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On the mechanism of Si-promoted destabilization of TiC_(x)particles in Al alloys

Journal of Materials Science & Technology 2023年第34期165卷 17-26页

作者： H.Dong y.C.guo y.z.Chen F.Xia Q.Q.guo Q.Chen G.L.Li J.y.zhao y.zhong J.P.Li School of Materials and Chemical Engineering Xi’an Technological UniversityXi’an 710021China State Key Lab.of Solidification Processing Northwestern Polytechnical UniversityXi’an 710072China School of Science Xi’an University of Science and TechnologyXi’an 710054China

TiC_(x)is an excellent composite strengthening particle and grain refiner for Al ***,the stability of TiC_(x)is poor when solute Si exists in Al alloy melts,which significantly depresses its strengthening and grain refining *** this work,the destabilization mechanisms of the TiC_(x)particles in Al-Si alloy melt with a composition of Al-7Si-7.5TiC were explored via experiments,first-principles calculations and thermodynamic *** experimental results show that Si atoms diffuse into TiC_(x)and Ti atoms are released into the Al melt to form a Ti-rich transition zone during the insulation of TiC_(x)in Al-Si melt,and the TiAlySiz and Al_(4)C_(3)phases are solidified in the Ti-rich zone and at Ti-rich zone/TiC_(x)interface,*** first principles calculations show that the low formation energy of C vacancies facilitates the rapid diffusion of Si atoms in TiC_(x),while the doping of Si atoms reduces the energy barrier of diffusion of Ti atoms in TiC_(x)and promotes the formation of Ti-rich *** thermodynamic calculations show that the wide crystallization temperature range of the destabilized product TiAlySiz phase is the key to continuous decomposition of TiC_(x)*** addition,the driving force of the main destabilization reaction of TiC_(x)in the Al-Si alloys is about 44 times higher than that in the Al alloys without Si *** indicates that the presence of solute Si remarkably promotes the subsequent decomposition process of TiC_(x)in the Al-Si alloy melts.

关键词： Al-Si alloy TiC_(x)particles Destabilization First principles calculations Thermodynamics

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An explicit solution to a three-dimensional wedge problem considering two edges effect

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Friction 2020年第2期8卷 370-383页

作者： L.guo z.M.zHANG W.WANG y.zHAO P.L.WONG School of Mechatronic Engineering and Automation Shanghai UniversityShanghai 200444China Department of Mechanical Engineering City University of Hong KongHong Kong SARChina

The paper presents an explicit matrix algorithm to solve the problem of an elastic wedge with three loaded *** algorithm makes use of a recently published concept of transformation matrix,by which the original surface loads are converted to equivalent loads in *** three loaded edges are considered *** developed algorithm is used to study the effects of two free edges of a steel block and tapered rollers with different contact *** two load-free edges can substantially increase deformation if the two edges are close in *** results of the tapered roller simulation show that deformation is considerably sensitive to the contact angle of the tapered *** largest deformation appears at the big end of the ***,empirical formulae for correction factors for the calculation of block or quarter-space deformation based on half-space solutions are summarized.

关键词： contact mechanics two edge surfaces finite line contact tapered roller contact

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Partition method and experimental validation for impact dynamics of flexible multibody system

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Acta Mechanica Sinica 2018年第3期34卷 482-492页

作者： J.y.Wang z.y.Liu J.z.Hong School of Naval Architecture Ocean and Civil EngineeringShanghai Jiao Tong University

The impact problem of a flexible multibody system is a non-smooth, high-transient, and strong-nonlinear dynamic process with variable boundary. How to model the contact/impact process accurately and efficiently is one of the main difficulties in many engineering applications. The numerical approaches being used widely in impact analysis are mainly from two fields： multibody system dynamics （MBS） and computational solid mechanics （CSM）. Approaches based on MBS provide a more efficient yet less accurate analysis of the contact/impact problems, while approaches based on CSM are well suited for particularly high accuracy needs, yet require very high computational effort. To bridge the gap between accuracy and efficiency in the dynamic simulation of a flexible multibody system with contacts/impacts, a partition method is presented considering that the contact body is divided into two parts, an impact region and a non-impact region. The impact region is modeled using the finite element method to guarantee the local accuracy, while the non-impact region is modeled using the modal reduction approach to raise the global efficiency. A three-dimensional rod-plate impact experiment is designed and performed to validate the numerical results. The principle for how to partition the contact bodies is proposed： the maximum radius of the impact region can be estimated by an analytical method, and the modal truncation orders of the non-impact region can be estimated by the highest frequency of the signal measured. The simulation results using the presented method are in good agreement with the experimental results. It shows that this method is an effec-rive formulation considering both accuracy and efficiency. Moreover, a more complicated multibody impact problem of a crank slider mechanism is investigated to strengthen this conclusion.

