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Acta Metallurgica Sinica(English Letters) 2018年第12期31卷 1361-1367页

作者： y.H.Zhu c.M.Luk Department of Industrial and Systems Engineering TheHong Kong Polytechnic UniversityHong KongChina Department of Applied Physics The Hong Kong PolytechnicUniversityHong KongChina

Electropulsing-induced phase decompositions and microstructural changes in AZO-5 thin films were studied by X-raydiffraction, scanning electron microscopy, atomic force microscopy, Hall effect measurement and photoluminescence （PL）measurement techniques. It was found that the electropulsing induced phase decomposition started with spinodaldecomposition, which was accompanied by discontinuous precipitation in the AZO-5 thin films. Both circular phasedecompositions and the crystal orientation occurred. Inappropriate electropulsing might damage zones, which resulted intremendous decrease in electrical conductivity. circular changes in both the peak position and the width of the PLwavelength were observed in the EPT AZO-5 thin films. Formation of zones favored reducing the roughness of the thinfilm.

关键词： Electropulsing Phase transformation Electrical conductivity Photoluminescence Thin-films AZO

Amplitude modulation and extreme events in turbulent channel flow

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Acta Mechanica Sinica 2018年第1期34卷 1-9页

作者： y.c.yao W.X.Huang c.X.Xu AML Department of Engineering Mechanics Tsinghua University

Amplitude modulation of near-wall turbulence by large-scale structures in the outer layer is investigated by direct numerical simulation of turbulent channel flows at Reynolds number Re= 540, 1000, 2000. The effect of modulation is obvious in the two-point cross-section correlation map, and the correlation coefficients increase significantly with the Reynolds number. The influence of modulation is reflected in the tail of the probability density function of the near-wall flow signals, which expands as the Reynolds number increases. The flatness factor provides a quantitative description of the high fluctuation events due to modulation. Vortical structures associated with modulation are revealed by conditionally averaging the flow field of the near-wall extreme events, providing a depiction of how the influence of the large-scale structures penetrate towards the near-wall region.

关键词： Wall turbulence Amplitude modulation Flatness Extreme events

The need to develop tailored tools for improving the quality of thematic bibliometric analyses: Evidence from papers published in Sustainability and Scientometrics

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Journal of Data and Information Science 2023年第4期8卷 10-35页

作者： Alvaro cabezas-clavijo yusnelkis Milanés-Guisado Ruben Alba-Ruiz Ángel MDelgado-Vázquez Universidad Internacional de La Rioja(UNIR) Avenida de la Paz137Logroño26006Spain Universidad Pablo de Olavide Ctra.de UtreraKm 1Sevilla41013Spain Hospital Universitario Virgen de las Nieves Avenida de las Fuerzas Armadas2Granada 18014Spain

Purpose: The aim of this article is to explore up to seven parameters related to the methodological quality and reproducibility of thematic bibliometric research published in the two most productive journals in bibliometrics, Sustainability(a journal outside the discipline) and Scientometrics, the flagship journal in the ***/methodology/approach: The study identifies the need for developing tailored tools for improving the quality of thematic bibliometric analyses, and presents a framework that can guide the development of such tools. A total of 508 papers are analysed, 77% of Sustainability, and 23% published in Scientometrics, for the 2019-2021 ***: An average of 2.6 shortcomings per paper was found for the whole sample, with an almost identical number of flaws in both journals. Sustainability has more flaws than Scientometrics in four of the seven parameters studied, while Scientometrics has more shortcomings in the remaining three *** limitations: The first limitation of this work is that it is a study of two scientific journals, so the results cannot be directly extrapolated to the set of thematic bibliometric analyses published in journals from all *** implications: We propose the adoption of protocols, guidelines, and other similar tools, adapted to bibliometric practice, which could increase the thoroughness, transparency, and reproducibility of this type of ***/value: These results show considerable room for improvement in terms of the adequate use and breakdown of methodological procedures in thematic bibliometric research, both in journals in the Information Science area and journals outside the discipline.

关键词： Thematic bibliometric analyses Sustainability Scientometrics Reproducibility Methodological quality

Improved mechanical properties and strengthening mechanism with the altered precipitate orientation in magnesium alloys

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Journal of Magnesium and Alloys 2022年第5期10卷 1256-1267页

作者： y.J.Wan y.Zeng y.c.Dou D.c.Hu X.y.Qian Q.Zeng K.X.Sun G.F.Quan Key Laboratory of Advanced Technologies of Materials Ministry of EducationSchool of Material Science and EngineeringSouthwest Jiaotong UniversityChengdu 610031China college of Materials Science and Engineering Sichuan University of Science and EngineeringZigong 643000China Department of Materials The University of ManchesterOxford RoadManchester M139PLUnited Kingdom

