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Microstructural evolutions of Cu(Ni)/AuSn/Ni joints during reflow

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Progress in Natural Science:Materials International 2011年第4期21卷 347-354页

作者： Xiao-feng WEI,ri-chu wang,Chao-qun PENG,Yan FENG,Xue-wei ZHU School of Materials Science and Engineering,Central South University,Changsha 410083,China School of Materials Science and Engineering Central South University Changsha 410083 China

Interfacial reactions of the Ni/AuSn/Ni and Cu/AuSn/Ni joints are experimentally studied at 330℃for various reflow *** microstructures and mechanical properties of the as-solidified solder joints are *** as-solidified solder matrix of Ni/AuSn/Ni presents a typical eutecticξ-(Au,Ni)5Sn+δ-(Au,Ni)Sn lamellar microstructure after reflow at 330℃for 30 *** reflow for 60 s,a thin and flat(Ni,Au)3Sn2intermetallic compound(IMC) layer is formed,and some needle-like(Ni,Au)3Sn2phases grow from the IMC layer into the solder *** the other hand,a cellular-typeξ(Cu) layer is found at the upper AuSn/Cu interface in the Cu/AuSn/Ni joint after reflow for 30 s,and a(Ni,Au,Cu)3Sn2IMC layer is also formed at the lower AuSn/Ni interface. For both joints the IMC layer grows significantly with the increase of reflow time,but the growth rate of(Ni,Au,Cu)3Sn2IMC in the Cu/AuSn/Ni joint is smaller than that of the(Ni,Au)3Sn2layer in the Ni/AuSn/Ni *** comparisons of the shear strength and fracture surface between the Ni/AuSn/Ni and Cu/AuSn/Ni joints suggest that the coupling effect of the Cu/AuSn/Ni sandwich joint is helpful to prevent the excessive growth of(Ni,Au)3Sn2,which in turn enhances the mechanical reliability of the solder joint.

关键词： Cu(Ni)/AuSn/Ni joints interfacial reaction intermetallic compound(IMC) coupling effect

Growth behavior and microstructure of intermetallics at interface of AuSn20 solder and metalized-Ni layer

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Transactions of Nonferrous Metals Society of China 2017年第5期27卷 1199-1205页

作者： Xiao-feng WEI Xue-wei ZHU ri-chu wang College of Mechanical and Electronic Engineering Northwest A&F University Yangling 712100 China School of Materials Science and Engineering Central South University Changsha 410083 China

The AuSn20/Ni joints were prepared by the reflow soldering technology and then annealed at solid-state temperature to form diffusion *** interfacial reactions and the growth kinetics of the intermetallic compounds(IMC)at the AuSn20/Ni soldering interface were investigated by scanning electron microscopy(SEM)and electron probe microanalysis(EPMA).The results show that,the(Ni,Au)3Sn2phases are formed at the AuSn20/Ni interface after soldering *** thickness l of the IMC layer monotonically increases with increasing annealing time t according to the relationship l=k(t/t0)n,where the exponent n is0.527,0.476and0.471for393,433and473K annealing,*** indicates that the volume diffusion contributes to the growth of the IMC layer at the AuSn20/Ni interface at solid-sate *** pre-exponential factor K0=1.23×10?7m2/s and the activation enthalpy QK=81.8kJ/mol are obtained from the results of the parabolic coefficient K by a least-squares method.

关键词： AuSn20/Ni joint interfacial reaction growth kinetics volume diffusion mechanism

Corrosion and discharge performance of Mg-9%Al-2.5%Pb alloy as anode for seawater activated battery

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Transactions of Nonferrous Metals Society of China 2016年第8期26卷 2144-2151页

作者： Min DENG ri-chu wang Yan FENG Nai-guang wang Lin-qian wang School of Materials Science and Engineering Central South University Changsha 410083 China

To obtain a new kind of Mg?Al?Pb alloy anode material with low content of Pb, the corrosion and discharge behavior of Mg?9%Al?2.5%Pb (hereafter in mass fraction) alloy were investigated by immersion tests and electrochemical techniques, and compared with those of Mg?6%Al?5%Pb alloy. The results indicate that Mg?9%Al?2.5%Pb alloy exhibits a lower self-corrosion rate and higher utilization efficiency in contrast with Mg?6%Al?5%Pb alloy because of the higher content of Al. As the result of the decrease of Pb content, the discharge activity of Mg?9%Al?2.5%Pb alloy is relatively weaker but still meets the requirement of anode. These results reveal that Mg?9%Al?2.5%Pb alloy with a low content of Pb can serve as a good candidate for the anode material used in seawater activated battery.

