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Synthesis and Characterization of Mesoporous Alumina via a Reverse Precipitation Method

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Journal of materials Science & technology 2012年第6期28卷 572-576页

作者： y.S.Wu J.ma F.Hu M.C.Li College of materials Science and Engineering Shenyang University of TechnologyShenyang 110870China

Mesoporous aluminaΥ-AI203 with high specific surface area and large pore volume is prepared by using a facile reverse precipitation method from sodium aluminate and nitric acid. the effects of terminal pH value, aging time and thermal stability on the characterization of Υ-Al2Oa are studied by means of X-ray diffraction （XRD）, Fourier transform infrared spectroscopy （FtIR）, Brunauer-Emmett-teller （BEt） method and scanning electron microscopy （SEM）. the results show that Υ-A1203 with better properties can be obtained by changing the preparation parameters. High BEt surface area of 340 m2/g can be obtained by calcining at 500℃ for 4 h with large pore volume of 0.90 cm3/g and average pore size of 7.6 nm. After calcining at 1000°, the surface area is still 86 m2//g and the pore volume is 0.37 cm31/g.

关键词： Mesoporous alumina Reverse precipitation thermal stability

Evolution of the Microstructure and Strength in the Nugget Zone of Friction Stir Welded SiCp/Al-Cu-Mg Composite

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Journal of materials Science & technology 2014年第1期30卷 54-60页

作者： D.Wang B.L.Xiao Q.Z.Wang Z.y.ma Shenyang National Laboratory for materials Science Institute of Metal ResearchChinese Academy of Sciences University of Science and technology of China

A 6 mm-thick SiCp/2009AI composite plate was successfully joined by friction stir welding （FSW） using an ultrahard material tool to investigate the evolution of the microstructure and the strength in the nugget zone （NZ）. While some SiC particles were broken up during FSW, most of them rotated in the matrix. Large compound particles on the interfaces were broken off during FSW, whereas the amorphous layer and small compound particles remained on the interfaces. the dynamically recrystallized AI grains nucleated on the surface of fractured SiC particles during FSW, forming nano-sized grains around the SiC particles. the yield strength of the NZ decreased slightly due to the variation in the size, shape, and distribution of the SiC particles. the clean interfaces were beneficial to the load transfer between SiC particles and AI matrix and then increased the ultimate tensile strength of the NZ.

关键词： Metal-matrix composites Friction stir welding Microstructure Mechanical properties

Friction Stir Welding of Discontinuously Reinforced Aluminum matrix Composites:A Review

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Acta Metallurgica Sinica(English Letters) 2014年第5期27卷 816-824页

作者： D.Wang B.L.Xiao D.R.Ni Z.y.ma Shenyang National Laboratory for materials Science Institute of Metal ResearchChinese Academy of Sciences

Friction stir welding （FSW） is considered a promising welding technique for joining the aluminum matrix composites （AMCs） to avoid the drawbacks of the fusion welding. High joint efficiencies of 60%-100% could be obtained in the FSW joints of AMCs. However, due to the existence of hard reinforcing particles in the AMCs, the wearing of welding tool during FSW is an unavoidable problem. Moreover, the low ductility of the AMCs limits the welding process window. As the hard materials such as Ferro-titanit alloy, cermet, and WC/Co were applied to produce the welding tools, the wearing of the tools was significantly reduced and the sound joints could be achieved at high welding speed for the AMCs with low reinforcement volume fraction. In this article, current state of understanding and development of welding tool wearing and FSW parameters of AMCs are viewed. Furthermore, the factors affecting the microstructure and mechanical properties of the joints are evaluated in detail.

关键词： Metal matrix composite Friction stir welding Particle, microstructure Wear

High-temperature Oxidation Behavior of a Ni-Cr-W-Al Alloy

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Journal of materials Science & technology 2011年第9期27卷 841-845页

作者： y.C. ma X.J. Zhao M. Gao K. Liu Institute of Metal Research Chinese Academy of Sciences Shenyang 110016 China

A study was conducted to examine the isothermal oxidation behavior of a new Ni-Cr-W-AI alloy in air at 1250℃ with different time. Oxidation kinetics was determined from weight-change measurements. the microstructure and composition of the oxide scale were investigated by means of scanning electron microcopy and X-ray diffraction. the results showed that the oxide scales of the alloy were a compact and continuous outer Cr2O3 and NiCr2O4 layer and an inner Al2O3 layer that was in dendrite shape. Oxides scales with good adherence were formed on the surface of the alloy, which made the alloy perform excellent high-temperature oxidation resistance.

