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A First-principles Study on the Adhesion Strength,Interfacial Stability,and Electronic Properties of Mg/Mg_(2)Y Interface

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Acta Metallurgica Sinica(English Letters) 2024年第3期37卷 537-550页

作者： Yunxuan Zhou Wenjun Tian Quan Dong Hailian Wang Jun Tan xianhua chen Kaihong Zheng Fusheng Pan College of Materials Science and Engineering National Engineering Research Center for Magnesium AlloysChongqing UniversityChongqing 400044China State Key Laboratory of Mechanical Transmission Chongqing UniversityChongqing 400044China Institute of New Materials Guangdong Academy of SciencesGuangzhou 510650China

The interfacial microstructures and configurations directly affect the comprehensive properties of the composites,but their interfacial adhesion mechanism is complicated to expound by experimental methods.In this work,based on the stacking sequence of the Mg/Mg_(2)Y interface models,nine different Mg/Mg_(2)Y interface configurations with top site,bridge site,and hollow site(HCP)under Mg1,Mg_(2),and Y terminations were successfully constructed and systematically explored by first-principles calculations.The results showed that the Mg_(2)Y(0001)surface with Y termination is the most stable when the yttrium chemical potential()is less than-1.09 eV;otherwise,Mg_(2)Y(0001)surface with Mg1 termination is the most stable.The seven-layer Mg(0001)and eleven-layer Mg_(2)Y(0001)slabs are employed to reflect the bulk-like interior properties.Additionally,the Mg(0001)/Mg_(2)Y(0001)with the Y-HCP stacking has the largest interface thermodynamic stability with the value of 2.383 J/m^(2) in all interface configurations owing to its largest work of adhesion.In addition,the interfacial energy of Y-HCP stacking is significantly smaller than those of Mg1-HCP when is approximately less than-0.55 eV,showing that it is more stable.The thermodynamic stability of Mg/Mg_(2)Y with Y-HCP is due to Mg-Y chemical bonds formed between Mg and Y atoms.Lastly,the Mg/Mg_(2)Y interfaces are strong interfaces based on the Griffith fracture theory.

关键词： Mg/Mg_(2)Y interface Interface stability Work of adhesion Electronic structure First-principles calculations

Interfacial Reaction of Ti6Al4V Lattice Structure-Reinforced VW92 Alloy Matrix Composites

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Acta Metallurgica Sinica(English Letters) 2024年第3期37卷 570-576页

作者： Haijun Wang Renju cheng xianhua chen Mingbo Yang Daiyi Deng Lirui Liu Yongfeng Zhou Yanlong Ma Kaihong Zheng Fusheng Pan College of Materials Science and Engineering Chongqing University of TechnologyChongqing 400054China College of Materials Science and Engineering Chongqing UniversityChongqing 400044China Institute of New Materials Guangdong Academy of SciencesGuangzhou 510650China

A novel melting infiltration by ultrasonic vibration was investigated and applied to fabricate Ti6Al4V(TC4)lattice structure-reinforced Mg-10Gd-2Y-1Zn-xZr(refer to VW92 hereafter,x=0,0.5 wt%)alloy matrix composites.The edge-to-edge matching model indicates that the well-matching and possible orientation relationships(ORs)between theα-Mg andα-Ti,[10-10]_(α-Mg)//[11-23]_(α-Ti) in(0002)_(α-Mg)//(10-10)_(α-Ti) possesses the smallest misfit of 0.4%(f_(r)),and thus theα-Mg grains can nucleate on the TC4 lattice structure.Interfacial reaction occurred in the TC4/VW92+0.5 wt%Zr composites,and the reaction product was confirmed to be Al_(2)Zr_(3),AlZr_(2) andα-Ti(Zr)particles formed by continuous solution of Zr-Ti.Among the interfacial products,the AlZr_(2) phase is a brittle phase with high-volume fraction,which is not conducive to the load transfer.But generally speaking,theα-Ti(Zr)and theα-Mg tend to form a coherent interface,which is beneficial for improving the interfacial bonding strength of composites.

