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Orientation-Dependent Mechanical Responses and Plastic Deformation Mechanisms of FeMnCoCrNi High-entropy Alloy:A Molecular Dynamics Study

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Acta Metallurgica Sinica(English Letters) 2021年第11期34卷 1511-1526页

作者： hai-feng zhang hai-Le Yan feng Fang Nan Jia Key Laboratory for Anisotropy and Texture of Materials(Ministry of Education) School of Material Science and EngineeringNortheastern UniversityShenyang 110819China State Key Lab Rolling&Automat Northeastern UniversityShenyang 110819China

Mechanical properties of high-entropy alloys(HEAs)with the face-centered cubic(fcc)structure strongly depend on their initial grain ***,the orientation-dependent mechanical responses and the underlying plastic fl ow mechanisms of such alloys are not yet well ***,deformation of the equiatomic FeMnCoCrNi HEA with various initial orientations under uniaxial tensile testing has been studied by using atomistic simulations,showing the results consistent with the recent experiments on fcc *** quantitative analysis of the activated deformation modes shows that the initiation of stacking faults is the main plastic deformation mechanism for the crystals initially oriented with[001],[111],and[112],and the total dislocation densities in these crystals are higher than that with the[110]and[123]*** faults,twinning,and hcp-martensitic transformation jointly promote the plastic deformation of the[110]orientation,and twinning in this crystal is more significant than that with other *** in the crystal oriented with[123]is dominated by the hcp-martensite *** of the mechanical behaviors in the FeMnCoCrNi alloy and the conventional materials,*** and Fe50Ni50,has shown that dislocation slip tends to be activated more readily in the *** is attributed to the larger lattice distortion in the HEA than the low-entropy materials,leading to the lower critical stress for dislocation nucleation and elastic–plastic transition in the *** addition,the FeMnCoCrNi HEA with the larger lattice distortion leads to an enhanced capacity of storing ***,for the[001]-oriented HEA in which dislocation slip and stacking fault are the dominant deformation mechanisms,the limited deformation modes activated are insu fficient to improve the work hardening ability of the material.

关键词： High-entropy alloy Molecular dynamics study Mechanical response Plastic deformation mechanism

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Reverse Transformation in[110]-Oriented Face-Centered-Cubic Single Crystals Studied by Atomic Simulations

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Acta Metallurgica Sinica(English Letters) 2022年第10期35卷 1631-1640页

作者： hai-feng zhang hai-Le Yan feng Fang Nan Jia Key Laboratory for Anisotropy and Texture of Materials(Ministry of Education) School of Material Science and EngineeringNortheastern UniversityShenyang110819China State Key Lab Rolling&Automat Northeastern UniversityShenyang110819China

Bidirectional transformations,which are achieved by triggering both dynamic forward transformation from the face-centered-cubic(fcc)austenite to the hexagonal-close-packed(hcp)martensite and the reverse transformation from martensite to austenite during cold deformation,have been previously reported in FeMnCoCr-based high-entropy alloys(HEAs).This leads to the permanent refinement of microstructure and hence enhances the work-hardening capacity of *** order to reveal the microscopic mechanism of the reverse transformation in HEAs under deformation,the effect of the sample aspect ratio,i.e.,Z/X,on the evolution of deformation systems in the equi-atomic FeMnCoCrNi alloy with[110]orientation during uniaxial tensile loading along the Z direction is investigated by atomic simulations in this *** the aspect ratio is 0.5,the reverse transformation is more significant compared with other models,while a good plasticity can still be *** then compare the micromechanical behavior of three fcc single crystals,i.e.,FeMnCoCrNi,FeCuCoCrNi,and pure *** results show that the stacking fault energy plays a major role in the activation of different deformation mechanisms;however,the lattice distortion in the HEA does not significantly affect the activation of deformation ***,for all materials dislocation slip leads to the softening,while strain hardening is attributed to the initiation of multiple deformation *** Shockley partials slip leads to bidirectional phase transition,twinning and detwinning in the three ***,the reverse transformation can occur in all metallic materials where the fcc to hcp phase transformation is the dominant deformation *** findings contribute to an in-depth understanding of the deformation mechanism in fcc-structured materials under severe plastic deformation and provide theoretical guidance for the design of alloys with superior strength–plasticity combinations.

