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Processing, Microstructure and Mechanical Properties of Ti6Al4V Particles-Reinforced Mg Matrix Composites

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Acta Metallurgica sinica(English Letters) 2016年第10期29卷 940-950页

作者： x.M.Wang x.J.Wang x.s.Hu K.wu M.Y.Zheng school of Materials science and Engineering Harbin Institute of Technology

Novel Ti6Al4V particles-reinforced AZ91 Mg matrix composites were successfully fabricated by stir casting method. The stirring time in semisolid condition directly affected the particle distribution and the quality of the ingots. Furthermore, the optimal speed of the heating and the liquid stirring could overcome particle settlement caused by the density difference between the matrix and the particles. Ti6Al4V particles distributed uniformly in the composites with different particle contents. The average grain size decreased with the increase in the particle contents. The Ti6A14V particles bonded pretty well with the alloy matrix. In addition, there were some interfacial reactions in the composites. There were rod-like A13Ti phases at the interface. The precipitates extended from the particle surface to the matrix, and they might improve the interfacial bonding strength. The ultimate tensile strength, yield strength and elastic modulus were enhanced as the particle contents increased, and the elongation was much better than that of the same matrix material reinforced with siC particles. Thus, the novel composites exhibit better comprehensive mechanical properties.

关键词： Magnesium matrix composites Ti6Al4V particles stir casting Microstructure Mechanicalproperties

Ultrahigh strength Mg-Y-Ni alloys obtained by regulating second phases

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Journal of Materials science & Technology 2020年第10期42卷 117-124页

作者： s.Z.wu x.G.Qiao M.Y.Zheng school of Materials science and Engineering Harbin Institute of TechnologyHarbin150001China

Mg-Y-Ni alloys with different second phases were designed by changing Y/Ni atomic ratio from 1.5 to *** microstructure and mechanical properties of as-cast and as-extruded alloys were *** as-cast Mg-Y-Ni alloy with Y/Ni ratio of 1.5 is composed ofα-Mg and long period stacking ordered(LPsO)*** Y/Ni ratio is equal to 1,nanoscale lamellarγ’phase and eutectic Mg2Ni phase are formed in addition to LPsO *** Y/Ni ratio decreases further,the amount of eutectic Mg2Ni phase increases,while the amount of LPsO phase *** extrusion,the LPsO andγ’phases are distributed along the extrusion direction,while eutectic Mg2Ni phase is broken and dispersed in the as-extruded *** phase and Mg2Ni phase in the alloys promote dynamic recrystallization(DRx)during extrusion,whileγ’phase inhibits ***,the Mg96Y2Ni2(at.%)alloy with LPsO phase andγ’phase as the main second phases shows the strongest basal texture after *** tensile yield strength of the as-extruded Mg-Y-Ni alloys increases first and then decreases with decreasing Y/Ni *** as-extruded Mg96Y2Ni2(at.%)alloy with Y/Ni=1 exhibits excellent mechanical properties with tensile yield strength of 465 MPa,ultimate tensile strength of 510 MPa and elongation to failure of 7.2%,which is attributed to the synergistic effect of bulk LPsO phase and nanoscaleγ’phase.

关键词： Mg-Y-Ni alloys LPsO γ’Phase Mg2Ni Mechanical properties

Mechanism of wavy vortex and sign laws in flow past a bluff body:vortex-induced vortex

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Acta Mechanica sinica 2019年第1期35卷 1-14,I0001页

作者： L.M.Lin s.Y.shi x.F.Zhong Y.x.wu Key Laboratory for Mechanics in Fluid solid Coupling systems Institute of MechanicsChinese Academy of SciencesBeijing 100190China school of Engineering sciences University of Chinese Academy of SciencesBeijing 100049China

As reported in a previous work by Lin et al.(Acta Meeh sin, 2018. https://***/10.1007/s 10409-018-0758-z), an interesting phenomenon was discovered based on the analysis of wavy vortex and vorticity distribution in the shear layers and near wake of a peak-perforated conic shroud, and two sign laws were summarized. In the present paper, the theory of a vortex-induced vortex is introduced to explore mechanisms in a wavy vortex and applicable sign laws for uniform and incompressible flow past a fixed bluff body. Based on the analysis of the nearest-wall How, two vortex-induced models for streamwise and vertical vortex pairs, respectively, are proposed under two boundary cases, denoting the induced vorticity introduced or distributed on and near the walls. As a result, the first sign law, for only streamwise and vertical components of vorticity, and the second sign law, for three components of vorticity, are obtained under their own particular conditions. The first sign law reveals the intrinsic physical relationship between streamwise and vertical vorticities, independent of the distribution of spanwise vortices in the whole flow field. It is also confirmed that the spanwise vortices, as well as the shear layers and wake width, distributed wavily across the span, are attributed to the introduced streamwise or vertical vortices. The two sign laws for vorticity are independent of the disturbed spanwise wavelength and the Reynolds number. Through the analysis of flow past the conic shroud, the two sign laws are successfully used to summarize typical spacial distributions of vorticity in three flow regions: on and near the front cylinder surfaces, the separated shear layers and the near wake.

