检索结果-南通市图书馆

STRUCTURAL DETERmiNATiON Of TiTANiUm-OXiDE NANOPARTiCLES By X-RAy ABSORPTiON SPECTROSCOPy

在线全文

学校读者我要写书评

暂无评论

Acta metallurgica Sinica(English Letters) 2002年第1期15卷 53-57页

作者： z.y. wu j. zhang k. ibrahim m.i. abbas G. Li y. Tao T.D. hu f.q. liu h.j. qian y.N. Xie q.h. zhang L. Gao z.z. Chen Beij.ng Synchrotron Radiat. facility Inst. of High Energy Phys. Chinese Acad. of Sci. Beijing 100039 China

As a potential application of titanium-oxide nanoparticles, it is extremely important to investigate a detailed picture of the surface and interior structural properties of nanocrystalline materials, such as rutile and anatase with diameters 7.0 and 4.5nm, respectively. X-ray absorption spectroscopy has been used to identify the local Ti environment and related electronic structure. We com.i.e the experimental results at the Ti edge in both bulk.and nano-crystals to determine the lattice distortion in terms of differently characteristic preedge features and the variation in the multiple-scattering region of X-ray absorption near-edge structure (XANES) spectra. The relationship between the transition peak. and the surface-to volume ratio is also discussed.

关键词： X-ray absorption near edge structure nano particle transition metal oxide

RESONANT PhOTOEmiSSiON Of BULk.CeO_(2) AND NANO-CeO_(2) fiLmS

在线全文

学校读者我要写书评

暂无评论

Acta metallurgica Sinica(English Letters) 2001年第6期14卷 539-543页

作者： m.i. abbas, k. ibrahim, z.y. wu, j. zhang, f.q. liu and h.j. qian (Beij.ng Synchrotron Radiation Laboratory, institute of high Energy Physics, The Chinese Academy of Sciences, P.O. Box 918, Beij.ng 100039, China) Beij.ng Synchrotron Radiat. Lab. Inst. of High Energy Phys. Chinese Acad. of Sci. Beijing 100039 P.O. Box 918 China

Photoemission behaviors of nano-CeO2 films with particle sizes ranging from 8 nm to 50 nm and bulk.CeO2 in Ce 4 d-4 f absorption region have been investigated. Resonant enhancements of Ce 4 f valance band and Ce 5 p bands for nano film and bulk.material have been observed. The variation of electron density of states in valance bands of nano and bulk.structures of CeO2 is discussed in terms of Ce 4 d-4 f resonance.

关键词： Nanostructured materials Optical films Oxides Photoemission Resonance

iNVESTiGATiON Of BONDiNG iN NANO-SiO_(2) By Si L_(2,3) X-RAy ABSORPTiON NEAR-EDGE STRUCTURE SPECTROSCOPy

在线全文

学校读者我要写书评

暂无评论

Acta metallurgica Sinica(English Letters) 2001年第6期14卷 473-478页

作者： z.y. wu, k. ibrahim, G. Li, j. zhang, f.q. liu, m.i.abbas, R. hu, h.j. qian and f.q. Tang ( Beij.ng Synchrotron Radiation facility, institute of high Energy Physics, The Chinese Academy of Sciences, Beij.ng 100039, China) ( Laboratori Nazionali di frascat inst. of high Energy Phys. Chinese Acad. of Sci. Beijing 100039 China

The Si L2,3 X-ray absorption near-edge structure (XANES) can be used to probe thelocal structure around Si and derive electronic information of the unoccupied s- andd-lik. partial density of states in nano-size SiO2. We present Si L2,3-edge for threedifferent size silicates acquired by total electron yield (TEy) at the photoemission sta-tion of Beij.ng Synchrotron Radiation facility (BSRf). The Si L2,3-edge spectra areinterpreted based on ab initio full multiple-scattering (mS) calculation. The Si L2.3-edge of nano-size materials has XANES similar to that of a-quartz. The similaritiesbetween the Si L2.3-edge shapes attest to a common molecular-orbital picture of theirSi-O bonding and the same coordination state. however, a considerable broadeningof Si L2,3-edge XANES spectra as decrease of particle size is also an indicative ofpolyhedral distortions.

