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Journal of Materials Science & Technology 2017年第7期33卷 682-689页

作者： y.Wang X.Q.cai Z.W.yang D.P.Wang X.G.liu y.c.liu Key Lab of Aclvanced Joining Technology School of Materials Science and Engineering Tianjin University Tiandin 300072 China

Vacuum brazing was successfully used to join Ti-22Al-25Nb alloy using Ti-Ni-Nb brazing alloys prepared by arc-melting. The influence of Nb content in the Ti-Ni-Nb brazing alloys on the interfacial microstructure and mechanical properties of the brazed joints was investigated. The results showed that the interfacial microstructure of brazed joint consisted of B2, O, ？3, and Ti2 Ni phase, while the width of brazing seams varied at different Nb contents. The room temperature shear strength reached359 MPa when the joints were brazed with eutectic Ti40Ni40Nb20 alloy at 1180？c for 20 min, and it was321, 308 and 256 MPa at 500, 650 and 800？c, respectively. cracks primarily initiated and propagated in ？3compounds, and partially traversed B2＋O region. Moreover, the fracture surface displayed typical ductile dimples when cracks propagated through B2＋O region, which was favorable for the mechanical properties of the brazed joint.

关键词： Ti-22Al-25Nb alloy Ti-Ni-Nb brazing alloy Nb content Microstructure Mechanical properties

Uncovering the softening mechanism and exploring the strengthening strategies in extremely fine nanograined metals:A molecular dynamics study

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Journal of Materials Science & Technology 2022年第14期109卷 186-196页

作者： H.R.Peng Z.y.Jian c.X.liu L.K.Huang y.M.Ren F.liu School of Materials and chemical Engineering Xi’an Technological UniversityXi’an 710021China State Key Laboratory of Solidification Processing Northwestern Polytechnical UniversityXi’an 710072China

The strength of polycrystalline metals increases with decreasing grain size,following the classical HallPetch ***,this relationship fails when softening occurs at very small grain sizes(typically less than 10 to 20 nm),which limits the development of ultrahigh-strength *** this work,using columnar-grained nanocrystalline cu-Ag‘samples’,molecular dynamics simulations were performed to investigate the softening mechanism and explore the strengthening strategies(e.g.,formation of solid solution or grain boundary(GB)segregation)in extremely fine nanograined ***,the softening of pure metals is induced by atomic sliding in the GB layer,rather than dislocation activities in the grain interior,although both occur during *** solid solution lowers the stacking fault energy and increases the GB energy,which leads to the softening of Nc *** segregation stabilizes GB structures,which causes a notable improvement in strength,and this improvement can be further enhanced by optimizing the solute concentration and GB *** work deepens the understanding of the softening mechanism due to atomic sliding in the GB layer and the strengthening mechanism arising from tailoring the GB stability of immiscible alloys and provides insights into the design of ultrahighstrength materials.

关键词： Softening Strengthening cu-Ag alloy Molecular dynamics Nanocrystalline

What is going on in magnesium alloys？

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Journal of Materials Science & Technology 2018年第2期34卷 245-247页

作者： X.J. Wang D.K. Xu R.Z. Wu X.B. chen Q.M. Peng L. Jin y.c. Xin Z.Q. Zhang y. liu X.H. chen G. chen K.K. Deng H.y. Wang School of Materials Science and Engineering Harbin Institute of Technology Harbin 150001 China Key Laboratory of Nuclear Materials and Safety Assessment Institute of Metal Research Chinese Academy of Sciences Shenyang 110016 China Key Laboratory of Superlight Materials & Surface Technology (Ministry of Education) Harbin Engineering University Harbin 150001 China School of Engineering RMIT University City Campus Carlton VIC 3053 Australia State Key Laboratory of Metastable Materials Science and Technology Yanshan University Qinhuangdao 066004 China National Engineering Research center of Light Alloy Net Forming Shanghai Jiao Tong University Shanghai 200240 China college of Materials Science and Engineering Chongqing University Chongqing 400030 China Key Lab of Electromagnetic Processing of Materials Ministry of Education Northeastern UniversityShnenyang 110819China Key Laboratory of Lightweight and High Strength Structural Materials of Jiangxi Province Nanchang University Nanchang 330031 China School of chemical Engineering and Technology Tianjin University Tianjin 300350 China Shanxi Key Laboratory of Advanced Magnesium-Based Materials Taiyuan University of Technology Taiyuan 030024 China Key Laboratory of Automobile Materials of Ministry of Education & School of Materials Science and Engineering Jilin University Changchun 130025 China

