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Misorientation dependent thermal condition-solute field cooperative effect on competitive grain growth in the converging case during directional solidification of a nickel-base superalloy

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Journal of Materials Science & technology 2022年第1期96卷 151-159页

作者： X.B.Meng J.G.li C.N.Jing J.D.liu S.Y.Ma J.J.liang C.W.Zhang M.Wang B.t.tang t.lin J.l.Chen X.l.Zhang q.li School of Mechanical and Automotive Engineering Qilu University of Technology(Shandong Academy of Sciences)Jinan 250353China Institute of Metal Research Chinese Academy of SciencesShenyang110016China School of Materials Science and Engineering Shandong Jianzhu UniversityJinan 250014China AECC Shenyang liming Aero-Engine Co. LTD.Shenyang110043China College of Material Science and Engineering North Minzu UniversityYinchuan 750021China Faculty of electro-mechanical information Weifang University of Science and TechnologyShouguang262700China

Nowadays,thermal condition and solute field are considered as the potential dominant factors controlling competitive grain growth during directional solidification ***,the controlling modes and critical conditions of competitive grain growth have been drastically debated over the past two *** this work,thermal condition and solute field are combined to study the competitive grain growth in the converging case by experimental observation and numerical simulation of bicrystal *** find the competitive grain growth is controlled by the cooperative effect of thermal condition and solute field,and the controlling modes are related to the bicrystal misorientation between favorably and unfavorably oriented *** the unfavorably oriented grain is low misoriented,unfavorably oriented grain dominates grain selection,and the competitive grain growth performs as solute field ***,with the increase of unfavorably oriented grain’s misorientation,the grain selection converts into favorably oriented grain domination,and the competitive grain growth changes to thermal condition *** explain these abnormal transformation phenomena,we propose a misorientation dependent thermal condition-solute field cooperative domination model and identify the critical conditions by a critical misorientation(θ_(cm)).According to dynamic equation of dendrite growth,we calculate the critical misorientationθ;to prove this *** theoretical calculation results agree well with the experimental results.

关键词： Competitive grain growth Cooperative effect thermal condition Solute field Critical misorientation unusual overgrowth Abnormal transformation

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青藏高原及其周边白垩纪综合地层、生物群与古地理演化

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中国科学：地球科学 2024年第4期54卷 1244-1307页

作者：席党鹏李国彪姜仕军饶馨江湉王天洋覃祚焕王亚苏贾建忠 Muhammad KAMRAN 史忠叶吴於洋王盘喜孙立新曾庆高万晓樵中国地质大学(北京)生物地质与环境地质国家重点实验室北京100083 河海大学海洋学院南京213200 中国科学院南京地质古生物研究所古生物学与油气地层应用重点实验室南京210008 中国科学院青藏高原研究所青藏高原地球系统与资源环境重点实验室北京100101 中国海洋石油国际有限公司北京100028 上海科技馆上海200120 西藏自治区地质矿产勘查开发局拉萨850000 中国地质调查局天津地质调查中心天津300170

白垩纪是新特提斯洋演化和青藏高原不同板块汇聚的关键时期,详细的地层框架和古地理格局是开展新特提斯洋演化和青藏高原形成研究的基础.本文对青藏高原及周边白垩纪地层、古生物、古地理和重大地质事件开展了系统分析,以建立综合地层框... 详细信息