关键词： Wavy vortex sign law Vortex-induced vortex Wake Bluff body

Highly mass activity electrocatalysts with ultralow Pt loading on carbon black for hydrogen evolution reaction

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International Journal of Minerals,Metallurgy and Materials 2025年第1期32卷 182-190页

作者： shaorou Ke Yajing Zhao xin Min Yanghong Li Ruiyu Mi Yangai Liu xiaowen wu Minghao Fang Zhaohui Huang Engineering Research Center of Ministry of Education for Geological Carbon storage and Low Carbon Utilization of Resources Beijing Key Laboratory of Materials Utilization of Nonmetallic Minerals and Solid WastersNational Laboratory of Mineral MaterialsSchool of Materials Science and TechnologyChina University of Geosciences(Beijing)Beijing 100083China

Pt-based nanocatalysts offer excellent prospects for various ***,the low loading of Pt with excellent performance for efficient and stable nanocatalysts still presents a considerable *** this study,nanocatalysts with ultralow Pt content,excellent performance,and carbon black as support were prepared through in-situ ***~2-nm particles uniformly and stably dispersed on carbon black because of the strong s-p-d orbital hybridizations between carbon black and Pt,which suppressed the agglomeration of Pt *** unique structure is beneficial for the hydrogen evolution *** catalysts exhibited remarkable catalytic activity for hydrogen evolution reaction,exhibiting a potential of 100 mV at 100 mA·cm^(-2),which is comparable to those of commercial Pt/C *** activity(1.61 A/mg)was four times that of a commercial Pt/C catalyst(0.37 A/mg).The ultralow Pt loading(6.84wt%)paves the way for the development of next-generation electrocatalysts.

关键词： hydrogen evolution reaction ultralow platinum in-situ synthesis ultrasound

THE sEEPAGE CHARACTERIsTICs OF HETEROGENEOUs BODY WITH DIFFERENT sPREADING sOLUTION MODEs AND ITs APPLICATIONs

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Acta Metallurgica sinica(English Letters) 2007年第5期20卷 363-372页

作者： H.J. Wang A.x. wu x.s. Chen J. Zhang Civil ＆ Environment Engineering school University of Science and Technology Beijing Beijing 100083 China school of Resources and safety Engineering Central South University Changsha 410083 China

As the dump was a typically heterogeneous body, the seepage was different with varied spreading solution modes. The phenomenon of lamination that occured in the site was simulated using three layers in an indoor experiment, and the seepage effect comparison experiment of the inside spreading solution model and the top spreading solution model have been carried out. In the inside spreading solution mode, the phreatic planar flew without infiltration and the parallel layer motion model was used to calculate the seepage coefficient and equivalent seepage coefficient of each state respectively. In the top spreading solution model, the phreatic planar flew with an even infiltration on the surface, and the vertical layer motion model was adopted to calculate the above coefficient. The results showed that the seepage coefficient of the inside model was larger than the top model in the heterogeneous body, The ratio of them was between 1.42 and 3.07. On the basis of these results, the following new technologies were discussed： installing a few small diameter mechanical pore sand piles with every lamination in the using dump; drilling some holes one-off in the unused dump. These two methods could changed the top spreading solution into the inside model, thus the seepage in the dump was improved.

关键词： heterogeneous body top spreading solution inside spreading solution sand pile drawing-injection drill

On resolution to wu's conjecture on Cauchy function's exterior singularities

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Acta Mechanica sinica 2011年第3期27卷 309-317页

作者： Theodore Yaotsu wu California Institute of Technology

This is a series of studies on wu＇s conjecture and on its resolution to be presented herein. Both are devoted to expound all the comprehensive properties of Cauchy＇s function f（z）（z = x ＋ iy） and its integral J[f（z）]≡（2πi）-∮cf（t）（t-z）-1dt taken along the unit circle as contour C,inside which（the open domain D＋） f（z） is regular but has singularities distributed in open domain Doutside C. Resolution is given to the inverse problem that the singularities of f（z） can be determined in analytical form in terms of the values f（t） of f（z） numerically prescribed on C（｜t｜ = 1） ,as so enunciated by wu＇s conjecture. The case of a single singularity is solved using complex algebra and analysis to acquire the solution structure for a standard reference. Multiple singularities are resolved by reducing them to a single one by elimination in principle,for which purpose a general asymptotic method is developed here for resolution to the conjecture by induction,and essential singularities are treated with employing the generalized Hilbert transforms. These new methods are applicable to relevant problems in mathematics,engineering and technology in analogy with resolving the inverse problem presented here.