关键词： TC4 VW92 composites TC4 lattice structure Interfacial reaction Mismatch

Aging Behavior of As-Extruded Ti Particles Reinforced VW94 Composites

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Acta Metallurgica Sinica(English Letters) 2024年第3期37卷 401-406页

作者： Dongmei Pu xianhua chen Jingfeng Wang Jun Tan Jianbo Li Hong Yang Bo Feng Kaihong Zheng Fusheng Pan College of Materials Science and Engineering Chongqing UniversityChongqing 400045China National Engineering Research Center for Magnesium Alloys Chongqing UniversityChongqing 400045China Institute of New Materials Guangdong Academy of SciencesGuangzhou 510650China

The ageing behavior of as-extruded Ti_(P)/VW94 composites was investigated.The peak hardness of the composites increases compared to the matrix alloy and the 5%Ti_(P)/VW94 composite presents the highest peak hardness of 148.7 HV after aging for about 50 h.However,the hardness increments first decrease and then slightly increase with increasing Ti particle content due to the introduction of high-density dislocations by Ti particles.

关键词： Magnesium matrix composites Ti particles Ageing behavior Hardness

Achieving Excellent Electromagnetic Interference Shielding Effectiveness in High Rare Earth Mg-12Gd-3Y alloy via Nd Addition Combined with Hot Rolling and Aging

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Acta Metallurgica Sinica(English Letters) 2023年第10期36卷 1665-1679页

作者： Wenlong Xu Chang Su Yuan Yuan Jingying Bai xianhua chen College of Materials Science&Engineering Chongqing UniversityChongqing400045China National Engineering Research Center for Mg Alloys Chongqing UniversityChongqing400045China Beijing Spacecrafts China Academy of Space TechnologyBeijing100194China

Achieving excellent electromagnetic interference(EMI)shielding effectiveness(SE)in high rare earth(RE)-content Mg alloys is currently a significant technical challenge.This work systematically investigated the effects of different Nd elements on the electrical conductivity and EMI SE of Mg-12Gd-3Y-xNd alloy by adding Nd elements to the high RE content Mg-12Gd-3Y alloy,followed by a combined process of hot rolling and aging(R-A).The results indicate that the addition of Nd elements leads to reduced solid solubility of Gd and Y,resulting in a large amount of precipitation.The Mg-12Gd-3Y-2.0Nd alloy has the optimum EMI SE after 63%R-A treatment,reaching 88-118 dB at 30-1500 MHz.The Mg-12Gd-3Y-xNd alloy has acicular and granular forms of the Mg5(Gd,Y,Nd)(abbreviated as Mg5RE)phase after R-A treatment.The granular Mg5RE phase gradually breaks up and refines into more minor scales with increasing rolling reduction and is diffusely distributed in the matrix.The acicular Mg5RE phase is densely arranged,with cross-distribution in some areas.The cross-distributed acicular Mg5RE phase,the delicate granular Mg5RE phase,and the denseβ′phase provide more interfaces for reflecting electromagnetic waves and increase the multiple reflection loss of incident electromagnetic waves.In addition,the Mg-12Gd-3Y-xNd alloy deflects most of the c-axis of the grains parallel to the normal direction(ND)as the rolling reduction increases,making the impedance difference between the plate surface and air larger.The increased impedance makes the material reflect more loss to incident electromagnetic waves.The combined use of these two leads to an excellent EMI SE of Mg-12Gd-3Y-xNd with high RE content after R-A treatment.

关键词： Mg-Gd-Y-Nd alloy Acicular phase Granular phase Electrical conductivity Electromagnetic interference shielding effectiveness

Aging properties and aging mechanism of activated waste rubber powder modified asphalt binder based on rheological properties and micro-characterization

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Frontiers of Structural and Civil Engineering 2023年第4期17卷 625-636页

作者： Peipei KONG Gang XU Liuxu FU xianhua chen Wei WEI School of Transportation Southeast UniversityNanjing 211189China School of Chemistry and Chemical Engineering Southeast UniversityNanjing 211189China

