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Segregation behavior and its regulating process in as-cast magnesium alloy containing heavy rare earth

Journal of Rare Earths 2022年第8期40卷 1291-1304页

作者： Xin Tong Guoqiang You Fanjin Yao Mahmoud Ebrahimi Xinyue Deng Shokouh Attarilar College of Materials Science and Engineering Chongqing UniversityChongqing 400045China National Engineering Research Center of Light Alloy Net Forming and State Key Laboratory of Metal Matrix Composites School of Materials Science and EngineeringShanghai Jiao Tong UniversityShanghai 200240China National Engineering Research Center for Magnesium Alloys Chongqing UniversityChongqing 400044China Department of Mechanical Engineering Faculty of EngineeringUniversity of MaraghehP.O.Box 55136-533MaraghehIran School of Materials Science and Engineering Iran University of Science and TechnologyTehranIran

Specific gravity segregation that occurs during the smelting process always leads to the low composition homogeneity and poor performance stability of the magnesium-rare earth(Mg-RE)*** this study,the segregation behavior of Mg-Gd alloy was investigated by sampling from different locations in the ingot fabricated in a resistance furnace without a pouring *** combined application of induction-heating and mechanical stirring with various speeds(0-130 r/min)was applied to promote the distribution homogeneity of Gd *** the resistance-heating fabricated ingot,Gd content at the bottom section reaches 407%of that at the *** coarse dendrites surrounded by the network-like eutectic structures are responsible for the brittle fracture with a poor elongation of 3.7%.By the combined employment of the induction heating and mechanical stirring with the speed of 87 r/min at 740℃for 40 s,the variation of the Gd content within the whole ingot can be reduced to be the minimum of 0.23 wt%.Corresponding formation and regulating models of segregation were also ***,the cooling rate of the melt is reduced by the continuous increase of the stirring speed to 130 r/min,which results in the grain coarsening and lower homogeneity of the ingot.

关键词： Mg-RE alloy Segregation Composition homogeneity Melting process mechanical stirring Rare earths

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Hardness-thermal stability synergy in nanograined Ni and Ni alloys:Superposition of nanotwin and low-energy columnar boundary

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Journal of materials science & Technology 2023年第6期137卷 123-131页

作者： F.H.Duan Y.Lin Q.Li J.H.Luan J.Lu J.Pan Y.Li Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China Laboratory of Nanomaterials&Nanomechanics Department of Mechanical EngineeringCity University of Hong KongHong KongChina State Key Laboratory of Material Processing and Die&Mould Technology and School of Materials Science and Engineering Huazhong University of Science and TechnologyWuhan 430074China Department of Materials Science and Engineering City University of Hong KongHong KongChina Centre for Advanced Structural Materials Greater Bay Joint DivisionShenyang National Laboratory for Materials ScienceCity University of Hong Kong Shenzhen Research InstituteShenzhen 518057China City U-Shenzhen Futian Research Institute Shenzhen 518045China

Refining grains into nanoscale can significantly strengthen and harden metallic materials;however,nanograined metals generally exhibit low thermal stability,hindering their practical *** this work,we exploit the superposition of the contribution of nanotwins,low-angle grain boundaries,and microalloying to tailor superior combinations of high hardness and good thermal stability in Ni and Ni *** the nanotwinned Ni having a twin thickness of∼2.9 nm and grain size of 28 nm,it exhibits a hardness over 8.0 GPa and an onset coarsening temperature of 623 K,both of which are well above those of nanograined ***/Mo microalloying can further improve the onset coarsening temperature to 773 K without comprising *** analyses reveal that high hardness is achieved via strengthen-ing offered by extremely fine ***,the superior thermal stability is mainly ascribed to the low driving force for grain growth induced by the low-angle columnar boundary architecture and to the additional pinning effect on the migration of twin/columnar boundaries provided by minor Re/Mo *** present work not only reveals a family of nanotwinned metals possessing the combination of ultra-high hardness and high thermal stability but also provides a strategy for tailoring properties of metallic materials by pairing low-angle grain boundaries and twin boundaries.