关键词： Oxidation kinetics Oxide scale High-temperature oxidation resistance

Selenium-fused y6 derivatives and their derived polymerized small molecule acceptors for efficient organic solar cells

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Science China Chemistry 2023年第3期66卷 615-619页

作者： Qunping Fan Francis RLin Wei ma Alex K.-y.Jen State Key Laboratory for Mechanical Behavior of materials Xi’an Jiaotong UniversityXi’an 710049China Department of Chemistry City University of Hong KongKowloon 999077Hong KongChina Department of materials Science and Engineering City University of Hong KongKowloon 999077Hong KongChina Hong Kong Institute for Clean Energy City University of Hong KongKowloon 999077Hong KongChina Department of materials Science and Engineering University of WashingtonSeattleWashington 98195-2120USA

Before 2015,only few organic solar cells(OSCs)obtained power conversion efficiencies(PCEs)over 10%because the commonly used fullerene derivatives as acceptors have narrow absorption,low extinction coefficient,and are difficult to adjust energy *** overcome these shortcomings,in 2015,Zhan et al.[1]developed acceptor(A)-donor(D)-A-type fused-ring small-molecule acceptors(Smas)with good planarity and strong intramolecular charge transfer(ICt)effect to fulfill both broad absorption and high extinction coefficient,offering the revolutionary PCEs of 13%–15%.In 2019,another milestone Sma(y6)with A-DA′D-A structure was developed by Zou et al.

关键词： fused extinction absorption

Dispersion and Damage of Carbon Nanotubes in Carbon Nanotube/7055Al Composites During High-Energy Ball Milling Process

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Acta Metallurgica Sinica(English Letters) 2021年第2期34卷 196-204页

作者： S.Bi B.L.Xiao Z.H.Ji B.S.Liu Z.y.Liu Z.y.ma Shi-changxu Innovation Center for Advanced materials Institute of Metal ResearchChinese Academy of Sciences72 Wenhua RoadShenyang 110016China School of material Science and Engineering University of Science and Technology of China72 Wenhua RoadShenyang 110016China AVIC manufacturing technology Institute Beijing 100024China

High-energy ball milling(HEBM)combined with powder metallurgy route was used to fabricate carbon nanotube(CNt)reinforced 7055 Al *** powder morphology evolution processes(HEBM-1 and HEBM-2)were designed to investigate the dispersion and damage of CNts during HEBM ***-1 evolution process involved powder fl attening,cold-welding and fracture,while HEBM-2 evolution process consisted of powder fl attening and *** HEBM-1,the repetitive fracture and cold-welding process was effective for dispersing ***,the powder fl attening process in HEBM-2 was unsuccessful in dispersing CNts due to two reasons:(1)the thickness of fl aky Al powders exceeded the critical value,and(2)the clustered CNts embedded in fl aky Al powders could not be *** of the broadening of D band and the appearance of a new defect-related D’band,product of I D/I G and full width half maximum of D band,rather than I D/I G,was used to evaluate the actual damage of *** indicates that the damage of CNts was severe in powder fl attening and fracture stages,while the damage of CNts was small in powder cold-welding stage.

关键词： Metal matrix composites Carbon nanotubes Powder evolution Dispersion and damage Powder metallurgy

Structure and properties of nanoporous FePt fabricated by dealloying a melt-spun Fe(60)Pt(20)B(20)alloy and subsequent annealing

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Journal of materials Science & technology 2020年第1期36卷 128-133页

作者： Dianguo ma yingmin Wang yanhui Li Rie y·Umetsu Shuli Ou Kunio yubuta Wei Zhang Key Laboratory of materials Modification by Laser Ionand Electron Beams(Ministry of Education)School of Materials Science and EngineeringDalian University of TechnologyDalian 116024China Institute for Materials ResearchTohoku UniversitySendai 980-8577Japan