The research and development of high-performance pavement materials has been intensified owing to the demand for long-life pavements.This study is performed to develop a novel pavement material using waste rubber powder,waste lubricating by-product(LBP),and asphalt.Subsequently,the aging properties and aging mechanism of activated waste rubber powder modified asphalt(ARMA)are investigated based on its rheological properties and microcharacterization.The rheological results show that,compared with waste rubber powder modified asphalt(RMA),ARMA offers a higher aging resistance and a longer fatigue life.A comparison and analysis of the rheological aging parameters of ARMA and RMA show that LBP activation diminishes the aging sensitivity of ARMA.The microcharacterization result shows that the aging of ARMA may be caused by the fact that LBP-activated waste rubber powder is more reactive and can form a dense colloidal structure with asphalt.Therefore,the evaporation loss of asphalt light components by heat and the damage to the colloidal structure by oxygen during the aging process are impeded,and the thermal-oxidative aging resistance of ARMA is improved.

关键词： rubber powder modified asphalt aging mechanism rheological characterization

Multi-Branch High-Dimensional Guided Transformer-Based 3D Human Posture Estimation

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Computers, Materials & Continua 2024年第3期78卷 3551-3564页

作者： xianhua Li Haohao Yu Shuoyu Tian Fengtao Lin Usama Masood School of Mechanical Engineering Anhui University of TechnologyHuainan232001China School of Artificial Intelligence Anhui University of TechnologyHuainan232001China Key Laboratory of Conveyance Equipment(East China Jiaotong University) Ministry of EducationNanchang330013China

The human pose paradigm is estimated using a transformer-based multi-branch multidimensional directed the three-dimensional(3D)method that takes into account self-occlusion,badly posedness,and a lack of depth data in the per-frame 3D posture estimation from two-dimensional(2D)mapping to 3D mapping.Firstly,by examining the relationship between the movements of different bones in the human body,four virtual skeletons are proposed to enhance the cyclic constraints of limb joints.Then,multiple parameters describing the skeleton are fused and projected into a high-dimensional space.Utilizing a multi-branch network,motion features between bones and overall motion features are extracted to mitigate the drift error in the estimation results.Furthermore,the estimated relative depth is projected into 3D space,and the error is calculated against real 3D data,forming a loss function along with the relative depth error.This article adopts the average joint pixel error as the primary performance metric.Compared to the benchmark approach,the estimation findings indicate an increase in average precision of 1.8 mm within the Human3.6M sample.

关键词： Key point detection 3D human posture estimation computer vision deep learning

Proactive Caching at the Wireless Edge:A Novel Predictive User Popularity-Aware Approach

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Computer Modeling in Engineering & Sciences 2024年第8期140卷 1997-2017页

作者： Yunye Wan Peng chen Yunni Xia Yong Ma Dongge Zhu Xu Wang Hui Liu Weiling Li xianhua Niu Lei Xu Yumin Dong College of Computer Science Chongqing UniversityChongqing400044China School of Computer and Software Engineering Xihua UniversityChengdu610039China School of Computer and Information Engineering Jiangxi Normal UniversityNanchang330022China Electric Power Research Institute of State Grid Ningxia Electric Power Co. Ltd.Yinchuan750002China College of Mechanical and Vehicle Engineering Chongqing UniversityChongqing400030China School of Computer Science and Technology Beijing Institute of TechnologyBeijing100083China School of Computer Science and Technology Dongguan University of TechnologyDongguan523808China School of Emergency Management Xihua UniversityChengdu610039China College of Computer and Information Science Chongqing Normal UniversityChongqing401331China

Mobile Edge Computing(MEC)is a promising technology that provides on-demand computing and efficient storage services as close to end users as possible.In an MEC environment,servers are deployed closer to mobile terminals to exploit storage infrastructure,improve content delivery efficiency,and enhance user experience.However,due to the limited capacity of edge servers,it remains a significant challenge to meet the changing,time-varying,and customized needs for highly diversified content of users.Recently,techniques for caching content at the edge are becoming popular for addressing the above challenges.It is capable of filling the communication gap between the users and content providers while relieving pressure on remote cloud servers.However,existing static caching strategies are still inefficient in handling the dynamics of the time-varying popularity of content and meeting users’demands for highly diversified entity data.To address this challenge,we introduce a novel method for content caching over MEC,i.e.,PRIME.It synthesizes a content popularity prediction model,which takes users’stay time and their request traces as inputs,and a deep reinforcement learning model for yielding dynamic caching schedules.Experimental results demonstrate that PRIME,when tested upon the MovieLens 1M dataset for user request patterns and the Shanghai Telecom dataset for user mobility,outperforms its peers in terms of cache hit rates,transmission latency,and system cost.

