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Evaluation on elevated-temperature stability of modified 718-type alloys with varied phase configurations

International Journal of Minerals,Metallurgy and Materials 2020年第8期27卷 1123-1132页

作者： Zhan Qiao Chong Li Hong-jun Zhang Hong-yan Liang Yong-chang Liu Yong Zhang State Key Lab of Hydraulic Engineering Simulation and Safety School of Materials Science&EngineeringTianjin UniversityTianjin 300354China Key Laboratory of the Ministry of Education for Modern Metallurgy Technology North China University of Science and TechnologyTangshan 063210China Science and Technology on Advanced High Temperature Structural Materials Laboratory AEEC Beijing Institute of Aeronautical MaterialsBeijing 100095China

Inconel 718 is a Ni–Fe-based superalloy widely used in aerospace engines because of its excellent mechanical ***,the inferior stability of theγ″phase limits the application of Inconel 718,which coarsens rapidly at temperatures greater than 650°*** improving the temperature tolerance of Inconel 718 requires optimization of the phase configuration via modification of the alloy’s chemical *** the aforementioned objective,this work was conducted to study the precipitation behavior and thermal stability of the strengthening phases with various structures in modified Inconel 718 alloys by tailoring the Al/Ti *** increasing Al/Ti ratio,three particle configurations were formed:γ′/γ″composite,isolatedγ′,andγ′/γ″/γ′composite *** results of aging tests demonstrate that the isolatedγ′and theγ′/γ″/γ′composite structure exhibited better thermal stability at temperature as high as 800°*** isolatedγ′exhibited a reduced coarsening rate compared with theγ′/γ″/γ′composite particles because the isolatedγ′phase was rich in Al,Ti,and ***,theγ′/γ″composite particles coarsened and decomposed rapidly during aging at temperatures greater than 700°C because of the lower stability resulting from the larger number ofγ″*** obtained results provide necessary data for the compositional optimization of novel 718-type alloys.

关键词： Inconel 718 structure thermal stability interface

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Evaluation of Automobile Design Scheme Based on Improved Grey Situation Decision Method

Evaluation of Automobile Design Scheme Based on Improved Gre...

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Mechanical, Automation and Electrical Engineering (CMAEE), International Conference on

作者： Yunfei Jia Qingsong Tian Debin Hu Tianjin Key Laboratory for Advanced Signal Processing Civil Aviation University of China Tianjin China Suzhou Weizhong Data Technology Co. Ltd Suzhou China

Evaluation of design scheme for new types of cars refers to multiple attribute comprehensive evaluation. In this paper, an improved grey-situation decision-making method is proposed. The advantage of our method lies in both the preference of decision maker and the objectiveness implicated in the data are incorporated. Firstly, AHP is exploited to build hierarchy and assign subjective weights to each attribute. This can incorporate the decision maker's successful experiences into comprehensive evaluation in a fine-grained way. Secondly, the Grading system is used to enhance the contribution of significant attributes with almost equal value. On the contrary, traditional gray-situation method usually overlooks the contribution of almost equal attributes, even if these attributes are greatly weighted at previous step. Finally, the effectiveness of the method is validated through a real-world automotive design scheme. Our method can be easily generalized and applied to wider domains.

关键词： Electrical engineering Automation Design methodology Analytic hierarchy process Automobiles Automotive engineering

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Three-dimensional Anatomically Realistic Numerical Head Model Construction based on T1-weighted MRIs for Microwave Hemorrhagic Stroke Imaging

Three-dimensional Anatomically Realistic Numerical Head Mode...

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IEEE MTT-S International Microwave Workshop Series on advanced Materials and Processes for RF and THz Applications (IMWS-AMP)

作者： Qinwei Li Lunxiao Wang Xiaoguang Lu Ming Yu Tianjin Key Laboratory for Advanced Signal Processing Civil Aviation University of China Tianjin China Technology Institute of Systems Engineering Academy of Military Sciences Tianjin China

A 3-D anatomically realistic numerical brain model construction process based on real magnetic resonance imaging (MRI) images is presented in this paper. This phantom serves as a simulation experimental verification basis for later microwave detection of intracranial hemorrhage. This numerical model is derived from the T1-weighted MRIs of the patients. The MRI case images were processed by separating, labeling, and categorizing each biological brain tissue. Each slice is transformed into uniform grids mapping different brain tissues' dielectric properties. The 3-D finite-difference time-domain (3D-FDTD) numerical phantom verifies the feasibility of the proposed construction method. Compared with earlier models, the construction of this model follows the real human brain tissue structure, giving a more accurate experimental platform for various imaging simulation techniques.

