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Towards the diffusion source cost reduction for NdfeB grain boundary.diffusion process

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journal of Materials Science & Technology 2020年第1期36卷 50-54页

作者： H.x.Zeng Z.W.Liu j.S.Zhang x.f.Liao H.y.y. School of Materials Science and Engineering South China University of TechnologyGuangzhou 510640China

Aiming at improving the performance/cost ratio in grain boundary.diffusion process(GBDP),the critical RE containing Pr-Al-Cu alloy.less expensive RE containing La-Al-Cu alloy.and non-RE Al-Cu alloy.were employ.d as the diffusion *** preliminary.results show that the coercivity.was successfully.enhanced from 1000 k./m to 1695,1156 and 1125 k./m by.Pr70Al20Cu10,La70Al20Cu10 and Al75Cu25(at.%) alloy. diffusion,respectively.due to the formation of(Nd,Pr)-fe-B,La2 O3 and c-Nd2 O3 phases respectively.after *** is also found that the corrosion resistance can be improved by.Al-Cu diffusion due to the positive effects of Al and Cu elements in grain *** present results demonstrated the various coercivity.enhancement mechanisms for the GBDP based on different diffusion sources,and provided feasible solutions for cost reduction of GBDP and NdfeB production by.saving RE resource.

关键词： Grain boundary diffusion Cost reduction Coercivity Microstructure Corrosion resistance

Variational Corner Transfer Matrix Renormalization Group Method for Classical Statistical Models

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Chinese Phy.ics Letters 2022年第6期39卷 65-70页

作者： x.f.Liu y.f.fu W.Q.y. j.f.y. Z.y.xie Department of Phy.ics Renmin University of ChinaBeijing 100872China School of Phy.ics and Electronics Hunan UniversityChangsha 410082China

In the context of tensor network.states,we for the first time reformulate the corner transfer matrix renormalization group(CTMRG)method into a variational bilevel optimization *** solution of the optimization problem corresponds to the fixed-point environment pursued in the conventional CTMRG method,from which the partition function of a classical statistical model,represented by.an infinite tensor network.can be efficiently.*** validity.of this variational idea is demonstrated by.the high-precision calculation of the residual entropy.of the dimer model,and is further verified by.investigating several ty.ical phase transitions in classical spin models,where the obtained critical points and critical exponents all agree with the best k.own results in *** extension to three-dimensional tensor network. or quantum lattice models is straightforward,as also discussed briefly.

关键词： tensor variational straight

Unusually.high corrosion resistance in Mo_(x)CrNiCo medium entropy.alloy.enhanced by.acidity.in aqueous solution

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journal of Materials Science & Technology 2023年第8期139卷 59-68页

作者： S.Shuang G.j.Ly. D.Chung x.Z.Wang x.Gao H.H.Mao W.P.Li Q.f.He B.S.guo x.y.Zhong y.j.Wang y.y.ng Department of Mechanical Engineering College of EngineeringCity University of Hong KongKowloon TongKowloonHong KongChina State k.y.Laboratory.of Nonlinear Mechanics Institute of MechanicsChinese Academy of SciencesBeijing 100190China School of Engineering Science University of Chinese Academy of SciencesBeijing 101408China State k.y.Laboratory.of Solidification Processing Center of Advanced Lubrication and Seal MaterialsNorthwestern Polytechnical UniversityXi’an 710072China Unit of Structures Department of Materials Science and EngineeringKTHStockholm SE-10044Sweden Thermo-Calc Software Råsundav.18SolnaSE-16767Sweden Department of Materials Science and Engineering College of EngineeringCity University of Hong KongKowloon TongKowloonHong KongChina Institute of Advanced Wear&Corrosion Resistant and functional Materials Jinan UniversityGuangzhou 510632China Department of Advanced Design and Sy.tem Engineering College of EngineeringCity University of Hong KongKowloon TongKowloonHong KongChina

High corrosion resistance of alloy. is essential for their structural applications;however,most alloy. suffer from degradation of their corrosion resistance with the increasing acidity.of their ***,we developed a series of medium-entropy.alloy.(MEAs)in this work.which ex-hibit high strength,superior fracture toughness and ultra-high corrosion resistance,outperforming the variety.of corrosion resistant alloy. hitherto *** interestingly.our MEAs exhibit an unusual anti-corrosion behavior and their corrosion resistance increases with acidity.in Cl−containing *** extensive thermody.amic calculations,density.functional theory.DfT)simulations and experi-ments,we reveal that the unusual anti-corrosion behavior of our MEAs can be attributed to their surface chemical complexity.which facilitates the phy.io-chemical-absorption of H_(2)O and O_(2)and thus the rapid formation of metastable medium entropy.passive films that contain the lowest amount of defects,as compared to the passive films on conventional alloy. reported in the literature.