关键词： Nanotwin Thermal stability Hardness Low-angle grain boundary Microalloying

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Emotion Recognition Using Ultra-Short-Term ECG Signals with a Hybrid Convolutional Neural Network and Long Short-Term Memory Network 1

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Innovative Manufacturing, Mechatronics and materials Forum, iM3F 2022

作者： Chang, Vui Chee Ho, Jee-Hou Chan, Bee Ting Chai, Ai Bao Department of Mechanical Materials and Manufacturing Engineering Faculty of Science and Engineering University of Nottingham Malaysia Jalan Broga Selangor Semenyih43500 Malaysia

ISBN: (数字)9789811987038

ISBN: (纸本)9789811987021

This research aims to investigate emotion recognition using ultra-short-term electrocardiogram (ECG) signals with a hybrid convolutional neural network and long short-term memory (CNN-LSTM) network. DREAMER dataset consists of 23 subjects was used in this study. Raw data were recorded in the form of audio-visual stimuli during affect elicitation. ECG signals acquired from this dataset were pre-processed to filter noises. Single ECG cycle with one R-R peak interval was extracted using Pan–Tompkins algorithm and fed to the hybrid CNN-LSTM network. Another type of input in the form of decomposed ECG signals via empirical mode decomposition (EMD) was also investigated. The network was trained to classify high/low valence, arousal and dominance, respectively. Results show that hybrid CNN-LSTM network outperformed the basic CNN and LSTM network with classification accuracy ranges from 60 to 88% compared to 40.6% to 86.8% using basic configuration. Meanwhile, using EMD as the input achieved better recognition rates. © 2023, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.

关键词： Electrocardiograms

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General Optimal Trajectory Planning:Enabling Autonomous Vehicles with the Principle of Least Action

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engineering 2024年第2期33卷 63-76页

作者： Heye Huang Yicong Liu Jinxin Liu Qisong Yang Jianqiang Wang David Abbink Arkady Zgonnikov School of Vehicle and Mobility Tsinghua UniversityBeijing 100084China Department of Cognitive Robotics Faculty of MechanicalMaritime and Materials Engineering(3mE)Delft University of TechnologyDelft 2628Netherlands Department of Software Technology Faculty of Electrical EngineeringMathematics and Computer ScienceDelft University of TechnologyDelft 2628Netherlands Xi’an Institute of High-Technology Xi’an 710051China

This study presents a general optimal trajectory planning(GOTP)framework for autonomous vehicles(AVs)that can effectively avoid obstacles and guide AVs to complete driving tasks safely and ***,we employ the fifth-order Bezier curve to generate and smooth the reference path along the road *** coordinates are then transformed to achieve the curvature continuity of the generated *** the road constraints and vehicle dynamics,limited polynomial candidate trajectories are generated and smoothed in a curvilinear coordinate ***,in selecting the optimal trajectory,we develop a unified and auto-tune objective function based on the principle of least action by employing AVs to simulate drivers’behavior and summarizing their manipulation characteristics of“seeking benefits and avoiding losses.”Finally,by integrating the idea of receding-horizon optimization,the proposed framework is achieved by considering dynamic multi-performance objectives and selecting trajectories that satisfy feasibility,optimality,and *** simulations and experiments are performed,and the results demonstrate the framework’s feasibility and effectiveness,which avoids both dynamic and static obstacles and applies to various scenarios with multi-source interactive traffic ***,we prove that the proposed method can guarantee real-time planning and safety requirements compared to drivers’manipulation.

关键词： Autonomous vehicle Trajectory planning Multi-performance objectives Principle of least action

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Enhanced strength-ductility synergy via high dislocation density-induced strain hardening in nitrogen interstitial CrMnFeCoNi high-entropy alloy

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Journal of materials science & Technology 2023年第10期141卷 184-192页

作者： Huabing Li Yu Han Hao Feng Gang Zhou Zhouhua Jiang Minghui Cai Yizhuang Li Mingxin Huang School of Metallurgy Northeastern UniversityShenyang 110819China Shi-changxu Innovation Center for Advanced Materials Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China School of Materials Science and Engineering Northeastern UniversityShenyang 110819China Department of Mechanical Engineering The University of Hong KongPokfulam RoadHong Kong 999077China

