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Precipitation on stacking faults in Mg–9.8wt%Sn alloy

journal of Materials Science & Technology 2020年第10期42卷 230-240页

作者： C.q.Liu C.He H.w.Chen j.F.Nie International joint Laboratory for Light Alloys(Ministry of Education) College of Materials Science and EngineeringChongqing UniversityChongqing400044China Department of Materials Science and Engineering Monash UniversityVictoria3800Australia Electron Microscopy Center Chongqing UniversityChongqing400044PR China

In this work,we have systematically investigated precipitation ofβ’-Mg3Sn phase on intrinsic stacking faults I1 and I2 in a Mg-9.8 wt%Sn alloy using aberration-corrected scanning transmission electron *** observed I1 faults are generated by the dissociation of c+a perfect dislocations and bounded by Frank partial dislocations having a Shockley *** ofβ’on I1 involves a shear of 1/3α,similar to its formation directly from theα-Mg ***β’phase often nucleates at one end of an I1 fault due to the interaction between shear strain fields ofβ’and the Shockley component of the Frank partial at that end,and subsequently grows towards the other end of the *** theβ’reaches to the other end,the Shockley partial bounding the lengthening end of theβ’reacts with the Frank partial bounding the fault,generating an a perfect dislocation that can glide away from the precipitate and the *** observed I2 faults are generated by the dissociation of a perfect dislocations and bounded by Shockley *** ofβ’on I2 does not need a shear of 1/3α,since the pre-existing I2 fault already provides an ABCA four-layer structure ofβ’.Thickening of theβ’that has already formed on the I2 involves the successive occurrence of three crystallographically equivalent shears of 1/3αon every second(0002)αplane of theα-Mg *** this thickening mechanism is similar to that of theβ’formed directly from theα-Mg matrix,an a perfect dislocation will be produced when theβ’is thickened to eight layers,and it can again glide away from the precipitate and the fault.

关键词： Heterogeneous precipitation HAADF-STEM Shockley partial dislocation Frank partial dislocation Dislocation reaction

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Tuning the morphologies of SiC nanowires via the change of the Co_xSi_y melts

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Nano-Micro Letters 2010年第1期2卷 11-17页

作者： j.j.Chen Y.Pan w.H.Tang q.Shi Department of Physics Center for Optoelectronics Materials and Devices Zhejiang Sci-Tech University Department of Materials Science and Engineering Zhejiang University Key Laboratory of Advanced Textile Materials and Manufacturing Technology (Zhejiang Sci-Tech University) Ministry of education

SiC nanowires and SiC/SiO2 core-shell structural nanowires were synthesized via a simple thermal evaporation of CoxSiy melts at the temperature of 1500?C. The morphologies and yields of those SiC nanowires can be tuned by altering the composition of CoxSiy. Nanowires obtained by thermal evaporation of Co Si are composed of SiC/SiO2 core-shell nanostructures with lengths up to several hundreds of micrometers, diameters of 4050 nm, and the thickness of amorphous SiO2 wrapping shell about 20 nm. SiC nanowires prepared by thermal evaporation of Co Si2 and Co2 Si melt are found to be hexagonal-prism-shaped nanorods, and the diameter of those nanorods is about 150 nm and the length is about 10 microns. All the SiC nanowires obtained possess [111] preferred growth direction with a high density stacking faults and twin defects. Taking into consideration the binary alloy diagram of Co Si and the participation of oxygen, we propose the vapor-solid growth mechanism of SiC nanowires and discuss the effect of the supersaturation of Si O on the morphology and yields of SiC nanowires.

关键词： Silicon carbide Nanowires Morphology

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Active{1121}and{1012}extension twinning in a wE43 Mg alloy

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journal of Materials Science & Technology 2023年第13期144卷 93-101页

作者： w.q.Chen S.Deng X.j.Zhao S.N.Luo Key Laboratory of Advanced Technologies of Materials Ministry of EducationSouthwest Jiaotong UniversityChengdu 610031China The Peac Institute of Multiscale Sciences Chengdu 610031China

Deformation twinning in a wE43 alloy subjected to uniaxial compression at room temperature is ***{1121}and{1012}extension twinning is *** activation of{1121}twinning in a certain grain is influenced not only by its own Schmid factor,but also by that of the basal ***-twin interactions of the co-zone{1121}twin variants are commonly observed and systematically studied,including the crystallographic characteristics of the four typically observed twin-twin junctions(TTjs)and the associated twin-twin *** the quilted-looking TTjs formed by the interaction of co-zone{1012}twin variants,crossing-like TTjs of co-zone{1121}twin variants are observed and their formation mechanisms are ***-like TTjs are also formed by the interaction of{1121}and{10¯12}*** morphology and thickening rate of{1121}and{1012}twins vary markedly due to the difference in twinning *** needle-like{1121}twins thicken more slowly than the lenticular{1012}*** nucleation is observed on the previously formed{1121}twin boundary due to the relatively large strain concentration on such interface,while twin nucleation on{1012}twin boundary is rarely observed.