白垩纪是新特提斯洋演化和青藏高原不同板块汇聚的关键时期,详细的地层框架和古地理格局是开展新特提斯洋演化和青藏高原形成研究的基础.本文对青藏高原及周边白垩纪地层、古生物、古地理和重大地质事件开展了系统分析,以建立综合地层框架,恢复不同时期的古地理格局,探讨重大地质事件的响应和耦合关系.青藏高原及其周边白垩纪地层以海相为主,发育少量海陆交互相和陆相沉积.印度-雅鲁藏布江缝合带发育以蛇绿岩套和含放射虫硅质岩为主的深海沉积,其南侧的特提斯喜马拉雅、印度河盆地等发育浅海至半深海-深海沉积,北侧的日喀则-拉达克弧前盆地发育浅海-半深海相沉积,拉萨地块、喀喇昆仑-塔里木盆地西部和西缅地块等发育浅海、海陆过渡相和陆相沉积,羌塘盆地等其余地区则以陆相沉积为主.青藏高原及其邻区白垩纪地层分布广泛,类型多样,富含有孔虫、钙质超微、放射虫、菊石、双壳类和孢粉等多门类化石;基于岩石地层、生物地层、同位素年代地层和稳定同位素地层等多重地层划分与对比,建立了不同分区地层的划分与对比关系,提出了新的东特提斯区白垩纪综合地层框架.划分了白垩纪新特提斯洋东段及周边不同地理分区的生物群落,阐明了其时空分布特征,恢复了不同时期的生物古地理面貌.青藏高原及周边白垩纪古地理演化可划分为3个阶段:(1)印度板块与澳大利亚-南极洲大陆逐步裂解、拉萨-羌塘地块早期碰撞阶段(145~125Ma);(2)印度板块向北漂移和拉萨-羌塘地块晚期碰撞阶段(125~100Ma);(3)印度板块快速向北漂移、塔里木-喀喇昆仑海湾形成和冈底斯山早期隆升阶段(100~66Ma).白垩纪中期(100Ma左右),印度-特提斯喜马拉雅生物区系经历了冈瓦纳大陆冷水型向特提斯暖水型的转变,海洋生物的多样性达到全盛;白垩纪末期,海洋生物急剧衰退.伴随着印度板块向北漂移和新特提斯洋的演化,新特提斯洋发生了大火成岩省、大洋缺氧、白垩纪大洋红层,以及生物辐射与灭绝等一系重大地质事件.

关键词：青藏高原特提斯白垩纪地层生物群古地理

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A New Proof for Congruent Number’s Problem via Pythagorician Divisors

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Advances in Pure Mathematics 2024年第4期14卷 283-302页

作者： léopold Dèkpassi Keuméan François Emmanuel tanoé uFR Mathematics and Computer Science F&#233lix Houphou&#235t Boigny University Abidjan Cote d&#8217Ivoire

Considering Pythagorician divisors theory which leads to a new parameterization, for Pythagorician triplets ( a,b,c )∈ ℕ 3∗ , we give a new proof of the well-known problem of these particular squareless numbers n∈ ℕ ∗ , called congruent numbers, characterized by the fact that there exists a right-angled triangle with rational sides: ( A α ) 2 + ( B β ) 2 = ( C γ ) 2 , such that its area Δ= 1 2 A α B β =n;or in an equivalent way, to that of the existence of numbers u 2 , V 2 , W 2 ∈ ℚ 2∗ that are in an arithmetic progression of reason n;Problem equivalent to the existence of: ( a,b,c )∈ ℕ 3∗ prime in pairs, and f∈ ℕ ∗ , such that: ( a−b 2f ) 2 , ( c 2f ) 2 , ( a+b 2f ) 2 are in an arithmetic progression of reason n;And this problem is also equivalent to that of the existence of a non-trivial primitive integer right-angled triangle: a 2 + b 2 = c 2 , such that its area Δ= 1 2 ab=n f 2 , where f∈ ℕ ∗ , and this last equation can be written as follows, when using Pythagorician divisors: (1) Δ= 1 2 ab= 2 S−1 d e ¯ ( d+ 2 S−1 e ¯ )( d+ 2 S e ¯ )=n f 2;Where ( d, e ¯ )∈ ( 2ℕ+1 ) 2 such that gcd( d, e ¯ )=1 and S∈ ℕ ∗ , where 2 S−1 , d, e ¯ , d+ 2 S−1 e ¯ , d+ 2 S e ¯ , are pairwise prime quantities (these parameters are coming from Pythagorician divisors). When n=1 , it is the case of the famous impossible problem of the integer right-angled triangle area to be a square, solved by Fermat at his time, by his famous method of infinite descent. We propose in this article a new direct proof for the numbers n=1 (resp. n=2 ) to be non-congruent numbers, based on an particular induction method of resolution of Equation (1) (note that this method is efficient too for general case of prime numbers n=p≡a ( ( mod8 ) , gcd( a,8 )=1 ). to prove it, we use a classical proof by induction on k , that shows the non-solvability property of any of the following systems ( t=0 , corresponding to case n=1 (resp. t=1 , corresponding to case n=2 )): ( Ξ t,k ){ X 2 + 2 t ( 2 k Y ) 2 = Z 2 X 2 + 2