关键词： Solid modeling Magnetic resonance imaging Biological system modeling Phantoms Brain modeling Microwave theory and techniques Numerical models

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Research on the Pressure Comfort of Pilot Helmets 32

Research on the Pressure Comfort of Pilot Helmets

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32nd Congress of the International Council of the Aeronautical Sciences, ICAS 2021

作者： Wang, Xiujuan Xu, Jing Wang, Juhao Mi, Jiachen Jiang, Yaming Aerospace Life-support Industries LTD Xiangyang441003 China Aviation Key Laboratory of Science and Technology on Life-support Technology Xiangyang441003 China Tiangong University School of Textile Science and Engineering Tianjin 300387 China Intel Engineering Simulation Technology Co. Ltd. Dalian116023 China

ISBN: (纸本)9783932182914

With the advancement of technology, the functions of pilot helmets are constantly being upgraded. The highly integrated helmets with display, positioning, sensing, night vision and camera are the future development trends. Although the multifunctional and highly integrated design enhances the combat maneuverability, the add-on components will result in local tenderness as the weight gain and center of gravity change, which seriously affects the pilot's wearing comfort, especially in high-speed overload conditions. These factors have become potential factors affecting flight safety. At present, experience-based methods are no longer suitable for new product development. Therefore, it is urgent to establish a simulation model on the pressure comfort of "helmet-head", the finite element method is used for simulation calculation. This paper studies different conditions of the center of gravity, and using the standard head shape, ball shape and real head shape as a control, to analyze the center of gravity, the difference of the head shape, and the influence of overload loading on the pressure distribution. By comparing with the actual flight situation, the simulation results are consistent with the actual situation, which proves that the simulation model has good credibility. © 2021 32nd Congress of the International Council of the Aeronautical Sciences, ICAS 2021. All rights reserved.

关键词： Flight simulators

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Bending-Induced Spatial Separation of Dopants in Single Crystalline Semiconductor Nanowires

SSRN

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SSRN 2023年

作者： Liu, Zhao Liu, Xu Wang, Tong Wang, Jing Liu, Ying Department of Physics and Hebei Advanced Thin Film Laboratory Hebei Normal University Shijiazhuang050024 China Beijing Computational Science Research Center Beijing100193 China Shenzhen Institute for Advanced Study University of Electronic Science and Technology of China Shenzhen518000 China National Key Laboratory for Materials Simulation and Design Beijing100083 China

The spatial separation of dopants is crucial in extending the lifetime of semiconductor nanowire p-n junctions, which is traditionally achieved through core-shell nanowire heterostructures at high cost. In this study, we employ atomistic quantum mechanical simulations combined with bond orbital theory to demonstrate that simple bending deformation leads to a remarkable doping preference in single crystalline semiconductor nanowires, making dopant atoms with larger (smaller) sizes than host atoms tend to reside on the tensile (compressive) side near the nanowire shell. We also show that this doping preference induces significant spatial separation of n-type and p-type dopants with different atomic sizes. As single crystalline semiconductor nanowires are easier to synthesize and cost-effective, our findings pave the way for designing long-lived semiconductor nanowire p-n junctions and doping modulation via inhomogeneous strain engineering. © 2023, The Authors. All rights reserved.

关键词： Nanowires

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Intrinsic and extrinsic anomalous transport properties of the Heusler ferromagnets Fe2CoAl and Fe2NiAl from first principles

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Physical Review B 2023年第22期107卷 224405-224405页

作者： Xiuxian Yang Wanxiang Feng Xiao-Ping Li Gui-Bin Liu Yuriy Mokrousov Yugui Yao Centre for Quantum Physics Key Laboratory of Advanced Optoelectronic Quantum Architecture and Measurement (MOE) School of Physics Beijing Institute of Technology Beijing 100081 China Beijing Key Lab of Nanophotonics and Ultrafine Optoelectronic Systems School of Physics Beijing Institute of Technology Beijing 100081 China School of Physical Science and Technology Inner Mongolia University Hohhot 010021 China Institute of Physics Johannes Gutenberg University Mainz 55099 Mainz Germany Peter Grünberg Institut and Institute for Advanced Simulation Forschungszentrum Jülich and JARA 52425 Jülich Germany

