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MIcROSTRUcTURES AND PROPERTIES OF REcIPROcATINGLY EXTRUDED Mg-6.4Zn-1.1Y ALLOYS

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Acta Metallurgica Sinica(English Letters) 2008年第1期21卷 37-42页

作者： Z.M. Zhang c.j. xu X.F. Guo School of Materials Science ＆ Engineering Xi＇an University of Technology Xi＇an 710048 China

An icosahedral Mg3 YZn6 quasicrystalline phase can be produced in Mg-Zn- Y system alloys when a proper amount of Zn and Y is contained, and it is feasible to prepare the quasicrystal phase-reinforced low-density magnesium alloy. In this article, phase constituents and the effect of reciprocating extrusion on microstructures and properties of the as-cast Mg-6.4Zn-1.1 Y alloy are analyzed. The microstructure of the as-cast Mg-6.4Zn-1.1 Y alloy consists of the α-Mg solid solution, icosahedral Mg3YZn6 quasicrystal, and Mg3 Y2Zn3 and MgZn2 compounds. After the alloy was reciprocatingly extruded for four passes, grains were refined, Mg3 Y2 Zn3 and MgZn2 phases dissolved into the matrix, whereas, Mg3 YZn6 precipitated and distributed uniformly. The alloy possesses the best performance at this state; the tensile strength, yield strength, and elongation are 323.4 MPa, 258.2 MPa, and 19.7%, respectively. In comparison with that of the as-cast alloy, the tensile strength, yield strength, and elongation of the reciprocatingly extruded alloy increase by 258.3%, 397.5%, and 18 times, respectively. It is concluded that reciprocating extrusion can substantially improve the properties of the as-cast Mg-6.4Zn-1.1 Y alloy, particularly for elongation. The high performance of the Mg-6.4Zn-1.1 Y alloy after reciprocating extrusion can be attributed to dispersion strengthening and grain-refined microstructures.

关键词： Reciprocating extrusion Mg-Zn- Y alloy Icosahedral quasicrystal

DAMPING BEHAVIOR OF ULTRAFINE-GRAINED PURE ALUMINUM L2 AND THE DAMPING MEcHANISM

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Acta Metallurgica Sinica(English Letters) 2006年第3期19卷 223-227页

作者： Z.M. Zhang c.j. xu j.c. Wang H.Z. Liu School of Materials Science ＆ Engineering Xi＇an University of Technology Xi＇an 710048 Ghina State Key Laboratory of Solidification Processing Northwestern Polytechnical University Xi＇an 710072 Ghina

Ultrafine-grained pure aluminum L2 with a mean grain size of 1.01μm was produced by equal channel angular pressing （EcAP） and annealing at 150℃ for 2h. Damping behavior of the alloy was measured using a dynamic mechanical thermal analyzer. The alloy had an excellent damping capacity Q^-1 with the ambient value being 9.8×10^-3 at 1.0Hz when the strain amplitude was 2.0×10^-5. The damping behavior of the alloy showed a non-linear damping variation tendency, that is, with an increase in temperature and a decrease of frequency, the damping capacity of the alloy increased. The damping capacity increased with the strain amplitude when the strain amplitude was less than 4.6×10^-5. When the strain amplitude was higher than 4.6×10^-5, the damping capacity became a constant and independent of strain amplitude. The high damping capacity was attributed to dislocation unpinning and a drag of dislocation on pinning points.

关键词： EcAP ultrafine grain damping capacity aluminum alloy

MIcROSTRUcTURE OF BINARY Mg-Al EUTEcTIc ALLOY WIRES PRODUcED BY THE OHNO cONTINUOUS cASTING PROcESS

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Acta Metallurgica Sinica(English Letters) 2008年第4期21卷 275-281页

作者： Z.M. Zhang T. Lü c.j. xu X.F. Guo School of Materials Science ＆ Engineering Xi＇an University of Technology Xi＇an 710048 China

Directionally solidified binary Mg-Al eutectic alloy wires of approximately 5 mm in diameter were produced by the Ohno continuous casting （Occ） process and the microstructure was examined. It was found that the wires possess obvious unidirectional growth characteristic along its axial direction. The microstructure consists of parallel columnar grains that resulted from the competitive growth of equiaxed grains solidified on the head of dummy bar. Each columnar grain comprises regular eutectic a-Mg and β-Mg17 Al12 phases, which grew along the axial direction of the wires. The morphology of the eutectic is mainly lamellar, meanwhile rod eutectic exists. The formation of rod eutectic was attributed to the ＂bridging effect＂ caused by incidental elements in the alloy.