关键词： Mg alloy Plastic deformation Twinning Twin-twin interaction Twin-twin junction

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STUDY OF THE INFLUENCE OF pH ON THE ELECTROCRYSTALLIZATION OF ZINC

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Acta Metallurgica Sinica(English Letters) 2005年第4期18卷 497-504页

作者： Z. Zhang w.H. Leng j. q. Zhang Department of Chemistry Zhejiang University Hangzhou 310027 China State Key Laboratory for Corrosion and Protection Institute of Metal Reseach The Chinese Academy of Sciences Shenyang 110016 China

The influence of pH value of the electrolyte solution on the zinc electroplating process was studied by means of cyclic voltammetry and chronoamperometry approaches. The results shown that, under this experimental conditions and at high overpotentials, the nucleation of zinc is instantaneous, and the nuclear densities N increase with the overpotentials. while at low potentials, no distinguished nucleation current can be observed. High pH promotes the deposition either by drifting the initial depositing potential positively, or by increasing the depositing current through the change of the total charge of the adsorption process qads, i.e., thevstructure of electrochemical double layer.

关键词： zinc electroplating nucleation growth mechanism

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COUPLED SIMULATION OF 3D ELECTRO-MAGNETO-FLOw FIELD IN HALL-HEROULT CELLS USIng FINITE ELEMENT METHOD

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Acta Metallurgica Sinica(English Letters) 2006年第2期19卷 105-116页

作者： j. Li w. Liu Y.q. Lai q.Y. Li Y.X. Liu School of Metallurgy Science and Engineering Central South University Changsha 410083 China Chemistry Department Guangxi Normal University Guilin 531400 China

Two full 3D steady mathematical models are developed by finite element method （FEM） to calcalate coupled physics fields. the electro-magnetic model is built and solved first and so is the fluid motion model with the acquired electromagnetic force as source body forces in Navier-Stokes equations. Effects caused by the ferromagnetic shell, busbar system around, and open boundary problem as well as inside induced current were considered in terms of the magnetic field. Furthermore, a new modeling method is found to set up solid models and then mesh them entirely with so-called structuralized grids, namely hex-mesh. Examples of 75kA prebaked cell with two kinds of busbar arrangements are presented. Results agree with those disclosed in the literature and confirm that the coupled simulation is valid. It is also concluded that the usage of these models facilitates the consistent analysis of the electric field to magnetic field and then flow motion to the greater extent, local distributions of current density and magnetic flux density are very much dependent on the cell structure, the steel shell is a shield to reduce the magnetic field and flow pattern is two dimensional in the main body of the metal pad.

关键词： coupled simulation electromagnetic field flow field aluminum reduction cell finite element analysis

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Long-term corrosion evolution associated with the structural heterogeneities of an Fe-based amorphous coating in H_(3)BO_(3)solution at various temperatures

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journal of Materials Science & Technology 2023年第9期140卷 233-248页

作者： D.B.wang j.wu j.P.Cui q.wang T.R.Li w.Emori S.D.Zhang j.q.wang Shenyang National Laboratory for Materials Science Institute of Metal ResearchCASShenyang110016China School of Materials Science and Engineering University of Science and Technology of ChinaShenyang110016China Key Laboratory of Biorheological Science and Technology Ministry of EducationCollege of BioengineeringChongqing UniversityChongqing400044China School of Materials Science and Engineering Sichuan University of Science and EngineeringZigong 643000SichuanChina