关键词： Partition method Impact dynamics Experimental investigation Efficiency and accuracy Partition principle

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High-Speed Friction Stir Welding of T6-Treated B4Cp/6061Al Composite

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Acta Metallurgica Sinica(English Letters) 2020年第1期33卷 67-74页

作者： y.z.Li y.N.zan Q.z.Wang B.L.Xiao z.y.Ma Key Laboratory of Nuclear Materials and Safety Assessment Institute of Metal ResearchChinese Academy of Sciences72 Wenhua RoadShenyang 110016China Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of Sciences72 Wenhua RoadShenyang 110016China University of Science and Technology of China Shenyang 110016China

T6-treated 20 wt% B4 Cp/6061 Al sheets were joined under welding speeds of 400–1200 mm/min by friction stir welding(FSW) with a threaded cermet pin. The macro-defect-free FSW joints could be achieved at high welding speeds up to 1200 mm/min, but larger plunge depth was required at the welding speeds of 800 and 1200 mm/min to eliminate the tunnel defect. In the nugget zone(Nz) of the joints, the B4 C particles were broken up and uniformly redistributed. The Nz exhibited lower hardness than the base metal(BM), and the hardness value almost did not change with increasing welding speed, attributable to the dissolution of precipitates. Compared with the BM, the joints showed lower tensile strength. As the welding speed increased from 400 to 800 mm/min, the joint efficiencies were nearly the same and up to ~ 73%. When the welding speed increased up to 1200 mm/min, the tensile strength significantly decreased, due to the occurrence of kissing bond defect at the bottom of the Nz. With increasing welding speed, the fracture location of the joints transferred gradually from the heat-affected zone to the Nz due to the kissing bond defects.

关键词： Metal-matrix composites Microstructures Mechanical properties Friction stir welding High-speed welding

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Perovskite LiBaH3 for photo-assisted dinitrogen fixation

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Science China Chemistry 2025年

作者： Kaixun Cui yeqin Guan yongli Cai Runze Wang Qianru Wang Wenbo Gao Jianping guo Ping Chen Department of Chemical Physics University of Science and Technology of China Dalian Institute of Chemical Physics Chinese Academy of Sciences Center of Materials and Optoelectronics Engineering University of Chinese Academy of Sciences

Establishing supply chains for future ammonia energy systems requires the development of efficient materials and processes for ammonia production under mild conditions. Recent researches disclose unique functionalities of binary alkali and alkaline earth metal hydrides in mediating ammonia synthesis. Thanks to the rich compositional and structural properties of the metalhydrogen system, we herein report that LiBaH3, as a narrow band gap perovskite hydride, exhibits a strong response to visible light illumination. Specifically, hydridic hydrogen undergoes reductive elimination of producing H2and creates an electron-rich surface. Such an environment favors dinitrogen fixation to form N–H bonds. Based on this chemical property, a chemical looping ammonia synthesis process mediated by LiBaH3and driven by both photo and thermal energies was proposed and *** work demonstrates that hydride perovskites are promising candidates for mediating photo-assisted nitrogen fixation reactions.

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LOW CyCLE FATIGUE BEHAVIOR OF Az91HP ALLOy IN AS HIGHP RESSURE DIE CASTING

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Acta Metallurgica Sinica(English Letters) 2000年第4期13卷 961-966页

作者： Liu, z. Xu, y.y. Wang, z.G. Wang, y. Liu, z.y. Inst of Metal Research Chinese Acad of Sciences Shenyang China

Fully reversed total strain-controlled low-cycle fatigue tests were conducted at room temperature in air to study the fatigue behavior of Az91HP magnesium alloy in as high pressure die casting and subsequently heat treatment. All the specimens in different heat histories exhibit cyclic strain hardening in different degrees. It is difficult to distinguish the fatigue behavior of the die casting specimens from that of the solution aging specimens. The solution treated specimens show longer fatigue life at high strain amplitude and shorter fatigue life at low strain amplitude than the die casting and solution aging specimens though they have the lowest yield strength with higher strain hardening. Fatigue fracture surfaces for strain amplitude larger than 0.005 show very similar to those found by monotonic tensile tests. The SEM examination reveals that the regions of fatigue crack growth and final fracture can be characterized by quasi-cleavage mechanisms, but some shallow dimples, slip bands and secondary cracks are found on the fracture surface in the fracture crack growth areas.

关键词： Cracks Die casting Fatigue of materials Heat treatment

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Grids of stellar models including second harmonic and colors:solar composition(z = 0.0172,X = 0.7024)

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Research in Astronomy and Astrophysics 2015年第12期15卷 2244-2262页

作者： Mutlu y?ld?z Ege University Department of Astronomy and Space Sciences

Grids of stellar evolution omy/astrophysics, such as planet hosting are required in many fields of astron- stars, binaries, clusters, chemically peculiar stars, etc. In this study, a grid of stellar evolution models with updated ingredients and recently determined solar abundances is presented. The solar values for the initial abundances of hydrogen, heavy elements and mixing-length parameter are 0.0172, 0.7024 and 1.98, respectively. The mass step is small enough （0.01 M） that interpolation for a given star mass is not required. The range of stellar mass is 0.74 to 10.00M. We present results in different forms of tables for easy and general appli- cation. The second stellar harmonic, required for analysis of apsidal motion of eclips- ing binaries, is also listed. We also construct rotating models to determine the effect of rotation on stellar structure and derive fitting formulae for luminosity, radius and the second harmonic as a function of rotational parameter. We also compute and list colors and bolometric corrections of models required for transformation between theo- retical and observational results. The results are tested for the Sun, the Hyades cluster, the slowly rotating chemically peculiar Am stars and eclipsing binaries with apsidal motion. The theoretical and observational results along isochrones are in good agree- ment. The grids are also applicable to rotating stars provided that equatorial velocity is given.