关键词： Mg-Al alloy Eutectic structure Directional solidification Occ process

REcIPROcATING EXTRUSION OF IN SITU Mg_2Si REINFORcED Mg-Al BASED cOMPOSITE

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Acta Metallurgica Sinica(English Letters) 2008年第3期21卷 169-177页

作者： Z.M. Zhang c.j. xu X.F. Guo S.Z. jia School of Materials Science ＆ Engineering Xi＇an University of Technology Xi＇an 710048 China

M92Si reinforced Mg-Al based composite with high amount o/silicon was prepared by permanent mould casting, and then extruded by reciprocating extrusion （RE） after the composite was processed by homogenization heat treatment. The effect of RE processing on the morphology and size of M92Si and the mechanical properties of the com- posite were investigated, to develop new ways to refine the M928i phase and improve its shape. The result showed that RE was very useful in refining the M92Si phase. The more the RE processing passes, the better the refining effect would be. Moreover, the uniform distribution of M928i phases would be more in the composite. After the composite was processed by RE for 12 passes, most M92Si phases were equiaxed, with granular diameter below 20 μm, and distributed uniformly in the matrix of the composite. The mechanical properties of the composite could be increased prominently by RE processing, and were much higher than that in the as-cast state. As the temperature rises, the tensile strength is reduced. For the composite RE processed for 12 passes, the tensile strength, yield strength, and elongation are 325.9 MPa, 211.4 MPa, and 3.3% at room temperature, whereas, 288.2 MPa, ,207.7 MPa, and 7.8%, respectively, at 150℃. In comparison with the properties at room temperature, the tensile strength and yield strength are high and only decrease by 11.6% and 1.8% at 150℃. The M928i reinforced Mg-Al based composite possesses good heat resistance at 150℃. The excellent resistance to effect of heat is attributed to the high melting tempera- ture and good thermal stability of fine Mg2Si phases, which are distributed uniformly in the composite, and effectively hinder the grain boundary gliding and dislocation movement.

关键词： Reciprocating extrusion Magnesium alloy In situ composite Elevated temperature property

Recent advances on bismuth oxyhalides for photocatalytic cO_(2)reduction

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journal of Environmental Sciences 2024年第6期140卷 183-203页

作者： Liangpang xu jimmy c.Yu Ying Wang Department of chemistry The Chinese University of Hong KongShatinNew TerritoriesHong Kong 999077China

Photocatalytic conversion of cO_(2)into fuels such as cO,cH_(4),and cH_(3)OH,is a promising approach for achieving carbon *** oxyhalides(BiOX,where X=cl,Br,and I)are appropriate photocatalysts for this purpose due to the merits of visible-light-active,efficient charge separation,and easy-to-modify crystal structure and surface *** practical applications,multiple strategies have been proposed to develop high-efficiency BiOX-based *** review summarizes the development of different approaches to prepare BiOX-based photocatalysts for efficient cO_(2)*** the review,the fundamentals of photocatalytic cO_(2)reduction are ***,several widely used modification methods for BiOX photocatalysts are systematacially discussed,including heterojunction construction,introducing oxygen vacancies(OVs),Bi-enrichment,heteroatom-doping,and morphology ***,the challenges and prospects in the design of future BiOX-based photocatalysis for efficient cO_(2)reduction are examined.

关键词： Bismuth oxyhalides Photocatalysis cO_(2)reduction Modification methods

A Sharding Scheme Based on Graph Partitioning Algorithm for Public Blockchain

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computer Modeling in Engineering & Sciences 2024年第6期139卷 3311-3327页

作者： Shujiang xu Ziye Wang Lianhai Wang Miodrag j.Mihaljevi′c Shuhui Zhang Wei Shao Qizheng Wang Key Laboratory of computing Power Network and Information Security Ministry of EducationShandong Computer Science CenterQilu University of Technology(Shandong Academy of Sciences)Jinan250014China Shandong Provincial Key Laboratory of computer Networks Shandong Fundamental Research Center for Computer ScienceJinan250014China Mathematical Institute The Serbian Academy of Sciences and ArtsBelgrade11000Serbia

Blockchain technology,with its attributes of decentralization,immutability,and traceability,has emerged as a powerful catalyst for enhancing traditional industries in terms of optimizing business ***,transaction performance and scalability has become the main challenges hindering the widespread adoption of *** to its inability to meet the demands of high-frequency trading,blockchain cannot be adopted in many *** improve the transaction capacity,researchers have proposed some on-chain scaling technologies,including lightning networks,directed acyclic graph technology,state channels,and shardingmechanisms,inwhich sharding emerges as a potential scaling ***,excessive cross-shard transactions and uneven shard workloads prevent the sharding mechanism from achieving the expected *** paper proposes a graphbased sharding scheme for public blockchain to efficiently balance the transaction *** crossshard transactions and evening-out workloads among shards,the scheme reduces transaction confirmation latency and enhances the transaction capacity of the ***,the scheme can achieve a high-frequency transaction as well as a better blockchain *** results show that the scheme effectively reduces the cross-shard transaction ratio to a range of 35%-56%and significantly decreases the transaction confirmation latency to 6 s in a blockchain with no more than 25 shards.

