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Evolution of microstructure and texture in copper during repetitive extrusion-upsetting and subsequent annealing

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journal of Materials science & Technology 2017年第7期33卷 690-697页

作者： Q.Chen d.Y.shu j.lin Y.Wu x.s.xia s.h.huang Z.d.Zhao O.V.Mishin g.l.Wu state Key laboratory of Mechanical Transmission Chongqing University Chongqing 400044 China

The evolution of the microstructure and texture in copper has been studied during repetitive extrusionupsetting（REU） to a total von Mises strain of 4.7 and during subsequent annealing at different temperatures. It is found that the texture is significantly altered by each deformation pass. A dupl.x.001 ＋ 111 fiber texture with an increased 111 component is observed after each extrusion pass,whereas the 110 fiber component dominates the texture after each upsetting pass. during REU, the microstructure is refined by deformation-induced boundaries. The average cell size after a total strain of 4.7 is measured to be ~0.3 μm. This refined microstructure is unstable at room temperature as is evident from the presence of a small number of recrystallized grains in the deformed matrix. Pronounced recrystallization took place during annealing at 200？C for 1 h with recrystallized grains developing predominantly in high misorientation regions. At 350？C the microstructure is fully recrystallized with an average grain size of only 2.3 μm and a very weak crystallographic texture. This REU-processed and subsequently annealed material is considered to be potentially suitable for using as a material for sputtering targets.

关键词： severe plastic deformation Repetitive extrusion-upsetting Copper deformation microstructure Texture Annealing

Effects of temperature and thermally-induced microstructure change on hydraulic conductivity of Boom Clay

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journal of Rock Mechanics and geotechnical Engineering 2017年第3期9卷 1-13页

作者： W.Z. Chen Y.s. Ma h.d. Yu F.F. li x.l. li x. sillen Research Centre of geotechnical and structural Engineering Shandong University Jinan Shandong 250061 China state Key laboratory of geomechanics and geotechnical Engineering Institute of Rock and Soil Mechanics Chinese Academy of Sciences Wuhan 430071 China University of Chinese Academy of sciences Beijing 100049 China European Underground Research Infrastructure for disposal of Nuclear Waste in Clay Environment EIG Euridice Mol 2400 Belgium ONdRAF/NIRAs Brussel 1210 Belgium

Boom Clay is one of the potential host rocks for deep geological disposal of high-level radioactive nuclear waste in Belgium. In order to investigate the mechanism of hydraulic conductivity variation under compl.x.thermo-mechanical coupling conditions and to better understand the thermo-hydromechanical(ThM) coupling behaviour of Boom Clay, a series of permeability tests using temperaturecontrolled triaxial cell has been carried out on the Boom Clay samples taken from Belgian underground research laboratory(URl) hAdEs. due to its sedimentary nature, Boom Clay presents acrossanisotropy with respect to its sub-horizontal bedding plane. direct measurements of the vertical(Kv)and horizontal(Kh)hydraulic conductivities show that the hydraulic conductivity at 80℃ is about 2.4 times larger than that at room temperature(23℃), and the hydraulic conductivity variation with temperature is basically reversible during heatingecooling cycle. The anisotropic property of Boom Clay is studied by scanning electron microscope(sEM) tests, which highlight the transversely isotropic characteristics of intact Boom Clay. It is shown that the sub-horizontal bedding feature accounts for the horizontal permeability higher than the vertical one. The measured increment in hydraulic conductivity with temperature is lower than the calculated one when merely considering the changes in water kinematic viscosity and density with temperature. The nuclear magnetic resonance(NMR) tests have also been carried out to investigate the impact of microstructure variation on the ThM properties of clay. The results show that heating under unconstrained boundary condition will produce larger size of pores and weaken the microstructure. The discrepancy between the hydraulic conductivity experimentally measured and predicted(considering water viscosity and density changes with temperature) can be attributed to the microstructural weakening effect on the thermal volume change behaviour of Boom Clay. Based on the ex

关键词： Boom Clay Permeability Thermal effect Anisotropy Microstructure

dedicated siPM array for g.d.of gECAM

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Radiation detection Technology and Methods 2022年第1期6卷 63-69页

作者： d.l.Zhang x.l.sun Z.h.An x.Q.li x.Y.Wen K.gong C.Cai Z.Chang g.Chen C.Chen Y.Y.du M.gao R.gao d.Y.guo j.j.he d.j.hou Y.g.li C.Y.li g.li l.li x.F.li M.s.li x.h.liang x.j.liu Y.Q.liu F.j.lu h.lu B.Meng W.x.Peng F.shi h.wang j.Z.wang Y.s.wang h.Z.wang x.Wen s.xiao s.l.x.ong Y.B.xu Y.P.xu s.Yang1 x.Zhou j.W.Yang Fan Zhang s.N.Zhang C.Y.Zhang C.M.Zhang Fei Zhang x.Y.Zhao Institute of high Energy Physics CASBeijing 100049China state Key laboratory of Particle detection and Electronics Beijing 100049China