关键词： multiple scattering calculation X-ray absorption nano particle electronic structure

Unusual he-ion irradiation strengthening and inverse layer thick.ess-dependent strain rate sensitivity in transformable high-entropy alloy/metal nanolaminates:A comparison of fe_(50)mn_(30)Co_(10)Cr_(10)/Cu vs fe_(50)mn_(30)Co_(10)Ni_(10)/Cu

在线全文

学校读者我要写书评

暂无评论

j.urnal of materials Science & Technology 2022年第21期116卷 199-213页

作者： y.f.zhao h.h.Chen D.D.zhang j.y.zhang y.q.Wang k.wu G.liu j.Sun State k.y Laboratory for mechanical Behavior of materials Xi’an Jiaotong UniversityXi’an 710049China

in this work.we prepare transformable hEA/Cu nanolaminates(NLs)with equal individual layer thick.ness(h)by the magnetron sputtering technique,i.e.,fe_(50)mn_(30)Co_(10)Cr_(10)/Cu and fe_(50)mn_(30)Co_(10)Ni_(10)/Cu,and comparatively study he-ion irradiation effects on their microstructure and mechanical *** ap-pears that the as-deposited hEA/Cu NLs manifest two size h-dependent hardness regimes(i.e.,increased hardness at small h and hardness plateau at large h),while the he-implanted ones exhibit monotonically increased *** to the fashion that smaller h renders less irradiation hardening in bimetal NLs,the fe_(50)mn_(30)Co_(10)Cr_(10)/Cu NLs manifest the trend that smaller h leads to greater irradiation *** contrast,the fe_(50)mn_(30)Co_(10)Ni_(10)/Cu NLs exhibit the maximum.i.radiation hardening at a critical h=50 *** this critical size,smaller h results in lower radiation hardening(similar to bimetal NLs),while above this size,smaller h results in greater radiation hardening(similar to fe_(50)mn_(30)Co_(10)Cr_(10)/Cu NLs).moreover,these transformable hEA/Cu NLs display inverse h-dependent strain rate sensitivity(SRS m)before and after he-ion ***,compared with as-deposited samples,the irradi-ated fe_(50)mn_(30)Co_(10)Cr_(10)/Cu NLs display reduced SRS,while the irradiated fe_(50)mn_(30)Co_(10)Ni_(10)/Cu NLs dis-play enhanced *** unusual size-dependent irradiation strengthening and inverse h effect on SRS in irradiated samples were rationalized by considering the block.ng effects of he bubbles on dislocation nucleation and motion,i.e.,dislocations shearing or bypassing he bubbles.

关键词： high entropy alloy/metal nanolaminates interfaces irradiation hardening Strain rate sensitivity Size effects

Design and optimization of the composition and mechanical properties for non-equiatomic CoCrNi medium-entropy alloys

在线全文

学校读者我要写书评

暂无评论

j.urnal of materials Science & Technology 2023年第8期139卷 232-244页

作者： j.X.yan z.j.zhang P.zhang j.h.liu h.yu q.m.hu j.B.yang z.f.zhang Shi-changxu innovation Center for Advanced materials Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China School of materials Science and Engineering Chongqing Jiaotong UniversityChongqing 400074China chool of materials Science and Engineering University of Science and Technology of ChinaShenyang 110016China School of materials Science and Engineering Northeastern UniversityShenyang 110819China School of information Science and Engineering Shenyang University of TechnologyShenyang 111003China

The development of multi-principal element alloys(mPEAs,also called as high-or medium-entropy al-loys,hEAs/mEAs)provides tremendous possibilities for materials ***,designing mPEAs with desirable mechanical properties confronts great challenges due to their vast composition *** this work.we provide an essential criterion to efficiently screen the CoCrNi mEAs with outstanding strength-ductility *** negative Gibbs free energy difference△E_(fCC-BCC)between the face-centered cubic(fCC)and body-centered cubic(BCC)phases,the enhancement of shear modulus G and the decline of stack.ng fault energy(SfE)γ_(isf)are com.i.ed as three requisites to improve the fCC phase stability,yield strength,deformation mechanisms,work.hardening ability and ductility in the *** effects of chemical composition on△E_(fCC-BCC),G andγisf were investigated with the first principles calculations for Co_(x)Cr_(33)Ni_(67-x),Co_(33)Cr_(y)Ni_(67-y)and Co_(z)Cr_(66-z)Ni_(34)(0≤x,y≤67 and 0≤z≤66)*** on the essential criterion and the calculation results,the composition space that displays the neg-ative Gibbs free energy difference△E_(fCC-BCC),highest shear modulus G and lowest SfEγ_(isf)was screened with the target on the com.i.ation of high strength and excellent *** this context,the optimal composition space of Co-Cr-Ni alloys was predicted as 60 at.%-67 at.%Co,30 at.%-35 at.%Cr and 0 at.%-6 at.%Ni,which coincides well with the previous experimental evidence for Co_(55)Cr_(40)Ni_(5)*** valid-ity of essential criterion is further proved after systematic comparison with numerous experimental data,which demonstrates that the essential criterion can provide significant guidance for the quick.exploitation of strong and ductile mEAs and promote the development and application of mPEAs.

