检索结果-南通市图书馆

Journal of Materials Science & Technology 2023年第1期132卷 201-212页

作者： d.d.zhang J.Kuang H.Xue J.Y.zhang G.Liu J.Sun State Key Laboratory for Mechanical Behavior of Materials Xi’an Jiaotong UniversityXi’an 710049China

In this work,we designed a novel NiCoCr-based medium-entropy alloy(MEA)strengthened by coher-ent L12-nanoparticles,i.e.,(NiCoCr)92 Al 6 Ta 2(at.%).The strengthening and deformation mechanisms of the material and the coarsening kinetics of the coherent precipitates were systematically *** results indicated that giant precipitation hardening and its synergy with other strengthening contributors confer on the aged material a yield strength as high as 1.0 ***,a unique particle-features-dependent plasticity mechanism was revealed in this *** is,the alloy with a lower volume frac-tion,denser distribution,and finer particles mainly deformed by dislocation planar slip,otherwise,stack-faults-mediated plasticity was favored,rationalized by the cooperative/competitive effect of stack-fault energy,spatial confinement,and applied ***,the coarsening behavior of precipitate fol-lowed a modified Lifshitz-Slyozov-Wagner(LSW)model,and the nanoparticles displayed remarkably su-perior thermal stability compared to most traditional superalloys and reported multicomponent *** superb coarsening resistance of precipitate originated from the coupled effect of intrinsic sluggish diffusion in multi-principal alloys and the dual-roles of Ta species as a precipitate *** work provides a new pathway to develop strong-yet-ductile multicomponent alloys as promising candidates for high-temperature applications.

关键词： Medium-entropy alloy Mechanical properties Precipitation hardening deformation mechanisms Coarsening kinetics

Unusual He-ion irradiation strengthening and inverse layer thickness-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

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 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 Key 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 irradiation 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 blocking 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

designing hetero-structured ultra-strong and ductile Zr-2.5Nb alloys:Utilizing the grain size-dependent martensite transformation during quenching

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2022年第30期125卷 198-211页

作者： S.Y.Liu J.Y.zhang J.Kuang X.Y.Bao d.d.zhang C.L.zhang J.K.Yang G.Liu J.Sun State Key Laboratory for Mechanical Behavior of Materials Xi’an Jiaotong UniversityXi’an 710049China

To further improve the service performance of Zr-2.5Nb alloy worked as pressure tubes in pressurized heavy water reactors,more investigation about the microstructure and thermomechanical processing route of Zr-2.5Nb alloy need to be *** this work,a hetero-structured Zr-2.5Nb alloy was prepared by applying a novel *** analysis reveals that the alloy exhibits a grain sizedependent martensite substructure transition during post-rolling *** hetero-structure consists of equiaxed primaryαgrains and the lamellae groups containing both parallelα’dislocation martensite andα’twin *** with the previously reported Zr-Nb alloys,the present Zr-2.5Nb alloys manifest the highest yield strength(∼710 MPa),together with a high ultimate tensile strength(∼844 MPa)and good ductility(∼17.1%).The enhanced mechanical properties are found to arise from the properly controlled fraction/size of the two types of martensite,which not only significantly strengthens the alloy but also contributes to a stronger strain hardening.A model based on the grain-size-dependent critical resolved shear stress for dislocation slip and twinning has been proposed to explain theα’martensite substructures transition at a critical grain size dc=3.3μ*** this size,the critical resolved shear stress(CRSS)for twinning is higher than that for the***,theα’dislocation martensite is more favorable to ***,theα’twin martensite would exhibit a high *** present work indicates that making use of the grain size-dependent martensite transformation to tailor the heterostructure in Zr alloys is an effective strategy to overcome the strength–ductility trade-off in the material.