Purpose The discovery of gravitational waves and gamma-ray bursts heralds the era of multi-messenger *** the adoption of two small satellites to achieve the all-sky monitoring of gamma-ray bursts,the gravitational wave highenergy electromagnetic counterpart all-sky monitor(gECAM)possesses a quasi-real-time early warning ability and plays an important role in positioning the sources of gravitational waves and in subsequent *** satellite of gECAM was fitted with 253-inch-diameter gamma-ray detectors(g.d.,covering an energy range of 8–2 *** have adopted silicon photomultiplier tubes(siPM)in lieu of photomultiplier tubes(PMT)to adapt to the dimensional limitations of *** A unique 3-inch circular siPM array was *** this design,646×6 mm chips were arrang.d.evenly in a circular manner with the seams filled with reflecting films,thus achieving satisfactory uniformity of light *** integrated pre-amplifier circuit on the back of the siPM array adopted two-level grouping and summing;further,it achieved a satisfactory signal-to-noise *** high-gain and low-gain channels were adopted to achieve a large dynamic range,and two independent power supply units were used,where each unit can be closed separately,thus improving *** Performance studies show that this siPM array meets the requirements of *** A 3-inch siPM array have been developed that uses grouped summation,reflective films,a circular arrangement,two groups of independent power supplies,high-and low-gain signals,differential signal output technologies,*** solution can be used not only for gECAM,but also as a general solution for siPM-based scintillation detectors.

关键词： siPM gECAM gamma-ray signal-to-noise ratio Reflecting film Pre-amplifier

On the texture evolution of Mg-Zn-Ca alloy with different hot rolling paths

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journal of Magnesium and Alloys 2017年第2期5卷 166-172页

作者： Q.li g.j.huang x.d.huang s.W.Pan C.l.Tan Q.liu College of Materials science and Engineering Chongqing UniversityChongqing 400044China state Key laboratory for Advanced Metals and Materials University of Science and Technology BeijingBeijing 100083China

In the present study,the texture evolution and mechanical anisotropy in a typical Mg–Zn–Ca alloy through hot cross rolling(CR)and unidirectional rolling(UR)were systematically *** results show that the rolling path greatly affects the annealed *** UR develops a texture with basal poles mainly distributing along the transverse direction(Td).By contrast,an ellipse-like(0002)texture with basal pole inclining largely away from the normal direction(Nd)is developed after hot cross rolling and ***,the CR is an effective method to tailor the texture of the experimental ***,this ellipse-like texture could not reserve during the subsequent unidirectional hot rolling and *** UR and CR plates exhibit a strong planar mechanical anisotropy compared with the traditional unidirectional rolled plate.

关键词： Mg alloys hot cross rolling Texture Mechanical anisotropy

EFFECT OF sIlICON AddITION ON RECRYsTAllIZATION ANd PhAsE TRANsFORMATION BEhAVIOR OF hIgh-sTRENgTh hOT-ROllEd TRIP sTEEl

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Acta Metallurgica sinica(English letters) 2008年第3期21卷 163-168页

作者： l.j. Zhu d. Wu x.M. Zhao College of Materials science and Engineering Jilin University Changchun 130025 China The state Key laboratory of Rolling Technology and Automation Northeastern University Shenyang110004 China

Because si is a noncarbide forming element, a multiphase microstructure consisting of ferrite, bainite, and retained austenite, at room temperature, can be formed by controlling the thermomechanical process strictly. The cooling schedules must be restricted by the formation of pearlite and cementite. In the present article, a new integrated mathematical model for prediction of microstructure evolution during controlled rolling and controlled cooling is developed for a typical kind of low carbon si-Mn TRIP steel, which consists of temperature simulation, recrystallization, and transformation models. The influence of si contents has been thoroughly investigated. The calculated results indicate that si retards recrystallization, restrains austenite grain growth as well as accelerates polygonal ferrite transformation.

关键词： TRIP steel Recrystallization Ferrite transformation Bainite transformation silicon

The design and performance of charg.d.particle detector onboard the gECAM mission

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Radiation detection Technology and Methods 2022年第1期6卷 53-62页

作者： Y.B.xu x.Q.li x.l.sun s.Yang h.wang W.x.Peng x.h.liang K.gong Y.Q.liu d.Y.guo x.Y.Zhao C.Y.li Z.h.An j.j.he x.j.liu x.Y.Wen s.l.x.ong Fan Zhang.d.l.Zhang C.Y.Zhang C.Cai Z.Chang g.Chen C.Chen Y.Y.du M.gao R.gao d.j.hou Y.g.li g.li l.li x.F.li M.s.li F.j.lu h.lu B.Meng F.shi j.Z.wang Y.s.wang h.Z.wang x.Wen s.xiao Y.P.xu j.W.Yang Q.B.Yi s.N.Zhang C.M.Zhang F.Zhang Y.Zhao x.Zhou Key laboratory of Particle Astrophysics Institute of High Energy PhysicsChinese Academy of SciencesBeijing 100049China

Background The gravitational wave highly energetic Electromagnetic Counterpart All-sky Monitor(gECAM)is dedicated to detecting gravitational wave gamma-ray *** is capable of all-sky monitoring over and discovering gamma-ray bursts and new radiation *** consists of two microsatellites,each equipped with 8 charg.d.particle detectors(CPds)and 25 gamma-ray detectors(g.d.).Purpose The CPd is used to measure charg.d.particles in the space environment,monitor energy and flow intensity changes,and identify between gamma-ray bursts and space charg.d.particle events in conjunction with *** CPd uses plastic scintillator as the sensitive material for detection,silicon photomultiplier array as the optically readable device,and the inlaid Am-241 radioactive source as the onboard calibration *** In this paper,we will present the working principle,physical design,functional implementation and preliminary performance test results of the *** a result,the energy range of electron,gamma-ray detection efficiency and dead time are tested to be better than the indexes required through the ground calibration experiment.