Aging prior to twinning deformation was proposed to alter the precipitate orientation of the plate-shapedβ-MgAlfrom(0002)basal planes(named basal plates)to■prismatic planes(named prismatic plates)in AZ31 Mg *** experimental results showed that the compressive yield strength(cyS)of the sample containing prismatic plates increased 40 MPa and the compression ratio raised by 22%compared to that containing basal *** underlying strengthening mechanism was analyzed via a yield strengthen(yS)model with a function of grain size,precipitate characters(size,oritention,fraction)and Schmid factor(SF).It revealed that the improvement of cyS was mainly attributed to the altered precipitate orientation and refined grain size produced by twinning ***,the prismatic plates always have a stronger hardening effect on basal slip than basal plates under the same varites of precipitate diameter and ***,the decreased cRSS ratio of prismatic slip to basal slip revealed that the activity of non-basal slip in Mg alloy might be *** activated slip systems provided more mobile dislocations,contributing to the large compression ratio of the Mg rolled sheet with prismatic plates.

关键词： Precipitate orientation Precipitation strengthening Grain boundary strengthening yield strength model

Distinct Electrical and Mechanical Responses of a cu-10Fe composite Prepared by Hot-Pressed Sintering and Post Treatment

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Acta Metallurgica Sinica(English Letters) 2024年第2期37卷 255-265页

作者： X.y.yue S.y.Peng X.Zhang c.N.He y.Z.Tian Key Laboratory for Anisotropy and Texture of Materials(Ministry of Education) School of Materials Science and EngineeringNortheastern UniversityShenyang110819China School of Materials Science and Engineering and Tianjin Key Laboratory of composite and Functional Materials Tianjin UniversityTianjin300350China Research centre for Metallic Wires Northeastern UniversityShenyang110819China

A cu-10wt%Fe composite was prepared through hot-pressed sintering,and the material was subsequently solution *** hot-pressed sintered and solution treated materials were rolled and *** precipitation behavior and performance changes were systematically studied by using scanning electron microscopy and transmission electron *** contrast to the hot-pressed sintered specimen,the solution treatment significantly affects the thermal stability and properties of the cu-10wt%Fe *** cu-10wt%Fe composite was prepared after solid solution,cold rolling and aging at 773 K for 1 h,and it obtained excellent tensile strength of 494 MPa,uniform elongation of 16.3%,electrical conductivity of 51.1%IAcS and softening temperature of 838 *** for the distinct difference in thermal stability and properties between hot-pressed sintered and solution treated specimens were *** findings provide a theoretical basis for designing high-performance cu-based in-situ composites by post treatment.

关键词： cu-Fe composite Hot-pressed sintering Thermal stability Strength Electrical conductivity

PREDIcTION FOR FORMING LIMIT OF AL2024T3 SHEET BASED ON DAMAGE THEORy USING FINITE ELEMENT METHOD

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Acta Mechanica Solida Sinica 2006年第2期19卷 174-180页

作者： Tang c.y. Fan Jianping Tsui c.P. Department of Industrial and Systems Engineering The Hong Kong Polytechnic University Hong Kong China School of civil Engineering and Mechanics Huazhong University of Science and Technology Wuhan 430074 China

This paper presents the application of anisotropic damage theory to the study of forming limit diagram of A12024T3 aluminum alloy sheet. In the prediction of limiting strains of the aluminum sheet structure, a finite element cell model has been constructed. The cell model consists of two phases, the aluminum alloy matrix and the intermetallic cluster. The material behavior of the aluminum alloy matrix is described with a fully coupled elasto-plastic damage constitutive equation. The intermetallic cluster is assumed to be elastic and brittle. By varying the stretching ratio, the limiting strains of the sheet under biaxial stretching have been predicted by using the necking criterion proposed. The prediction is in good agreement with the experimental findings. Moreover, the finite element cell model can provide information for understanding the microscopic damage mechanism of the aluminum alloy. Over-estimation of the limit strains may result if the effect of material damage is ignored in the sheet metal forming study.

关键词： forming limit diagram (FLD) anisotropic damage finite element method (FEM) limit strain localized necking elasto-plastic deformation

Effect of Heat Treatment Time on Dy–cu Alloy Diffusion Process in Dy-containing commercial Nd–Fe–B Sintered Magnets

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Acta Metallurgica Sinica(English Letters) 2018年第5期31卷 496-502页

作者： H.y.Liu G.Wang y.Hong D.c.Zeng School of Materials Science and Engineering South China University of Technology

In this paper, the grain boundary diffusion process（GBDP） using a Dy70cu30（at.%） alloy as the diffusion source was performed in a commercial sintered Nd–Fe–B magnet, and the effect of heat treatment time on the microstructure and magnetic properties of the magnet was investigated in detail. For the processed magnets heat-treated at 860℃, as heat treatment time increased, the coercivity and the depth of（Nd,Dy）2Fe14B core–shell structure increased first and then decreased. However, when the heat treatment time was more than 2 h, the diffusion path of Dy from the Dy-rich shell phase into the Nd2Fe14B grains was revealed, and a nearly homogeneous（Nd,Dy）2Fe14B phase was formed, which brought on the decrease in both the depth of visible core–shell structure and the coercivity of Nd–Fe–B magnet.

