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Effects of Current Stressing on Shear Properties of Sn-3.8Ag-0.7Cu Solder j.ints

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j.urnal of Materials Science & Technology 2010年第8期26卷 737-742页

作者： X.j. Wang Q.l. zeng Q.S. zhu z.G. Wang j.K. Shang Shenyang National laboratory for Materials Science Institute of Metal Research Chinese Academy of Sciences Shenyang 110016 China Department of Materials Science and Engineering University of Illinois at Urbana-Champaign Urbana IL 61801 USA

Effects of electromigration on microstructure, shear strength, and fracture behavior of solder j.ints were investigated by single-ball shear samples of eutectic Sn-3.8Ag-0.7Cu （SAC） j.ined by Cu plates at two sides. The electromigration tests were conducted at a current density of about 1.1×10^3 A/cm2 and a working temperature of about 83℃. The results showed that the shear strength and flow stress decreased greatly after current stressing. Such a decrease was associated with no significant loss of the fracture strain at short electromigration but a great reduction in the fracture strain after long-term current stressing. The variation of the fracture strain with the electromigration time was shown to result from the shift of the fracture surface from the center of the solder towards the intermetallic compound （IMC） interface at the cathode.

关键词： Strength Fracture strain Voids Solder

Synthesis of Single-Crystal TiO_2 Nanowire Using Titanium Monoxide Powder by Thermal Evaporation

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j.urnal of Materials Science & Technology 2012年第5期28卷 385-390页

作者： z.G.Shang z.Q.liu P.j.Shang j.K.Shang Shenyang National laboratory for Materials Science Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China

TiO 2 nanowires were synthesized successfully in a large quantity by thermal evaporation using titanium monoxide powder as precursor. X-ray diffraction results showed that all the products were pure rutile phase of TiO 2 . According to microstructural observations, the nanowires have two typical morphologies, a long straight type and a short tortuous type. The straight nanowires were obtained at a wide temperature range of 900–1050 ℃, while the tortuous ones were formed below 900 ℃. Transmission electron microscopy characterization revealed that both the straight and the tortuous nanowires are single-crystal rutile TiO 2 . The preferential growth direction of the nanowires was determined as [110] orientation according to electron diffraction and high-resolution image analyses. The morphological change of TiO 2 nanowires was discussed by considering the different atomic diffusion rates of Ti atoms caused by the phase transformation in Ti substrate at around 900 ℃.

关键词： Rutile-TiO 2 Alloy nanowires Transmission electron microscopy (TEM) characterization Crystal structure identification Growth mechanism Thermal evaporation

Capability of Searching for Kilonova Associated with a Short Gamma-Ray Burst by SVOM

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Research in Astronomy and Astrophysics 2024年第11期24卷 71-75页

作者： j.Wang l.P.Xin Y.l.Qiu l.lan W.j.Xie z.P.j.n j.Y.Wei Key laboratory of Space Astronomy and Technology National Astronomical ObservatoriesChinese Academy of SciencesBeijing 100101China Guangxi Key laboratory for Relativistic Astrophysics School of Physical Science and TechnologyNanning 530004China Key laboratory of Dark Matter and Space Astronomy Purple Mountain ObservatoryChinese Academy of SciencesNanjing 210023China

In spite of the importance of studying the cosmic generation of heavy elements through the r-process,the detection of a kilonova resulting from the merger of a neutron star binary is still a challenging *** this paper,we show that the Visible Telescope(VT)onboard the ongoing SVOM space mission is powerful for identifying kilonova candidates associated with short gamma-ray bursts up to a distance of 600 Mpc.A significant color variation,turning blue and then turning red,is revealed by calculating the light curves in both red and blue channels of VT by a linear combination of an afterglow and an associated *** maximum color variation is as high as~0.5-1 mag,which is far larger than the small photometry error of~0.2 mag of VT for a point source with a brightness of 23 *** to a distance of 600 Mpc,~1-2 kilonova candidates per year are predicted to be identified by VT.

关键词： instrumentation photometers-telescopes-stars neutron-(stars:)gamma-ray burst general

Wide Absorption Spectrum Measuring Methods by DFB-lDs in Water Vapor Detection System

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Photonic Sensors 2014年第3期4卷 230-235页

作者： Y. N. lIU j. CHANG j. lIAN Q. WANG G. P. lV W. j. WANG z. lIU X. z. lIU S. S. zHANG z. l. WANG S. j.ANG C. G. zHU W. WEI B.N. SUN School of Information Science and Engineering and Shandong Provincial Key laboratory of laser Technology andApplication Shandong University Jinan 250100 China Institute of Automation Shandong Academy of Sciences Jinan 250014 China

