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Exceptional thermal stability and enhanced hardness in a nanostructured Mg-Gd-Y-Zn-Zr alloy processed by high pressure torsion

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Journal of Magnesium and Alloys 2023年第12期11卷 4589-4602页

作者： Wanting Sun Yang He Xiaoguang Qiao Xiaojun Zhao Houwen Chen Nong Gao Marco J.Starink mingyi zheng School of Materials Science and Engineering Harbin Institute of TechnologyHarbin 150001China College of Materials Science and Engineering Chongqing UniversityChongqing 400044China Materials Research Group School of EngineeringUniversity of SouthamptonSouthampton SO171BJUnited Kingdom Center for Composite Materials and Structures Harbin Institute of TechnologyHarbin 150001China Department of Industrial and Systems Engineering The Hong Kong Polytechnic UniversityHung HomHong KongChina

A Mg-8.2Gd-3.8Y-1.0Zn-0.4Zr(wt.%) alloy is processed by solution treatment and high pressure torsion(HPT) at room temperature to produce a nanostructured light material with high hardness. The stability of this alloy is subsequently tested through isochronal annealing for 0.5 h at 373 K to 673 K. The results reveal a thermal stability that is vastly superior to that of conventional Mg-based alloys processed by severe plastic deformation: the grain size remains at around 50 nm on heating to 573 K, and as the temperature is increased to 673 K,grain growth is restricted to within 500 nm. The stability of grain refinement of the present alloy/processing combination allowing grain size to be limited to 55 nm after exposure at 573 K, appears to be nearly one order of magnitude better than for the other SPD processed Mg-RE type alloys, and 2 orders of magnitude better than those of SPD processed RE-free Mg alloys. This superior thermal stability is attributed to formation of co-clusters near and segregation at grain boundaries, which cause a thermodynamic stabilization of grain size, as well as formation of β-Mg_(5)RE equilibrium phase at grain boundaries, which impede grain growth by the Zener pinning effect. The hardness of the nanostructured Mg-Gd-Y-Zn-Zr alloy increases with increasing annealing temperature up to 573 K, which is quite different from the other SPD-processed Mg-based alloys. The high hardness of 136 HV after annealing at 573 K is mainly due to solute segregation and solute clustering at or near grain boundaries.

关键词： Mg-RE alloy High pressure torsion Thermal stability Grain growth Solute segregation Phase transformation

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Structure-function integrated magnesium alloys and their composites

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Journal of Magnesium and Alloys 2023年第10期11卷 3511-3544页

作者： Junbin Hou Ding Li Zejia Liu Zhikang Ji Shoufu Guan Chongchao Li Xiaoguang Qiao Igor S.Golovin mingyi zheng School of Material Science and Engineering Harbin Institute of TechnologyHarbin 150001China Department of Physical Metallurgy of Non-Ferrous Metals National Research Technological University“MISiS”Leninskiy pr.4Moscow 119049Russia Moscow Polytechnic University B.Semenovskay 38Moscow 107023Russia

Magnesium-based materials not only exhibit desirable characteristics such as low density and high specific strength, but also possess exceptional functional properties, including high damping capacity, high thermal conductivity, high electromagnetic interference shielding capacity, flame retardancy, and dissolvability. However, achieving a balance between strength and functional properties remains a significant challenge in Mg alloys community. Typically, strength depends on the pinning effect of defects, such as solute atoms and second phases,which hinder dislocation motion. On the other hand, optimal functional properties usually necessitate relative perfect crystal structures, as the presence of solute atoms and second phases can have adverse effects on damping capacity and thermal conductivity. Balancing these conflicting requirements is difficult. The trade-off between strength and functional properties of the Mg alloys should be broken to meet the urgent need in aerospace, automotive, 3C(computers, communications, and consumer electronics) and energy industries for high performance structural-functional integrated Mg-based materials. This review summarizes recent progress in understanding the mechanisms and influencing factors for the functional properties of Mg alloys. The mechanisms underlying the trade-off between strength and functional properties of Mg alloys is discussed. The latest developed structural-functional integrated Mg alloys and their composites are summarized, including high strength Mg-based materials with high damping capacity/high thermal conductivity/strong electromagnetic shielding capability/excellent flame-resistance/high dissolution rate. The future works of developing structure-function integrated Mg-based materials are proposed.