Understanding the long-term corrosion behavior of neutron absorber materials in H_(3)BO_(3)solution is crucial for the materials applications in spent fuel *** this paper,long-term corrosion evolution for 180 d in relation to the structural heterogeneities of an Fe-based amorphous coating(AMC)in H_(3)BO_(3)solution at various temperatures was systematically *** indicate that the coating corrosion could be divided into three distinct ***,the corrosion resistance increased owing to the thickening and composition evolution of the passive ***,the corrosion rate was kept almost constant in the second stage,which connected with the steady state of the passive ***,the corrosion resistance of coating reduced gradually owing to the initiation and penetration of local-ized ***,it was revealed that the localized corrosion was initiated at the relatively Cr-depleted amorphous matrix in the deep pores of the *** could be attributed to the synergy of Cr-depletion and occlusive effect in the deep pores during long-term *** the elevation of temperature,the localized corrosion was enhanced due to the accumulation of the H+in the pores to swiftly reach the critical conditions for passive film *** work provides insights into the long-term corrosion mechanism of Fe-based AMCs in H_(3)BO_(3)solution and offers meaningful contributions to the design of new corrosion resistant neutron absorbing coatings for spent fuel storage applications.

关键词： AMC Boric acid EIS Long-term corrosion Temperature

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Effect of Base Material on Microstructure and Texture Evolution of a Ti–6Al–4V Electron-Beam welded joint

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Acta Metallurgica Sinica(English Letters) 2017年第5期30卷 499-504页

作者： G.q.wang Z.B.Zhao B.B.Yu j.R.Liu q.j.w.ng j.H.Zhang R.Yang j.w.Li School of Materials Science and Engineering University of Science and Technology of China Institute of Metal Research Chinese Academy of Sciences Science and Technology on Power Beam Processes Laboratory Beijing Aeronautical Manufacturing Technology Research Institute

The effect of base material（BM） on microstructure and crystallographic orientation evolution of a Ti–6Al–4V electron-beam welded joint was investigated. Meanwhile, the crystallographic orientation of prior b grains was studied by advanced electron backscattered diffraction data processing. The inhomogeneity of microstructure within welded joint was formed due to the different microstructures of BM. By comparing microstructure details of the welded joint, including microstructure morphology and crystallographic orientation with those of the base material, it can be found that both the microstructure morphology and crystallographic orientation of the EBw joint would be controlled by BM.

关键词： Electron-beam welding Titanium alloys Prior b orientation Microstructure Texture

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青藏高原及其周边新近纪综合地层、生物群与古地理演化

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中国科学：地球科学 2024年第4期54卷 1343-1378页

作者：邓涛方小敏李强王世骐吴飞翔侯素宽马姣江左其杲孙丹辉郑妍史勤勤孙博阳李录中国科学院古脊椎动物与古人类研究所中国科学院脊椎动物演化与人类起源重点实验室北京100044 中国科学院生物演化与环境卓越创新中心北京100044 中国科学院大学地球与行星科学学院北京100049 中国科学院青藏高原研究所中国科学院青藏高原地球科学卓越创新中心北京100101 北京大学地球与空间科学学院造山带与地壳演化教育部重点实验室北京100871

青藏高原在新近纪的显著隆升对东亚乃至全球的气候环境产生了巨大的影响,因此,建立青藏高原新近纪地层框架对地球科学各领域的研究都有重要的意义.国际新近纪年代地层系统以海相为标准,分为中新统的6个阶和上新统的2个阶.新生代以来,陆... 详细信息

