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Effect of extrusion temperature on microstructure and mechanical properties of a low-alloying and ultra-high strength Mg-Zn-Ca-Mn matrix composite containing trace TiC nanoparticles

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Journal of Magnesium and Alloys 2020年第3期8卷 676-691页

作者： k.B.Nie Z.H.Zhu k.k.deng J.G.Han College of Materials Science and Engineering Taiyuan University of TechnologyTaiyuan 030024PR China Sharvci key laboratory of advanced magnesium-based materials Taiyuan University of TechnologyTaiyuan 030024PR China

Mechanical properties of microalloying Mg-2.2Zn-1.8Ca-0.5Mn(wt%)matrix composites reinforced by 0.5 wt%TiC nanoparticles before and after extrusion were investigated based on the detailed microstructural analysis.A uniform distribution of TiC nanoparticles was realized in the nanocomposite by the method of ultrasonic-assisted semisolid *** morphology of eutectic Ca2Mg6Zn3 phases changed from plate-like in the free TiC nanoparticles region to lamellar in the dense TiC nanoparticles region for the as-cast *** the grain structure and precipitates were obviously refined as the extrusion temperature decreased from 350 to 270℃.The nanocomposite exhibited excellent tensile yield strength(352-428 MPa)which was governed by the extrusion *** grain refinement strengthening with the contribution ratio of^80%to this strength increment was much higher relative to thermal expansion effect,Orowan strengthening and dislocation *** recrystallized grain structure with a substantial of ne precipitates appeared in the nanocomposite extruded at 270℃.The refined grain structure was not only due to dynamic recrystallization,but also the synergistic pinning effect of nano-TiCp,precipitated MgZn2 and α-Mn *** tensile toughness value of nanocomposite after extrusion improved with increasing the extrusion *** micro-cracks formed along the remnant coarse Ca2Mg6Zn3 led to the structural failure during tension.

关键词： Magnesium matrix nanocomposite Microstructure Mechanical properties:Strengthening mechanism Extrusion

LATERAL STABILITY OF ALTERNATIVE HORIZONTAL LEVITATION ELECTROMAGNETIC CONTINUOUS CASTING OF ALUMINIUM SHEET

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中国有色金属学会会刊：英文版 1998年第3期8卷 86-89页

作者： deng, k Shen, M Ren, ZM Shanghai Univ Coll Mat Sci & Engn Shanghai 200072 Peoples R China Shanghai Univ Shanghai Inst Appl Math & Mech Shanghai 200072 Peoples R China

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关键词： stability horizontal continuous casting electromagnetic casting aluminium sheet

Plastic deformation of a Zr-based bulk metallic glass fabricated by selective laser melting

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Journal of Materials Science & Technology 2021年第1期60卷 139-146页

作者： L.deng k.kosiba R.Limbach L.Wondraczek U.kühn S.Pauly IFW Dresden Institute for Complex MaterialsHelmholtzstraße 20D-01069DresdenGermany Otto Schott Institute of Materials Research University of JenaFraunhoferstraße 6D-07743JenaGermany University of Applied Sciences Aschaffenburg Würzburger Straße 45D-63743AschaffenburgGermany

Fully amorphous Zr_(52.5)Cu_(17.9)Ni_(14.6)Al_(10)Ti_(5) bulk metallic glass(BMG) samples with a relative density exceeding 98% were fabricated via selective laser melting(SLM).High fracture stresses of around1700 MPa and a reproducible plastic strain of about 0.5% were obtained for cylindrical SLM *** analysis of the observed serrations during compressive loading implies that the shear-band dynamics in the additively manufactured samples distinctly differ from those of the as-cast *** phenomenon appears to originate from the presence of uniformly dispersed spherical pores as well as from the more pronounced heterogeneity of the glass itself as revealed by instrumented *** these heterogeneities,the shear bands are straight and form in the plane of maximum shear *** manufacturing,hence,might not only allow for producing large BMG samples with complex geometries but also for manipulating their deformation behaviour through tailoring porosity and structural heterogeneity.