关键词： Structure-function integrated Mg alloys Composites Strength Damping capacity Thermal conductivity Electromagnetic interference shielding Ignition resistance Dissolvability

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Combining gradient structure and supersaturated solid solution to achieve superior mechanical properties in WE43 magnesium alloy

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Journal of Materials Science & Technology 2022年第4期99卷 223-238页

作者： Wanting Sun Bo Wu Hui Fu Xu-Sheng Yang Xiaoguang Qiao mingyi zheng Yang He Jian Lu San-Qiang Shi State Key Laboratory of Ultra-precision Machining Technology Department of Industrial and Systems EngineeringThe Hong Kong Polytechnic UniversityHung HomHong KongChina Hong Kong Polytechnic University Shenzhen Research Institute ShenzhenChina Department of Mechanical Engineering The Hong Kong Polytechnic UniversityHung HomHong KongChina School of Materials Science and Engineering Harbin Institute of TechnologyHarbin 150001China Centre for Composite Materials and Structures Harbin Institute of TechnologyHarbin 150080China Department of Mechanical Engineering City University of Hong KongKowloonHong KongChina

In this study,surface mechanical attrition treatment was employed to sucessfully produce a gradient nanostructured layer on WE43 magnesium alloy.X-ray diffraction,energy dispersive X-ray spectrometer,and high-resolution transmission electron microscope observations were mainly performed to uncover the microstructure evolution responsible for the refinement mechanisms.It reveals that the grain refinement process consists of three transition stages along the depth direction from the core matrix to the topmost surface layer,i.e.,dislocation cells and pile-ups,ultrafine subgrains,and randomly orientated nanograins with the grain size of~40 nm.Noticeably,the original Mg;RE second phase is also experienced refinement and then re-dissolved into the α-Mg matrix phase,forming a supersaturated solid solution nanostructuredα-Mg phase in the gradient refined layer.Due to the cooperative effects of grain refinement hardening,dislocation hardening,and supersaturated solid-solution hardening,the gradient nanostructured WE43 alloy contributes to the ultimate tensile strength of~435 MPa and ductility of~11.0%,showing an extraordinary strain hardening and mechanical properties among the reported severe plastic deformation-processed Mg alloys.This work provides a new strategy for the optimization of mechanical properties of Mg alloys via combining the gradient structure and supersaturated solid solution.

关键词： Mg-RE alloy Surface mechanical attrition treatment Gradient nanostructure Supersaturated solid solution High strength and ductility Strengthening mechanisms

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Influence of size and distribution of W phase on strength and ductility of high strength Mg-5.1Zn-3.2Y-0.4Zr-0.4Ca alloy processed by indirect extrusion

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Journal of Materials Science & Technology 2018年第2期34卷 277-283页

作者： Hansi Jiang Xiaoguang Qiao Chao Xu Shigeharu Kamado Kun Wu mingyi zheng School of Materials Science and Engineering Harbin Institute of Technology Department of Mechanical Engineering Nagaoka University of Technology

A high strength Mg-5.1Zn-3.2Y-0.4Zr-0.4Ca （wt%） alloy containing W phase （Mg3Y2Zn3） prepared by permanent mold direct-chill casting is indirectly extruded at 350 ℃ and 400 ℃, respectively. The extruded alloys show bimodal grain structure consisting of fine dynamic recrystallized （DRXed） grains and unre- crystallized coarse regions containing fine W phase and β2′ precipitates. The fragmented W phase particles induced by extrusion stimulate nucleation of DRXed grains, leading to the formation of fine DRXed grains, which are mainly distributed near the W particle bands along the extrusion direction. The alloy extruded at 350 ℃ exhibits yield strength of 373 MPa, ultimate tensile strength of 403 MPa and elongation to failure of 5.1%. While the alloy extruded at 400 ℃ shows lower yield strength of 332 MPa, ultimate tensile strength of 352 MPa and higher elongation to failure of 12%. The mechanical properties of the as-extruded alloys vary with the distribution and size of W phase. A higher fraction of DRXed grains is obtained due to the homogeneous distribution of micron-scale broken W phase particles in the alloy extruded at 400 ℃, which can lead to higher ductility. In addition, the nano-scale dynamic W phase precipitates distributed in the unDRXed regions are refined at lower extrusion temperature. The smaller size of nano-scale W phase precipitates leads to a higher fraction of unDRXed regions which contributes to higher strength of the alloy extruded at 350 ℃.