china has been developed into one of the most active regions in terms of both fundamental and applied research on magnesium （Mg） and its alloys in the world from a solid base laid by its prominent metallurgist and materials scientists over the past decades. Nowadays, a large number of young-generation researchers have been inspired by their predecessors and become the key participants in the fields of Mg alloys, which consequently led to the establishment of china youth Scholar Society for Magnesium Alloys Research in 2015. Since then, the first two china youth Scholars Symposiums on Mg Alloys Research had been held at Harbin （2015） and chongqing （2016） china, respectively. A number of crucial research inter- ests related to fundamental and applied Mg research were discussed at the conferences and summarized in this short perspective, aiming to boost far-reaching initiatives for development of new Mg-based materials to satisfy the requirements for a broad range of industrial employments. Herein, four main aspects are included as follows： i） Plastic deformation mechanism and strengthening strategy, ii） Design and development of new Mg-based materials, iii） Key service properties, and iv） New processing technologies.

关键词： Mg alloys Plastic deformation Strengthening Alloying design High performance corrosion Fatigue behavior creep Processing technologies Purification

Point process microstructural model of metallic thin films with implications for coarsening

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npj computational Materials 2023年第1期9卷 2074-2082页

作者： J.M.Rickman K.Barmak y.Epshteyn c.liu Department of Materials Science and Engineering Lehigh UniversityBethlehemPA 18015USA Department of Physics Lehigh UniversityBethlehemPA 18015USA Department of Applied Physics and Applied Mathematics Columbia UniversityNew YorkNY 10027USA Department of Mathematics The University of UtahSalt Lake CityUT 84112USA Department of Applied Mathematics Illinois Institute of TechnologyChicagoIL 60616USA

We develop a thin-film microstructural model that represents structural markers(i.e.,triple junctions in the two-dimensional projections of the structure of films with columnar grains)in terms of a stochastic,marked point process and the microstructure itself in terms of a grain-boundary *** advantage of this representation is that it is conveniently applicable to the characterization of microstructures obtained from crystal orientation mapping,leading to a picture of an ensemble of interacting triple junctions,while providing results that inform grain-growth models with experimental *** specifically.c.lculated quantities such as pair,partial pair and mark correlation functions,along with the microstructural mutual information(entropy),highlight effective triple junction interactions that dictate microstructural *** validate this approach,we characterize microstructures from Al thin films via crystal orientation mapping and formulate an approach,akin to classical density functional theory,to describe grain growth that embodies triple-junction interactions.

关键词： grain microstructure process

Exit problem of stochastic SIR model with limited medical resource

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Theoretical & Applied Mechanics Letters 2023年第1期13卷 8-13页

作者： y.c.Mao X.B.liu State Key Lab of Mechanics and control for Mechanical Structures College of Aerospace EngineeringNanjing University of Aeronautics and AstronauticsNanjing 210016China

Nonlinearity and randomness are both the essential attributes for the real world,and the case is the same for the models of infectious diseases,for which the deterministic models can not give a complete picture of the ***,although there has been a lot of work on stochastic epidemic models,most of them focus mainly on qualitative properties,which makes us somewhat ignore the original meaning of the parameter *** this paper we extend the classic susceptible-infectious-removed(SIR)epidemic model by adding a white noise excitation and then we utilize the large deviation theory to quantitatively study the long-term coexistence exit problem with ***,in order to extend the meaning of parameters in the corresponding deterministic system,we tentatively introduce two new thresholds which then prove rational.

关键词： Stochastic epidemic model Stochastic dynamical system Large deviation theory Exit problem

Advances in additively manufactured titanium alloys by powder bed fusion and directed energy deposition:Microstructure,defects,and mechanical behavior

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Journal of Materials Science & Technology 2024年第16期183卷 32-62页

作者： H.y.Ma J.c.Wang P.Qin y.J.liu L.y.c.en L.Q.Wang L.c.Zhang centre for Advanced Materials and Manufacturing School of EngineeringEdith Cowan University270 Joondalup DriveJoondalupPerthWA 6027SA School of Engineering M050The University of Western Australia35 Stirling HighwayCrawleyPerthWA 6009SA Institute of Metals College of Material Science and EngineeringChangsha University of Science&TechnologyChangsha 410004China School of Material Science and Engineering Jiangsu University of Science and TechnologyZhenjiang 212100China State Key Laboratory of Metal Matrix composites School of Material Science and EngineeringShanghai Jiao Tong UniversityShanghai 200240China