关键词： stars: interior -- stars: evolution -- binaries: eclipsing -- stars: chemi-cally peculiar

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Preface to the Special Issue:Friction Stir Welding and Processing

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Acta Metallurgica Sinica(English Letters) 2020年第1期33卷 1-2页

作者： z.y.Ma Institute of Metal Research Chinese Academy of SciencesShenyangChina

Friction stir welding(FSW),a highly effi cient solid-state joining technique,was invented at The Welding Institute,UK,in *** frictional and adiabatic heating,plastic deformation and solid-state diff usion,FSW has been widely accepted as a“green”welding technology owing to its energy effi ciency and environment ***,FSW has achieved broad application in various industries,such as aerospace and transportation,and is considered the most signifi cant development in the fi eld of material joining over the past two *** stir processing(FSP),later developed based on the fundamental principles of FSW,has been demonstrated as an eff ective and versatile metalworking technique for modifying and fabricating metallic materials.

关键词： FSP Preface to the Special Issue:Friction Stir Welding and Processing

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NEWLy-DEVELOPED AND CHEAP NANOCRySTALLINE Fe-Cu-Nb-Mo-Si-B ALLOyS FOR SWITCHING MODE POWER SUPPLy

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Acta Metallurgica Sinica(English Letters) 1997年第6期10卷 489-494页

作者： zhang, y.z. Shanghai Iron and Steel Research Inst Shanghai China

The synthetical soft magnetic properties were reported for newly-developed nanocrystalline Fe73.5Cu1Nb0.9 Mo2.1Si13.5B9 and Fe73.5Cu1Nb0.5 Mo2.5Si13.5B9 alloys. The levels of high-frequency losses of the new alloys are P3/100k=612 and 670 kWm-3, P2/200k=880 and 973kWm-3, P2/500k=4300 and 4600 kWm-3, P0.5/1000k=860 and 920 kWm-3, respectively. They are significantly lower than those of the superior power Mn-zn ferrite H7c4. The dependence of core loss on frequency and amplitude flux density has been analyzed. The practical applications of the new alloys to switching mode power supplies with the output power of 1 and 2kW were reported.

关键词： Boron Copper alloys Electric power systems Magnetic materials Molybdenum alloys Nanostructured materials Niobium alloys Silicon alloys

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Advances and applications in single-cell and spatial genomics

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Science China Life Sciences 2025年

作者： Jingjing Wang Fang ye Haoxi Chai yujia Jiang Teng Wang Xia Ran Qimin Xia ziye Xu yuting Fu guodong zhang Hanyu Wu guoji guo Hongshan guo yijun Ruan yongcheng Wang Dong Xing Xun Xu zemin zhang Beijing Advanced Innovation Center for Genomics (ICG) Peking University Guangdong Provincial Key Laboratory of Genome Read and Write BGI Research Bone Marrow Transplantation Center of the First Affiliated Hospital & Liangzhu Laboratory Zhejiang University School of Medicine Life Sciences Institute and The Second Affiliated Hospital Zhejiang University BGI Research Biomedical Pioneering Innovation Center (BIOPIC) and School of Life Sciences Peking University Academy for Advanced Interdisciplinary Studies Peking University Institute of Hematology Zhejiang University Department of Laboratory Medicine of The First Affiliated Hospital & Liangzhu Laboratory Zhejiang University School of Medicine Center for Stem Cell and Regenerative Medicine Zhejiang University School of Medicine zhejiang Provincial Key Lab for Tissue Engineering and Regenerative Medicine Dr.Li Dak Sum & Yip Yio Chin Center for Stem Cell and Regenerative Medicine

The applications of single-cell and spatial technologies in recent times have revolutionized the present understanding of cellular states and the cellular heterogeneity inherent in complex biological systems. These advancements offer unprecedented resolution in the examination of the functional genomics of individual cells and their spatial context within tissues. In this review, we have comprehensively discussed the historical development and recent progress in the field of single-cell and spatial genomics. We have reviewed the breakthroughs in single-cell multi-omics technologies, spatial genomics methods, and the computational strategies employed toward the analyses of singlecell atlas data. Furthermore, we have highlighted the advances made in constructing cellular atlases and their clinical applications,particularly in the context of disease. Finally, we have discussed the emerging trends, challenges, and opportunities in this rapidly evolving field.

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