关键词： Zr-Nb alloys Heterogeneous structure Martensitic transformation Grain size Strength

Achieving excellent strength-ductility synergy in twinned NiCoCr medium-entropy alloy via Al/Ta co-doping

在线全文

学校读者我要写书评

暂无评论

Journal of Materials Science & Technology 2021年第28期87卷 184-195页

作者： d.d.zhang H.Wang J.Y.zhang H.Xue G.Liu J.Sun State Key Laboratory for Mechanical Behavior of Materials Xi’an Jiaotong UniversityXi’an710049PR China Science and Technology on Reactor Fuel and Materials Laboratory Nuclear Power Institute of ChinaChengdu610041PR China

Alloying is an effective strategy to tailor microstructure and mechanical properties of metallic materials to overcome the strength-ductility trade-off *** this work,we combined a novel alloy design principle,*** pronounced solid solution hardening(SSH)based on the misfit volumes engineering,and simultaneously,architecting the ductile matrix based on the valence electron concentrations(VEC)criterion,to fulfill an excellent strength-ductility synergy for the newly emerging high/medium-entropy alloys(HEAs/MEAs).Based on this strategy,Al/Ta co-doping within NiCoCr MEA leads to an efficient synthetic approach,that is minor Al/Ta co-doping not only renders significantly enhanced strength with notable SSH effect and ultrahigh strain-hardening capability,but also sharply refines grains and induces abnormal twinning behaviors of(NiCoCr)_(92)Al_(6)Ta_(2) *** with the partially twinned NiCoCr MEA,the yield strength(σy)and ultimate tensile strength(σUTS)of fully twinned Al/Ta-containing MEA were increased by~102%to~600 MPa and~35%to~1000 MPa,respectively,along with good ductility beyond 50%.different from the NiCoCr MEA with deformation twins(dTs)/stacking faults(SFs)dominated plasticity,the extraordinary strain-hardening capability of the solute-hardened(NiCoCr)_(92)Al_(6)Ta_(2) MEA,deactivated deformation twinning,originates from the high density of dislocation walls,microbands and abundance of *** abnormal twinning behaviors,i.e.,prevalence of annealing twins(ATs)but absence of dTs in(NiCoCr)_(92)Al_(6)Ta_(2) MEA,are explained in terms of the relaxation of grain boundaries(for ATs)and the twinning mechanism transition(for dTs),respectively.

关键词： Medium-entropy alloys Mechanical properties Solid solution hardening Twinning behavior Strength-ductility synergy

Microscale shaping and rounding of ridge arrays and star pattern features on nickel mould via electrochemical polishing

在线全文

学校读者我要写书评

暂无评论

Advances in Manufacturing 2024年第2期12卷 207-226页

作者： Sana Zaki Nan zhang Michael d.Gilchrist School of Mechanical and Materials Engineering University College DublinBelfieldDublin 4Ireland

High quality micro mould tools are critical for ensuring defect-free production of micro injection moulded *** demoulding stage of the micro injection moulding can adversely affect the surface integrity due to friction,adhesion and thermal stresses between the metallic mould and polymeric replicated *** the present work,we propose the use of precision electropolishing(EP)as a shaping and polishing process to control the draft angle and fillet radius of micro features in order to ease *** defects that occur in replicated polymer parts include cracks,burrs and distorted features.A nickel mould having multiple linear ridges and star shape patterns was designed for the present investigation to have characteristic dimensions ranging from 10μm to 150μm and with various aspect ratios to study the effect of electropolishing on modifying the shape of micro features and surface morphology.A transient 2d computational analysis has been conducted to anticipate the effect of shaping on the Ni mould after electrochemical polishing with non-uniform material removal rates,based on the distribution of current *** experimental results indicate that after shaping using EP,the draft angle of star-patterns and linear patterns can be effectively increased by approximately 3.6°,while the fillet radius increases by up to 5.0μ*** controlling the electropolishing process,the surface roughness can be maintained under 50 *** work uses a green and environmental friendly nickel sulfamate electrolyte which can be effective for shaping of nickel micro features without causing any surface deposition.