Ti and its alloys have been broadly adopted across various industries owing to their outstanding proper-ties,such as high strength-to-weight ratio,excellent fatigue performance,exceptional corrosion resistance and so *** manufacturing(AM)is a complement to,rather than a replacement for,traditional manufacturing *** enhances flexibility in fabricating complex components and resolves machin-ing challenges,resulting in reduced lead times for custom ***,owing to distinctions among various AM technologies,Ti alloys fabricated by different AM methods usually present differences in mi-crostructure and defects,which can significantly influence the mechanical performance of built ***,having an in-depth knowledge of the scientific aspects of fabrication and material properties is crucial to achieving high-performance Ti alloys through different AM *** article reviews the mechanical properties of Ti alloys fabricated by two mainstream powder-type AM techniques:powder bed fusion(PBF)and directed energy deposition(DED).The review examines several key aspects,en-compassing phase formation,grain size and morphology,and defects,and provides an in-depth analysis of their influence on the mechanical behaviors of Ti *** review can aid researchers and engi-neers in selecting appropriate PBF or DED methods and optimizing their process parameters to fabricate high-performance Ti alloys for a wide range of industrial applications.

关键词： Powder bed fusion Directed energy deposition Titanium alloys Phase transformation Defects Mechanical property

EFFEcT OF LASER INPUT ENERGy ON AuSn_x INTERMETALLIc cOMPOUNDS FORMATION IN SOLDER JOINTS WITH DIFFER-ENT THIcKNESS OF Au SURFAcE FINISH ON PADS

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Acta Metallurgica Sinica(English Letters) 2008年第3期21卷 183-190页

作者： W. liu c.Q. Wang y.H. Tian M.y. Li Department of Electronics Packaging Technology State Key Lab of Advanced Welding Production Technology Harbin Institute of Technology Harbin 150001 China Shenzhen Graduate School of Harbin Institute of Technology Shenzhen 518055 China

Formation of AuSnx intermetallic compounds （IMcs） in laser reflowed solder joints was investigated. The results showed that few IMcs formed at the solder/0. 1μm Au interface. Needlelike AuSn4 IMcs were observed at the solder/0.5μm Au interface. In Sn-2.0Ag-O,75cu-3,0Bi and Sn-3.5Ag-O.75cu solder joints, when the laser input energy was increased, AuSn4 IMcs changed .from a layer to needlelike or dendritic distribution at the solder/0.9μm Au interface. As for the solder joints with 4.0 μm thickness of Au surface finish on pads, AuSn4 , AuSnx, AuSn IMcs, and Au2Sn phases formed at the interface. Moreover, the content of AuSnx IMcs, such as, AuSn4 and AuSn2, which contained high Sn concentration, would become larger as the laser input energy increased. In the Sn-37Pb solder joints with 0.9 μm or 4.0 μm thickness of the Au surface finish on pads, AuSn4 IMcs were in netlike distribution. The interspaces between them were filled with Pb-rich phases.

关键词： Laser soldering Inlermetallics Au films

EFFEcT OF NANOcRySTALLINE AND TWIN BOUNDARIES ON cORROSION BEHAVIOR OF 316L STAINLESS STEEL USING SMAT

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Acta Metallurgica Sinica(English Letters) 2006年第3期19卷 183-189页

作者： A.Q. Lü y. Zhang y. Li G. liu Q.H. Zang c.M. liu School of Materials and Metallurgy Northeastern University Shenyang 110004 China Jiuquan Iron ＆ Steel （Group） Go. Ltd Jiayuguan 735100 China State Key Laboratory for corrosion and Protection of Metals Institute of Metal Research The Chinese Academy of Sciences Shenyang 110015 China Shenyang National Laboratory for Materials Science Institute of Metal Research The Chinese Academy of Science Shenyang 110016 China

By means of surface mechanical attrition treatment （ SMAT）, the groin size with a diameter of aboat 60hm formed at about 20μm depth and numerous mechanical twins at about 50μm depth from the treated surface were synthesized in 316L stainless steel because of the different distributions of strain and strain rate along depth orientation. For instance the maximum strain rate reached 10^3-10^4s^-1 on the top surface. The relationship between the microsturcture and the corrosion property was studied in 0.05M H2SO4＋ 0.25M Na2SO4 aqueous solution, and the results show an extreme improvement of corrosion resistance owing to the appearance of twin boundaries and the obvious reduction in corrosion resistance attributed to the presence of nanocrystaline boundaries.