关键词： medium-entropy alloys first-principles calculations Phase stability Stack.ng-fault energy Strength Ductility

first-Principles Study of the influence of Lattice misfit on the Behavior and the Ductility Effect of hafnium.i. Ni-Ni3Ai System

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

Acta metallurgica Sinica(English Letters) 2014年第1期27卷 87-94页

作者： y. wu j. Guo W. zhang X. ma q. zhang j. hou R. huang X. liu institute of molecular Engineering and Applied Chemistry Anhui University of Technology Ma'anshan 243002 China Shenyang National Laboratory for materials Science Instituteof Metal Research Chinese Academy of SciencesShenyang 110016 China College of Physics Science and Technology Shenyang NormalUniversity Huanghe Street 253 Shengyang 110034 China School of materials Science and Engineering Anhui Universityof Technology Ma'anshan 243002 China

Two Ni/Ni3Al-interface-contained cluster models with/without lattice misfit are studied by first-principles method to clarify the debates about the segregation behaviors of hafnium （hf） and explore the influence of lattice misfit on the ductility effect of hr. it is found that though hf prefers to substitute A1 rather than Ni in Ni3A1 phase within most of the investigated misfit range, its stronger preferring to Ni phase than NiaA1 phase mak.s it impossible to go into Ni3A1 phase to occupy A1 site in Ni-Ni3A1 alloys. Bond order analysis in hf-free case shows that lattice misfit has different effects on the Griffith work.of interfacial cleavage 27int/E and the maximum theoretical shear stress zmax of Ni and Ni3A1, contributing to the existence of anomalous strength-temperature phenomena in NiaA1 alloys. however, the addition of hf will mak. the 27int/E （or zmax） of both Ni3A1 and Ni decrease （or increase） with lattice misfit, indicating that the addition of hf may mak. the anomalous strength-temperature relationship in Ni3A1 region disappear locally.

关键词： hafnium Lattice misfit Segregation Ductility

microstructure evolution and shape memory behaviors of Ni_(47)Ti_(44)Nb_(9)alloy subj.cted to multistep thermomechanical loading with different prestrain levels

在线全文

学校读者我要写书评

暂无评论

j.urnal of materials Science & Technology 2024年第4期171卷 80-93页

作者： y.h.zhang h.Li z.W.yang X.liu q.f.Gu State k.y Laboratory of Solidification Processing School of Materials Science and EngineeringNorthwestern Polytechnical UniversityXi’an 710072China Shaanxi k.y Laboratory of high-Performance Precision forming Technology and Equipment Northwestern Polytechnical UniversityXi’an 710072China

Ni_(47)Ti_(44)Nb_(9)shape memory alloy(SmA)is a promising material in the aerospace field due to its wide transformation *** application of shape memory effect depends on multistep thermomechan-ical loading,viz.,low-temperature deformation and subsequent heating to ***-temperature deformation prestrain plays a pivotal role in shape memory properties tailoring of SmA ***,microstructure evolution and deformation mechanisms of Ni_(47)Ti_(44)Nb_(9)SmA subj.cted to vari-ous prestrain levels are still *** this end,microstructure evolution and shape memory behaviors of Ni_(47)Ti_(44)Nb_(9)alloy subj.cted to multistep thermomechanical loading with prestrain levels of 8%-16%at-28℃(m_(s)+30℃)were *** results demonstrate that the stress-strain curve of the specimen exhibits four distinct stages at a maximal prestrain of 16%.Whereas stageⅡand stageⅢend at prestrains of∼8%and∼12%,*** stageⅡ,the stress-induced martensitic transformation is accompanied by the dislocation slip of the NiTi matrix andβ-Nb *** stageⅢ,in addition to the higher density of dislocations and further growth of stress-induced martensite variants(SimVs),(001)compound twins are introduced as a result of the(001)deformation twinning in stress-induced ***{20-1}martensite twins are gradually introduced in stageⅣ.Correspondingly,after subsequent unloading and heating,a higher density ofmaustenite twins form.i. the specimen with a larger prestrain of 16%.With increasing prestrain from 8%to 16%,the recoverable strainε_(re)^(T)upon heating increases first and then ***ε_(re)^(T)obtains a maximum of 7.03%at 10%prestrain and de-creases to 6.17%at 16%*** increase ofε_(re)^(T)can be attributed to the formation of new SimVs,the further growth of existing SimVs,and the recoverable(001)compound *** the decrease ofε_(re)^(T)is m.i.ly associated with the irrecoverable strain by{20−1}martensite *** effe