Two measuring methods of the wide absorption spectrum by distributed feedback laser diodes （DFB-lDs） are presented in detecting the water vapor absorption line. One is the subsection scanning method, and it takes advantage of the wide spectrum tuning range by the temperature modulation and fast spectrum tuning speed by current modulation. Specifically, this method is real.zed by dividing a target spectral region into several sections which correspond to the specific temperature of DFB-lD, scanning every section by current modulation for hundreds times, and averaging the data to raise the signal to noise ratio （SNR）, then combining all sections to get the whole spectrum. An accuracy of 10ppmv had been obtained in the measurement of water vapor with a 10-cm path length by this method. Another is data fitting method, based on the absorption line-shape function; the absorption line can be described by fitting with partial measured data. The fitting absorption line was fitted well with the measured data, and the square of correlation coefficient （R-square） was no less than 0.99.

关键词： DFB-lD wide spectrum subsection scanning data fitting water vapor detection

Forging strength-ductility unity in a high entropy steel

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j.urnal of Materials Science & Technology 2022年第18期113卷 158-165页

作者： S.j.Tsianikas Y.Chen j.j.ong S.zhang z.Xie School of Mechanical Engineering The University of AdelaideSA 5005Australia Centre for Advanced Thin Film Materials and Devices Faculty of Materials and EnergySouthwest UniversityChongqing 400715China Max-Planck-Institut für Eisenforschung Max-Planck-Straße 1Düsseldorf 40237Germany

Fe_(72.4)Co_(13.9)Cr_(10.4)Mn_(2.7)B_(0.34)high entropy steel was prepared by magnetron *** alloy exhibits a high yield strength of 2.92±0.36 GPa while achieving appreciable plasticity of 13.7±1.9%at the ultimate compressive strength(3.37±0.36 GPa).The distribution of iron and chromium shows an un-usual,characteristic spinodal-like pattern at the nanometer scale,where compositions of Fe and Cr show strong anticorrelation and vary by as much as 20 at.%.The high strength is largely attributable to the compositional modulations,combined with fine grains with body-centered cubic(BCC)crystal structure,as well as grain boundary segregation of interstitial *** impressive plasticity is accommodated by the formation and operation of multiplanar,multicharacter dislocation slips,mediated by coherent in-terfaces,and controlled by shear *** excellent strength-ductility combination is thus enabled by a range of distinctive strengthening mechanisms,rendering the new alloy a potential candidate for safety-critical,load-bearing structural applications.

关键词： Deformation mechanisms Micromechanical testing Compositional fluctuations Body-centered cubic High entropy steel

Microstructural evaluation and nanohardness of an AlCoCuCrFeNiTi high-entropy alloy

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International j.urnal of Minerals,Metallurgy and Materials 2019年第5期26卷 634-641页

作者： C.D.Gómez-Esparza R.Peréz-Bustamante j.M.Alvarado-Orozco j.Mu?oz-Salda?a R.Martínez-Sánchez j.M.Olivares-Ramírez A.Duarte-Moller Centro de Investigación en Materiales Avanzados (CIMAV) Laboratorio Nacional de Nanotecnología CONACYT-Corporación Mexicana de Investigación en Materiales S.A.de C.V.(COMIMSA) Centro de Ingeniería y Desarrollo Industrial Querétaro Campus Centro de Investigación y de Estudios Avanzados del IPN Unidad Querétaro Universidad Tecnológica de San j.an del Río Escuela de Ingeniería Civil Industrialy Mecánica Universidad De La Salle Bajío

An AlCoCuCrFeNiTi high-entropy alloy(HEA) was prepared by mechanical alloying and sintering to study the effect of Ti addition to the widely studied AlCoCuCrFeNi system. The structural and microstructural characteristics were investigated by X-ray diffraction(XRD), scanning electron microscopy(SEM), and transmission electron microscopy(TEM). The formation of four micrometric phases was detected: a Cu-rich phase with a face-centered cubic(fcc) structure, a body-centered cubic(bcc) solid solution with Cu-rich plate-like precipitates(fcc), an ordered bcc phase, and a tetragonal structure. The XRD patterns corroborate the presence of a mixture of bcc-, fcc-, and tetragonal-structured phases. The Vickers hardness of the alloy under study was more than twice that of the AlCoCuCrFeNi alloy. Nanoindentation tests were performed to evaluate the mechanical response of the individual phases to elucidate the relationship between chemical composition, crystal structure, and mechanical performance of the multiphase microstructure of the AlCoCuCrFeNiTi HEA.