The present work demonstrates that nitrogen doping inhibits the formation of deformation twins in a CrMnFeCoNi high entropy alloy,while significantly increases the strength without sacrificing much duc-tility at 77 *** characterization and first-principles calculations were employed to unveil the role of interstitial nitrogen atoms in obtaining such an excellent combination of strength and ductility at 77 *** is found that nitrogen addition increases generalized stacking fault energy(GSFE)and reduces ***,the pinning of dislocations by nitrogen atoms effectively suppresses dislocation cross-slip and dynamic recovery and in turn,promotes the accumulation of *** high dislocation density induces a high strain hardening capacity and improves uniform elongation,which compensates for the ductility loss accompanied by solid solution *** effect of nitrogen doping enriches the design concept of high-and medium-entropy alloys,providing an economical and effective strategy to develop ultra-high-performance alloys that are suitable for cryogenic applications.

关键词： High-entropy alloy Interstitials mechanical properties First-principles calculations Stacking fault energy

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Pressure-induced nano-crystallization and high hardness of optically transparentα-Si_(3)N_(4) ceramics

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science China(Physics,Mechanics & Astronomy) 2025年第5期68卷 183-191页

作者： Shuailing Ma Wei Li Xiaoqi Zhang Kathy Lu Min Lian Xinmiao Wei Yilong Pan Hai Jiang Hongwei Wang Zihan Zhang Qiang Tao Tian Cui Ralf Riedel Pinwen Zhu Institute of High-Pressure Physics School of Physical Scientific and TechnologyNingbo UniversityNingbo 315211China Synergetic Extreme Condition High-Pressure Science Center State Key Laboratory of Superhard MaterialsCollege of PhysicsJilin UniversityChangchun 130012China Department of Mechanical and Materials Engineering University of Alabama at BirminghamBirmingham AL 35294USA Department of Materials and Earth Sciences Technical University of DarmstadtDarmstadt 64287Germany

Transparent silicon nitride ceramics with good optical and mechanical properties are promising ceramics for scientific and industrial window materials with a long service *** optical transparency and mechanical strength will be substantially enhanced in dense nano-polycrystalline ***,the synthesis of nano-polycrystallineα-Si_(3)N_(4) has not been realized due to the limitations of conventional sintering ***,nano-polycrystallineα-Si_(3)N_(4) was prepared by direct conversion of micron-grain silicon nitride without additives under high-pressure conditions of 5 GPa and a limited temperature range 1650℃-1700℃.The micron-sized grains undergo grain refinement and recrystallization to form uniform nano-grains under high pressure and high ***,transparentα-Si_(3)N_(4) samples exhibit the highest Vickers hardness of 26.7 GPa,which is far higher than that of specimens with or without additives used in other sintering methods(e.g.,SPS,and HP).According to the Hall-Petch and Taylor dislocation hardening effects,the refined nano-grains,coherent grain boundaries,and high dislocation density lead to high ***,the high density,nanoscale grains,and fine grain boundaries are ascribed to the improvement of ***-pressure sintering induces grain refinement,grain coherency,and increased dislocation in silicon nitrides,thus providing a promising method for preparing advanced transparent ceramic windows in the future.

关键词： silicon nitride high pressure and high temperature transparent ceramics hardness

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MXene Enhanced 3D Needled Waste Denim Felt for High‑Performance Flexible Supercapacitors

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Nano-Micro Letters 2024年第2期16卷 383-394页

作者： Wei Fan Qi Wang Kai Rong Yang Shi Wanxi Peng Handong Li Zhanhu Guo Ben Bin Xu Hua Hou Hassan Algadi Shengbo Ge Key Laboratory of Functional Textile Material and Product of the Ministry of Education School of Textile Science and EngineeringInstitute of Flexible electronics and Intelligent TextileXi’an Polytechnic UniversityXi’an 710048People’s Republic of China Co‑Innovation Center of Efficient Processing and Utilization of Forest Resources College of Materials Science and EngineeringNanjing Forestry UniversityNanjing 210037People’s Republic of China Henan Province International Collaboration Lab of Forest Resources Utilization School of ForestryHenan Agricultural UniversityZhengzhou 450002People’s Republic of China Integrated Composites Lab Department of Mechanical and Construction EngineeringNorthumbria UniversityNewcastle Upon Tyne NE18STUK College of Materials Science and Engineering Taiyuan University of Science and TechnologyTaiyuan 030024People’s Republic of China Department of Electrical Engineering Faculty of EngineeringNajran University11001 NajranSaudi Arabia