Recently, Heusler ferromagnets have been found to exhibit unconventional anomalous electric, thermal, and thermoelectric transport properties. In this study, we employed first-principles density functional theory calculations to systematically investigate both intrinsic and extrinsic contributions to the anomalous Hall effect (AHE), anomalous Nernst effect (ANE), and anomalous thermal Hall effect (ATHE) in two Heusler ferromagnets: Fe2CoAl and Fe2NiAl. Our analysis reveals that the extrinsic mechanism originating from disorder dominates the AHE and ATHE in Fe2CoAl, primarily due to the steep band dispersions across the Fermi energy and corresponding high longitudinal electronic conductivity. Conversely, the intrinsic Berry phase mechanism, physically linked to nearly flat bands around the Fermi energy and gapped by spin-orbit interaction band crossings, governs the AHE and ATHE in Fe2NiAl. With respect to ANE, both intrinsic and extrinsic mechanisms are competing in Fe2CoAl as well as in Fe2NiAl. Furthermore, Fe2CoAl and Fe2NiAl exhibit tunable and remarkably pronounced anomalous transport properties. For instance, the anomalous Nernst and anomalous thermal Hall conductivities in Fe2NiAl attain giant values of 8.29 A/Km and 1.19 W/Km, respectively, at room temperature. To provide a useful comparison, we also thoroughly investigated the anomalous transport properties of Co2MnGa. Our findings suggest that Heusler ferromagnets Fe2CoAl and Fe2NiAl are promising candidates for spintronics and spin caloritronics applications.

关键词： Anomalous Hall effect Magnetism Transport phenomena Alloys

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Enhanced mechanical and electrical properties of multi-walled carbon nanotubes reinforced Cu/Ti_(3)SiC_(2)/C nanocomposites via high-pressure torsion

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Transactions of Nonferrous Metals Society of China 2024年第12期34卷 4005-4019页

作者： Zi-xuan WU Pei-fan ZHANG Xiao-song JIANG Hong-liang SUN Yan-jun LI Pål CHRISTIAN Liu YANG Key Laboratory of Advanced Technologies of Materials Ministry of EducationSouthwest Jiaotong UniversityChengdu 610031China School of Materials Science and Engineering Southwest Jiaotong UniversityChengdu 610031China School of Engineering and Materials Science Queen Mary University of LondonLondon E14NSUnited Kingdom Teaching and Research Support Center Naval Aviation UniversityYantai 264001China Department of Materials Science and Engineering Norwegian University of Science and TechnologyTrondheim 7491Norway Institute for Applied Materials Karlsruhe Institute of TechnologyKarlsruhe 76131Germany

In order to achieve combined mechanical and electrical properties,multi-walled carbon nanotubes(MWCNTs)reinforced Cu/Ti_(3)SiC_(2)/C nanocomposites were further processed by high-pressure torsion(HPT).The maximum microhardness values of central and edge from the composites with 1 wt.%MWCNTs reached HV 130.0 and HV 363.5,which were 43.9%and 39.5%higher than those of the original samples,*** the same content of MWCNTs,its electrical conductivity achieved 3.42×10^(7) S/m,which was increased by 78.1%compared with that of original *** synergistic improvement of mechanical and electrical properties is attributed to the obtained microstructure with increased homogenization and refinement,as well as improved interfacial bonding and reduced *** strengthening mechanisms include dispersion and refinement strengthening for mechanical properties,as well as reduced electron scattering for electrical properties.

关键词： Cu/Ti_(3)SiC_(2)/C nanocomposites multi-walled carbon nanotubes high-pressure torsion microstructure microhardness electrical conductivity

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Frequency-dependent squeezing via Einstein–Podolsky–Rosen entanglement based on silicon nitride microring resonators

arXiv

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arXiv 2024年

作者： Xu, Haodong Shu, Zijun Li, Nianqin Shen, Yang Ji, Bo Yang, Yongjun Wu, Tengfei Long, Mingliang He, Guangqiang State Key Laboratory of Advanced Optical Communication Systems and Networks Department of Electronic Engineering Shanghai Jiao Tong University Shanghai200240 China State Key Laboratory of Precision Spectroscopy East China Normal University Shanghai200062 China Science and Technology on Metrology and Calibration Laboratory Changcheng Institute of Metrology Measurement Aviation Industry Corporation of China Beijing100095 China Shanghai Astronomical Observatory Chinese Academy of Sciences China