A nanoporous FePt alloy has been fabricated by dealloying a melt-spun Fe(60)Pt(20)B(20)alloy composed of nanoscale amorphous and face-centered-cubic FePt(fcc-FePt)phases in H2 SO4 aqueous *** nanoporous alloy consists of single fcc-FePt phase with an Fe/Pt atomic ratio of about 55.3/44.7,and possesses a uniform interpenetrating ligament-channel structure with average ligament and pore sizes of 27 nm and 12 nm,*** nanoporous fcc-FePt alloy shows soft magnetic characteristics with a saturation magnetization of 37.9 emu/g and better electrocatalytic activity for methanol oxidation than commercial Pt/C in acidic *** phase transformation from disordered fcc-Fe Pt into ordered face-centered-tetragonal FePt(L10-FePt)in the nanoporous alloy has been realized after annealing at823-943 K for 600 *** volume fraction of the L10-FePt phase in the alloy increases with the rise of annealing temperature,which results in the enhancements of coercivity and saturation magnetization from 0.14 kOe and 38.5 emu/g to 8.42 kOe and 51.4 emu/g,*** ligament size of the samples is increased after annealing.

关键词： Nanoporous metals Fe-Pt-B alloy Dealloying L10-FePt magnetic property

Structural Origins for Enhanced thermal Stability and Glass‑Forming Ability of Co–B Metallic Glasses with y and Nb Addition

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Acta Metallurgica Sinica(English Letters) 2023年第6期36卷 962-972页

作者： Shuang ma Junyu Zhang Xudong Wang Rie y.Umetsu Li Jiang Wei Zhang man yao Key Laboratory of materials Modification by Laser Ionand Electron Beams(Ministry of Education)School of Materials Science and EngineeringDalian University of TechnologyDalian 116024China Institute for materials Research Tohoku UniversitySendai 980‑8577Japan

the effects of y and Nb addition on thermal stability,glass-forming ability(GFA),and magnetic softness of Co75B25 metallic glass(MG)were comprehensively *** experimental results indicated that the thermal stability,GFA,and magnetic softness of the studied MGs increase in the order Co_(75)B_(25)y_(3.5)B_(25)y_(3.5)Nb_(2)B_(25).the structural origins of the improved properties were revealed by ab initio molecular dynamics(AIMD)simulations and density functional theory(DFt)*** showed that the B-centered prism units are the primary structure-forming units of the four MGs,connect through vertex-,edge-,and face-shared(VS,ES,and FS)atoms,and Co-centered units tend to connect with Co/B-centered units via the intercross-shared(IS)*** addition of y and Nb not only plays the role of connecting atoms but also enhances both bond strengths and the fractions of icosahedral-like units in increasing order Co_(75)B_(25)y_(3.5)B_(25)y_(3.5)Nb_(2)B_(25),which is conducive to the enhancement of the structural stability,atomic packing density,and viscosity,thereby improving thermal stability and *** addition,the improvement of structural stability and homogeneity leads to enhanced magnetic softness.

关键词： Co-based metallic glasses thermal stability Glass-forming ability Soft magnetic property Ab initio molecular dynamics simulations Local atomic structure

Micro injection of metallic glasses parts under ultrasonic vibration

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Journal of materials Science & technology 2017年第7期33卷 703-707页

作者： X.Liang J.ma X.y.Wu B.Xu F.Gong J.G.Lei t.J.Peng R.Cheng Guangdong Provincial Key Laboratory ofMicro/Nano Optomechatronics Engineering College of Mechatronics and Control and Engineering Shenzhen University Shenzhen 518060 China Shenzhen ESUN Exhibition Company Limited Shenzhen 518048. China

this work investigates the evolution of structure and mechanical performance of metallic glasses（MGs）under a proposed rapid forming approach. through the unique ultrasonic-assisted micro injection method, micro MGs parts with fine dimensional accuracy were successfully fabricated. the temperature during the micro injection is higher than the glass transition temperature and lower than the crystallization temperature. Differential scanning calorimeter curve and X-ray diffraction pattern show that the MGs micro parts keep the amorphous nature after the ultrasonic-assisted micro injection. Our results propose a novel route for the fast forming of MGs and have promising applications in the rapid fabrication of micro scale products and devices.

关键词： Metallic glasses Micro injection Ultrasonic vibration