关键词： Powder bed fusion Selective laser melting Bulk metallic glass Serrated flow Heterogeneity

Laser additive manufactured high-performance Fe-based composites with unique strengthening structure

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Journal of Materials Science & Technology 2021年第30期89卷 242-252页

作者： Hongyu Chen Dongdong Gu Liang deng Tiwen Lu Uta kühn konrad kosiba College of Materials Science and Technology Nanjing University of Aeronautics and AstronauticsNanjing 210016China Jiangsu Provincial Engineering Laboratory for Laser Additive Manufacturing of High-Performance Metallic Components Nanjing University of Aeronautics and AstronauticsNanjing 210016China Leibniz IFW Dresden Institute for Complex MaterialsP.O.Box 270116D-01069 DresdenGermany

Steel matrix composites(SMCs),reinforced by ceramic particles,have received a consistent attention in recent *** conventional methods to prepare SMCs is generally challenging,and the mechanical properties of conventionally fabricated SMCs are *** this study,we successfully fabricated highperformance SMCs by laser powder bed fusion(LPBF)of a composite powder consisting of Fe-based alloy powder and submicron-sized WC *** effect of laser energy density on the phase formation,microstructural evolution,overall density and resulting mechanical properties of LPBF-fabricated composites was *** present results show that a novel Fe_(2)W_(4)C carbidic network precipitates in the solidified microstructure entailing segregations along the boundaries of cellular *** presence of this carbidic network hampers the growth of sub-grains even at elevated temperatures,and hence,stabilizes the grain size though prepared at a broad range of different energy *** exact distribution of the Fe_(2)W_(4)C carbides depends on the employed laser energy densities,as for instance they are more uniformly distributed at higher energy *** density of LPBF samples reaches the maximum value of 99.4%at 150 J/mm^(3).In this parameter set,high microhardness of~753 HV,compression strength of~3350 MPa and fracture strain of~24.4%are *** enhanced mechanical properties are ascribed to less metallurgical defects,higher volume fraction of the martensitic phase and increasing pile-up dislocations resulting from the pinning effect by Fe_(2)W_(4)C carbide.

关键词： Laser additive manufacturing Laser powder bed fusion Steel matrix composite Microstructures Mechanical properties

On significance of initial microstructure in governing mechanical behavior and fracture of dual-phase steels

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Journal of Iron and Steel Research International 2018年第9期25卷 932-942页

作者： Yong-gang deng Hong-shuang Di R. D. k. Misra State key Laboratory of Rolling and Automation Northeastern University Shenyang 110819 Liaoning China Laboratory for Excellence in Advanced Steel Research University of Texas El Paso TX 79968 USA

Different initial microstructures were obtained through combination of intercritical annealing and cold-rolling. Subsequently, steels with different microstructures of ferrite-pearlite （FP）, ferrite-martensite （FM） and complete martensite （M） were intercritically annealed at 780 ℃ for 5 min and water quenched to obtain ferrite-martensite microstructure. The significance of initial microstructures on ultimate microstructure, mechanical properties, strain-hardening ability and fracture behavior in dual-phase steels has been elucidated. Initial microstructures of FP, FM and M yielded different martensite morphologies, notably chain-like network structure, fine and fibrous martensite structure, respectively. Furthermore, with increasing martensite content in the initial microstructure, the average grain size of ferrite was significantly refined from about 12.3 to 2.1 μm, which results in that the ultimate tensile strength （UTS） and yield strength were increased, total elongation remained unaffected, and uniform elongation （UE） and strain-hardening ability were increased. A comparison of mechanical properties for different initial microstructures suggested that when the initial microstructure was complete martensite, the steel had excellent mechanical properties, with UTS × UE of 122.5 J cm^-3, which was 24% greater than the conventional continuously annealed steels with ferrite-pearlite initial microstructure （98.8 J cm^-3）. The variation in tensile properties, strain-hardening ability and fracture mechanism of steels with different initial microstructures were discussed in relation to the ultimate microstructures.

关键词： Dual-phase steel Microstructure Mechanical property Strain-hardening Fracture

Recent progress on the study of asymmetric vortex flow over slender bodies

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Acta Mechanica Sinica 2008年第5期24卷 475-487页

作者： X.Y.deng W.Tian B.F.Ma Y.k.Wang key Laboratory of Fluid Mechanics Ministry of EducationBeihang University100083 BeijingChina

The investigations of forebody vortex flow and its flow control have great importance in both academic field and engineering application areas. A large number of papers and many review papers have been published. However in this research field of forebody asymmetric vortices, three problems such as tip perturbation effect, Reynolds number effect and flow instability are less studied and thus not understood completely. So many researches are still working on the issues in recent years. The present paper attempts to provide a review of recent research progress on first two problems. The first problem is mainly concerned with how the vortex flow evolves after tip perturbation; how to solve the problem of repeatability and reproducibility of wind tunnel testing data; how to develop a conception of active flow control technique with tip perturbation based on the study of vortex flow response to tip perturbation. For the second problem one is mainly concerned that how the asymmetric vortices are developed with the increase of Reynolds number; how to classify the vortex flow patterns in different Reynolds number regimes; how to develop an appropriate boundary layer transition technique to simulate flows at high Reynolds number in the convention wind tunnels. Finally, some important ques- tions that deserve answers are proposed in the concluding remarks.