关键词： gECAM CPd siPM

The data acquisition algorithm designed for the siPM-based detectors of gECAM satellite

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Radiation detection Technology and Methods 2022年第1期6卷 70-77页

作者： Y.Q.liu K.gong x.Q.li x.Y.Wen Z.h.An C.Cai Z.Chang g.Chen C.Chen Y.Y.du M.gao R.gao d.Y.guo j.j.he d.j.hou Y.g.li C.Y.li g.li l.li x.F.li M.s.li x.h.liang x.j.liu F.j.lu h.lu B.Meng W.x.Peng F.shi x.l.sun h.wang j.Z.wang Y.s.wang h.Z.wang x.Wen s.xiao s.l.x.ong Y.B.xu Y.P.xu s.Yang j.W.Yang Q.B.Yi Fan Zhang.d.l.Zhang s.N.Zhang C.Y.Zhang C.M.Zhang Fei Zhang x.Y.Zhao Y.Zhao x.Zhou Key laboratory of Particle Astrophysics Institute of High Energy PhysicsChinese Academy of SciencesBeijing 100049China University of Chinese Academy of sciences Chinese Academy of SciencesBeijing 100049China Physics and space science College China West Normal UniversityNanchong 637002China

Background The gravitational Wave high-energy Electromagnetic Counterpart All-sky Monitor(gECAM)consists of 2 microsatellites,each of which contains 25 g.d.laBr3)detectors and 8 CPd(plastic scintillator)*** silicon photomultiplier(siPM)array is used to read each *** output signal of these detectors with siPM array is very special and challenging to *** this study,a novel data acquisition(dAQ)algorithm for these detectors is designed and implemented,and the content of the output event packet is *** and Conclusion The performances,including the event acquisition efficiency of this dAQ algorithm,are extensively verified through experimental *** the on-ground and in-flight tests,this algorithm has excellent performance despite the very limited resources and short development time of gECAM mission.

关键词： silicon photomultiplier digital waveform processing data acquisition

Quality assurance test and failure analysis of siPM arrays of gECAM satellites

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Radiation detection Technology and Methods 2022年第1期6卷 35-42页

作者： d.l.Zhang M.gao x.l.sun x.Q.li Z.h.An x.Y.Wen C.Cai Z.Chang g.Chen C.Chen Y.Y.du R.gao K.gong.d.Y.guo j.j.he d.j.hou Y.g.li C.Y.li g.li l.li x.F.li M.s.li x.h.liang x.j.liu Y.Q.liu F.j.lu h.lu B.Meng W.x.Peng F.shi h.wang j.Z.wang Y.s.wang h.Z.wang x.Wen s.xiao s.l.x.ong Y.B.xu Y.P.xu s.Yang j.W.Yang Fan.Zhang s.N.Zhang C.Y.Zhang C.M.Zhang Fei Zhang x.Y.Zhao x.Zhou Institute of high Energy Physics CASBeijing 100049People’s Republic of China

Background The gravitational wave high-energy Electromagnetic Counterpart All-sky Monitor(gECAM)satellite developed a siPM-based gamma-ray detector to monitor the gravitational wave-related gRBs and guide subsequent observations in other wavelengths of *** As all the available siPM devices belong to commercial grade,quality assurance tests need to be performed in accordance with the aerospace *** In the siPM application of gECAM,quality assurance experiments were *** mechanism of the failure of siPM devices was analyzed during the development *** Based on the quality assurance test results,the fnal pass rate of siPM array was 95%.Based on the failure analysis,it was found that a piece of siPM had a leakage channel after longtime operation due to device *** According to the accumulated experience,in the reliability test of siPM,it is necessary to pay special attention to test the impedance of each pin of siPM to ground and confrm that the power switch state of siPM is controllable.

关键词： gravitational waves gamma-ray detectors silicon photomultipliers Quality assurance test Failure analysis

Nanostructured steels for advanced structural applications

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Materials Futures 2022年第1期1卷 97-100页

作者： h j Kong T Yang T l Zhang B x Cao C T liu department of Mechanical Engineering Department of Material Science and EngineeringHong Kong Institute for Advanced StudyCity University of Hong KongHong KongPeople’s Republic of China

This vision summarizes the recent advancement of nanostructured steels foradvanced structural applications, foresees possible challenges and pinpoints futuredirections as well as opportunities in this new era of indus... 详细信息

关键词： nanostructured steels extreme environments advanced manufacturing shape memory