关键词： Sintered Nd-Fe-B magnets Grain boundary diffusion Heat treatment time coercivity Micromagnetic simulation

Assessment of Timoshenko Beam Models for Vibrational Behavior of Single-Walled carbon Nanotubes using Molecular Dynamics

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Advances in Applied Mathematics and Mechanics 2009年第1期1卷 89-106页

作者： y.y.Zhang c.M.Wang V.B.c.Tan Department of Mechanical Engineering National University of SingaporeKent RidgeSingapore 119260 Engineering Science Programme and Department of civil Engineering National University of SingaporeKent RidgeSingapore 117574

In this paper,we study the flexural vibration behavior of single-walled carbon nanotubes(SWcNTs)for the assessment of Timoshenko beam ***tensive molecular dynamics(MD)simulations based on second-generation reactive empirical bond-order(REBO)potential and Timoshenko beam modeling are performed to determine the vibration frequencies for SWcNTs with various length-todiameter ratios,boundary conditions,chiral angles and initial *** effectiveness of the local and nonlocal Timoshenko beam models in the vibration analysis is assessed using the vibration frequencies of MD simulations as the *** is shown herein that the Timoshenko beam models with properly chosen parameters are applicable for the vibration analysis of *** simulation results show that the fundamental frequencies are independent of the chiral angles,but the chirality has an appreciable effect on higher vibration *** SWcNTs is very sensitive to the initial strain even if the strain is extremely small.

关键词： Vibration carbon nanotubes molecular dynamics Timoshenko beam models

Effect of post-bond heat treatment on the microstructure and high temperature mechanical property of a TLP bonded γ'-strengthened co-based single crystal superalloy

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Journal of Materials Science & Technology 2021年第21期80卷 244-258页

作者： S.y.Wang y.Sun c.y.cui X.F.Sun y.Z Zhou y.M.Ma H.L.An Institute of Metal Research Chinese Academy of SciencesShenyang 110016China School of Materials Science and Engineering University of Science and Technology of ChinaHefei 230026China Harbin Welding Institute China Academy of Machinery Science and TechnologyHarbin 150028China

Post-bond heat treatment(PBHT) applied to a transient liquid phase(TLP) bonding joint is an effective approach to remove the brittle borides and improve its ***,we proposed two types of PBHT strategies to obtain a TLP bonded γ'-strengthened co-based single crystal superalloy,and the microstructural characteristics and tensile properties of the two heat treated joints were compared to identify the optimal PBHT *** evolution of the brittle boride in the joint after the PBHT was studied by using in-situ *** experimental results allowed to provide a theoretic model to quantitatively evaluate the distribution of the brittle phase after the optimal PBHT and analyze the joint fractures to understand the failure *** obtained results revealed that a post-bond solid solution treatment performed to the joint at a high temperature(over 1275℃) could decrease the area fraction of the boride from 7.2 % to 1.4 % and increase the elongation from 1.9 % to 7.8 %.This work emphasizes the relevance of solid solution temperature when a PBHT strategy is applied.

关键词： Transient liquid phase(TLP) γ'-strengthened co-based single crystal superalloy Heat treatment sequence Brittle boride Tensile property

coating behavior and surface hardening of Pd_(77)cu_6Si_(17) thin film metallic glass on AZ31 magnesium alloy

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2013年第12期14卷 898-905页

作者： X.H.DU y.c.cHANG H.J.PEI B.y.cHEN M.c.KUO J.c.HUANG School of Materials Sciences and Engineering Shenyang Aerospace University Department of Materials and Optoelectronic Science National Sun Yat-Sen University Department of Materials Engineering Kun Shan University

Pd77cu6Si17(PcS) thin film metallic glasses(TFMGs) with high glass forming ability and hardness were selected as a hard coating for improving the surface hardness of AZ31 magnesium alloy. Both microindentation and nanoindentation tests were conducted on specimens with various PcS film thicknesses from 30 to 2000 nm. The apparent hardness and the relative indentation depth(β) were integrated using a quantitative model. The interaction parameters involved and relative hardness values were extracted from iterative calculations. According to the results, surface hardness can be enhanced greatly by PcS TFMGs in the shallow region, followed by gradual decrease with increasing β ratio. In addition, specimens with thinner coatings(e.g., 200nm) showed greater substrate-film interaction and those with thick coatings(e.g., 2000nm) became prone to film cracking. The optimum TFMG coating thickness in this study was estimated to be around 200 nm.

关键词： Thin film metallic glass(TFMG) Magnesium alloy Sputtering process Nanoindentation coating thickness