关键词： Blockchain sharding graph partitioning algorithm

Dissociation cross sections ofψ(3770),ψ(4040),ψ(4160),andψ(4415)mesons with nucleons

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communications in Theoretical Physics 2024年第4期76卷 93-112页

作者： Ruo-Qing Ding Xiao-Ming xu H j Weber Department of Physics Shanghai UniversityBaoshanShanghai 200444China Department of Physics University of VirginiaCharlottesvilleVA 22904United States of America

We study the dissociation of ψ(3770), ψ(4040), ψ(4160), and ψ(4415) mesons in collision with nucleons, which takes place in high-energy proton-nucleus collisions. The quark interchange between a nucleon and a ■ meson leads to the dissociation of the ■ meson. We consider the reactions:■, and■, where R stands for ψ(3770), ψ(4040), ψ(4160), or ψ(4415). A reaction of a neutron and a ■ meson corresponds to a reaction of a proton and the ■ meson by replacing the up quark with the down quark and vice versa. Transition-amplitude formulas are derived from the S-matrix *** cross sections are calculated with the transition amplitudes for scattering in the prior form and in the post form. The cross sections relate to nodes in the radial wave functions of ψ(3770), ψ(4040), ψ(4160), and ψ(4415) mesons.

关键词： inelastic nucleon-charmonium scattering quark interchange relativistic constituent quark potential model

Error field penetration in j-TEXT tokamak based on two-fluid drift-MHD model

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chinese Physics B 2024年第4期33卷 545-551页

作者：王文徐涛张仪 the j-TEXT team State Key Laboratory of Advanced Electromagnetic Technology International Joint Research Laboratory of Magnetic Confinement Fusion and Plasma PhysicsSchool of Electrical and Electronic EngineeringHuazhong University of Science and TechnologyWuhan 430074China

An externally generated resonant magnetic perturbation can induce complex non-ideal MHD responses in their resonant *** have studied the plasma responses using Fitzpatrick's improved two-fluid model and program *** calculated the error field penetration threshold for *** addition,we find that the island width increases slightly as the error field amplitude increases when the error field amplitude is below the critical penetration ***,the island width suddenly jumps to a large value because the shielding effect of the plasma against the error field disappears after the *** scanning the natural mode frequency,we find that the shielding effect of the plasma decreases as the natural mode frequency ***,we obtain the m/n=2/1 penetration threshold scaling on density and temperature.

关键词： plasma responses drift-MHD model error field penetration

Biochar-based materials as remediation strategy in petroleum hydrocarbon-contaminated soil and water:Performances,mechanisms,and environmental impact

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journal of Environmental Sciences 2024年第4期138卷 350-372页

作者： Zhuo Wei YiWei Yang Liu Shuai Niu Yaxi xu jong-Hwan Park jim j.Wang Faculty of Environmental Science&Engineering Kunming University of Science&TechnologyKunming 650500China School of Plant Environment&Soil SciencesLouisiana State University AgCenter.Baton RougeLA 70803USA Department of Life Resources Industry Dong-A University37Nakdong-daero 550 beon-gilSaha-guBusan 49315South Korea

Petroleum contamination is considered as a major risk to the health of humans and *** as low-cost and eco-friendly carbon materials,have been widely used for the removal of petroleum hydrocarbon in the *** purpose of this paper is to review the performance,mechanisms,and potential environmental toxicity of biochar,modified biochar and its integration use with other materials in petroleum contaminated soil and ***,the use of biochar in oil-contaminated water and soil as well as the factors that could influence the removal ability of biochar were systematically *** addition,the modification and integrated use of biochar for improving the removal efficiency were summarized from the aspects of sorption,biodegradation,chemical degradation,and ***,the functional impacts and associated ecotoxicity of pristine and modified biochars in various environments were ***,some shortcoming of current approaches,and future research needs were provided for the future direction and challenges of modified biochar ***,this paper gain insight into biochar application in petroleum remediation from the perspectives of performance enhancement and environmental sustainability.

关键词： Petroleum contamination Adsorbent Bioremediation Biochar modification Ecotoxicity