关键词： Micro feature shaping and electropolishing Micro mould tools Green electrolyte demoulding micro patterns

Global patterns and ecological drivers of taxonomic and phylogenetic endemism in angiosperm genera

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

Plant diversity 2024年第2期46卷 149-157页

作者： Hong Qian Brent d.Mishler Jian zhang Shenhua Qian Research and Collections Center Illinois State Museum1011 East Ash StreetSpringfieldIL 62703USA University and Jepson Herbaria Department of Integrative BiologyUniversity of CaliforniaBerkeleyCA 94720-2465USA Center for Global Change and Complex Ecosystems Zhejiang Tiantong Forest Ecosystem National Observation and Research StationSchool of Ecological and Environmental SciencesEast China Normal UniversityShanghai 200241China Shanghai Institute of Pollution Control and Ecological Security Shanghai 200092China Key Laboratory of the Three Gorges Reservoir Region's Eco-Environment Ministry of EducationChongqing UniversityChongqing 400045China

Endemism of lineages lies at the core of understanding variation in community composition among geographic regions because it reflects how speciation,extinction,and dispersal have influenced current ***,we investigated geographic patterns and ecological drivers of taxonomic and phylogenetic endemism of angiosperm genera across the *** identify centers of paleo-endemism and neo-endemism of angiosperm genera,and show that they are mostly located in the Southern Hemisphere in tropical and subtropical regions,particularly in Asia and *** categories of phylogenetic endemism centers can be differentiated using current climate *** climate,historical climate change,and geographic variables together explained~80%of global variation in taxonomic and phylogenetic endemism,while 42-46%,1%,and 15%were independently explained by these three types of variables,*** our findings show that past climate change,current climate,and geography act together in shaping endemism,which are consistent with the findings of previous studies that higher temperature and topographic heterogeneity promote *** study showed that many centers of phylogenetic endemism of angiosperms,including regions in Amazonia,Venezuela,and west-central tropical Africa that have not previously been identified as biodiversity hotspots,are missed by taxon-based measures of endemism,indicating the importance of including evolutionary history in biodiversity assessment.

关键词： Angiosperm Current climate Endemism Historical climate change Topographic heterogeneity

Subpulse drifting of PSR J1110–5637

在线全文

学校读者我要写书评

暂无评论

Research in Astronomy and Astrophysics 2022年第6期22卷 109-117页

作者： S.J.dang L.H.Shang L.Lin Q.J.Zhi R.S.Zhao C.B.Wu Z.Y.You A.J.dong J.T.Bai X.Xu d.d.zhang H.Yang Q.W.Lin School of Physics and Electronic Science Guizhou Normal UniversityGuiyang 550001China Guizhou Provincial Key Laboratory of Radio Astronomy and data Processing Guizhou Normal UniversityGuiyang 550001China School of Physics Science and Technology Xinjiang UniversityUrumqi 830011China

We report a detailed study of polarization characteristics and subpulse drifting in PSR J1110-5637 with the observations of the Parkes 64 m radio telescope at 1369 *** observations revealed that the trailing component of the pulse profile has obvious subpulse drifting,while the leading component has no subpulse *** the two-dimensional fluctuation spectrum(2dFS),we detected three distinct emission modes in the trailing component(modes A,B and C).The emission in mode A is chaotic and indistinguishable,while modes B and C have obvious subpulse *** vertical modulation periods P3of modes B and C are around the mean values of 12 P and 8 P,*** subpulse drifting of PSR J1110-5637 will expand the pulsar sample with multiple subpulse drifting rates,and this will help future systematic studies on the physical origin of the subpulse drifting phenomenon.

关键词： (stars:)pulsars general-(stars:)pulsars individual(PSR J1110-5637)-Stars

Environmental records of carbon in recent lake sediments

在线全文

学校读者我要写书评

暂无评论

Science China Earth Sciences 2002年第10期45卷 875-884页

作者：陈敬安万国江汪福顺张峰黄荣贵 d.d.zhang R.Schmidt State Key Laboratory of Environmental Geochemistry Institute of Geochemistry Chinese Academy of Sciences Guiyang 550002 China department of Geography and Geology University of Hong Kong Pokfulam Road Hong Kong China Institute of Limnology Austrian Academy of Sciences A-5310 Mondsee Austria

Based on careful sampling and accurate analysis of recent sediments in Lake Chenghai, this paper discusses the staggered positive/negative correlation between organic carbon (OC) concentration and inorganic carbon (IC) concentration. The result indicates that temperature change, and its induced relative changes are the main factors affecting the relationship between IC concentration, δ13C of carbonate and OC concentration. When temperature and its induced photosynthesis strength change control autochthonous calcite precipitation, OC concentration is positively correlated with IC concentration and δ13C of carbonate. When temperature and its induced physical/chemical changes dominate, OC concentration displays negative correlation with IC concentration and δ13C of carbonate. IC concentration and δ13C of carbonate in sediments of Lake Chenghai are good proxies for climatic warm/cold changes.

