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Relationship between texture and residual macro-strain in CVD diamond films based on phenomenological analysis

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Journal of University of Science and Technology Beijing 2008年第2期15卷 197-201页

作者： Weimin Mao Hongxi Zhu leng chen Huiping Feng School of Materials Science and Engineering University of Science and Technology Beijing Beijing 100083 China State Key Laboratory of Advanced Metals and Materials University of Science and Technology Beijing Beijing 100083 China

The relationship between texture and elastic properties of chemical vapor deposition （CVD） diamond films was analyzed based on the phenomenological theory, which reveals the influence of crystalline orientation and texture on the residual macro-strain and macro-stress. The phenomenological calculations indicated that the difference in Young＇s modulus could be 15% in single diamond crystals and 5% in diamond films with homogeneously distributed strong fiber texture. The experimentally measured residual strains of free-standing CVD diamond films were in good agreement with the correspondingly calculated Young＇s modulus in connection with the multi-fiber textures in the films, though the difference in Young＇s modulus induced by texture was only around 1%. It is believed that texture should be one of the important factors influencing the residual stress and strain of CVD diamond films.

关键词： diamond films elastic behavior texture residual stresses chemical vapor deposition (CVD)

Solute Clusters/Enrichment at the Early Stage of Ageing in Mg-Zn-Gd Alloys Studied by Atom Probe Tomography

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Acta Metallurgica Sinica(English Letters) 2019年第2期32卷 187-193页

作者： Xin-Fu Gu Tadashi Furuhara leng chen Ping Yang School of Materials Science and Engineering University of Science and Technology Beijing Institute for Materials Research Tohoku University

Three-dimensional distribution of solute elements in an Mg–Zn–Gd alloy during ageing process is quantitatively characterized by three-dimensional atom probe(3DAP) tomography. Based on the radius distribution function, it is found that Zn–Gd solute pairs in Mg matrix appear mainly at two peaks at early stage of ageing, and the separation distance between Zn and Gd atoms could be well rationalized by the first-principle calculation. Moreover, the fraction of Zn–Gd solute pairs increases first and then decreases due to the precipitation of long-period stacking ordered(LPSO) structures. Both the composition of the structural unit in LPSO structure and the solute enrichment around it are quantified. It is found that Zn and Gd elements are synchronized in the LPSO structure, and solute segregation of pure Zn or Gd is not observed at the transformation front of the LPSO structure in this alloy. In addition, the crystallography of transformation front is further determined by 3DAP data.

关键词： Magnesium alloy Long-period stacking ordered(LPSO) Atomic cluster Three-dimensional atom probe(3DAP) Crystallography

Measurement and Simulation of Grain Size in Strong Textured and Coarse-Grained Metal Sheets

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Journal of Materials Science & Technology 2003年第Z1期19卷 115-116页

作者： leng chen Weimin MAO Yongning YU Huiping FENG Department of Materials University of Science and Technology Beijing Beijing 100083 China Department of Materials University of Science and Technology Beijing Beijing 100083 China Department of Materials University of Science and Technology Beijing Beijing 100083 China Department of Materials University of Science and Technology Beijing Beijing 100083 China

An X-ray diffractometer that equipped with a two-dimensional detector is used for developing the technique of grainsize measurement for strong textured and coarse-grained Si steel sheet. The method is based on the concept thatthe position of diffraction spots depends on the orientation of individual grains. The two-dimensional detector hasthe ability to collect abundant diffraction information in seconds, thus it can be determined rapidly and accuratelywhether a series of diffraction spots come from the same grain. The experimental results show that this method canbe used for measuring grain size and its distribution in strong textured and coarse-grained metal sheets.