关键词： Ni_(47)Ti_(44)Nb_(9)shape memory alloy Wide transformation hysteresis Thermomechanical loading microstructure evolution Shape memory behaviors Stress-induced martensitic transformation Deformation twinning

Soft computing approach for prediction of surface settlement induced by earth pressure balance shield tunneling

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

Underground Space 2021年第4期6卷 353-363页

作者： W.G.zhang h.R.Li C.z.wu y.q.Li z.q.liu h.L.liu k.y Laboratory of New Technology for Construction of Cities in mountain Area Chongqing UniversityChongqing 400045China National j.int Engineering Research Center of Geohazards Prevention in the Reservoir Areas Chongqing UniversityChongqing 400045China School of Civil Engineering Chongqing UniversityChongqing 400045China Norwegian Geotechnical institute(NGi) Sognsveien 720855 OsloNorway

Estimating surface settlement induced by excavation construction is an indispensable task.in tunneling,particularly for earth pressure balance(EPB)shield *** this study,predictive models for assessing surface settlement caused by EPB tunneling were established based on extreme gradient boosting(XGBoost),artificial neural network.support vector machine,and multivariate adaptive regression *** from three tunnel construction proj.cts in Singapore were used,with m.i. input parameters of cover depth,advance rate,earth pressure,mean standard penetration test(SPT)value above crown level,mean tunnel SPT value,mean m.i.ture content,mean soil elastic modulus,and grout *** performances of these soft computing models were evaluated by comparing predicted deformation with measured *** demonstrate the acceptable accuracy of the model in predicting ground settlement,while XGBoost demonstrates a slightly higher *** addition,the ensemble method of XGBoost is more computationally efficient and can be used as a reliable alternative in solving multivariate nonlinear geo-engineering problems.

关键词： EPB Surface settlement Soft computing XGBoost multivariate adaptive regression spline

What is going on in magnesium alloys？

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

j.urnal of materials Science & Technology 2018年第2期34卷 245-247页

作者： X.j. Wang D.k. Xu R.z. wu X.B. Chen q.m. Peng L. j.n y.C. Xin z.q. zhang y. liu X.h. Chen G. Chen k.k. Deng h.y. Wang School of materials Science and Engineering Harbin Institute of Technology Harbin 150001 China k.y Laboratory of Nuclear materials and Safety Assessment Institute of Metal Research Chinese Academy of Sciences Shenyang 110016 China k.y Laboratory of Superlight materials & Surface Technology (ministry of Education) Harbin Engineering University Harbin 150001 China School of Engineering RMIT University City Campus Carlton VIC 3053 Australia State k.y Laboratory of metastable materials Science and Technology Yanshan University Qinhuangdao 066004 China National Engineering Research Center of Light Alloy Net forming Shanghai Jiao Tong University Shanghai 200240 China College of materials Science and Engineering Chongqing University Chongqing 400030 China k.y Lab of Electromagnetic Processing of materials Ministry of Education Northeastern UniversityShnenyang 110819China k.y Laboratory of Lightweight and high Strength Structural materials of j.angxi Province Nanchang University Nanchang 330031 China School of Chemical Engineering and Technology Tianjin University Tianjin 300350 China Shanxi k.y Laboratory of Advanced magnesium-Based materials Taiyuan University of Technology Taiyuan 030024 China k.y Laboratory of Automobile materials of ministry of Education & School of materials Science and Engineering Jilin University Changchun 130025 China

China has been developed into one of the most active regions in terms of both fundamental and applied research on magnesium （mg） and its alloys in the world from a solid base laid by its prominent metallurgist and materials scientists over the past decades. Nowadays, a large number of young-generation researchers have been inspired by their predecessors and become the k.y participants in the fields of mg alloys, which consequently led to the establishment of China youth Scholar Society for magnesium Alloys Research in 2015. Since then, the first two China youth Scholars Symposiums on mg Alloys Research had been held at harbin （2015） and Chongqing （2016） China, respectively. A number of crucial research inter- ests related to fundamental and applied mg research were discussed at the conferences and summarized in this short perspective, aiming to boost far-reaching initiatives for development of new mg-based materials to satisfy the requirements for a broad range of industrial employments. herein, four m.i. aspects are included as follows： i） Plastic deformation mechanism and strengthening strategy, ii） Design and development of new mg-based materials, iii） k.y service properties, and iv） New processing technologies.

关键词： mg alloys Plastic deformation Strengthening Alloying design high performance Corrosion fatigue behavior Creep Processing technologies Purification