关键词： lake sediment, organic carbon, inorganic carbon, δ13C.

在线全文

学校读者我要写书评

暂无评论

湖泊现代沉积物碳环境记录研究

中国科学（d辑） 2002年第1期32卷 73-80页

作者：陈敬安万国江汪福顺黄荣贵张峰 d.d.zhang R.Schmidt 中国科学院地球化学研究所环境地球化学国家重点实验室贵阳550002 department Institute

通过对云南程海现代沉积物的精细采样和分析,研究了湖泊沉积物中有机碳与无机碳含量阶段性的正相关和负相关变化.结果表明,温度及其引起的相关变化是控制沉积物无机碳含量、碳酸盐δ13C和有机碳含量变化关系的主要因素.当温度及其引起... 详细信息

通过对云南程海现代沉积物的精细采样和分析,研究了湖泊沉积物中有机碳与无机碳含量阶段性的正相关和负相关变化.结果表明,温度及其引起的相关变化是控制沉积物无机碳含量、碳酸盐δ13C和有机碳含量变化关系的主要因素.当温度及其引起的光合作用强度变化对湖泊自生碳酸钙沉淀起主导作用时,沉积物有机碳含量与无机碳含量及碳酸盐δ13C呈正相关变化;当温度及其引起的蒸发速率等其他物理化学因素变化对湖泊自生碳酸钙沉淀起主导作用时,沉积物有机碳含量与无机碳含量及碳酸盐δ13C呈负相关变化.程海沉积物无机碳含量和碳酸盐δ13C是湖区气候冷暖变化的良好代用指标.

关键词：湖泊沉积物有机碳无机碳 δ^13C 碳酸盐云南温度气候变化

Advances in ground heat exchangers for space heating and cooling:Review and perspectives

在线全文

学校读者我要写书评

暂无评论

Energy and Built Environment 2024年第2期5卷 255-269页

作者： Ping Cui Weibo Yang Wenke zhang Ke Zhu Jeffrey d.Spitler Mingzhi Yu School of Thermal Engineering Shandong Jianzhu UniversityJinanShandong 250101China College of Electrical Energy and Power EngineeringYangzhou UniversityYangzhouJiangsu 225127China department of Mechanical Engineering Oklahoma State UniversityStillwaterOKUSA

As a renewable energy source,geothermal energy has been widely used to provide space heating and cooling for *** thermal performance of ground heat exchanger(GHE)is significant for the operating efficiency of the ground source heat pump(GSHP)*** paper presents a comprehensive review of developments and advances of three kinds of GHE,including vertical borehole GHE(VBGHE),Pile GHE(PGHE),and deep borehole GHE(dBGHE)which are currently popular in larger GSHP ***,analytical models proposed to ana-lyze heat transfer process of VBGHE with different geological conditions are summarized,such as homogenous or heterogeneous ground,with or without groundwater *** and short-time step models and measures to improve GHE thermal performance are also ***,a summary of research advances in PGHE is provided,which includes the heat transfer models of PGHE,the effects of geometric structure,oper-ation modes,pile spacing,use of phase change material(PCM),thermal properties of PCM,thermo-mechanical behavior and/or thermal performance of *** effects of groundwater flow direction and velocity on PGHE are also summarized in ***,models of three kinds of dBGHEs,i.e.,deep coaxial GHE(dCGHE),deep U-bend GHE(dUGHE)and super-long gravity heat pipe(SLGHP),are *** physical bases of the dif-ferent analytical models are elaborated and also their advantages and disadvantages are *** in numerical modelling and improving numerical model calculation speed of dCBHE,dCBHE array,and dUBHE are *** review provides a meaningful reference for the further study of GHEs.

关键词： Vertical borehole ground heat exchanger Pile ground heat exchanger deep borehole ground heat exchanger Modelling