关键词： Grain size, Texture, Two-dimensional detectorleng

Textures of high-strength and low-expansion Fe-Ni alloy wires during cold-drawing processes

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International Journal of Minerals,Metallurgy and Materials 2009年第6期16卷 667-671页

作者： leng chen Jian-fu Zhang Li Zhang Li Meng School of Materials Science and Engineering University of Science and Technology Beijing Beijing 100083 China Department of Ftmctional Materials Central/roll and Steel Research Institute Beijing 100081 China

Textures of high-strength and low-expansion Fe-Ni alloy wires during cold-drawing processes were investigated using X-ray diffraction （XRD） and electron back scatter diffraction （EBSD） techniques. The experimental results show that the 〈111〉 and 〈100〉 fibre textures are the main texture components, and crystalline grains in the surface are more fine and uniform than those in the center of Fe-Ni alloy wires during cold-drawing processes. It is found that the volume fraction of the 〈111〉 fibre texture component determined by quantitative regression calculation of the Gaussian distribution function reaches more than 60% and the strong 〈111〉 fibre texture component favors the torsional property of Fe-Ni alloy wires.

关键词： Fe-Ni alloy cold-drawing texture pole figure orientation mapping

Influence of reaction stresses induced by dislocation slips onthe orientation evolution in bcc metals

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Chinese Science Bulletin 2003年第2期48卷 204-207页

作者： MAO Weimin chen leng YU Yongning Department of Materials University of Science and Technology BeijingBeijing 100083China

A plastic deformation model for bcc metals is proposed in consideration of reaction stresses. The shear strains and the corresponding reaction stresses induced by the activation of dislocations are calculated in the model, which will influence the following dislocation activation. The rolling texture in bcc metals is simulated up to 80% reduc-tion, while the ratio of critical resolved shear stresses be-tween the dislocations slipping on the {110} and {112} planes is chosen as 0.95. The corresponding calculation is also con-ducted with the activation of second dislocation, if the dif-ference between the orientation factor of the two dislocations with maximal orientation factors is lower than 5%. It is shown that the simulated texture is closer to that of the 80% rolled interstitial free steels than other modeling. It is be-lieved that the new model can give more attention to both of the strain and stress continuities during the plastic deforma-tion of polycrystalline metals, and therefore approaches closer to the real deformation process in bcc metals.

关键词： bcc metals plastic deformation texture stress strain simulation

Hourglass-GCN for 3D Human Pose Estimation Using Skeleton Structure and View Correlation

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Computers, Materials & Continua 2025年第1期82卷 173-191页

作者： Ange chen chengdong Wu Chuanjiang leng Faculty of Robot Science and Engineering Northeastern UniversityShenyang110169China

Previous multi-view 3D human pose estimation methods neither correlate different human joints in each view nor model learnable correlations between the same joints in different views explicitly,meaning that skeleton structure information is not utilized and multi-view pose information is not completely ***,existing graph convolutional operations do not consider the specificity of different joints and different views of pose information when processing skeleton graphs,making the correlation weights between nodes in the graph and their neighborhood nodes *** Graph Convolutional Networks(GCNs)cannot extract global and deeplevel skeleton structure information and view correlations *** solve these problems,pre-estimated multiview 2D poses are designed as a multi-view skeleton graph to fuse skeleton priors and view correlations explicitly to process occlusion problem,with the skeleton-edge and symmetry-edge representing the structure correlations between adjacent joints in each viewof skeleton graph and the view-edge representing the view correlations between the same joints in different *** make graph convolution operation mine elaborate and sufficient skeleton structure information and view correlations,different correlation weights are assigned to different categories of neighborhood nodes and further assigned to each node in the *** on the graph convolution operation proposed above,a Residual Graph Convolution(RGC)module is designed as the basic module to be combined with the simplified Hourglass architecture to construct the Hourglass-GCN as our 3D pose estimation ***-GCNwith a symmetrical and concise architecture processes three scales ofmulti-viewskeleton graphs to extract local-to-global scale and shallow-to-deep level skeleton features *** results on common large 3D pose dataset Human3.6M and MPI-INF-3DHP show that Hourglass-GCN outperforms some excellent methods in 3D pose estimati

