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Science Bulletin 2018年第2期63卷 126-132页

作者： Zhigao Luo Sainan Liu Yangshen Cai Shi Li Anqiang Pan Shuquan Liang School of materials Science and engineering Central South University key laboratory of nonferrous metal materials Science and engineering Ministry of Education Central South University

Polypyrrole and sulfur derived hollow carbon nanofibers co-doped with nitrogen/sulfur are synthesized and applied as the anode for Na-ion batteries(NIBs). Successful doping of hollow carbon nanofiber with nitrogen and sulfur is confirmed by X-ray photoelectron spectroscopy, scanning and tunneling electron microscopy. Further analysis certifies that sulfur doping has a significant impact in improving the elecctrochemical performance of the carbon-based anodes for NIBs. The obtained N-doped hollow carbon nanofiber and N/S co-doped hollow carbon nanofiber exhibit similar morphologies but different electrochemical behavior. As expected, the N/S co-doped hollow carbon nanofiber anode exhibits enhanced electrochemical performance, including high specific capacity, outstanding long-term stability, and good rate stability.

关键词：电气化学阳极 Na 性能电池离子碳硫

Necklace-like Si@C nano?bers as robust anode materials for high performance lithium ion batteries

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Science Bulletin 2019年第4期64卷 261-269页

作者： Xiangzhong Kong Yuchao Zheng Yaping Wang Shuquan Liang Guozhong Cao Anqiang Pan School of materials Science & engineering Central South University Department of materials Science & engineering University of Washington Key Laboratory of Nonferrous Metal Materials and Engineering Ministry of Education Central South University

Silicon is believed to be a promising anode material for lithium ion batteries because of its highest theoretical capacity and low discharge potential. However, severe pulverization and capacity fading caused by huge volume change during cycling limits its practical application. In this work, necklace-like N-doped carbon wrapped mesoporous Si nanofibers(NL-Si@C) network has been synthesized via electrospinning method followed by magnesiothermic reduction reaction process to suppress these issues. The mesoporous Si nanospheres are wrapped with N-doped carbon shells network to form yolk-shell structure.Interestingly, the distance of adjacent Si@C nanospheres can be controllably adjusted by different addition amounts of SiO_2 nanospheres. When used as an anode material for lithium ion batteries, the NL-Si@C-0.5 exhibits best cycling stability and rate capability. The excellent electrochemical performances can be ascribed to the necklace-like network structure and N-doped carbon layers, which can ensure fast ions and electrons transportation, facilitate the electrolyte penetration and provide finite voids to allow large volume expansion of inner Si nanoparticles. Moreover, the protective carbon layers are also beneficial to the formation of stable solid electrolyte interface film.

关键词： Necklace-like Carbon shells network N-doped Mesoporous silicon Lithium ion batteries

Influence of cerium on microstructures and electrochemical properties of Al-Mg-Sn-Hg anode materials for seawater battery

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Journal of Rare Earths 2015年第9期33卷 1010-1016页

作者：冯艳李晓庚王日初彭超群刘莉 School of materials Science and engineering Central South University key laboratory of nonferrous metal materials Science and engineering Ministry of Education

Aluminum is an innovative anode material for seawater battery. But large polarization and low electrochemical activity restrict its application. In this research, A1-Mg-Sn-Hg-Ce anode materials were prepared and the microstructures were investigated by scanning electron microscopy （SEM）. The electrochemical properties of A1-Mg-Sn-Hg-Ce anode materials were measured by potentiodynamic polarization and potential-time discharge in a 4.5 wt.%NaOH solution at 353 K. The results indicated that the increasing content of cerium addition refined the grain structure of A1-Mg-Sn-Hg alloy and promoted the uniform distribution of Sn and Hg elements in A1 matrix. The morphology of second phases changed from disperse granular to intergranulate strip with the increasing content of cerium addition in AI-Mg-Sn-Hg alloy. During the half-cell tests at a 650 mA/cm3 current density, the discharge activity of AI-Mg-Sn-Hg-Ce alloy was improved with the increasing content of cerium addition. The average discharge potential of AI-Mg-Sn-Hg-0.3 wt.%Ce alloy was -1.721 V （vs. SCE）, which was more negative than -1.406 V （vs. SCE） in AZglD. The best corrosion resistance occurred in A1-Mg-Sn-Hg-0.05 wt.%Ce alloy with the corrosion current density, 18.84± 2.21 mA/cm2. The corrosion behaviours of A1-Mg-Sn-Hg-Ce alloys were also analyzed.