Significant efforts have been made to enhance the performance of displacement sensors limited by quantum noise, such as gravitational wave detectors. Techniques like frequency-dependent squeezing have overcome the standard quantum limit in optomechanical force measurements, leading to substantial overall progress. These advancements, coupled with major developments in integrated photonics, have paved the way for the emergence of integrated Kerr quantum frequency combs (QFCs). A platform has been established for designing EPR entangled quantum frequency combs using on-chip silicon nitride microring resonators, enabling thorough analysis and optimization of entanglement performance, as well as effective noise reduction adjustments. This platform, incorporating the quantum dynamics of Kerr nonlinear microresonators, supports at least 12 continuous-variable quantum modes in the form of 6 simultaneous two-mode squeezed pairs (EPR entangled pairs). Additionally, by selecting the detection angle of the idler mode, a single-mode squeezed state is generated in the signal mode. Given the frequency-dependent nature of the detection angle, frequency-dependent squeezing is achieved. A comparative analysis of the results under different dispersion conditions is also conducted. Copyright © 2024, The Authors. All rights reserved.

关键词： Silicon nitride

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Analysis of abnormal texture formation and strengthening mechanism in an extruded Mg-Gd-Y-Zn-Zr alloy

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Journal of Materials Science & technology 2020年第10期42卷 133-145页

作者： Xueze Jin Wenchen Xu Zhongze Yang Can Yuan Debin Shan BugangTeng Bo Cheng Jin National Key Laboratory for Precision Hot Processing of Metals&School of Materials Science and Engineering Harbin Institute of TechnologyHarbin150001China Advanced Composites Simulation Lab University of Southern CaliforniaLos AngelesCA 90089-0241USA

A Mg-Gd-Y-Zn-Zr magnesium alloy with different initial states was extruded under different extrusion *** effect of solution treatment and extrusion parameters on the microstructure,texture and mechanical properties were analyzed in detail,and the abnormal texture formation and strengthening mechanism was *** extruded at low temperature and small extrusion ratio,the bimodal microstructure consisting of fine dynamically recrystallized grains and coarse deformed grains occurred both in the as-cast alloy and solution-treated *** the extrusion temperature and extrusion ratio were increased,the amount and size of dynamically recrystallized grains increased and the grain size of the solution-treated alloy showed higher growth ***,an abnormal texture with<0001>parallel with extrusion direction developed due to the occurrence of non-basal slip and continuous dynamic *** could be enhanced by solution treatment,high temperature,and large extrusion *** the as-cast alloy and solution-treated alloy exhibited the highest tensile strength after extrusion at 300℃with an extrusion ratio of *** refinement was the main strengthening mechanism utilized in both the as-cast alloy and the solution-treated *** hardening played an important role in the sample extruded at low temperature and small extrusion ratio,with the highest contribution of about 33 MPa after extrusion at 300℃with an extrusion ratio of *** strengthening contributed more in the sample extruded at high temperature and large extrusion ratio,but no more than 24.1 *** strengthening was another strengthening mechanism in the extruded as-cast alloy,especially at high temperature and large extrusion ratio(no more than 9 MPa).

关键词： Hot extrusion Heat treatment Abnormal texture Strengthening mechanism Quantitative analysis

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An Extended Multi-Step Kinetic Model for Thermal Degradation of Ceramizable Polymer

SSRN

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SSRN 2023年

作者： Gong, Zheng Wang, Huanfang Deng, Zongyi Chen, Shuwen Zhang, Chao School of Civil Aviation Northwestern Polytechnical University Shaanxi Xi’an710072 China Key Laboratory on the Impact Protection and Safety Assessment of Civil Aviation Vehicle Jiangsu Taicang215400 China School of Aeronautics Northwestern Polytechnical University Shaanxi Xi’an710072 China Key laboratory of Advanced Technology for Specially Functional Materials Ministry of Education Wuhan University of Technology Wuhan430070 China School of Astronautics Northwestern Polytechnical University Shaanxi Xi’an710072 China

The pyrolysis and oxidation processes of a phenolic resin modified with boron carbide–containing talc (B4C talc) in N2 atmosphere and air were studied, and an accurate kinetic model was established. Non-isothermal pyrolysis experiments were conducted on the modified boron phenolic resin at different heating rates using a thermogravimetric analyzer, and the results show that there are three main causes for the weight change of the modified resin: volatilization of small molecules, pyrolysis of the boron-phenolic resin, and oxidation of the inorganic fillers. In the kinetic analysis, an extended independent parallel reaction model was developed to describe the complex pyrolysis and oxidation of the modified resin, including weight gain reactions and weight loss reactions. Deconvolution based on pyrolysis and oxidation further enhances the plausibility and coherence of this method, and the goodness of fit of the thermogravimetric curve was found to be greater than 0.98. © 2023, The Authors. All rights reserved.

关键词： Oxidation

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