关键词： Mg.Al.Pb alloy anode material self-corrosion rate utilization efficiency discharge activity

Microstructure and properties of Cu matrix composites reinforced with surface-modified Kovar particles

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Transactions of Nonferrous Metals Society of China 2024年第10期34卷 3251-3264页

作者： Tao MENG ri-chu wang Zhi-yong CAI Ying-jun YAO School of Materials Science and Engineering Central South UniversityChangsha 410083China Key Laboratory of Electronic Packaging and Advanced Functional Materials Central South UniversityChangsha 410083China

The thermal conductivity of Cu/Kovar composites was improved by suppressing element diffusion at the interfaces through the formation of FeWO_(4)coating on the Kovar particles via vacuum *** matrix composites reinforced with unmodified(Cu/Kovar)and modified Kovar(Cu/Kovar@)particles were prepared by hot *** results demonstrate that the interfaces of Cu/FeWO_(4)and FeWO_(4)/Kovar in the Cu/Kovar@composites exhibit strong bonding,and no secondary phase is *** presence of FeWO_(4)impedes interfacial diffusion within the composite,resulting in an increase in grain size and a decrease in dislocation *** surface modification of the Kovar particle,the thermal conductivity of Cu/Kovar@composite is increased by 110%from 40.6 to 85.6 W·m^(-1)·K^(-1).Moreover,the thermal expansion coefficient of the Cu/Kovar@composite is 9.8×10^(-6)K^(-1),meeting the electronic packaging requirements.

关键词： electronic packaging material Cu/Kovar composite surface modification thermal conductivity

Effect of Gd on microstructure, mechanical properties, and corrosion behavior of as-homogenized Mg-8Li-3Al-2Zn-0.2Zr alloy

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Transactions of Nonferrous Metals Society of China 2022年第8期32卷 2494-2509页

作者： Yue-hua SUN ri-chu wang Chao-qun PENG Xiao-feng wang School of Materials Science and Engineering Anhui University of TechnologyMaanshan 243002China School of Materials Science and Engineering Central South UniversityChangsha 410083China

The microstructure observation,tensile test,electrochemical measurement,and corrosion morphology characterization were conducted to study the effect of Gd on the microstructure,mechanical properties,and corrosion behavior of as-homogenized Mg−8Li−3Al−2Zn−0.2Zr(LAZ832−0.2Zr)*** addition of trace Gd can improve the mechanical properties of as-homogenized LAZ832−0.2Zr alloy by refining the microstructure,reducing the content of AlLi softening phase,and forming Al_(2)Gd strengthening ***,the addition of trace Gd can weaken the microgalvanic corrosion between matrix phase and AlLi phase,inhibit the galvanic corrosion betweenα-Mg phase andβ-Li phase,and result in the formation of dense oxide film containing Gd_(2)O_(3),thereby improving the corrosion resistance of the *** the Gd content is 1.0 wt.%,the alloy shows the best comprehensive properties with the ultimate tensile strength of 189.8 MPa,elongation of 42.3%,and corrosion rate(determined by hydrogen evolution)of 0.86 mm·a^(−1).

关键词： Mg-Li alloy rare earth Gd microstructure mechanical properties corrosion behavior

Discharge performance of Mg-Al-Pb-La anode for Mg-air battery

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Transactions of Nonferrous Metals Society of China 2018年第11期28卷 2275-2287页