关键词： surface mechanical attrition treatment 316L stainless steel corrosion property twin boundary nanocrystaline boundary

Multi boron-doping effects in hard carbon toward enhanced sodium ion storage

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Journal of Energy.c.emistry 2025年第1期100卷 730-738页

作者： Peng Zheng Wang Zhou ying Mo Biao Zheng Miaomiao Han Qin Zhong Wenwen yang Peng Gao Lezhi yang Jilei liu college of Materials Science and Engineering Hunan Joint International Laboratory of Advanced Materials and Technology for Clean Energy Hunan Province Key Laboratory for Advanced Carbon Materials and Applied Technology Hunan University Greater Bay Area Institute for Innovation Hunan University changsha Research Institute of Mining & Metallurgy.c.. LTD.

Hard carbon （Hc） has been considered as promising anode material for sodium-ion batteries （SIBs）.The optimization of hard carbon’s microstructure and solid electrolyte interface （SEI） property are demonstrated effective in enhancing the Na+storage capability,however,a one-step regulation strategy to achieve simultaneous multi-scale structures optimization is highly ***,we have systematically investigated the effects of boron doping on hard carbon’s microstructure and interface chemistry.A variety of structure characterizations show that appropriate amount of boron doping can increase the size of closed pores via rearrangement of carbon layers with improved graphitization degree,which provides more Na+storage ***-situ Fourier transform infrared spectroscopy/electrochemical impedance spectroscopy （FTIR/EIS） and X-ray photoelectron spectroscopy （XPS） analysis demonstrate the presence of more Bc3and less B–c–O structures that result in enhanced ion diffusion kinetics and the formation of inorganic rich and robust SEI,which leads to facilitated charge transfer and excellent rate *** a result,the hard carbon anode with optimized boron doping content exhibits enhanced rate and cycling *** general,this work unravels the critical role of boron doping in optimizing the pore structure,interface chemistry and diffusion kinetics of hard carbon,which enables rational design of sodium-ion battery anode with enhanced Na+storage performance.

关键词： X ray photoelectron spectroscopy

Real-world evidence on the efficacy and safety of vonoprazanamoxicillin dual therapy for Helicobacter pylori treatment in elderly patients

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World Journal of Gastroenterology 2025年第1期31卷 68-78页

作者： Wen Gao Jing-Wen Li Hui ye Xue-Zhi Zhang Jian-Xiang liu Hong cheng Department of Gastroenterology Peking University First HospitalBeijing 100034China School of Medicine Tsinghua MedicineTsinghua UniversityBeijing 100034China Department of Traditional chinese Medicine and Integrative Medicine Peking University First HospitalBeijing 100034China

BAcKGROUND A dual therapy regimen containing amoxicillin is a common treatment option for the eradication of Helicobacter pylori(***).While substantial research supports the efficacy and safety of vonoprazan and amoxicillin(VA)dual therapy in the general population,there is still a lack of studies specifically focusing on its safety in elderly *** To evaluate efficacy and safety of VA dual therapy as first-line or rescue treatment for *** in elderly *** As a real-world retrospective study,data were collected from elderly patients aged 60 years and above who accepted VA dual therapy(vonoprazan 20 mg twice daily+amoxicillin 1000 mg thrice daily for 14 days)for *** eradication in the Department of Gastroenterology at Peking University First Hospital between June 2020 and January *** status was evaluated by^(13)c-urease breath test 6 weeks after *** adverse events(AEs)during treatment were *** In total,401 cases were ***-one cases were excluded due to loss to follow-up,lack of re-examination,or unwillingness to take *** total of 380 included cases comprised 250 who received VA dual therapy as first-line treatment and 130 who received VA dual therapy as rescue *** was successfully eradicated in 239 cases(95.6%)in the first-line treatment group and 116 cases(89.2%)in the rescue treatment *** overall incidence of AEs was 9.5%for both ***,9.2%of patients experienced an AE in the first-line treatment group and 10.0%in the rescue treatment *** patients discontinued treatment due to AE,with a discontinuation rate of 1.3%.No serious AE *** The VA dual therapy regimen as a first-line treatment and a rescue therapy was effective and safe for elderly patients aged 60 and older.

关键词： Helicobacter pylori Vonoprazan Amoxicillin Dual therapy Elderly