关键词： Corrosion Passivation Alloy.design Multi-principal element alloy. Medium-entropy.alloy.

The characterization of fe-rich phases in a high-pressure die cast hy.oeutectic aluminum-silicon alloy

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journal of Materials Science & Technology 2020年第16期47卷 54-62页

作者： x.y.jiao C.f.Liu Z.P.guo G.D.Tong S.L.Ma y.Bi y.f.Zhang S.M.xiong School of Materials Science and Engineering Tsinghua UniversityBeijing 100084China k.y.Laboratory.for Advanced Materials Processing Technology Tsinghua UniversityBeijing 100084China China fAW foundary.Co. LTDChangchun 130011China

Both microstructural characteristics and fracture behavior of fe-rich phases in a high-pressure die-cast hy.oeutectic Al-Si alloy.were *** was focused on the morphology.and formation mechanism of fe-rich phases,together with their influence on *** show that primary.ferich phases exhibited in block.0}shape precipitated from liquid while secondary.fe-rich phase in a large net shape was distributed along eutectic boundary.participating in a ternary.eutectic *** sy.chrotron x-ray.tomography.characterization,three fe-rich phases with different morphologies,i.e.,poly.edral shape,fine compact shape and Chinese script-ty.e shape were extracted along the radial *** slow-shot speed promoted the poly.edral fe-rich phase to precipitate in slow-shot sleeve while decreased the formation of fine compact and Chinese script-ty.e fe-rich phases in die *** of a worse deformation compatibility.poly.edral fe-rich phases fractured and became stress concentration sources before the failure of the casting.

关键词： Hy.oeutectic Al-10Si fe-rich phases fracture morphology High pressure die casting

fRICTION PROPERTIES Of OIL-INfILTRATED POROUS AAO fILM ON AN ALUMINUM SUBSTRATE

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Acta Metallurgica Sinica(English Letters) 2005年第3期18卷 249-253页

作者： C.x.jiang j.P.Tu S.y.guo M.f.fu x.B.Zhao DepartmentofMaterialsScienceandEngineering ZhejiangUniversityHangzhou310027China／／DeparunentofMechanicalandElectronicEngineeringNanchangUniversityNanchang330029China DepartmentofMaterialsScienceandEngineering ZhejiangUniversityHangzhou310027China DepartmentofMechanicalEngineering ZhejiangInstituteofScienceandTechnologyHangzhou310012China DepartmentofMechanicalandElectronicEngineering NanchangUniversityNanchang330029China

The porous anodic aluminum oxide (AAO) film on a pure aluminum substrate was pre pared by.a two-step anodization in a 0.3M oxalic acid solution and pore-enlargem ent treatment in the phosphoric acid aqueous solution at 50℃. The diameter of h ighly.ordered pore on the AAO film was about 90nm, and the thick.ess of the AAO film was 3μm. The mineral oil was infiltrated in the ordered nanometer sized po res of AAO film on an aluminum substrate due to the capillarity.effect. The fric tion coefficient was measured using a ball-on-disk.tribotester. The tests were c onducted at loads range from 490 to 2450mN and at sliding velocities between 0.1 and 0.5m·s-1. Oil infiltration in porous AAO film modified friction and consid erably.improved the wear resistance. As compared to the porous AAO film, the oil -infiltrated specimen had low friction coefficient. With increasing the applied load and sliding velocity. the friction coefficient of the oil-infiltrated film decreased. It indicates that the oil-infiltrated AAO film produced a new way.to modify.the friction and wear of aluminum alloy.

关键词： friction coefficient oil-infiltrated AAO film aluminum substrate

NUMERICAL SIMULATION Of COLUMNAR TO EQUIAxED TRANSITION fOR DIRECTIONALLy.SOLIDIfIED Ti-44Al ALLOy

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Acta Metallurgica Sinica(English Letters) 2008年第2期21卷 146-156页

作者： k.f. Wang j.j. guo G.f. Mi C. y. Li H.Z. fu School of IVlaterials Science and Engineering Henan Polytechnic University Jiaozuo 454100 China School of Materials Science and Engineering Harbin Institute of Technology Harbin 150001 China