青藏高原在新近纪的显著隆升对东亚乃至全球的气候环境产生了巨大的影响,因此,建立青藏高原新近纪地层框架对地球科学各领域的研究都有重要的意义.国际新近纪年代地层系统以海相为标准,分为中新统的6个阶和上新统的2个阶.新生代以来,陆相地层在陆地上所占的比例迅速增加,到新近纪时已远远超过海相地层,在青藏高原及其周边地区几乎全部为陆相地层.中国的中新统包括5个阶,上新统包括2个阶,除中中新统的通古尔阶以15Ma为底界外,其余各阶都与对应的国际海相阶具有相同的古地磁定义和时限.哺乳动物化石在新生代陆相地层的划分对比中占有非常重要的地位,在新近系尤其倚重于啮齿类、食肉类、长鼻类、奇蹄类和偶蹄类化石.青藏高原有不少地层出露好且富含哺乳动物化石的盆地,新近系谢家阶和灞河阶的底界层型剖面分别位于西宁盆地和临夏盆地,并有精细的古地磁定年与哺乳动物化石相互配合,其余各阶的底界在青藏高原也可以有效确定.东亚地区许多哺乳动物首现属出现在青藏高原及其周边地区,在东北缘的临夏盆地和西南缘的西瓦立克地区尤为典型,其中,西瓦立克的原恐象Prodeinotherium首现于中新统底界,旧大陆最早的三趾马Hipparion首现于临夏盆地的灞河阶底界.对青藏高原及其周缘地区新生代沉积物及其所含的哺乳动物化石进行的牙釉质和古土壤碳氧同位素分析重建了气候环境背景及植被发育特征,发现其既与全球变化相关,又有地区性的特点.根据碳同位素变化得到的晚中新世C4植物扩张事件证据来自于青藏高原南缘,但形成鲜明对比的是,多个食草哺乳动物类群和古土壤碳酸盐及有机质的δ13C指示在青藏高原北缘直到新近纪末期仍然缺少明确或显著的C4植物信号.δ^(18)O分析显示在新生代存在几次重大的气候变化事件,尤其是晚中新世末期约7Ma的δ^(18)O正漂指示了青藏高原南北两侧向更干旱环境的转变.青藏高原在晚中新世的强烈隆升强化了海陆热力对比,由此加强了季风环流并导致C4植被在南亚扩张,但能够为中国北方带来大气降水和C4植物适宜气候的东亚夏季风还不足以影响到青藏高原北部地区.青藏高原在中新世整体上已上升至海拔3000m左右,成为阻碍大型哺乳动物交流的屏障;至上新世达到4000m以上的现代海拔高度,由此形成冰冻圈环境,导致冰期动物群祖先类型出现.

关键词：青藏高原新近系陆相地层哺乳动物化石古地磁

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DECREASIng PITTIng SUSCEPTIBILITY OF PASSIVE FILMS ON X70 PIPELINE STEEL IN NaCl SOLUTIONS BY ILLUMINATION

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Acta Metallurgica Sinica(English Letters) 2006年第2期19卷 91-97页

作者： w.C. Zhu w.H. Leng j.q. Zhang C.N. Cao Department of Chemistry Zhejiang University Hangzhou 310027 China State Key Laboratory for Corrosion and Protection of Metals Institute of Metal Research The Chinese Academy of Sciences Shenyang 110016 China

The influence of UV illumination on passivity and pitting susceptibility on X70 pipoeline steel in a borate buffer （pH=8.4 ） solution containing NaCl is described. It is observed that illumination of the sample leads to a decrease in its pitting susceptibility as indicated by pitting potential and incubation time measurements in chloride containing electrolytes. This effect is strongly dependent on the applied potential during passivation. The electronic properties of the passive films on X70 steel were studied by Mott-Schottky analysis and photocurrent transient measurements. The results indicated that illumination during passivation led to modifications in the electronic properties of the passive films, mainly to a decrease of the bulk doping and an increase in the surface state density. The cause for the decrease in the pitting susceptibility is preliminary explained in terms of such modifications of the passive flm.

关键词： X70 pipeline steel pitting susceptibility illumination passivation

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An effective approach for bonding of TZM and Nb-Zr system:Microstructure evolution,mechanical properties,and bonding mechanism

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journal of Materials Science & Technology 2021年第25期84卷 16-26页

作者： Z.w.Yang j.M.Lin j.F.Zhang q.w.qiu Y.wang D.P.wang j.Song Tianjin Key Lab of Advanced joining Technology School of Materials Science and EngineeringTianjin UniversityTianjin300072China Department of Mining and Materials Engineering McGill UniversityMontréalQuébecH3A 0C5Canada

A novel method of liquid metallic film(LMF)bonding was developed to join titanium zirconium molybdenum alloy(TZM)and Nb-Zr alloy with a Ni *** this method,a Ni-Zr liquid phase was formed by the eutectic reaction and then squeezed out from the gap due to a transient pressure,leaving an *** not only achieved a reliable metallurgical bonding but also served as a transition layer between TZM and Nb-Zr alloy to reduce the mismatch between them thus further improving its *** bonding mechanism of the TZM and Nb-Zr system was discussed based on theoretical calculation and high-resolution microscopy *** advantages of this method were established by comparing the microstructure and mechanical properties of LMF bonded joints with that of traditional contact-reaction brazing and direct diffusion ***,the feasibility of the LMF bonding method was also demonstrated by the reliable joining of other high-temperature and immiscible systems.

关键词： Bonding Titanium zirconium molybdenum alloy(TZM) Diffusion Microstructure Mechanical properties

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