作者： Yan FENG Ge LEI Yu-qing HE ri-chu wang Xiao-feng wang School of Materials Science and Engineering Central South UniversityChangsha 410083China

b The discharge performance of Mg-Al-Pb-La anode was investigated by electrochemical techniques and compared withthat of Mg-Al-Pb alloy. The results indicate that the Mg-Al-Pb-La anode provides enhanced corrosion resistance at open circlepotential, and exhibits better discharge activity than the Mg-Al-Pb alloy. The utilization efficiency of Mg-Al-Pb-La anode ishigher than that of commercial Mg-Al-Zn （AZ） and Mg-Al-Mn （AM） alloys. A single Mg-air battery with Mg-Al-Pb-La alloy asthe anode and air as the cathode has an average discharge potential of 1.295 V and a discharge capacity of 1370 mA·h/g duringdischarge at 10 mA/cm2, which is higher than that of batteries using Mg-Li anodes. The enhancement in discharge performance ofthe Mg-Al-Pb-La anode is caused by its modified microstructure, which reduces the self-corrosion and accelerates the spalling ofoxidation products during battery discharge. Furthermore, the dissolution mechanism of Mg-Al-Pb-La anode during the dischargeprocess was analyzed.

关键词： Mg-air battery Mg-Al-Pb-La alloy corrosion resistance discharge activity utilization efficiency

Recent progress in Mg-Li matrix composites

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Transactions of Nonferrous Metals Society of China 2019年第1期29卷 1-14页

作者： Yue-hua SUN ri-chu wang Chao-qun PENG Yan FENG Ming YANG School of Materials Science and Engineering Central South University Changsha 410083 China

Mg-Li matrix composites are one of the ideal structural materials in the fields of aerospace and military due to their high specific strength and stiffness, good damping and wear resistance, and small thermal expansion coefficient. The preparation technologies of Mg-Li matrix composites including powder metallurgy, pressure infiltration, stir-casting, foil metallurgy, and in-situ synthesis were introduced, and their advantages and disadvantages were compared. The common matrix alloys and reinforcements for Mg-Li matrix composites as well as the structure and performance of typical composites were mainly summarized. Then the interface chemistry between matrix and reinforcement was briefly reviewed. Finally, some problems existing at present and the possible solutions were discussed.

关键词： Mg-Li alloy composites preparation reinforcement interface chemistry

Corrosion behavior and surface treatment of superlight Mg-Li alloys

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Transactions of Nonferrous Metals Society of China 2017年第7期27卷 1455-1475页

作者： Yue-hua SUN ri-chu wang Chao-qun PENG Yan FENG Ming YANG School of Materials Science and Engineering Central South University Changsha 410083 China

Mg-Li alloy,as a superlight metallic engineering material,shows great potential in the fields of aerospace and militarydue to its high specific strength,better formability,and excellent electromagnetic shielding *** research process ofMg-Li alloys is reviewed and three main problems are pointed *** at the poor corrosion resistance of Mg-Li alloys,thecorrosion behavior is mainly *** surface treatment technologies,including electroplating,electroless plating,plasmaspraying,molten salt replacement,conversion coating,anodizing,micro-arc oxidation,organic coating,and organic-inorganic hybridcoating,are introduced in ***,the future development of corrosion and protection of Mg?Li alloys is discussed.

关键词： Mg-Li alloy specific strength formability electromagnetic shielding corrosion behavior surface treatment hybrid coating

Hierarchical porous Co_(3)O_(4) spheres fabricated by modified solvothermal method as anode material in Li-ion batteries

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Transactions of Nonferrous Metals Society of China 2022年第4期32卷 1253-1260页

作者： Yan FENG Cai-yu CAO Jing ZENG ri-chu wang Chao-qun PENG Xiao-feng wang School of Materials Science and Engineering Central South UniversityChangsha 410083China Hunan Provincial Key Laboratory of Electronic Packaging and Advanced Functional Materials Changsha 410083China School of Metallurgy and Environment Central South UniversityChangsha 410083China

Hierarchical porous Co_(3)O_(4)spheres were synthesized by a solvothermal method followed by high-temperature ***,SEM,TEM and electrochemical tests were used to study the structure and performance of the hierarchical porous Co_(3)O_(4)*** results show that the Co_(3)O_(4)synthesized at a calcination temperature of 700°C(Co_(3)O_(4)-700)is micro-sized spheres(1-2μm)consisting of plentiful nanoparticles(50-200 nm)and numerous pores(~100 nm).Due to its numerous porous morphology,the Co_(3)O_(4)-700 anode exhibits the highest cycling performance with excellent reversible discharge and charge specific capacities of 745 and 755 m A·h/g at the current density of 100 m A/g after 100 charge-discharge cycles,respectively.

关键词： Co_(3)O_(4) lithium-ion batteries porous structure spheres calcination