关键词： Mg alloy Extrusion temperature Mechanical properties W phase Dynamic precipitation Bimodal structure

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Microstructure and Mechanical Behavior of Squeeze Cast SiC_w/AZ91 Magnesium Matrix Composites

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Journal of Materials Science & Technology 2001年第1期17卷 21-22页

作者： mingyi zheng Kun WU and Congkai YAO School of Materials Science and Engineering, Harbin Institute of Technology, Harbin 15000l, China Sch. of Mater. Sci. Harbin Inst. of Technol. Harbin 150001 China

The interfacial microstructure and tensile properties of the squeeze cast SiCw/AZ91 Mg composites were characterized. There exist uniform, line and discrete MgO particles at the interface between SiC whisker and magnesium in the composites using acid aluminum phosphate binder. The interfacial reaction products MgO are beneficial to interfacial bonding between SiCw and the Mg matrix. resulting in an improvement of the mechanical properties of the composite.

关键词： AZ SiC Microstructure and Mechanical Behavior of Squeeze Cast SiC_w/AZ91 Magnesium Matrix Composites Cast

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Effect of forging temperature on the microstructures and mechanical properties of the SiC_p/AZ91 magnesium matrix composite

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Acta Metallurgica Sinica(English Letters) 2010年第2期23卷 99-105页

作者： Kun WU Kunkun DENG Hai CHANG Yewei WU Xiaoshi HU mingyi zheng School of Materials Science and Engineering Harbin Institute of Technology Harbin 150001 China

In this paper, 10 vol. pct SiCp/AZ91 magnesium matrix composite was fabricated by stir casting technology. The ingots were forged at temperatures of 320, 370 and 420 ℃, respectively. XRD, OM and SEM were used to characterize microstructure of the＇composites. It was shown that the clusters of particles in the as-cast composite were largely eliminated, and that the tensile strength was improved obviously.

关键词： Magnesium matrix composite Forging Mechanical properties

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On-surface synthesis and characterization of polyynic carbon chains

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National Science Review 2024年第3期11卷 192-199页

作者： Wenze Gao Wei zheng Luye Sun Faming Kang zheng Zhou Wei Xu Interdisciplinary Materials Research Center School of Materials Science and Engineering Tongji University

Carbyne, an elusive sp-hybridized linear carbon allotrope, has fascinated chemists and physicists for decades. Due to its high chemical reactivity and extreme instability, carbyne was much less explored in contrast to the sp2-hybridized carbon allotropes such as graphene. Herein, we report the on-surface synthesis of polyynic carbon chains by demetallization of organometallic polyynes on the Au（111） surface;the longest one observed consists of ～60 alkyne units（120 carbon atoms）. The polyynic structure of carbon chains with alternating triple and single bonds was unambiguously revealed by bond-resolved atomic force microscopy. Moreover, an atomically precise polyyne, C14, was successfully produced via tip-induced dehalogenation and ring-opening of the decachloroanthracene molecule(C14Cl10) on a bilayer NaCl/Au（111） surface at 4.7 K, and a band gap of 5.8 eV was measured by scanning tunnelling spectroscopy,in a good agreement with the theoretical HOMO–LUMO gap（5.48 eV）.

关键词： polyyne scanning probe microscopy carbon allotrope on-surface synthesis organometallic polyyne

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Plate tectonics in the Archean:Observations versus interpretations

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Science China Earth Sciences 2024年第1期67卷 1-30页

作者： YongFei zheng School of Earth and Space Sciences University of Science and Technology of ChinaHefei 230026China Key Laboratory of Crust-Mantle Materials and Environment Chinese Academy of SciencesHefei 230026China Center of Excellence for Comparative Planetology Chinese Academy of SciencesHefei 230026China