MXene,a transition metal carbide/nitride,has been prominent as an ideal electrochemical active material for ***,the low MXene load limits its practical *** environmental concerns and sustainable development become more widely recognized,it is necessary to explore a greener and cleaner technology to recycle textile by-products such as *** present study proposes an effective 3D fabrication method that uses MXene to fabricate waste denim felt into ultralight and flexible supercapacitors through needling and *** 3D structure provided more sites for loading MXene onto Z-directional fiber bundles,resulting in more efficient ion exchange between the electrolyte and ***,the carbonization process removed the specific adverse groups in MXenes,further improving the specific capacitance,energy density,power density and electrical conductivity of *** electrodes achieve a maximum specific capacitance of 1748.5 mF cm-2 and demonstrate remarkable cycling stability maintaining more than 94%after 15,000 galvanostatic charge/discharge ***,the obtained supercapacitors present a maximum specific capacitance of 577.5 mF cm^(-2),energy density of 80.2μWh cm^(-2)and power density of 3 mW cm^(-2),*** resulting supercapacitors can be used to develop smart wearable power devices such as smartwatches,laying the foundation for a novel strategy of utilizing waste cotton in a high-quality manner.

关键词： MXene 3D needled waste denim felt Supercapacitors Carbonization

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Ultra-high strength yet superplasticity in a hetero-grain-sized nanocrystalline Au nanowire

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Journal of materials science & Technology 2022年第6期101卷 95-106页

作者： Libo Fu Deli Kong Chengpeng Yang Jiao Teng Yan Lu Yizhong Guo Guo Yang Xin Yan Pan Liu Mingwei Chen Ze Zhang Lihua Wang Xiaodong Han Beijing Key Lab of Microstructure and Properties of Advanced Materials Beijing University of TechnologyBeijing 100124China Department of Material Physics and Chemistry University of Science and Technology BeijingBeijing 100083China School of Mechanical Engineering and Automation Beihang UniversityBeijing 100191China School of Materials Science and Engineering Shanghai Jiao Tong UniversityShanghai 200240China Department of Materials Science and Engineering Johns Hopkins UniversityBaltimoreMD 21218United States School of Materials Science and Engineering Zhejiang UniversityHangzhou 310027China

Nanocrystalline metals often display a high strength up to the gigapascal level,yet they suffer from poor *** studies have shown that the development of hetero-sized grains can efficiently overcome the strength-ductility trade-off of nanocrystalline ***,whether this strategy can lead to the fabrication of nanocrystalline nanowires exhibiting both high strength and superplasticity is unclear,similar to the atomistic deformation *** this paper,we show that ultra-small nanocrystalline Au nanowires comprising grains in both the Hall–Petch and inverse Hall–Petch grain-size regions can exhibit extremely high uniform elongation(236%)and high strength(2.34 gigapascals)at room *** situ atomic-scale observations revealed that the plastic deformation underwent two *** the first stage,the super-elongation ability originated from the intergrain plasticity of small grains via mechanisms such as grain boundary migration and grain *** intergrain plasticity caused the grains in the heterogeneous-structured nanowires to grow very *** the second stage,the superelongation ability originated from intragrain plasticity accompanied by the diffusion of surface *** results show that the hetero-grain-sized nanocrystalline nanowires,comprising grains with sizes both in the strongest Hall–Petch effect region and the inverse Hall–Petch effect region,were simultaneously ultrastrong and *** displayed neither a strength-ductility trade-off nor plastic instability.