关键词： high-entropy alloys mechanical alloying microstructure nanoindentation

Superb Strengthening Effect of Net-like Distributed Amorphous Al_(2)O_(3)on Creep Resistance of(B_(4)C+Al_(2)O_(3))/Al Neutron-Absorbing Materials

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Acta Metallurgica Sinica(English letters) 2022年第12期35卷 2007-2013页

作者： Y.N.zan X.lei j.F.zhang D.Wang Q.z.Wang B.l.Xiao z.Y.Ma Key laboratory of Nuclear Materials and Safety Assessment Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China Shi-Changxu Innovation Center for Advanced Materials Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China Nuclear Equipment Division Beijing Institute of Nuclear EngineeringChina Nuclear Power Engineering Co.LtdBejing 100840China

B4C reinforced Al composites are widely used as neutron absorbing materials(NAMs)due to excellent neutron absorbing efficiency,however,such NAMs exhibit poor high-temperature *** meet the requirement for structure-function integration,NAMs with enhanced high-temperature mechanical properties are *** this work,a novel(B4 C+Al_(2)O_(3))/Al NAM with netlike distribution of Al_(2)O_(3)was fabricated by powder metallurgy method and subj.cted to high-temperature tensile creep *** was shown that the creep resistance was enhanced by several orders of magnitude via the addition of only2.1 vol.%netlike-distributed Al_(2)O_(3).(B_(4)C+Al_(2)O_(3))/Al exhibited high apparent stress exponents ranging from 16 to 25 and high apparent activation energy of 364 kj.*** creep behaviour could be rational.zed using the substructure-invariant model and its rupture behaviour could be described by the Dobes-Milicka equation.

关键词： Neutron absorber material Al matrix composite Tensile creep B_(4)C/Al

Mechanism transition of cross slip with stress and temperature in face-centered cubic metals

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j.urnal of Materials Science & Technology 2020年第22期54卷 159-171页

作者： K.Q.li z.j.zhang j.X.Yan j.B.Yang z.F.zhang laboratory of Fatigue and Fracture for Materials Institute of Metal ResearchChinese Academy of SciencesShenyang110016China School of Materials Science and Engineering University of Science and Technology of ChinaShenyang 110016China

A/2 screw dislocation is commonly dissociated into two /6 Shockley partial dislocations on{111} planes in face-centered cubic *** the two partials are not purely screw,different mechanisms of cross-slip could take place,depending on the stacking fault energy,applied stress and tempe *** is crucial to classify the mechanisms of cross-slip because each mechanism possesses its own reaction path with a special activation *** this work,molecular dynamics simulations have been performed systematically to explore the cross-slip mechanism under different stresses and temperatures in three different metals Ag,Cu and Ni that have different stacking fault energies of 17.8,44.4 and 126.8 mj.m^2,re *** Ag and Cu with low stacking fault energy,it is observed that the cross-slip mechanism of screw dislocations changes from the Fleischer obtuse angle(FlOA),to the Friedel-Escaig(FE),and then to the Fl acute angle(FlAA) at low temperatures,with increasing the applied ***,when the temperature increases,the FE mechanism gradually becomes dominant,while the FlAA only occurs at the high stress *** particular,the FlOA has not been observed in Ni because of its high stacking fault energy.

关键词： Cross-slip Molecular dynamics simulation Face-centered cubic metals Stacking fault energy

Reliability-based multidisciplinary design optimization using incremental shifting vector strategy and its application in electronic product design

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Acta Mechanica Sinica 2018年第2期34卷 285-302页

作者： z.l.Huang Y.S.zhou C.j.ang j.zheng X.Han School of Mechanical and Electrical Engineering Hunan City University State Key laboratory of Advanced Design and Manufacturing for Vehicle Body College of Mechanical and Vehicle Engineering Hunan University

Use of multidisciplinary analysis in reliabilitybased design optimization(RBDO) results in the emergence of the important method of reliability-based multidisciplinary design optimization(RBMDO). To enhance the efficiency and convergence of the overall solution process,a decoupling algorithm for RBMDO is proposed ***, to decouple the multidisciplinary analysis using the individual disciplinary feasible(IDF) approach, the RBMDO is converted into a conventional form of RBDO. Secondly,the incremental shifting vector(ISV) strategy is adopted to decouple the nested optimization of RBDO into a sequential iteration process composed of design optimization and reliability analysis, thereby improving the efficiency significantly. Finally, the proposed RBMDO method is applied to the design of two actual electronic products: an aerial camera and a car pad. For these two applications, two RBMDO models are created, each containing several finite element models(FEMs) and relatively strong coupling between the involved disciplines. The computational results demonstrate the effectiveness of the proposed method.

关键词： Reliability-based design optimization(RBDO) Multidisciplinary design optimization(MDO) Incremental shifting vector(ISV) Decoupling algorithm Electronic product