关键词： Prime Numbers-Diophantine Equations of Degree 2 & 4 Factorization Greater Common Divisor Pythagoras Equation Pythagorician triplets Congruent Numbers Inductive Demonstration Method Infinite Descent BSD Conjecture

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Heavy fermions in high magnetic fields

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Chinese Physics B 2019年第1期28卷 25-38页

作者： M Smidman B Shen C Y Guo l Jiao X lu H q Yuan Center for Correlated Matter and Department of Physics Zhejiang UniversityHangzhou 310058China Collaborative Innovation Center of Advanced Microstructures Nanjing UniversityNanjing 210093China

Heavy fermion materials are prototypical strongly correlated electron systems, where the strong electron–electron interactions lead to a wide range of novel phenomena and emergent phases of matter. Due to the low energy scales, the relative strengths of the Ruderman–Kittel–Kasuya–Yosida(RKKY) and Kondo interactions can often be readily tuned by non-thermal control parameters such as pressure, doping, or applied magnetic fields, which can give rise to quantum criticality and unconventional superconductivity. Here we provide a brief overview of research into heavy fermion materials in high magnetic fields, focussing on three main areas. Firstly we review the use of magnetic fields as a tuning parameter,and in particular the ability to realize different varieties of quantum critical behaviors. We then discuss the properties of heavy fermion superconductors in magnetic fields, where experiments in applied fields can reveal the nature of the order parameter, and induce new novel phenomena. Finally we report recent studies of topological Kondo systems, including topological Kondo insulators and Kondo–Weyl semimetals. Here experiments in magnetic fields can be used to probe the topologically non-trivial Fermi surface, as well as related field-induced phenomena such as the chiral anomaly and topological Hall effect.

关键词： heavy fermions high magnetic fields quantum phase transitions heavy fermion superconductivity topological Kondo systems

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Influence of thermal cycling on the martensitic transformation and shape memory effect of a Fe－16Mn－

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功能材料 1994年第6期 505-510页

作者： q. Gu,J.Van Humbeeck and l. Delaey(Dept. of Metallurgy and Materials Engineering,K.u.leuven,3001 leuven, Belgium)

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关键词： martensitic transformation. thermal cycling transformation heat transformation temperature

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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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INItIAl AtMOSPHERIC CORROSION OF ZINC IN tHE PRESENCE OF NH_4Cl

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Acta Metallurgica Sinica(English letters) 2004年第2期17卷 161-165页

作者： q.qu C.W.Yan l.li l.Zhang G.H.liu C.N.Cao DepartmentofChemistry YunnanUniversityKunming650091China StakeKeylaboratoryforCorrosionandProtection InstituteofMetalResearchTheChineseAcademy laboratoryforConservationandutilizationofBio-Resources YunnanUniversityKunming650091China

Influence of NH_4 Cl on the initial atmospheric corrosion of zinc was investigated viaquartz crystal microbalance (qCM) in laboratory at 80%RH and 25℃. the resultsshow that NH_4 Cl can accelerate the initial corrosion of zinc. Mass gain increase withthe exposure time, but mass gain in the later doesn't change obviously due to theformation of the insoluble simonkolleite on zinc surface in the presence of NH_4 *** transform infrared spectroscopy (FtIR) and X-ray diffraction (XRD) wasused to characterize the corrosion products. Zn_5Cl_2(OH)_8·H_2O,(NH_4)_2ZnCl_4 andZnO are the corrosion products on zinc. Brief discussion on the mechanisms of at-mospheric corrosion of zinc in the presence of NH_4 Cl was introduced.