关键词： Face-centered-cubic materials Atomic simulation Plastic deformation Reverse transformation

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Spontaneous infiltration and wetting behaviors of a Zr-based alloy melt on a porous SiC substrate

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International Journal of Minerals,Metallurgy and Materials 2018年第7期25卷 817-823页

作者： zhang Wen Li Hong Li hai-feng zhang School of Materials Science and Engineering Shenyang Aerospace UniversityShenyang 110136China School of Materials Science and Engineering Shenyang Ligong UniversityShenyang 110159China Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China

The spontaaleous infiltration aald wetting behaviors of a Zr-based alloy melt on porous a SiC ceramic plate were studied using tile sessile drop metilod by continuous heating and holding for 1800 s at different temperatures in a high-vacuum furnace. The results showed that tile Zr-based alloy melt could pastly infiltrate tile porous SiC substrate without pressure due to tile effect of capillary pressure. Wettability and infiltration rates increased witil increasing temperature, and interracial reaction products （ZrC0.7 and TiC） were detected in tile Zr-based alloy/SiC ceramic system, likely because of tile reaction of tile active elements Zr and Ti witil elemental C. Furtilelinore, tile redundant ele- ment Si diffused into tile alloy melt.

关键词： spontaneous infiltration wetting interface porous SiC Zr-based alloy

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Micro-angle tilt detection for the rotor of a novel rotational gyroscope with a 0.47″resolution

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Frontiers of Information Technology & Electronic Engineering 2017年第5期18卷 591-598页

作者： hai LI Xiao-wei LIU Rui WENG hai-feng zhang MEMS Center Harbin Institute of TechnologyHarbin 150001China MOE Key Laboratory of Micro-Systems and Micro-Structures Manufacturing Harbin 150001China

Differential capacitive detection has been widely used in the displacement measurement of the proof mass of vibratory gyroscopes, but it did not achieve high resolutions in angle detection of rotational gyroscopes due to restrictions in structure, theory, and interface circuitry. In this paper, a differential capacitive detection structure is presented to measure the tilt angle of the rotor of a novel rotational gyroscope. A mathematical model is built to study how the structure's capacitance changes with the rotor tilt angles. The relationship between differential capacitance and structural parameters is analyzed, and preliminarily optimized size parameters are adopted. A lownoise readout interface circuit is designed to convert differential capacitance changes to voltage signals. Rate table test results of the gyroscope show that the smallest resolvable tilt angle of the rotor is less than 0.47(0.00013?),and the nonlinearity of the angle detection structure is 0.33%, which can be further improved. The results indicate that the proposed detection structure and the circuitry are helpful for a high accuracy of the gyroscope.

关键词： Micro-angle detection Differential capacitive structure Rotational gyroscope Structure optimization

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Dynamics of a Reaction-diffusion-ODE System in a Heterogeneous Media

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Acta Mathematicae Applicatae Sinica 2024年第2期40卷 275-301页

作者： Cong-hui zhang hai-feng zhang Mei-rong zhang School of Science Beijing University of Civil Engineering and ArchitectureBeijing 102616China Institute of Applied System Analysis Jiangsu UniversityZhenjiang 212013China Department of Mathematical Sciences Tsinghua UniversityBeijing 100084China

The existence and stability of stationary solutions for a reaction-diffusion-ODE system are investigated in this *** first show that there exist both continuous and discontinuous stationary *** a good understanding of the stability of discontinuous stationary solutions is gained under an appropriate *** addition,we demonstrate the influences of the diffusion coefficient on stationary *** results we obtained are based on the super-/sub-solution method and the generalized mountain pass ***,some numerical simulations are given to illustrate the theoretical results.