关键词： A1 anode materials rare earths corrosion resistance electrochemical activity scanning electron microscopy

On the low cycle fatigue behaviour of an Al-Zn-Mg-Cu alloy processed via non-isothermal ageing

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Journal of materials Science & Technology 2024年第1期168卷 227-238页

作者： Guangyi Guo Guofu Xu Yuan Tang Zhihao Zhao Zhihao Yi Haoran Li Ruohan Wang Xiaoyan Peng School of materials Science and engineering Central South UniversityChangsha 410083China key laboratory of nonferrous materials Science and engineering of ministry of education Changsha 410083China

The low cycle fatigue behaviour of an Al-Zn-Mg-Cu alloy processed via non-isothermal ageing(NIA)was examined at different strain amplitudes.We showed that NIA improved the low cycle fatigue life(more than 7000 cycles)by optimising the precipitate configuration within 5.5 h while maintaining comparable mechanical properties(570 MPa for tensile strength)and conductivity(nearly 39%IACS)to conventional isothermal ageing,simultaneously.Experimental observation combined with molecular dynamic simula-tion revealed that precipitation configuration manipulated by NIA had a crucial effect on fatigue resis-tance.A great number of repeatedly sheared and locally destructed GP zones enhanced co-planar slip and slip localisation in the under-aged alloy during the early stage of NIA,responsible for the dramatic displacement steps on the surface and resultant poor fatigue performance.As the NIA further proceeded,moderately coarsened precipitates with an average dimension of 6.0 nm and elevated number density ef-fectively impeded the dislocation movement and weaken the slip localisation to a great extent,improving the fatigue performance within a few hours.

关键词： Non-isothermal ageing Fatigue Al-Zn-Mg-Cu alloy Precipitate manipulation Slip localization

Phase relationship of Dy-Fe-Mn system at 773 K

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Journal of Rare Earths 2014年第7期32卷 655-662页

作者：杜成梅马君姚路陈国坚杨通晗曾维敬何维 key laboratory of nonferrous metal materials and New Processing Technology College of Materials Science and EngineeringMinistry of EducationGuangxi University

Rare-earth intermetallic compounds formed in many R-Fe-Mn（R=rare-earth element） systems exhibit excellent properties. In order to understand the existence and stability of the compounds in the system and further search for the potential application of R-Fe-Mn alloys in various aspects, it is necessary to investigate the phase relations of the Dy-Fe-Mn ternary system. A total of 96 samples of the Dy-Fe-Mn alloys were prepared by arc-melting and examined by metallographic analysis, X-ray diffraction（XRD）, scanning electron microscopy（SEM） and energy dispersive spectroscopy（EDS） techniques. The phase relationship of the Dy-Fe-Mn system at 773 K was determined. It was found that the isothermal section was characterized by intermediate solid solutions based on the substitutions of Fe/Mn atoms and the large extensions of the binaries into the ternary domains. The solid solubilities of the third element in the binary compounds and the phase boundaries were also determined by XRD technique using the phase disappearing method combined with the lattice parameter method and SEM/EDS technique. Two pairs of corresponding binary compounds in the Dy-Fe and Dy-Mn systems（DyFe2 and DyMn2, Dy6Fe23 and Dy6Mn23） formed a continuous series of solid solution at 773 K, respectively.