关键词： 3D human pose estimation multi-view skeleton graph elaborate graph convolution operation Hourglass-GCN

Austenite transformation and work hardening of medium manganese steel

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Journal of Iron and Steel Research International 2018年第12期25卷 1265-1269页

作者： Lei Zhang Cun-yu Wang Heng-chang Lu Wen-quan Cao Chang Wang Han Dong leng chen School of Materials Science and Engineering University of Science and Technology BeijingBeijing 100083China Special Steel Institute of Central Iron and Steel Research Institute Beijing 100081China Mechanical Engineering Department of Tangshan Polytechnic College Tangshan 063299HebeiChina

The austenite transformation behavior and mechanical properties of medium manganese steel subjected to tensile strain were studied by electron backscatter diffraction,X-ray diffraction and tensile *** results show that the austenite phases are mainly distributed on the grain boundary in the duplex microstructure of austenite and ferrite,and it is easy for the big-size austenite to transform at small beginning tension strain following the mechanisms of both austenite (fcc)→ε- martensite (hcp)→α-martensite (bcc)and austenite (fcc)→α-martensite (bcc).Both yield strength and tensile strength increase with the increase in pre-strain,and the total elongation decreases,while the value of pre-strain plus total elongation almost keeps *** tensile deformation,transformation from austenite into martensite improves work-hardening rate remarkably.

关键词： Medium manganese steel Austenite Martensite Microstructure Mechanical property

Signal-to-noise ratio of Raman signal measured by multichannel detectors

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Chinese Physics B 2021年第9期30卷 31-44页

作者： Xue-Lu Liu Yu-chen leng Miao-Ling Lin Xin Cong Ping-Heng Tan State Key Laboratory of Superlattices and Microstructures Institute of SemiconductorsChinese Academy of SciencesBeijing 100083China Center of Materials Science and Optoelectronics Engineering&CAS Center of Excellence in Topological Quantum Computation University of Chinese Academy of SciencesBeijing 100049China

Raman spectroscopy has been widely used to characterize the physical properties of two-dimensional materials(2DMs).The signal-to-noise ratio(SNR or S/N ratio)of Raman signal usually serves as an important indicator to evaluate the instrumental performance rather than Raman intensity *** detectors with outstanding sensitivity,rapid acquisition speed and low noise level have been widely equipped in Raman instruments for the measurement of Raman *** this mini-review,we first introduce the recent advances of Raman spectroscopy of *** we take the most commonly used CCD detector and IGA array detector as examples to overview the various noise sources in Raman measurements and analyze their potential influences on SNR of Raman signal in *** overview can contribute to a better understanding on the SNR of Raman signal and the performance of multichannel detector for numerous researchers and instrumental design for industry,as well as offer practical strategies for improving spectral quality in routine measurement.

关键词： multichannel detectors signal-to-noise ratio dark noise shot noise

Mg AmorphousZr_(0.9)Ti_(0.1)(Ni_(0.57)Mn_(0.28)V_(0.1)Co_(0.05))_(2.1)Composite for Hydrogen Storage

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Journal of Materials Science & Technology 2003年第2期19卷 141-144页

作者： Haiyan leng, Demin chen, Manqi LU, Haifeng ZHANG, Huiming chenG and Ke YANGInstitute of Metal Research, Chinese Academy of Sciences, Shenyang 110016, China Inst. of Metal Res. Chinese Acad. of Sci. Shenyang 110016 China

The reactive mechanical alloying (RMA) method was used to produce Mg-40 wt pet amorphous Zr0.9Ti0.1(Nio.57-Mn0.28\/***.o5)2.i composite in this study, and the absorption/desorption property of the composite was improved remarkably. The composite possessed excellent kinetic properties even at moderate temperature (393 K) without activation. Owing to the formation of the embrittle MgH2, the reactive mechanical milling process reduced the particle size of Mg and made the composite phase being highly efficiently distributed, which determined the excellent hydriding properties of the composite.

关键词： Mg Hydrogen storage material RMA Amorphous