关键词： reaction-diffusion-ODE system discontinuous stationary solutions stability asymptotic behavior monotone solutions

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Experiment on diffuse reflection laser ranging to space debris and data analysis

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Research in Astronomy and Astrophysics 2015年第6期15卷 909-917页

作者： Hao Sun hai-feng zhang Zhong-Ping zhang Bin Wu Shanghai Astronomical Observatory Chinese Academy of Sciences University of Chinese Academy of Sciences

Space debris poses a serious threat to human space activities and needs to be measured and cataloged. As a new technology for space target surveillance, the measurement accuracy of diffuse reflection laser ranging （DRLR） is much higher than that of microwave radar and optoelectronic measurement. Based on the laser ranging data of space debris from the DRLR system at Shanghai Astronomical Observatory acquired in March-April, 2013, the characteristics and precision of the laser ranging data are analyzed and their applications in orbit determination of space debris are discussed, which is implemented for the first time in China. The experiment indicates that the precision of laser ranging data can reach 39 cm-228 cm. When the data are sufficient enough （four arcs measured over three days）, the orbital accuracy of space debris can be up to 50 m.

关键词： space vehicles -- astrometry -- celestial mechanics -- methods data analysis

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High Tensile Strength and Superelasticity of Directionally Solidified Ti_(30)Ni_(30)Fe_(10)Hf_(10)Nb_(20) Eutectic High Entropy Alloy

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Acta Metallurgica Sinica(English Letters) 2022年第10期35卷 1583-1590页

作者： Huan Li Shuai Zeng Yong-Kang Zhou hai-Long Li Hong-Wei zhang hai-feng zhang Zheng-Wang Zhu Shi-Changxu Innovation Center for Advanced MaterialsInstitute of Metal Research Chinese Academy of SciencesShenyang110016China School of Materials Science and Engineering University of Science and Technology of ChinaHefei230026China CAS Key Laboratory of Nuclear Materials and Safety Assessment Institute of Metal ResearchChinese Academy of SciencesShenyang110016China

Superelasticity has been widely used in various *** elastic limit simultaneously with large superelasticity is urgent in the critical *** this study,we have employed the high entropy alloy(HEA)concept to develop a new TiHfNiFe-Nb eutectic HEA(EHEA)based on the TiNi-Nb eutectic *** results show the directional catkin-like microstructure with the fiber eutectic in the center and the lamella eutectic in the outside form along the directional solidification direction when the growth rate is 60 mm/*** corresponding specimens display the high strength of 1409 MPa and superelasticity of 3.1%in tension at room temperature,which is attributed to the synergetic effect of high entropy,preferred orientation,ordered body-centered cubic(B2)phase and disordered body-centered cubic phase in the eutectic *** work sheds light on designing the high-performance superelastic function materials with EHEAs.

关键词： High-entropy alloy Eutectic alloy Directional solidification Superelasticity Tensile strength

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Quantitative Analysis of Non-Crystalline and Crystalline Solids in Blast Furnace Slag

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Journal of Iron and Steel Research International 2011年第1期18卷 8-10页

作者： WANG hai feng zhang Chun-xia QI Yuan hong State Key l.aboratory ot Advanced Steel Processes and Products Central Iron and Steel Research Institute Beijing 100081 China

The granulation of blast furnace slag （BFS） with water quenching treatment has some disadvantages, such as high water consumption and difficulty for recovery heat. So developing a new dry granulation technique to treat BFS is very important. The applicability of BFS directly depends on the content of non-crystalline solids in the slag after treatment. So it is of theoretical and practical significance to analyze the content of non-crystalline solids in the slag quantitatively and simply. Metallographical test is mainly adopted to quantify the non-crystalline in BFS so far with the shortages such as complex sample, difficult determination, ect. The diffraction intensity of non-crystalline is proportionate to the content of non-crystalline in BFS, ~ray diffraction method was adopted to quantify the noncrystalline and the crystalline solids in BFS. The quantitative coefficient between the crystalline and the non-crystalline solids of BFS is 0.70 of BFS whose main composition （mass percent, %） is： CaO 38.2, SiO2 35.7, Al2Oa 16.3, and MgO 8.3. The relative error of X-ray diffractometer for quantitatively analyzing non-crystalline content of BFS is less than 1%.