关键词： Dy-Fe-Mn phase diagram crystal structure X-ray diffraction rare earths

Sintering behavior,phase composition,microstructure,and dielectric characteristics of garnet-type Ca_(3)Fe_(2)Ge_(3)O_(12) microwave ceramics

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Journal of Materiomics 2023年第3期9卷 472-481页

作者： Guoqiang He Yanjun Liu Huanfu Zhou Xiuli Chen key laboratory of nonferrous materials and New Processing Technology Ministry of EducationSchool of Materials Science and EngineeringGuilin University of TechnologyGuilin541004China

This paper describes the solid-state production of a unique yellowish-grey microwave dielectric ceramic,Ca_(3)Fe_(2)Ge_(3)O_(12)(CFG).Rietveld refinement demonstrated that CFG corresponds to a cubic system(space group 230:Ia 3 d).The relative density of the ceramic initially increased and then decreased with the sintering temperature,reaching a maximum of 96.92%at 1330℃.According to scanning electron mi-croscopy and energy-dispersive spectroscopy results,the CFG ceramic grains are spherical and consistent in size;furthermore,they have distinct grain boundaries and a uniform distribution of the four con-stituent elements.The CFG ceramic has a superior crystal structure and a high crystallinity,according to transmission electron microscopy.Raman spectroscopy revealed that the Q×f value of the ceramic and the full width at half maximum of the Raman peak are negatively correlated.The ceramic possesses the best overall dielectric characteristics after sintering at 1330℃for 4 h:ε_(r)=10.31,Q×f=82636 GHz,andτ_(f)=-45.66×10^(-6)℃^(-1),showing that it is a promising candidate for use in mobile devices.

关键词： Low permittivity Garnet-type structure Microwave dielectric properties Ca_(3)Fe_(2)Ge_(3)O_(12)

Effects of Ag Addition on Precipitation and Fatigue Crack Propagation Behavior of a Medium-Strength Al–Zn–Mg Alloy

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Journal of materials Science & Technology 2018年第3期34卷 534-540页

作者： Lianghua Lin Zhiyi Liu Wenjuan Liu Yaru Zhou Tiantian Huang School of Material Science and engineering Central South University key laboratory of nonferrous metal materials Science and engineering Ministry of Education Central South University

Effects of trace addition of Ag on the fatigue crack propagation behavior and microstructure of a mediumstrength aged AI-Zn-Mg alloy were investigated in the present work. The results show that a combination of enhanced tensile strength and improved fatigue crack propagation resistance in Al-Zn-Mg alloys is achieved with small addition of Ag. The enhanced strength is attributed to the high density of η＇ precip- itates within the grains and narrow precipitate free zones in the vicinity of grain boundaries. The main contribution to the improvement of fatigue crack propagation resistance comes from the coarser precipitates within the grains. When subjected to two-step aging. Ag-added alloy shows larger semi-coherent matrix precipitates. These relatively coarser precipitates increase the homogeneity of deformation and therefore improve the fatigue crack propagation resistance. In addition, microstructure analysis indicates that the size and distribution of inclusions as well as the grain structures of Al-Zn-Mg alloys are independent of Ag addition.

关键词： Aluminum alloy Fatigue crack propagation Precipitate free zones Silver

Preparation of highly dispersed superfine W-20 wt% Cu composite powder with excellent sintering property by highly concentrated wet ball-milled process

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Rare metals 2018年第11期37卷 961-967页

作者： Bo-Hua Duan Zhen Fu Cheng-Kang Qi Hui-Jiang Liu Ao-Kui Sun De-Zhi Wang School of materials Science and engineering Central South University Key Laboratory of Ministry of Education for Nonferrous Materials Science and Engineering

The ball milling process and the CuWO-WOprecursors were investigated, and a new highly concentrated wet ball-milled process(HWM) was designed. W-20 wt% Cu composite powders with excellent sintering property were synthesized by highly concentrated wet ballmilled process and co-reduction. The powders were characterized by scanning electron microscopy(SEM), X-ray diffraction(XRD), field electron transmission electron microscopy(FESEM) and laser-diffraction diameter tester.The results indicate that particle size of W03-CuO powder mixtures decreases to 390 nm rapidly with the milling time increasing to 5 h. The CuWOprecursors promote the microstructural homogeneity of W and Cu. W-Cu composite powders have a highly dispersed and well sintering property. The particle size of W-Cu powders milled by HWM for 5 h is about 680 nm. High-resolution transmission electron microscopy(HRTEM) result suggests that W phase and Cu phase are mixed at nanometer scale. The above W-Cu composite powders reach the relative density of about 99.3%.