关键词： High angle of attack aerodynamics ,Asymmetric vortex Tip perturbation Slender body ,Reynolds number effect

Evaluation of SIFOM-FVCOM system for high-fidelity simulation of small-scale coastal ocean flows

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Journal of Hydrodynamics 2016年第6期28卷 994-1002页

作者： k.QU H.S.TANG A.AGRAWAL C.B.JIANG B.deng Department of Civil Engineering City College City University of New York School of Hydraulic Engineering Changsha University of Sciences and Technology

This paper evaluates the SIFOM-FVCOM system recently developed by the authors to simulate multiphysics coastal ocean flow phenomena, especially those at small scales. First, its formulation for buoyancy is examined with regard to solution accu- racy and computational efficiency. Then, the system is used to track particles in circulations in the Jamaica Bay, demonstrating that large-scale patterns of trajectories of fluid particles are sensitive to small-scales flows from which they are released. Finally, a simulation is presented to illustrate the SIFOM-FVCOM system＇s capability, which is beyond the reach of other existing models, to directly and simultaneously model large-scale storm surges as well as small-scale flow structures around bridge piers within the Hudson River during the Hurricane Sandy.

关键词： coastal ocean flow multiscale multiphysics hybrid method domain decomposition SIFOM-FVCOM system

Fabrication of 3D-printed molds for polydimethylsiloxane-based microfluidic devices using a liquid crystal display-based vat photopolymerization process:printing quality,drug response and 3D invasion cell culture assays

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Microsystems & Nanoengineering 2023年第6期9卷 205-219页

作者： Matthew D.Poskus Tuo Wang Yuxuan deng Sydney Borcherding Jake Atkinson Ioannis k.Zervantonakis Department of Bioengineering UPMC Hillman Cancer CenterUniversity of PittsburghPittsburghPAUSA McGowan Institute of Regenerative Medicine PittsburghPAUSA

Microfluidic platforms enable more precise control of biological stimuli and environment dimensionality than conventional macroscale cell-based assays;however,long fabrication times and high-cost specialized equipment limit the widespread adoption of microfluidic *** improvements in vat photopolymerization three-dimensional(3D)printing technologies such as liquid crystal display(LCD)printing offer rapid prototyping and a cost-effective solution to microfluidic *** information is available about how 3D printing parameters and resin cytocompatibility impact the performance of 3D-printed molds for the fabrication of polydimethylsiloxane(PDMS)-based microfluidic platforms for cellular *** a low-cost,commercially available LCD-based 3D printer,we assessed the cytocompatibility of several resins,optimized fabrication parameters,and characterized the minimum feature *** evaluated the response to both cytotoxic chemotherapy and targeted kinase therapies in microfluidic devices fabricated using our 3D-printed molds and demonstrated the establishment of flow-based concentration ***,we monitored real-time cancer cell and fibroblast migration in a 3D matrix environment that was dependent on environmental *** results demonstrate how vat photopolymerization LCD-based fabrication can accelerate the prototyping of microfluidic platforms with increased accessibility and resolution for PDMS-based cell culture assays.

关键词： invasion printing culture

Hot Deformation Behavior and Processing Maps of a Medium Manganese TRIP Steel

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Acta Metallurgica Sinica(English Letters) 2019年第8期32卷 1021-1031页

作者： Ning Yan Hong-Shuang Di Hui-Qiang Huang R.D.k.Misra Yong-Gang deng State key Laboratory of Rolling and Automation Northeastern UniversityShenyang 110819China Laboratory for Excellence in Advanced Steel Research Department of MetallurgicalMaterials and Biomedical EngineeringUniversity of Texas El PasoEl PasoTX 7996&USA

The hot deformation behavior of a medium-Mn steel was studied in terms of hot compression flow curves in the temperature range of 850–1050 ℃ and strain rates of 0.05–10 *** thermo-mechanical analysis was carried out and suggested that the microstructure during deformation was completely austenite which had high tendency for dynamic recrystallization(DRX).The flow behavior was characterized by significant flow softening at deformation temperatures of 950–1050 ℃ and lower strain rates of 0.05–5 s-1, which was attributed to heating during deformation, DRX and flow instability.A step-by-step calculating procedure for constitutive equations is *** verification of the modified equations indicated that the developed constitutive models could accurately describe the flow softening behavior of studied ***, according to the processing maps and microstructure analysis, it suggested that hot working of medium Mn steel should be carried out at 1050 ℃, and the strain rate of 0.05–10 s-1 resulted in significantly recrystallized microstructures in the in *** flow localization is mainly flow instability mechanism for experimental steel.

关键词： Medium-Mn steel Hot deformation behavior Constitutive equations Flow instability mechanism Recrystallized microstructure