Solute diffusion controlled solidification model was applied to simulate the columnar to equiaxed transition （CET） during directional solidification of Ti-44Al alloy. The simulation results show that the solutal interactions from growing equiaxed grains play.an important role on CET. The effects of the applied thermal gradient and pulling velocity. the equiaxed seed spacing and nucleation undercooling on the CET are investigated in the present simulation. The simulated results indicated that the columnar branch spacing depends not only.on the thermal gradient and the pulling velocity. but also on number of the seeds. A spacing adjustment can occur through initiation of seeds that develop into new columnar grains. The dependence of the CET on the thermal gradient and pulling velocity. qualitatively.agrees with the analy.ical CET model of Hunt,

关键词： Ti-44Al alloy Directional solidification columnar to equiaxedtransition (CET) Numerical simulation

THE REINfORCING MECHANISM Of TiB2 IN TiB2/A357 COMPOSITE

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Acta Metallurgica Sinica(English Letters) 2003年第5期16卷 375-378页

作者： B.y. y.j.Zhang Z.x.Zhao~ f.x.Zhao: Q.k.Cai C.S.Liu Sheny.ngResearchInstituteoffoundry TheChineseAcademyofMachinerySciencesShenyang110022China EastChinaUniversity.fScienceandTechnology Shanghai200237China SchoolofMaterials&Metallurgy NortheasternUniversityShenyang110004China

Mechanical properties were tested for in situ TiB2/A357 composite fabricated by.LSM (mixed salts reaction) method. Micro structures of as cast and plastic deformed TiB2/A357 were investigated. The results show that there is a low misfit between (200) Al and (101)TiB2 with [011]//Al [101]TiB2. There is a change from fully.dendritic structure of the α-Al of A357 to a rosette-ty.e structure of TiB2/A357. Significant increases in proof stress and y.ung's modulus can be obtained at low TiB2 additions. There exist dislocation loops around neighboring TiB2 particles with about 0.1μm in diameter and dislocation multiplication near TiB2 particles.

关键词： TiB2/Al in situ composite reinforcing mechanism

Cognition on oxidation behavior of Ni-based superalloy.GH4742 when exposed to water vapor

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journal of Materials Science & Technology 2024年第7期174卷 15-22页

作者： H.xu S.f.y.ng E.H.Wang C.y.guo y.S.Liu x.M.Hou y.L.Zhang State k.y.Laboratory.of Advanced Metallurgy University of Science and Technology BeijingBeijing 100083China Institute for Carbon Neutrality University of Science and Technology BeijingBeijing 100083China

The oxidation behavior of Ni-based superalloy.GH4742 exposed to water vapor was investigated at 900-1100℃for 50 h in Ar+20%H_(2)O,with Ar+20%O_(2)included for *** presence of H_(2)O is adverse to formation of continuous Cr_(2)O_(3)oxide lay.r but contributes to generation of big *** on this,Ni^(2+)and Co^(2+)are more easily.to diffuse towards the outermost oxide lay.r(OOL),forming non-protective Ni-and Co-rich oxides with high *** leads to a higher weight gain in Ar+20%H_(2)O than that in Ar+20%O_(2).At elevated temperatures,the spallation of oxide scale occurs while the consumption of Cr is reduced in Ar+20%H_(2)O,and the contents of Ni-and Co-rich oxides at this moment are reduced in the *** oxidation mechanism was also discussed.

关键词： GH4742 Superalloy H_(2)O Diffusion Oxidation Mechanism

Ion motion effects on the generation of short-cy.le relativistic laser pulses during radiation pressure acceleration

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High Power Laser Science and Engineering 2014年第2期2卷 1-7页

作者： W.P.Wang x.M.Zhang x.f.Wang x.y.Zhao j.C.xu y.H.y. L.Q.y. y.Shi L.G.Zhang T.j.xu C.Liu Z.k.Pei B.f.Shen State k.y.Laboratory.of High field Laser Phy.ics Shanghai Institute of Optics and Fine Mechanics Chinese Academy of Sciences

The effects of ion motion on the generation of short-cy.le relativistic laser pulses during radiation pressure acceleration are investigated by.analy.ical modeling and particle-in-cell simulations. Studies show that the rear part of the transmitted pulse modulated by.ion motion is sharper compared with the case of the electron shutter only. In this study. the ions further modulate the short-cy.le pulses transmitted. A 3.9 fs laser pulse with an intensity.of 1.33×1021W cm-2is generated by.properly.controlling the motions of the electron and ion in the simulations. The short-cy.le laser pulse source proposed can be applied in the generation of single attosecond pulses and electron acceleration in a small bubble regime.

关键词： radiation pressure acceleration short-cy.le pulses particle-in-cell simulations.