关键词： In situ mechanical property Metallic nanowires Transmission electron microscopy Plastic deformation

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VISION-iT:A Framework for Digitizing Bubbles and Droplets

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Energy and AI 2024年第1期15卷 26-35页

作者： Youngjoon Suh Sanghyeon Chang Peter Simadiris Tiffany B.Inouye Muhammad Jahidul Hoque Siavash Khodakarami Chirag Kharangate Nenad Miljkovic Yoonjin Won Department of Mechanical and Aerospace Engineering University of CaliforniaIrvine4200 Engineering GatewayCA 92617-2700USA Department of Electrical Engineering and Computer Science University of CaliforniaIrvine5200 Engineering HallCA 92617-2700USA Department of Mechanical Science and Engineering University of Illinois at Urbana-ChampaignUrbanaIL 61801USA Mechanical and Aerospace Engineering Department Case Western Reserve UniversityClevelandOH44106USA Department of Electrical and Computer Engineering University of Illinois at Urbana-ChampaignUrbanaIL61801USA Materials Research Laboratory University of Illinois at Urbana-ChampaignUrbanaIL61801USA International Institute for Carbon Neutral Energy Research(WPI-12CNER) Kyushu University744 Moto-okaNishi-kuFukuoka 819-0395Japan

Quantifying the nucleation processes involved in liquid-vapor phase-change phenomena,while dauntingly challenging,is central in designing energy conversion and thermal management *** technological advances in the deep learning and computer vision field offer the potential for quantifying such complex two-phase nucleation processes at unprecedented *** leveraging these new technologies,a multiple object tracking framework called“vision inspired online nuclei tracker(VISION-iT)”has been proposed to extract large-scale,physical features residing within boiling and condensation ***,extracting high-quality features that can be integrated with domain knowledge requires detailed discussions that may be field-or case-specific *** this regard,we present a demonstration and discussion of the detailed construction,algorithms,and optimization of individual modules to enable adaptation of the framework to custom *** concepts and procedures outlined in this study are transferable and can benefit broader audiences dealing with similar problems.

关键词： Deep learning Computer vision Nucleation Heat transfer Phase-change phenomena

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Clarification of the mechanism of hot tearing susceptibility reduction by Sr addition in Al-Mg-Mn-based die casting alloy using acoustic emission method

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Keikinzoku/Journal of Japan Institute of Light Metals 2023年第7期73卷 315-321页

作者： Tsuchiya, Ao Nagata, Yoshihiro Kumaki, Takumi Faiz, Muhammad Khairi Okimura, Yasuhiko Okane, Toshimitsu Yoshida, Makoto Modern Mechanical Engineering School of Creative Science and Engineering Waseda University 3-4-1 Okubo Shinjuku-ku Tokyo169-8555 Japan Creative Science and Engineering Waseda University Shinjuku-ku Tokyo Japan Department of Mechanical Engineering Faculty of Engineering Universiti Malaya Kuala Lumpur Malaysia Department of Manufacturing Technologies Faculty of Technologists Institute of Technology Gyoda-shi Saitama Japan Kagami Memorial Research Institute for Materials Science and Technology Waseda University Shinjuku-ku Tokyo Japan

In our previous study, Al-4.5Mg-1.0Mn based alloy with addition of both Si, Sr, Ti, B and hydrogen over 0.5 ml/100 gAl was developed with around 15% of fracture elongation and low hot tearing susceptibility (HTS). It was suggested that the mechanism of HTS reduction by the addition of Sr should be attributed to the decrease in the tensile thermal load due to the formation of hydrogen gas porosity at a relatively low solid fraction under the solidification shrinkage is constrained. In this study, we verified the above hypothesis by using acoustic emission (AE) method. The effect of the hydrogen content and Sr addition on AE signals were examined in the constrained castings during solidification. As a result, it was found that AE peak volts which indicates the occurrence of shrinkage and/or gas porosity were reduced under the condition with 1.0 ml/100 gAl hydrogen and Sr. By the addition of hydrogen, AE signals from non-constrained castings during solidification indicated that the formation of hydrogen gas porosity reduced the AE peak volts. These results revealed that the addition of 1.0 ml/100 gAl hydrogen and Sr reduces the AE peak volts due to the promotion of hydrogen gas porosity. Therefore, the hypothesis should be reasonable. © 2023 The Japan Institute of Light Metals.

关键词： Aluminum alloys

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