关键词： Keywords Cauchy function. singularity distribution . wu's conjecture - Resolution by induction

Crystallization Modulation and Holistic Passivation Enables Efficient Two‑Terminal Perovskite/CuIn(Ga)se_(2)Tandem solar Cells

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Nano-Micro Letters 2025年第1期17卷 205-215页

作者： Cong Geng Kuanxiang Zhang Changhua Wang Chung Hsien wu Jiwen Jiang Fei Long Liyuan Han Qifeng Han Yi‑Bing Cheng Yong Peng state Key Laboratory of Advanced Technology for Materials synthesis and Processing Wuhan University of TechnologyWuhan 430070People’s Republic of China Triumph Photovoltaic Materials Co. Ltd.No.1001 Yannan AvenueHigh‑Tech Development DistrictBengbuAnhui 233000People’s Republic of China College of Materials science and Engineering Guilin University of TechnologyGuilin 541004People’s Republic of China state Key Laboratory of Metal Matrix Composites Shanghai Jiao Tong UniversityShanghai 200240People’s Republic of China

Two-terminal(2-T)perovskite(PVK)/CuIn(Ga)se_(2)(CIGs)tandem solar cells(TsCs)have been considered as an ideal tandem cell because of their best bandgap matching regarding to shockley–Queisser(s–Q)***,the nature of the irregular rough morphology of commercial CIGs prevents people from improving tandem device *** this paper,D-homoserine lactone hydrochloride is proven to improve coverage of PVK materials on irregular rough CIGs surfaces and also passivate bulk defects by modulating the growth of PVK *** addition,the minority carriers near the PVK/C60 interface and the incompletely passivated trap states caused interface recombination.A surface reconstruction with 2-thiopheneethylammonium iodide and N,N-dimethylformamide assisted passivates the defect sites located at the surface and grain ***,LiF is used to create this field effect,repelling hole carriers away from the PVK and C60 interface and thus reducing *** a result,a 2-T PVK/CIGs tandem yielded a power conversion efficiency of 24.6%(0.16 cm^(2)),one of the highest results for 2-T PVK/CIGs TsCs to our *** validation underscores the potential of our methodology in achieving superior performance in PVK/CIGs tandem solar cells.

关键词： PVK/CIGs TsCs Irregular rough surfaces Modulating the growth PVK/C60 interface recombination

Measurement and Prediction of Insertion Force for the Mosquito Fascicle Penetrating into Human skin

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Journal of Bionic Engineering 2009年第2期6卷 143-152页

作者： x Q Kong C W wu state Key Laboratory of structural Analysis for Industrial Equipment Department of Engineering MechanicsDalian University of Technology

Mosquitoes are exceptional in their ability to pierce into human skin with a natural ultimate painless microneedle, named fascicle. Here the structure of the Aedes albopictus mosquito fascicle is obtained using a scanning Electron Microscope (sEM), and the whole process of the fascicle inserting into human skin is observed using a high-speed video imaging technique. Direct measurements of the insertion force for mosquito fascicle to penetrate into human skin are reported. Results show that the mosquito uses a very low force (average 18 μN) to penetrate into the skin. This force is at least three orders of magnitude smaller than the reported lowest insertion force for an artificial microneedle with an ultra sharp tip to insert into the human skin. In order to understand the piercing mechanism of mosquito fascicle tip into human multilayer skin tissue, a numerical simulation is conducted to analyze the insertion process using a nonlinear finite element method. A good agreement occurs between the numerical results and the experimental measurements.

关键词： biomimetic microneedle mosquito fascicle mechanics penetration

Magnesium matrix composite reinforced by nanoparticles-A review

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Journal of Magnesium and Alloys 2021年第1期9卷 57-77页

作者： K.B.Nie x.J.Wang K.K.Deng x.s.Hu K.wu state Key Laboratory of Advanced Welding and Joining Harbin Institute of TechnologyHarbin 150001China College of Materials science and Engineering Taiyuan University of TechnologyTaiyuan 030024China

significant progress has been made in magnesium-based composites during recent decades,especially for the appearance of magnesium matrix composite reinforced by *** nanoparticles added not only exhibit a good strengthening effect,but also maintain the initial toughness of the matrix,effectively balancing the contradiction between the strength and plasticity in the traditional magnesium matrix *** magnesium matrix nanocomposites with excellent mechanical properties have pushed the development of magnesium matrix composites to a new ***,it is very difficult to disperse the nanoparticles in metal melt especially in magnesium melt which is different from other metal melts and dangerous during the cast *** means that the preparation of magnesium matrix nanocomposite is extremely ***,the magnesium matrix nanocomposites possess a distinctive characteristic in deformation behavior,strengthening and toughening mechanism due to their special size effect of ***,this review will focus on the new preparation technologies,deformation behavior,mechanical properties and strengthening and toughening *** potential applications,development trends and future research ideas of magnesium matrix nanocomposite are also prospected.©2020 Published by Elsevier *** behalf of Chongqing University.

关键词： Magnesium matrix nanocomposite Microstructure Mechanical properties strengthening mechanism