Plate tectonics theory,established in the 1960s,has been successful in explaining many geological phenomena,processes and events that occurred in the Phanerozoic.However,the theory has often struggled to provide a coherent framework in interpreting geological records in continental interior and Precambrian period.In dealing with the relationship between plate tectonics and continental geology,continental interior tectonics was often separated from continental margin tectonics in the inheritance and development of their structure and composition.This separation led to the illusion that the plate tectonics theory is not applicable to Precambrian geology,particularly in explaining the fundamental geological characteristics of Archean cratons.Although this illusion does not mean that the Archean continental crust did not originate from a regime of plate tectonics,it led to the development of alternative tectonic models,often involving vertical movements under a regime of stagnant lid tectonics,including not only endogenous processes such as gravitational sagduction,mantle plumes and heat pipes but also exogenous processes such as bolide impacts.These vertical processes were not unique to the Archean but persisted into the Phanerozoic.They result from mantle poloidal convection at different depths,not specific to any particular period.Upgrading the plate tectonics theory from the traditional kinematic model in the 20th century to a holistic kinematic-dynamic model in the 21st century and systematically examining the vertical transport of matter and energy at plate margins,it is evident that plate tectonics can explain the common geological characteristics of Archean cratons,such as lithological associations,structural patterns and metamorphic evolution.By deciphering the structure and composition of convergent plate margins as well as their dynamics,the formation and evolution of continental crust since the Archean can be divided into ancient plate tectonics in the Precambrian and modern plate tectonics in the Phanero

关键词： Plate tectonics Archean geology Continental origin Crustal reworking Plate interior Plate margin

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Orthogonal Combinatorial Raman Codes Enable Rapid High-Throughput-Out Library Screening of Cell-Targeting Ligands

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Research 2024年第1期2023卷 199-208页

作者： Yuchen Tang Xingxing zheng Tingjuan Gao China Key Laboratory of Pesticide and Chemical Biology of Ministry of Education College of ChemistryCentral China Normal UniversityWuhan 430079China

High-throughput assays play an important role in the fields of drug discovery,genetic analysis,and clinical diagnostics.Although super-capacity coding strategies may facilitate labeling and detecting large numbers of targets in a single assay,practically,the constructed large-capacity codes have to be decoded with complicated procedures or are lack of survivability under the required reaction conditions.This challenge results in either inaccurate or insufficient decoding outputs.Here,we identified chemical-resistant Raman compounds to build a combinatorial coding system for the high-throughput screening of cell-targeting ligands from a focused 8-mer cyclic peptide library.The accurate in situ decoding results proved the signal,synthetic,and functional orthogonality for this Raman coding strategy.The orthogonal Raman codes allowed for a rapid identification of 63 positive hits at one time,evidencing a high-throughput-out capability in the screening process.We anticipate this orthogonal Raman coding strategy being generalized to enable efficient high-throughput-out screening of more useful ligands for cell targeting and drug discovery.

关键词： enable throughput allowed

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Recent advances in cancer-associated fibroblast:Biomarkers,signaling pathways,and therapeutic opportunities

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Chinese Medical Journal 2024年第6期137卷 638-650页

作者： Donger Zhou Lei zheng Department of Hepatobiliary-Pancreatic Surgery The Second Affiliated HospitalZhejiang University School of MedicineHangzhouZhejiang 310009China Sidney Kimmel Comprehensive Cancer Center The Skip Viragh Pancreatic Cancer Center for Clinical Research and Careand The Bloomberg-Kimmel Institute for Immunotherapy at Johns Hopkins University School of MedicineBaltimoreMD 21287USA

Anti-cancer therapies usually focus on tumor cells,but non-tumor stromal components in the tumor microenvironment also play vital roles in tumor initiation and progression,which may be the prognostic factors and potential therapeutic targets.Cancer-associated fibroblasts(CAFs)are the essential component in the tumor environment,exhibiting high heterogeneity in their cell origin and phenotype with diverse functions that influence tumor angiogenesis,immune systems,and metabolism.Single-cell RNA sequencing and genetically engineered mouse models have increased our understanding of CAF diversity,and many subtypes have been defined.However,the precise functions of these subtypes need to be studied and validated.Studies of signaling pathways and epigenetic changes in CAFs facilitate understanding of the phenotypes of CAFs and the crosstalk between tumor cells and CAFs to provide potential therapeutic targets.Some clinical trials,including phase III trials targeting CAFs,have been performed recently.However,few of these trials have generated promising results,which indicates that the complexity of CAFs in the tumor microenvironment remains largely unknown,and in-depth investigations of CAFs should be performed.This review summarizes the research on CAFs,focusing on the heterogeneity of their phenotypes and functions,specific signaling pathways,and the therapeutic strategies involving CAFs.Additionally,we briefly discuss the current technologies commonly used in CAF studies and describe the challenges and future perspectives of CAF research.

关键词： Cancer-associated fibroblasts Tumor microenvironment Anti-cancer therapy Targeted therapy

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