杂岩的热演化历史.这些样品碎片中的锆石显示多期年龄,反映了... 详细信息

本文使用激光剥蚀电感耦合等离子体质谱(LA-ICPMS)和二次离子质谱(SIMS)对Acasta片麻杂岩样品碎片(大小约1cm2)中的锆石、磷灰石和榍石进行了原位微区定年,以制约Acasta片麻杂岩的热演化历史.这些样品碎片中的锆石显示多期年龄,反映了继承锆石的存在或者锆石结晶后的再生长过程.结合前人研究,本文锆石数据揭示, Acasta片麻杂岩经历的多期岩浆事件发生时间分别为:>3.96、约3.72和约3.57Ga.样品AY199中榍石的PbPb等时线年龄为(2911±22)Ma(95%置信水平, MSWD=1.5),与Acasta片麻杂岩记录的太古宙最后一次岩浆事件年龄一致.样品AC478和AY066中榍石U-Pb年龄分别为(1932±270)Ma(95%置信水平, MSWD=2.3)和(1813±45)Ma(95%置信水平, MSWD=2.3).样品P090803-C中磷灰石的Pb-Pb等时线年龄为(1833±26)Ma(95%置信水平,MSWD=1.4).样品AC478、AY199和AY066中磷灰石U-Pb年龄分别为(1850±20)Ma(95%置信水平, MSWD=1.3)、(1827±100)Ma(95%置信水平, MSWD=6.3)和(1807±58)Ma(95%置信水平, MSWD=3.9).样品AC478和AY066中的榍石U-Pb年龄以及本文所有样品中的磷灰石Pb-Pb或U-Pb年龄相同,均为约1.9~1.8Ga,指示Wopmay造山作用导致的矿物U-Pb体系重置,证明了Wopmay造山作用的峰期温度超过了磷灰石的U-Pb体系封闭温度,并接近或者超过榍石的U-Pb体系封闭温度.

关键词：锆石榍石磷灰石 Acasta片麻杂岩 Wopmay造山带

Current diffusion and efficiency droop in vertical light emitting diodes

在线全文

学校读者我要写书评

暂无评论

Chinese Physics B 2019年第1期28卷 561-569页

作者： R Q Wan T Li Z Q Liu X Y Yi J X Wang J h Li W h Zhu J M Li L C Wang State Key Laboratory of high Performance Complex Manufacturing College of Mechanical and Electrical EngineeringCentral South University Semiconductor Lighting Technology Research and Development Center Institute of SemiconductorsChinese Academy of Sciences College of Materials Science and Opto-Electronic Technology University of Chinese Academy of Sciences

Current diffusion is an old issue, nevertheless, the relationship between the current diffusion and the efficiency of light emitting diodes(LEDs) needs to be further quantitatively clarified. By incorporating current crowding effect(CCE) into the conventional ABC model, we have theoretically and directly correlated the current diffusion and the internal quantum efficiency(IQE), light extraction efficiency(LEE), and external quantum efficiency(EQE) droop of the lateral ***, questions still exist for the vertical LEDs(V-LEDs). here firstly the current diffusion length L_s(I) and L_s(II) have been clarified. Based on this, the influence of CCE on the EQE, IQE, and LEE of V-LEDs were investigated. Specifically to our V-LEDs with moderate series resistivity, L_s(III) was developed by combining L_s(I) and L_s(II), and the CCE effect on the performance of V-LEDs was investigated. The wall-plug efficiency(WPE) of V-LEDs ware investigated finally. Our works provide a deep understanding of the current diffusion status and the correlated efficiency droop in V-LEDs, thus would benefit the V-LEDs' chip design and further efficiency improvement.

关键词： efficiency droop vertical light emitting diodes current crowding effect current blocking layer

Sintering behavior of combusted iron powder in a packed bed reactor with nitrogen and hydrogen

在线全文

学校读者我要写书评

暂无评论

Particuology 2023年第12期83卷 8-17页

作者： C.J.M.hessels A.h.J.Smeets G.Finotello N.G.Deen Y.Tang Power and Flow Group Department of Mechanical EngineeringEindhoven University of TechnologyPO Box 5135600MBEindhoventhe Netherlands Eindhoven Institute for Renewable Energy Systems(EIRES) PO Box 5135600MBEindhoventhe Netherlands

Sintering behavior of micron-sized combusted iron powder is studied in a packed bed reactor,at various temperatures under inert(nitrogen)and reducing(hydrogen)*** tests are subsequently used to quantify the degree of sintering.A sintering model,based on the formation of a solid bridge through solid state surface diffusion of iron atoms,matches the experimental *** of combusted iron occurs at temperatures≥575°C in both nitrogen and hydrogen atmospheres and increases exponentially with *** observed decrease in reduction rate at high temperatures is not caused by the sintering process but by the formation of wüstite as an intermediate species,leading to the formation of a dense iron *** whiskers form at high temperatures(≥700°C)in combination with low reduction rates(≤25 vol%h2),leading to the production of sub-micron fines.