关键词： blast furnace slag non crystalline crystalline quantitative analysis

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Fabrication and Photocatalytic Activity of Cu_2O Nanobelts on Nanoporous Cu Substrate

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Acta Metallurgica Sinica(English Letters) 2019年第1期32卷 63-73页

作者： Yun Li Chuan Ji Yu-Chen Chi Zhen-Hua Dan hai-feng zhang feng-Xiang Qin School of Materials Science and Engineering Nanjing University of Science and Technology College of Materials Science and Engineering Nanjing Tech University Shengyang National Laboratory for Materials Science Institute of Metal Research Chinese Academy of Science

In this paper, we report the fabrication of the photocatalysts composed of Cu_2O nanobelts and nanoporous Cu(NP Cu)substrate, which is obtained by soaking the NP Cu in dehydrated ethanol. The NP Cu substrate is achieved by dealloying of Ti_(40.6)Zr_(9.4)Cu_(40.6)Ni_(6.3)Sn_(3.1) amorphous ribbons in HF solutions. The dealloying process is considered to be a thermally activated process, obeying the Arrhenius law. The surface diffusivity increases with increasing dealloying temperature and concentration of HF solutions. The activation energy of the diffusion of Cu adatoms is estimated to be 76.4 kJ/mol. The Cu_2O nanobelts with the width of 10–15 nm and the length of about 1 lm are formed on the surface of NP Cu after immersion in dehydrated ethanol. The photocatalysts of Cu_2O on nanoporous Cu exhibit superior photocatalytic activity toward the degradation of methyl orange and methylene blue under the irradiation of the sunlight due to the coexistence of Cu_2O semiconductor nanobelts and large amount of heterojunctions as flowing path for photoelectrons.

关键词： Nanoporous Cu Dealloying Cu2O Photocatalytic activity

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Evaluating and Improving Linear Regression Based Profiling:On the Selection of Its Regularization

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Journal of Computer Science & Technology 2020年第5期35卷 1175-1197页

作者： Xiang-Jun Lu Chi zhang Da-Wu Gu Jun-Rong Liu Qian Peng hai-feng zhang School of Electronic Information and Electrical Engineering Shanghai Jiao Tong UniversityShanghai 200240China ZhiXun Crypto Testing and Evaluation Technology Co.Ltd. Shanghai 200240China Department of Microelectronics and Nanoelectronics Tsinghua UniversityBeijing 100084China Beijing Smartchip Microelectronics Technology Co. Ltd.Beijing 100082China

Side-channel attacks(SCAs)play an important role in the security evaluation of cryptographic *** a form of SCAs,profiled differential power analysis(DPA)is among the most powerful and efficient by taking advantage of a profiling phase that learns features from a controlled *** regression(LR)based profiling,a special profiling method proposed by Schindler et al.,could be extended to generic-emulating DPA(differential power analysis)by on-the-fly *** formal extension was proposed by Whitnall et *** SLR-based ***,to improve SLR-based method,Wang et *** a method based on ridge ***,the constant format of L-2 penalty still limits the performance of *** this paper,we generalize the ridge-based method and propose a new strategy of using variable *** then analyze from a theoretical point of view why we should not use constant penalty format for all *** speaking,our work reveals the underlying mechanism of how different formats affect the profiling process in the context of side ***,by selecting a proper regularization,we could push the limits of LR-based ***,we conduct simulation-based and practical experiments to confirm our ***,the results of our practical experiments show that the proper formats of regularization are different among real devices.

关键词： side-channel attack(SCA) cryptography linear regression based profiling generic-emulating differential power analysis regularization

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