关键词： W-Cu composite powder Ultrafine powder Wet ball-milled Co-reduction Calcination

Developing Core-Shell Nano-Structures in FeCrAl-ODS Ferritic Alloys with the Co-Addition of Ni and Zr

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Acta metallurgica Sinica(English Letters) 2024年第2期37卷 364-372页

作者： Wenquan Ding Jieli Ma Yong Jiang Yiren Wang Huiqun Liu key laboratory for nonferrous materials of ministry of education School of Materials Science and EngineeringCentral South UniversityChangsha410083China National key laboratory for Powder metallurgy Central South UniversityChangsha410083China

A new Ni+Zr co-alloyed FeCrAl-ODS(oxide-dispersion-strengthened)ferritic alloy was fabricated by ball-milling and hot-isostatic-pressing.Using electron microscopy and atom probe tomography,the dispersive formation of high density core-shelled nano-particles of various sizes was confirmed with a common B2-NiAl shell.Among which,median-sized nano-particles(20-50 nm)typically have an Y_(4)Al_(2)O_(9)nano-core of<~20 nm,ultra-fine nano-particles(<~20)nm have an Y_(4)Zr_(3)O_(12)nano-core of<~10 nm,and larger-sized nano-particles(50-100 nm)incorporate an ultra-fine Y_(4)Al_(2)O_(9)nano-core and a few ultra-fine Y_(4)Zr_(3)O_(12)nano-oxides.All these nano-phases were highly coherent with the ferritic matrix.No large Y--Al-O nano-oxides were formed.The total number density of ultra-fine nano-particles was estimated as~2×10^(23)m^(-3)with a mean size of 6.3 nm only,and accordingly,the new alloy achieved an excellent combination of strength and ductility at high temperatures.

关键词： FeCrAl Oxide-dispersion-strengthened(ODS)alloy Mechanical alloying Nano-oxides Core-shell

Realizing enhanced energy storage and hardness performances in 0.90NaNbO_(3)-0.10Bi(Zn_(0.5)Sn_(0.5))O_(3)ceramics

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Journal of Advanced Ceramics 2022年第5期11卷 729-741页

作者： Xiaoyan DONG Xu LI Hongyun CHEN Qinpeng DONG Jiaming WANG Xiang WANG Yue PAN Xiuli CHEN Huanfu ZHOU Collaborative Innovation Center for Exploration of Hidden nonferrous metal Deposits and Development of New materials in Guangxi Key Laboratory of Nonferrous Materials and New Processing TechnologyMinistry of EducationSchool of Materials Science and EngineeringGuilin University of TechnologyGuilin 541004China College of materials Science and engineering Sichuan UniversityChengdu 610064China

Ceramic dielectric capacitors have a broad scope of application in pulsed power supply devices.Relaxor behavior has manifested decent energy storage capabilities in dielectric materials due to its fast polarization response.In addition,an ultrahigh energy storage density can also be achieved in NaNbO_(3)(NN)-based ceramics by combining antiferroelectric and relaxor characteristics.Most of the existing reports about lead-free dielectric ceramics,nevertheless,still lack the relevant research about domain evolution and relaxor behavior.Therefore,a novel lead-free solid solution,(1-x)NaNbO_(3)-xBi(Zn_(0.5)Sn_(0.5))O_(3)(abbreviated as xBZS,x=0.05,0.10,0.15,and 0.20)was designed to analyze the domain evolution and relaxor behavior.Domain evolutions in xBZS ceramics confirmed the contribution of the relaxor behavior to their decent energy storage characteristics caused by the fast polarization rotation according to the low energy barrier of polar nanoregions(PNRs).Consequently,a high energy storage density of 3.14 J/cm^(3)and energy efficiency of 83.30%are simultaneously available with 0.10 BZS ceramics,together with stable energy storage properties over a large temperature range(20-100℃)and a wide frequency range(1-200 Hz).Additionally,for practical applications,the 0.10 BZS ceramics display a high discharge energy storage density(W_(dis)≈1.05 J/cm^(3)),fast discharge rate(t_(0.9)≈60.60 ns),and high hardness(H≈5.49 GPa).This study offers significant insights on the mechanisms of high performance lead-free ceramic energy storage materials.

关键词： energy storage NaNbO3(NN)-based domain evolutions hardness