关键词： Metal energy carrier Combusted iron Whiskers Solid bridge force Sintering

Microstructural evolution,dislocation density and tensile properties of Al–6.5Si–2.1Cu–0.35Mg alloy produced by different casting processes

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2021年第36期95卷 145-157页

作者： S.Samat M.Z.Omar A.h.Baghdadi I.F.Mohamed A.Rajabi A.M.Aziz Department of Mechanical and Manufacturing Engineering Faculty of Engineering and Built EnvironmentUniversiti Kebangsaan MalaysiaBangiUKM 43600Malaysia

Al–Si–Cu–Mg foundry alloys are used in casting process ***,their strength properties remain low due to their microstructural characteristics and *** this work,the microstructural characteristics,dislocation densities,and mechanical properties of Al–Si–Cu–Mg cast alloys prepared through different casting methods were studied *** casting processes,namely,gravity casting(GC),rheocasting(RC),thixoforming(Thixo),and Thixo with heat treatment,were *** GC and RC samples had mainly dendriticα-Al phase microstructures and exhibited coarse Si particles and intermetallic compounds in their interdendritic *** contrast,the Thixo and heat-treated Thixo(hT-Thixo)samples exhibited microstructural refinement with uniformly distributedα-Al globules,fine fibrous Si particles,and fragmented intermetallic compounds amongα-Al *** accumulation of dislocation densities increased in the Thixo sample as the strain was increased due to plastic ***,the ultimate tensile strength and yield strength of the hT-Thixo sample increased by 87%and 63%,respectively,relative to those of the GC *** cleavage fracture displayed by the GC and RC samples led to brittle ***,the Thixo and hT-Thixo samples presented dimple-based ductile fracture.

关键词： Al–Si–Cu–Mg alloy Thixoforming Microstructure Mechanical property Dislocation density

Anisotropic Inter-granular Corrosion Behaviors and Microstructures of AlMgSiCu Alloy Sheets Made by Thermal–Mechanical Treatments

在线全文

学校读者我要写书评

暂无评论

作者： Ben h. Winters.

学校读者我要写书评

暂无评论

Acta Metallurgica Sinica(English Letters) 2022年第2期35卷 275-284页

作者： L.M.Liu Y.X.Lai C.L.Wu Z.Zhang J.h.Chen Center for high-Resolution Electron Microscopy College of Materials Science and EngineeringHunan UniversityChangsha 410082China

This study investigates the microstructure and local corrosion behavior of an Al-Mg-Si-Cu alloy,which has been subjected to cold-rolling with different deformation strain ratios(DSRs)and followed by artificial *** corrosion tests show that peak-aged samples with a small DSR(5-10%)are sensitive to inter-granular corrosion(IGC)along both the normal and rolling *** the DSR increases to medium strength(20-40%),IGC sensitivity decreases along both directions and corrosion propagates *** the DSR is 60-80%,IGC sensitivity along the normal direction continues to decrease,but increases along the rolling direction,indicating pronounced corrosion *** characterization reveals the decreased IGC sensitivity is mainly attributed to a reduction in element segregation at high-angle grain boundaries and the kinked and discontinuous grain boundary corrosion *** increased IGC sensitivity along the rolling direction could be related to the significantly flattened grains.

关键词： Al alloys Local corrosion Anisotropy Transmission electron microscopy(TEM) Electron backscattering diffraction(EBSD)

Rehabilitation of vulnerable groups in emergencies and disasters： A systematic review

在线全文

学校读者我要写书评

暂无评论

World Journal of Emergency Medicine 2017年第4期8卷 253-263页

作者： hojjat Sheikhbardsiri Mohammad h. Yarmohammadian Fatemeh Rezaei Mohammad Reza Maracy Department of Emergency Operation Center (EOC) Disasters and Emergencies Management Center Kerman Universityof Medical Sciences Kerman Iran health Management and Economics Research Center Faculty of Management and Medical Informatics IsfahanUniversity of Medical Sciences Isfahan Iran Department of Epidemiology & Biostatistics School of Public Health Isfahan University of Medical Sciences Isfahan Iran

BACKGROUND: Natural and man-made disasters, especially those occurring in large scales not only result in human mortality, but also cause physical, psychological, and social disabilities. Providing effective rehabilitation services in time can decrease the frequency of such disabilities. The aim of the current study was to perform a systematic review related to rehabilitation of vulnerable groups in emergencies and ***: The systematic review was conducted according to the preferred reporting items for systematic reviews and meta-analyses(PRISMA) guidelines. The key words "recovery", "rehabilitation", "reconstruction", "transformation", "transition", "emergency", "disaster", "crisis", "hazard", "catastrophe", "tragedy", "mass casualty incident", "women", "female", "children", "pediatric", "disable", "handicap", "elder", "old" and "vulnerable" were used in combination with Boolean operators OR and AND. ISI Web of Science, PubM ed, Scopus, Science Direct, Ovid, ProQ uest, Wiley, Google Scholar were ***: In this study a total of 11 928 articles were considered and 25 articles were selected for f inal review of rehabilitation of vulnerable groups based on the objective of this study. Twenty-f ive studies including six qualitative, sixteen cross-sectional and three randomized controlled trials were reviewed for rehabilitation of vulnerable groups in emergencies and disasters. Out of the selected papers, 23 were studied based on rehabilitation after natural disasters and the remaining were man-made disasters. Most types of rehabilitation were physical, social, psychological and ***: The review of the papers showed different programs of physical, physiological, economic and social rehabilitations for vulnerable groups after emergencies and disasters. It may help health field managers better implement standard rehabilitation activities for vulnerable groups.

关键词： Rehabilitation Vulnerable group Emergencies Disasters