关键词： Mobile edge computing content caching system average cost deep reinforcement learning collaborative mechanism

Effect of Zn on mechanical and corrosion properties of Mg-Sc-Zn alloys

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Journal of Materials Science & Technology 2023年第27期158卷 31-42页

作者： Wenjun Ci xianhua chen Yue Sun Xu Dai Guanzheng Zhu Di Zhao Fusheng Pan International Joint Laboratory for Light Alloys(MOE) College of Materials Science and EngineeringChongqing UniversityChongqing 400045China National Engineering Research Center for Magnesium Alloys Chongqing UniversityChongqing 400045China State Key Laboratory of Power Transmission Equipment&System Security and New Technology Chongqing UniversityChongqing 400044China School of Mechanical Engineering Suzhou University of Science and TechnologySuzhou 215009China

The effect of different Zn concentrations(0 wt.%,1 wt.%,3 wt.%,and 6 wt.%)on the microstructure,cor-rosion property,and mechanical property of Mg-0.3Sc-x Zn(x=0 wt.%,1 wt.%,3 wt.%,and 6 wt.%)alloys was investigated.Here,MSZ1 alloy exhibits the highest corrosion resistance(0.194 mm/y)and appropriate mechanical properties with an ultimate tensile strength of 228 MPa and elongation of 19%.The superior corrosion resistance of Mg-0.3Sc-1Zn alloys is attributed to the homogeneous volta-potential distribution and the dense corrosion product film.With the increase in zinc content,the strength and plasticity of Mg-0.3Sc-x Zn alloys(x=0 wt.%,1 wt.%,3 wt.%,6 wt.%)improved to some extent.The precipitated ScZn phase plays the role of the second phase strengthening,which enables MSZ6 to obtain the maximum tensile strength.However,the ScZn phase with low volta potential intensifies the galvanic corrosion,re-sulting in the decline of the corrosion performance.

关键词： High corrosion resistance Mechanical performance Mg-Sc-Zn alloys SKPFM Corrosion product film

Annealing hardening effect aroused by solute segregation in gradient ultrafine-grained Mg-Gd-Zr alloy

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Journal of Materials Science & Technology 2023年第13期144卷 70-80页

作者： Chunquan Liu xianhua chen Domonkos Tolnai Yaobo Hu Wei Zhang Yusheng Zhang Fusheng Pan College of Materials Science and Engineering Chongqing UniversityChongqing 400045China National Engineering Research Centre for Magnesium Alloys Chongqing UniversityChongqing 400045China Institute of Metallic Biomaterials Helmholtz-Zentrum HereonMax-Planck Street 1Geesthacht 21502Germany Northwest Institute for Nonferrous Metal Research Xi’an 710016China

In this study,a remarkable annealing hardening effect was detected in gradient ultrafine-grained(UFG)Mg-0.32Gd-0.11Zr(at.%)alloy sheet fabricated by sliding friction treatment(SFT).Under the precipitation-free condition,the annealed UFG structure shows an obvious hardness increment from 1.40 GPa to 1.89 GPa after 200℃ heating for 12 h,which exhibits a much higher hardening response than the annealed coarse-grained(CG)structure.The high-angle annular dark-field scanning transmission elec-tron microscopy(HAADF-STEM)and elemental mapping reveal prominent segregation of solute Gd atoms along grain boundaries,which endows the UFG structure with excellent grain boundary stability.More-over,Gd segregation is also found around the extrinsic stacking fault(E-SFs)and the low-angle grain boundaries composed of edge dislocations.The large-scale solute partitioning provides a significant seg-regation hardening effect,which completely resists the softening effect aroused by the grain coarsening and dislocation annihilation.This work realizes a good combination of surface mechanical processing for fabricating UFGs and subsequent heat treatment,which earns desirable segregation hardening effects.

关键词： Ultrafine grains Segregation Annealing hardening