关键词： atmospheric corrosion zinc NH_4Cl

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Suppressing Effect of Heat treatment on the Portevin–le Chatelier Phenomenon of Mg–4%li–6%Zn–1.2%Y Alloy

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Journal of Materials Science & technology 2016年第12期32卷 1232-1238页

作者： C.q.li D.K.Xu B.J.Wang l.Y.Sheng E.H.Han School of Materials Science and Engineering Northeastern University Shenyang 110819 China Key laboratory of Nuclear Materials and Safety Assessment Institute of Metal Research Chinese Academy of Sciences Shenyang 110016 China Environmental Corrosion Center Institute of Metal Research Chinese Academy of Sciences Shenyang 110016 China Shenzhen Institute Shenzhen Key Lab Human Tissue Regenerate and Repair Peking University Shenzhen 518057 China

Microstructural evolution and Portevin-le Chatelier（PlC） phenomenon of the as-extruded Mg-4%li-6%Zn-1.2%Y alloy before and after heat treatment have been *** has been demonstrated that for the as-extruded and solid solution treated（t4） samples,the PlC phenomenon could be obviously observed on tensile stress-strain ***,the PlC phenomenon in t4 samples was more salient than that in the as-extruded condition,suggesting that the occurrence of PlC phenomenon was closely related to the super-saturation degree of solute atoms in the *** most of solute atoms were consumed for the formation of Mg Zn precipitates（β1′ and a little of β2′） during the subsequent ageing treatment（t6）,the PlC phenomenon of t6 samples was ***,due to the pinning effect of the formed Mg Zn precipitates on mobile dislocations,the tensile strength of t6 samples was relatively higher than those of the other two conditions.

关键词： Mg-li alloy Heat treatment Portevin-le Chatelier (PlC) effect Precipitates

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Bipolar tri-state resistive switching characteristics in ti/CeO_x/Pt memory device

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Chinese Physics B 2014年第12期23卷 333-338页

作者： M.Ismail M.W.Abbas A.M.Rana I.talib E.Ahmed M.Y.Nadeem t.l.tsai u.Chand N.A.Shah M.Hussain A.Aziz M.t.Bhatti Department of Physics Bahauddin Zakariya University Department of Electronics Engineering and Institute of Electronics National Chiao Tung University thin Films technology Research laboratory Department of Physics COMSATS Institute of Information Technology Center for High Energy Physics University of Punjab

Highly repeatable multilevel bipolar resistive switching in ti/Ce Ox/Pt nonvolatile memory device has been demonstrated. X-ray diffraction studies of Ce O2 films reveal the formation of weak polycrystalline structure. the observed good memory performance, including stable cycling endurance and long data retention times（〉10^4s） with an acceptable resistance ratio（～10^2）, enables the device for its applications in future non-volatile resistive random access memories（RRAMs）. Based on the unique distribution characteristics of oxygen vacancies in Ce Ox films, the possible mechanism of multilevel resistive switching in Ce Ox RRAM devices has been discussed. the conduction mechanism in low resistance state is found to be Ohmic due to conductive filamentary paths, while that in the high resistance state was identified as Ohmic for low applied voltages and a space-charge-limited conduction dominated by Schottky emission at high applied voltages.

关键词： multilevel resistive switching Schottky emission cerium oxide oxygen vacancy

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the effects of fabrication atmosphere condition on the microstructural and mechanical properties of laser direct manufactured stainless steel 17-4 PH

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Journal of Materials Science & technology 2019年第7期35卷 1315-1322页

作者： D.Wang C.t.Chi W.q.Wang Y.l.li M.S.Wang X.G.Chen Z.H.Chen X.P.Cheng Y.J.Xie Institute of Applied Physics Jiangxi Academy of SciencesNanchang 330029China Institute of Metal Research Chinese Academy of SciencesShenyang 110016China School of Mechanical and Electrical Engineering Nanchang UniversityNanchang 330029China Jiangxi Reman Additive technology Co. ltd Nanchang 330096China

the effects of atmosphere conditions on microstructural and mechanical properties of stainless steel 17-4PH components fabricated by laser direct manufacturing (lDM) were investigated through mea-surements on phase constitution, porosity, tensile strength, fracture morphology, hardness and evolution of substrate temperature. Results showed that the samples produced in air atmosphere condition pos-sessed higher tensile strength and hardness for both as-deposited and heat-treated states than that in Ar chamber condition, due to dispersion strengthening effect of amorphous oxide particles and nitrogen solution strengthening as a result of higher content of oxygen and nitrogen. the temperature of substrate heat accumulation was higher in Ar chamber condition, leading to dramatically lower porosity and more reverse austenite, which also contributed to the lower strength and hardness.

关键词： Additive manufacturing laser direct manufacturing 17-4 PH stainless steel Fabrication atmosphere Mechanical properties

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